| /* |
| * Copyright (C) 2015 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.internal.widget; |
| |
| import android.annotation.DrawableRes; |
| import android.content.Context; |
| import android.content.res.Resources; |
| import android.content.res.TypedArray; |
| import android.database.DataSetObserver; |
| import android.graphics.Canvas; |
| import android.graphics.Rect; |
| import android.graphics.drawable.Drawable; |
| import android.os.Bundle; |
| import android.os.Parcel; |
| import android.os.Parcelable; |
| import android.util.AttributeSet; |
| import android.util.Log; |
| import android.util.MathUtils; |
| import android.view.FocusFinder; |
| import android.view.Gravity; |
| import android.view.KeyEvent; |
| import android.view.MotionEvent; |
| import android.view.SoundEffectConstants; |
| import android.view.VelocityTracker; |
| import android.view.View; |
| import android.view.ViewConfiguration; |
| import android.view.ViewGroup; |
| import android.view.ViewParent; |
| import android.view.accessibility.AccessibilityEvent; |
| import android.view.accessibility.AccessibilityNodeInfo; |
| import android.view.accessibility.AccessibilityNodeInfo.AccessibilityAction; |
| import android.view.animation.Interpolator; |
| import android.widget.EdgeEffect; |
| import android.widget.Scroller; |
| |
| import com.android.internal.R; |
| |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.Comparator; |
| |
| /** |
| * Layout manager that allows the user to flip left and right |
| * through pages of data. You supply an implementation of a |
| * {@link android.support.v4.view.PagerAdapter} to generate the pages that the view shows. |
| * |
| * <p>Note this class is currently under early design and |
| * development. The API will likely change in later updates of |
| * the compatibility library, requiring changes to the source code |
| * of apps when they are compiled against the newer version.</p> |
| * |
| * <p>ViewPager is most often used in conjunction with {@link android.app.Fragment}, |
| * which is a convenient way to supply and manage the lifecycle of each page. |
| * There are standard adapters implemented for using fragments with the ViewPager, |
| * which cover the most common use cases. These are |
| * {@link android.support.v4.app.FragmentPagerAdapter} and |
| * {@link android.support.v4.app.FragmentStatePagerAdapter}; each of these |
| * classes have simple code showing how to build a full user interface |
| * with them. |
| * |
| * <p>For more information about how to use ViewPager, read <a |
| * href="{@docRoot}training/implementing-navigation/lateral.html">Creating Swipe Views with |
| * Tabs</a>.</p> |
| * |
| * <p>Below is a more complicated example of ViewPager, using it in conjunction |
| * with {@link android.app.ActionBar} tabs. You can find other examples of using |
| * ViewPager in the API 4+ Support Demos and API 13+ Support Demos sample code. |
| * |
| * {@sample development/samples/Support13Demos/src/com/example/android/supportv13/app/ActionBarTabsPager.java |
| * complete} |
| */ |
| public class ViewPager extends ViewGroup { |
| private static final String TAG = "ViewPager"; |
| private static final boolean DEBUG = false; |
| |
| private static final int MAX_SCROLL_X = 2 << 23; |
| private static final boolean USE_CACHE = false; |
| |
| private static final int DEFAULT_OFFSCREEN_PAGES = 1; |
| private static final int MAX_SETTLE_DURATION = 600; // ms |
| private static final int MIN_DISTANCE_FOR_FLING = 25; // dips |
| |
| private static final int DEFAULT_GUTTER_SIZE = 16; // dips |
| |
| private static final int MIN_FLING_VELOCITY = 400; // dips |
| |
| private static final int[] LAYOUT_ATTRS = new int[] { |
| com.android.internal.R.attr.layout_gravity |
| }; |
| |
| /** |
| * Used to track what the expected number of items in the adapter should be. |
| * If the app changes this when we don't expect it, we'll throw a big obnoxious exception. |
| */ |
| private int mExpectedAdapterCount; |
| |
| static class ItemInfo { |
| Object object; |
| boolean scrolling; |
| float widthFactor; |
| |
| /** Logical position of the item within the pager adapter. */ |
| int position; |
| |
| /** Offset between the starting edges of the item and its container. */ |
| float offset; |
| } |
| |
| private static final Comparator<ItemInfo> COMPARATOR = new Comparator<ItemInfo>(){ |
| @Override |
| public int compare(ItemInfo lhs, ItemInfo rhs) { |
| return lhs.position - rhs.position; |
| } |
| }; |
| |
| private static final Interpolator sInterpolator = new Interpolator() { |
| public float getInterpolation(float t) { |
| t -= 1.0f; |
| return t * t * t * t * t + 1.0f; |
| } |
| }; |
| |
| private final ArrayList<ItemInfo> mItems = new ArrayList<ItemInfo>(); |
| private final ItemInfo mTempItem = new ItemInfo(); |
| |
| private final Rect mTempRect = new Rect(); |
| |
| private PagerAdapter mAdapter; |
| private int mCurItem; // Index of currently displayed page. |
| private int mRestoredCurItem = -1; |
| private Parcelable mRestoredAdapterState = null; |
| private ClassLoader mRestoredClassLoader = null; |
| private final Scroller mScroller; |
| private PagerObserver mObserver; |
| |
| private int mPageMargin; |
| private Drawable mMarginDrawable; |
| private int mTopPageBounds; |
| private int mBottomPageBounds; |
| |
| /** |
| * The increment used to move in the "left" direction. Dependent on layout |
| * direction. |
| */ |
| private int mLeftIncr = -1; |
| |
| // Offsets of the first and last items, if known. |
| // Set during population, used to determine if we are at the beginning |
| // or end of the pager data set during touch scrolling. |
| private float mFirstOffset = -Float.MAX_VALUE; |
| private float mLastOffset = Float.MAX_VALUE; |
| |
| private int mChildWidthMeasureSpec; |
| private int mChildHeightMeasureSpec; |
| private boolean mInLayout; |
| |
| private boolean mScrollingCacheEnabled; |
| |
| private boolean mPopulatePending; |
| private int mOffscreenPageLimit = DEFAULT_OFFSCREEN_PAGES; |
| |
| private boolean mIsBeingDragged; |
| private boolean mIsUnableToDrag; |
| private final int mDefaultGutterSize; |
| private int mGutterSize; |
| private final int mTouchSlop; |
| /** |
| * Position of the last motion event. |
| */ |
| private float mLastMotionX; |
| private float mLastMotionY; |
| private float mInitialMotionX; |
| private float mInitialMotionY; |
| /** |
| * ID of the active pointer. This is used to retain consistency during |
| * drags/flings if multiple pointers are used. |
| */ |
| private int mActivePointerId = INVALID_POINTER; |
| /** |
| * Sentinel value for no current active pointer. |
| * Used by {@link #mActivePointerId}. |
| */ |
| private static final int INVALID_POINTER = -1; |
| |
| /** |
| * Determines speed during touch scrolling |
| */ |
| private VelocityTracker mVelocityTracker; |
| private final int mMinimumVelocity; |
| private final int mMaximumVelocity; |
| private final int mFlingDistance; |
| private final int mCloseEnough; |
| |
| // If the pager is at least this close to its final position, complete the scroll |
| // on touch down and let the user interact with the content inside instead of |
| // "catching" the flinging pager. |
| private static final int CLOSE_ENOUGH = 2; // dp |
| |
| private final EdgeEffect mLeftEdge; |
| private final EdgeEffect mRightEdge; |
| |
| private boolean mFirstLayout = true; |
| private boolean mCalledSuper; |
| private int mDecorChildCount; |
| |
| private OnPageChangeListener mOnPageChangeListener; |
| private OnPageChangeListener mInternalPageChangeListener; |
| private OnAdapterChangeListener mAdapterChangeListener; |
| private PageTransformer mPageTransformer; |
| |
| private static final int DRAW_ORDER_DEFAULT = 0; |
| private static final int DRAW_ORDER_FORWARD = 1; |
| private static final int DRAW_ORDER_REVERSE = 2; |
| private int mDrawingOrder; |
| private ArrayList<View> mDrawingOrderedChildren; |
| private static final ViewPositionComparator sPositionComparator = new ViewPositionComparator(); |
| |
| /** |
| * Indicates that the pager is in an idle, settled state. The current page |
| * is fully in view and no animation is in progress. |
| */ |
| public static final int SCROLL_STATE_IDLE = 0; |
| |
| /** |
| * Indicates that the pager is currently being dragged by the user. |
| */ |
| public static final int SCROLL_STATE_DRAGGING = 1; |
| |
| /** |
| * Indicates that the pager is in the process of settling to a final position. |
| */ |
| public static final int SCROLL_STATE_SETTLING = 2; |
| |
| private final Runnable mEndScrollRunnable = new Runnable() { |
| public void run() { |
| setScrollState(SCROLL_STATE_IDLE); |
| populate(); |
| } |
| }; |
| |
| private int mScrollState = SCROLL_STATE_IDLE; |
| |
| /** |
| * Callback interface for responding to changing state of the selected page. |
| */ |
| public interface OnPageChangeListener { |
| |
| /** |
| * This method will be invoked when the current page is scrolled, either as part |
| * of a programmatically initiated smooth scroll or a user initiated touch scroll. |
| * |
| * @param position Position index of the first page currently being displayed. |
| * Page position+1 will be visible if positionOffset is nonzero. |
| * @param positionOffset Value from [0, 1) indicating the offset from the page at position. |
| * @param positionOffsetPixels Value in pixels indicating the offset from position. |
| */ |
| public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels); |
| |
| /** |
| * This method will be invoked when a new page becomes selected. Animation is not |
| * necessarily complete. |
| * |
| * @param position Position index of the new selected page. |
| */ |
| public void onPageSelected(int position); |
| |
| /** |
| * Called when the scroll state changes. Useful for discovering when the user |
| * begins dragging, when the pager is automatically settling to the current page, |
| * or when it is fully stopped/idle. |
| * |
| * @param state The new scroll state. |
| * @see com.android.internal.widget.ViewPager#SCROLL_STATE_IDLE |
| * @see com.android.internal.widget.ViewPager#SCROLL_STATE_DRAGGING |
| * @see com.android.internal.widget.ViewPager#SCROLL_STATE_SETTLING |
| */ |
| public void onPageScrollStateChanged(int state); |
| } |
| |
| /** |
| * Simple implementation of the {@link OnPageChangeListener} interface with stub |
| * implementations of each method. Extend this if you do not intend to override |
| * every method of {@link OnPageChangeListener}. |
| */ |
| public static class SimpleOnPageChangeListener implements OnPageChangeListener { |
| @Override |
| public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { |
| // This space for rent |
| } |
| |
| @Override |
| public void onPageSelected(int position) { |
| // This space for rent |
| } |
| |
| @Override |
| public void onPageScrollStateChanged(int state) { |
| // This space for rent |
| } |
| } |
| |
| /** |
| * A PageTransformer is invoked whenever a visible/attached page is scrolled. |
| * This offers an opportunity for the application to apply a custom transformation |
| * to the page views using animation properties. |
| * |
| * <p>As property animation is only supported as of Android 3.0 and forward, |
| * setting a PageTransformer on a ViewPager on earlier platform versions will |
| * be ignored.</p> |
| */ |
| public interface PageTransformer { |
| /** |
| * Apply a property transformation to the given page. |
| * |
| * @param page Apply the transformation to this page |
| * @param position Position of page relative to the current front-and-center |
| * position of the pager. 0 is front and center. 1 is one full |
| * page position to the right, and -1 is one page position to the left. |
| */ |
| public void transformPage(View page, float position); |
| } |
| |
| /** |
| * Used internally to monitor when adapters are switched. |
| */ |
| interface OnAdapterChangeListener { |
| public void onAdapterChanged(PagerAdapter oldAdapter, PagerAdapter newAdapter); |
| } |
| |
| /** |
| * Used internally to tag special types of child views that should be added as |
| * pager decorations by default. |
| */ |
| interface Decor {} |
| |
| public ViewPager(Context context) { |
| this(context, null); |
| } |
| |
| public ViewPager(Context context, AttributeSet attrs) { |
| this(context, attrs, 0); |
| } |
| |
| public ViewPager(Context context, AttributeSet attrs, int defStyleAttr) { |
| this(context, attrs, defStyleAttr, 0); |
| } |
| |
| public ViewPager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { |
| super(context, attrs, defStyleAttr, defStyleRes); |
| |
| setWillNotDraw(false); |
| setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); |
| setFocusable(true); |
| |
| mScroller = new Scroller(context, sInterpolator); |
| final ViewConfiguration configuration = ViewConfiguration.get(context); |
| final float density = context.getResources().getDisplayMetrics().density; |
| |
| mTouchSlop = configuration.getScaledPagingTouchSlop(); |
| mMinimumVelocity = (int) (MIN_FLING_VELOCITY * density); |
| mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); |
| mLeftEdge = new EdgeEffect(context); |
| mRightEdge = new EdgeEffect(context); |
| |
| mFlingDistance = (int) (MIN_DISTANCE_FOR_FLING * density); |
| mCloseEnough = (int) (CLOSE_ENOUGH * density); |
| mDefaultGutterSize = (int) (DEFAULT_GUTTER_SIZE * density); |
| |
| if (getImportantForAccessibility() == IMPORTANT_FOR_ACCESSIBILITY_AUTO) { |
| setImportantForAccessibility(IMPORTANT_FOR_ACCESSIBILITY_YES); |
| } |
| } |
| |
| @Override |
| protected void onDetachedFromWindow() { |
| removeCallbacks(mEndScrollRunnable); |
| super.onDetachedFromWindow(); |
| } |
| |
| private void setScrollState(int newState) { |
| if (mScrollState == newState) { |
| return; |
| } |
| |
| mScrollState = newState; |
| if (mPageTransformer != null) { |
| // PageTransformers can do complex things that benefit from hardware layers. |
| enableLayers(newState != SCROLL_STATE_IDLE); |
| } |
| if (mOnPageChangeListener != null) { |
| mOnPageChangeListener.onPageScrollStateChanged(newState); |
| } |
| } |
| |
| /** |
| * Set a PagerAdapter that will supply views for this pager as needed. |
| * |
| * @param adapter Adapter to use |
| */ |
| public void setAdapter(PagerAdapter adapter) { |
| if (mAdapter != null) { |
| mAdapter.unregisterDataSetObserver(mObserver); |
| mAdapter.startUpdate(this); |
| for (int i = 0; i < mItems.size(); i++) { |
| final ItemInfo ii = mItems.get(i); |
| mAdapter.destroyItem(this, ii.position, ii.object); |
| } |
| mAdapter.finishUpdate(this); |
| mItems.clear(); |
| removeNonDecorViews(); |
| mCurItem = 0; |
| scrollTo(0, 0); |
| } |
| |
| final PagerAdapter oldAdapter = mAdapter; |
| mAdapter = adapter; |
| mExpectedAdapterCount = 0; |
| |
| if (mAdapter != null) { |
| if (mObserver == null) { |
| mObserver = new PagerObserver(); |
| } |
| mAdapter.registerDataSetObserver(mObserver); |
| mPopulatePending = false; |
| final boolean wasFirstLayout = mFirstLayout; |
| mFirstLayout = true; |
| mExpectedAdapterCount = mAdapter.getCount(); |
| if (mRestoredCurItem >= 0) { |
| mAdapter.restoreState(mRestoredAdapterState, mRestoredClassLoader); |
| setCurrentItemInternal(mRestoredCurItem, false, true); |
| mRestoredCurItem = -1; |
| mRestoredAdapterState = null; |
| mRestoredClassLoader = null; |
| } else if (!wasFirstLayout) { |
| populate(); |
| } else { |
| requestLayout(); |
| } |
| } |
| |
| if (mAdapterChangeListener != null && oldAdapter != adapter) { |
| mAdapterChangeListener.onAdapterChanged(oldAdapter, adapter); |
| } |
| } |
| |
| private void removeNonDecorViews() { |
| for (int i = 0; i < getChildCount(); i++) { |
| final View child = getChildAt(i); |
| final LayoutParams lp = (LayoutParams) child.getLayoutParams(); |
| if (!lp.isDecor) { |
| removeViewAt(i); |
| i--; |
| } |
| } |
| } |
| |
| /** |
| * Retrieve the current adapter supplying pages. |
| * |
| * @return The currently registered PagerAdapter |
| */ |
| public PagerAdapter getAdapter() { |
| return mAdapter; |
| } |
| |
| void setOnAdapterChangeListener(OnAdapterChangeListener listener) { |
| mAdapterChangeListener = listener; |
| } |
| |
| private int getPaddedWidth() { |
| return getMeasuredWidth() - getPaddingLeft() - getPaddingRight(); |
| } |
| |
| /** |
| * Set the currently selected page. If the ViewPager has already been through its first |
| * layout with its current adapter there will be a smooth animated transition between |
| * the current item and the specified item. |
| * |
| * @param item Item index to select |
| */ |
| public void setCurrentItem(int item) { |
| mPopulatePending = false; |
| setCurrentItemInternal(item, !mFirstLayout, false); |
| } |
| |
| /** |
| * Set the currently selected page. |
| * |
| * @param item Item index to select |
| * @param smoothScroll True to smoothly scroll to the new item, false to transition immediately |
| */ |
| public void setCurrentItem(int item, boolean smoothScroll) { |
| mPopulatePending = false; |
| setCurrentItemInternal(item, smoothScroll, false); |
| } |
| |
| public int getCurrentItem() { |
| return mCurItem; |
| } |
| |
| boolean setCurrentItemInternal(int item, boolean smoothScroll, boolean always) { |
| return setCurrentItemInternal(item, smoothScroll, always, 0); |
| } |
| |
| boolean setCurrentItemInternal(int item, boolean smoothScroll, boolean always, int velocity) { |
| if (mAdapter == null || mAdapter.getCount() <= 0) { |
| setScrollingCacheEnabled(false); |
| return false; |
| } |
| |
| item = MathUtils.constrain(item, 0, mAdapter.getCount() - 1); |
| if (!always && mCurItem == item && mItems.size() != 0) { |
| setScrollingCacheEnabled(false); |
| return false; |
| } |
| |
| final int pageLimit = mOffscreenPageLimit; |
| if (item > (mCurItem + pageLimit) || item < (mCurItem - pageLimit)) { |
| // We are doing a jump by more than one page. To avoid |
| // glitches, we want to keep all current pages in the view |
| // until the scroll ends. |
| for (int i = 0; i < mItems.size(); i++) { |
| mItems.get(i).scrolling = true; |
| } |
| } |
| |
| final boolean dispatchSelected = mCurItem != item; |
| if (mFirstLayout) { |
| // We don't have any idea how big we are yet and shouldn't have any pages either. |
| // Just set things up and let the pending layout handle things. |
| mCurItem = item; |
| if (dispatchSelected && mOnPageChangeListener != null) { |
| mOnPageChangeListener.onPageSelected(item); |
| } |
| if (dispatchSelected && mInternalPageChangeListener != null) { |
| mInternalPageChangeListener.onPageSelected(item); |
| } |
| requestLayout(); |
| } else { |
| populate(item); |
| scrollToItem(item, smoothScroll, velocity, dispatchSelected); |
| } |
| |
| return true; |
| } |
| |
| private void scrollToItem(int position, boolean smoothScroll, int velocity, |
| boolean dispatchSelected) { |
| final int destX = getLeftEdgeForItem(position); |
| |
| if (smoothScroll) { |
| smoothScrollTo(destX, 0, velocity); |
| |
| if (dispatchSelected && mOnPageChangeListener != null) { |
| mOnPageChangeListener.onPageSelected(position); |
| } |
| if (dispatchSelected && mInternalPageChangeListener != null) { |
| mInternalPageChangeListener.onPageSelected(position); |
| } |
| } else { |
| if (dispatchSelected && mOnPageChangeListener != null) { |
| mOnPageChangeListener.onPageSelected(position); |
| } |
| if (dispatchSelected && mInternalPageChangeListener != null) { |
| mInternalPageChangeListener.onPageSelected(position); |
| } |
| |
| completeScroll(false); |
| scrollTo(destX, 0); |
| pageScrolled(destX); |
| } |
| } |
| |
| private int getLeftEdgeForItem(int position) { |
| final ItemInfo info = infoForPosition(position); |
| if (info == null) { |
| return 0; |
| } |
| |
| final int width = getPaddedWidth(); |
| final int scaledOffset = (int) (width * MathUtils.constrain( |
| info.offset, mFirstOffset, mLastOffset)); |
| |
| if (isLayoutRtl()) { |
| final int itemWidth = (int) (width * info.widthFactor + 0.5f); |
| return MAX_SCROLL_X - itemWidth - scaledOffset; |
| } else { |
| return scaledOffset; |
| } |
| } |
| |
| /** |
| * Set a listener that will be invoked whenever the page changes or is incrementally |
| * scrolled. See {@link OnPageChangeListener}. |
| * |
| * @param listener Listener to set |
| */ |
| public void setOnPageChangeListener(OnPageChangeListener listener) { |
| mOnPageChangeListener = listener; |
| } |
| |
| /** |
| * Set a {@link PageTransformer} that will be called for each attached page whenever |
| * the scroll position is changed. This allows the application to apply custom property |
| * transformations to each page, overriding the default sliding look and feel. |
| * |
| * <p><em>Note:</em> Prior to Android 3.0 the property animation APIs did not exist. |
| * As a result, setting a PageTransformer prior to Android 3.0 (API 11) will have no effect.</p> |
| * |
| * @param reverseDrawingOrder true if the supplied PageTransformer requires page views |
| * to be drawn from last to first instead of first to last. |
| * @param transformer PageTransformer that will modify each page's animation properties |
| */ |
| public void setPageTransformer(boolean reverseDrawingOrder, PageTransformer transformer) { |
| final boolean hasTransformer = transformer != null; |
| final boolean needsPopulate = hasTransformer != (mPageTransformer != null); |
| mPageTransformer = transformer; |
| setChildrenDrawingOrderEnabled(hasTransformer); |
| if (hasTransformer) { |
| mDrawingOrder = reverseDrawingOrder ? DRAW_ORDER_REVERSE : DRAW_ORDER_FORWARD; |
| } else { |
| mDrawingOrder = DRAW_ORDER_DEFAULT; |
| } |
| if (needsPopulate) populate(); |
| } |
| |
| @Override |
| protected int getChildDrawingOrder(int childCount, int i) { |
| final int index = mDrawingOrder == DRAW_ORDER_REVERSE ? childCount - 1 - i : i; |
| final int result = ((LayoutParams) mDrawingOrderedChildren.get(index).getLayoutParams()).childIndex; |
| return result; |
| } |
| |
| /** |
| * Set a separate OnPageChangeListener for internal use by the support library. |
| * |
| * @param listener Listener to set |
| * @return The old listener that was set, if any. |
| */ |
| OnPageChangeListener setInternalPageChangeListener(OnPageChangeListener listener) { |
| OnPageChangeListener oldListener = mInternalPageChangeListener; |
| mInternalPageChangeListener = listener; |
| return oldListener; |
| } |
| |
| /** |
| * Returns the number of pages that will be retained to either side of the |
| * current page in the view hierarchy in an idle state. Defaults to 1. |
| * |
| * @return How many pages will be kept offscreen on either side |
| * @see #setOffscreenPageLimit(int) |
| */ |
| public int getOffscreenPageLimit() { |
| return mOffscreenPageLimit; |
| } |
| |
| /** |
| * Set the number of pages that should be retained to either side of the |
| * current page in the view hierarchy in an idle state. Pages beyond this |
| * limit will be recreated from the adapter when needed. |
| * |
| * <p>This is offered as an optimization. If you know in advance the number |
| * of pages you will need to support or have lazy-loading mechanisms in place |
| * on your pages, tweaking this setting can have benefits in perceived smoothness |
| * of paging animations and interaction. If you have a small number of pages (3-4) |
| * that you can keep active all at once, less time will be spent in layout for |
| * newly created view subtrees as the user pages back and forth.</p> |
| * |
| * <p>You should keep this limit low, especially if your pages have complex layouts. |
| * This setting defaults to 1.</p> |
| * |
| * @param limit How many pages will be kept offscreen in an idle state. |
| */ |
| public void setOffscreenPageLimit(int limit) { |
| if (limit < DEFAULT_OFFSCREEN_PAGES) { |
| Log.w(TAG, "Requested offscreen page limit " + limit + " too small; defaulting to " + |
| DEFAULT_OFFSCREEN_PAGES); |
| limit = DEFAULT_OFFSCREEN_PAGES; |
| } |
| if (limit != mOffscreenPageLimit) { |
| mOffscreenPageLimit = limit; |
| populate(); |
| } |
| } |
| |
| /** |
| * Set the margin between pages. |
| * |
| * @param marginPixels Distance between adjacent pages in pixels |
| * @see #getPageMargin() |
| * @see #setPageMarginDrawable(android.graphics.drawable.Drawable) |
| * @see #setPageMarginDrawable(int) |
| */ |
| public void setPageMargin(int marginPixels) { |
| final int oldMargin = mPageMargin; |
| mPageMargin = marginPixels; |
| |
| final int width = getWidth(); |
| recomputeScrollPosition(width, width, marginPixels, oldMargin); |
| |
| requestLayout(); |
| } |
| |
| /** |
| * Return the margin between pages. |
| * |
| * @return The size of the margin in pixels |
| */ |
| public int getPageMargin() { |
| return mPageMargin; |
| } |
| |
| /** |
| * Set a drawable that will be used to fill the margin between pages. |
| * |
| * @param d Drawable to display between pages |
| */ |
| public void setPageMarginDrawable(Drawable d) { |
| mMarginDrawable = d; |
| if (d != null) refreshDrawableState(); |
| setWillNotDraw(d == null); |
| invalidate(); |
| } |
| |
| /** |
| * Set a drawable that will be used to fill the margin between pages. |
| * |
| * @param resId Resource ID of a drawable to display between pages |
| */ |
| public void setPageMarginDrawable(@DrawableRes int resId) { |
| setPageMarginDrawable(getContext().getDrawable(resId)); |
| } |
| |
| @Override |
| protected boolean verifyDrawable(Drawable who) { |
| return super.verifyDrawable(who) || who == mMarginDrawable; |
| } |
| |
| @Override |
| protected void drawableStateChanged() { |
| super.drawableStateChanged(); |
| final Drawable marginDrawable = mMarginDrawable; |
| if (marginDrawable != null && marginDrawable.isStateful() |
| && marginDrawable.setState(getDrawableState())) { |
| invalidateDrawable(marginDrawable); |
| } |
| } |
| |
| // We want the duration of the page snap animation to be influenced by the distance that |
| // the screen has to travel, however, we don't want this duration to be effected in a |
| // purely linear fashion. Instead, we use this method to moderate the effect that the distance |
| // of travel has on the overall snap duration. |
| float distanceInfluenceForSnapDuration(float f) { |
| f -= 0.5f; // center the values about 0. |
| f *= 0.3f * Math.PI / 2.0f; |
| return (float) Math.sin(f); |
| } |
| |
| /** |
| * Like {@link android.view.View#scrollBy}, but scroll smoothly instead of immediately. |
| * |
| * @param x the number of pixels to scroll by on the X axis |
| * @param y the number of pixels to scroll by on the Y axis |
| */ |
| void smoothScrollTo(int x, int y) { |
| smoothScrollTo(x, y, 0); |
| } |
| |
| /** |
| * Like {@link android.view.View#scrollBy}, but scroll smoothly instead of immediately. |
| * |
| * @param x the number of pixels to scroll by on the X axis |
| * @param y the number of pixels to scroll by on the Y axis |
| * @param velocity the velocity associated with a fling, if applicable. (0 otherwise) |
| */ |
| void smoothScrollTo(int x, int y, int velocity) { |
| if (getChildCount() == 0) { |
| // Nothing to do. |
| setScrollingCacheEnabled(false); |
| return; |
| } |
| int sx = getScrollX(); |
| int sy = getScrollY(); |
| int dx = x - sx; |
| int dy = y - sy; |
| if (dx == 0 && dy == 0) { |
| completeScroll(false); |
| populate(); |
| setScrollState(SCROLL_STATE_IDLE); |
| return; |
| } |
| |
| setScrollingCacheEnabled(true); |
| setScrollState(SCROLL_STATE_SETTLING); |
| |
| final int width = getPaddedWidth(); |
| final int halfWidth = width / 2; |
| final float distanceRatio = Math.min(1f, 1.0f * Math.abs(dx) / width); |
| final float distance = halfWidth + halfWidth * |
| distanceInfluenceForSnapDuration(distanceRatio); |
| |
| int duration = 0; |
| velocity = Math.abs(velocity); |
| if (velocity > 0) { |
| duration = 4 * Math.round(1000 * Math.abs(distance / velocity)); |
| } else { |
| final float pageWidth = width * mAdapter.getPageWidth(mCurItem); |
| final float pageDelta = (float) Math.abs(dx) / (pageWidth + mPageMargin); |
| duration = (int) ((pageDelta + 1) * 100); |
| } |
| duration = Math.min(duration, MAX_SETTLE_DURATION); |
| |
| mScroller.startScroll(sx, sy, dx, dy, duration); |
| postInvalidateOnAnimation(); |
| } |
| |
| ItemInfo addNewItem(int position, int index) { |
| ItemInfo ii = new ItemInfo(); |
| ii.position = position; |
| ii.object = mAdapter.instantiateItem(this, position); |
| ii.widthFactor = mAdapter.getPageWidth(position); |
| if (index < 0 || index >= mItems.size()) { |
| mItems.add(ii); |
| } else { |
| mItems.add(index, ii); |
| } |
| return ii; |
| } |
| |
| void dataSetChanged() { |
| // This method only gets called if our observer is attached, so mAdapter is non-null. |
| |
| final int adapterCount = mAdapter.getCount(); |
| mExpectedAdapterCount = adapterCount; |
| boolean needPopulate = mItems.size() < mOffscreenPageLimit * 2 + 1 && |
| mItems.size() < adapterCount; |
| int newCurrItem = mCurItem; |
| |
| boolean isUpdating = false; |
| for (int i = 0; i < mItems.size(); i++) { |
| final ItemInfo ii = mItems.get(i); |
| final int newPos = mAdapter.getItemPosition(ii.object); |
| |
| if (newPos == PagerAdapter.POSITION_UNCHANGED) { |
| continue; |
| } |
| |
| if (newPos == PagerAdapter.POSITION_NONE) { |
| mItems.remove(i); |
| i--; |
| |
| if (!isUpdating) { |
| mAdapter.startUpdate(this); |
| isUpdating = true; |
| } |
| |
| mAdapter.destroyItem(this, ii.position, ii.object); |
| needPopulate = true; |
| |
| if (mCurItem == ii.position) { |
| // Keep the current item in the valid range |
| newCurrItem = Math.max(0, Math.min(mCurItem, adapterCount - 1)); |
| needPopulate = true; |
| } |
| continue; |
| } |
| |
| if (ii.position != newPos) { |
| if (ii.position == mCurItem) { |
| // Our current item changed position. Follow it. |
| newCurrItem = newPos; |
| } |
| |
| ii.position = newPos; |
| needPopulate = true; |
| } |
| } |
| |
| if (isUpdating) { |
| mAdapter.finishUpdate(this); |
| } |
| |
| Collections.sort(mItems, COMPARATOR); |
| |
| if (needPopulate) { |
| // Reset our known page widths; populate will recompute them. |
| final int childCount = getChildCount(); |
| for (int i = 0; i < childCount; i++) { |
| final View child = getChildAt(i); |
| final LayoutParams lp = (LayoutParams) child.getLayoutParams(); |
| if (!lp.isDecor) { |
| lp.widthFactor = 0.f; |
| } |
| } |
| |
| setCurrentItemInternal(newCurrItem, false, true); |
| requestLayout(); |
| } |
| } |
| |
| public void populate() { |
| populate(mCurItem); |
| } |
| |
| void populate(int newCurrentItem) { |
| ItemInfo oldCurInfo = null; |
| int focusDirection = View.FOCUS_FORWARD; |
| if (mCurItem != newCurrentItem) { |
| focusDirection = mCurItem < newCurrentItem ? View.FOCUS_RIGHT : View.FOCUS_LEFT; |
| oldCurInfo = infoForPosition(mCurItem); |
| mCurItem = newCurrentItem; |
| } |
| |
| if (mAdapter == null) { |
| sortChildDrawingOrder(); |
| return; |
| } |
| |
| // Bail now if we are waiting to populate. This is to hold off |
| // on creating views from the time the user releases their finger to |
| // fling to a new position until we have finished the scroll to |
| // that position, avoiding glitches from happening at that point. |
| if (mPopulatePending) { |
| if (DEBUG) Log.i(TAG, "populate is pending, skipping for now..."); |
| sortChildDrawingOrder(); |
| return; |
| } |
| |
| // Also, don't populate until we are attached to a window. This is to |
| // avoid trying to populate before we have restored our view hierarchy |
| // state and conflicting with what is restored. |
| if (getWindowToken() == null) { |
| return; |
| } |
| |
| mAdapter.startUpdate(this); |
| |
| final int pageLimit = mOffscreenPageLimit; |
| final int startPos = Math.max(0, mCurItem - pageLimit); |
| final int N = mAdapter.getCount(); |
| final int endPos = Math.min(N-1, mCurItem + pageLimit); |
| |
| if (N != mExpectedAdapterCount) { |
| String resName; |
| try { |
| resName = getResources().getResourceName(getId()); |
| } catch (Resources.NotFoundException e) { |
| resName = Integer.toHexString(getId()); |
| } |
| throw new IllegalStateException("The application's PagerAdapter changed the adapter's" + |
| " contents without calling PagerAdapter#notifyDataSetChanged!" + |
| " Expected adapter item count: " + mExpectedAdapterCount + ", found: " + N + |
| " Pager id: " + resName + |
| " Pager class: " + getClass() + |
| " Problematic adapter: " + mAdapter.getClass()); |
| } |
| |
| // Locate the currently focused item or add it if needed. |
| int curIndex = -1; |
| ItemInfo curItem = null; |
| for (curIndex = 0; curIndex < mItems.size(); curIndex++) { |
| final ItemInfo ii = mItems.get(curIndex); |
| if (ii.position >= mCurItem) { |
| if (ii.position == mCurItem) curItem = ii; |
| break; |
| } |
| } |
| |
| if (curItem == null && N > 0) { |
| curItem = addNewItem(mCurItem, curIndex); |
| } |
| |
| // Fill 3x the available width or up to the number of offscreen |
| // pages requested to either side, whichever is larger. |
| // If we have no current item we have no work to do. |
| if (curItem != null) { |
| float extraWidthLeft = 0.f; |
| int itemIndex = curIndex - 1; |
| ItemInfo ii = itemIndex >= 0 ? mItems.get(itemIndex) : null; |
| final int clientWidth = getPaddedWidth(); |
| final float leftWidthNeeded = clientWidth <= 0 ? 0 : |
| 2.f - curItem.widthFactor + (float) getPaddingLeft() / (float) clientWidth; |
| for (int pos = mCurItem - 1; pos >= 0; pos--) { |
| if (extraWidthLeft >= leftWidthNeeded && pos < startPos) { |
| if (ii == null) { |
| break; |
| } |
| if (pos == ii.position && !ii.scrolling) { |
| mItems.remove(itemIndex); |
| mAdapter.destroyItem(this, pos, ii.object); |
| if (DEBUG) { |
| Log.i(TAG, "populate() - destroyItem() with pos: " + pos + |
| " view: " + ii.object); |
| } |
| itemIndex--; |
| curIndex--; |
| ii = itemIndex >= 0 ? mItems.get(itemIndex) : null; |
| } |
| } else if (ii != null && pos == ii.position) { |
| extraWidthLeft += ii.widthFactor; |
| itemIndex--; |
| ii = itemIndex >= 0 ? mItems.get(itemIndex) : null; |
| } else { |
| ii = addNewItem(pos, itemIndex + 1); |
| extraWidthLeft += ii.widthFactor; |
| curIndex++; |
| ii = itemIndex >= 0 ? mItems.get(itemIndex) : null; |
| } |
| } |
| |
| float extraWidthRight = curItem.widthFactor; |
| itemIndex = curIndex + 1; |
| if (extraWidthRight < 2.f) { |
| ii = itemIndex < mItems.size() ? mItems.get(itemIndex) : null; |
| final float rightWidthNeeded = clientWidth <= 0 ? 0 : |
| (float) getPaddingRight() / (float) clientWidth + 2.f; |
| for (int pos = mCurItem + 1; pos < N; pos++) { |
| if (extraWidthRight >= rightWidthNeeded && pos > endPos) { |
| if (ii == null) { |
| break; |
| } |
| if (pos == ii.position && !ii.scrolling) { |
| mItems.remove(itemIndex); |
| mAdapter.destroyItem(this, pos, ii.object); |
| if (DEBUG) { |
| Log.i(TAG, "populate() - destroyItem() with pos: " + pos + |
| " view: " + ii.object); |
| } |
| ii = itemIndex < mItems.size() ? mItems.get(itemIndex) : null; |
| } |
| } else if (ii != null && pos == ii.position) { |
| extraWidthRight += ii.widthFactor; |
| itemIndex++; |
| ii = itemIndex < mItems.size() ? mItems.get(itemIndex) : null; |
| } else { |
| ii = addNewItem(pos, itemIndex); |
| itemIndex++; |
| extraWidthRight += ii.widthFactor; |
| ii = itemIndex < mItems.size() ? mItems.get(itemIndex) : null; |
| } |
| } |
| } |
| |
| calculatePageOffsets(curItem, curIndex, oldCurInfo); |
| } |
| |
| if (DEBUG) { |
| Log.i(TAG, "Current page list:"); |
| for (int i=0; i<mItems.size(); i++) { |
| Log.i(TAG, "#" + i + ": page " + mItems.get(i).position); |
| } |
| } |
| |
| mAdapter.setPrimaryItem(this, mCurItem, curItem != null ? curItem.object : null); |
| |
| mAdapter.finishUpdate(this); |
| |
| // Check width measurement of current pages and drawing sort order. |
| // Update LayoutParams as needed. |
| final int childCount = getChildCount(); |
| for (int i = 0; i < childCount; i++) { |
| final View child = getChildAt(i); |
| final LayoutParams lp = (LayoutParams) child.getLayoutParams(); |
| lp.childIndex = i; |
| if (!lp.isDecor && lp.widthFactor == 0.f) { |
| // 0 means requery the adapter for this, it doesn't have a valid width. |
| final ItemInfo ii = infoForChild(child); |
| if (ii != null) { |
| lp.widthFactor = ii.widthFactor; |
| lp.position = ii.position; |
| } |
| } |
| } |
| sortChildDrawingOrder(); |
| |
| if (hasFocus()) { |
| View currentFocused = findFocus(); |
| ItemInfo ii = currentFocused != null ? infoForAnyChild(currentFocused) : null; |
| if (ii == null || ii.position != mCurItem) { |
| for (int i=0; i<getChildCount(); i++) { |
| View child = getChildAt(i); |
| ii = infoForChild(child); |
| if (ii != null && ii.position == mCurItem) { |
| final Rect focusRect; |
| if (currentFocused == null) { |
| focusRect = null; |
| } else { |
| focusRect = mTempRect; |
| currentFocused.getFocusedRect(mTempRect); |
| offsetDescendantRectToMyCoords(currentFocused, mTempRect); |
| offsetRectIntoDescendantCoords(child, mTempRect); |
| } |
| if (child.requestFocus(focusDirection, focusRect)) { |
| break; |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| private void sortChildDrawingOrder() { |
| if (mDrawingOrder != DRAW_ORDER_DEFAULT) { |
| if (mDrawingOrderedChildren == null) { |
| mDrawingOrderedChildren = new ArrayList<View>(); |
| } else { |
| mDrawingOrderedChildren.clear(); |
| } |
| final int childCount = getChildCount(); |
| for (int i = 0; i < childCount; i++) { |
| final View child = getChildAt(i); |
| mDrawingOrderedChildren.add(child); |
| } |
| Collections.sort(mDrawingOrderedChildren, sPositionComparator); |
| } |
| } |
| |
| private void calculatePageOffsets(ItemInfo curItem, int curIndex, ItemInfo oldCurInfo) { |
| final int N = mAdapter.getCount(); |
| final int width = getPaddedWidth(); |
| final float marginOffset = width > 0 ? (float) mPageMargin / width : 0; |
| |
| // Fix up offsets for later layout. |
| if (oldCurInfo != null) { |
| final int oldCurPosition = oldCurInfo.position; |
| |
| // Base offsets off of oldCurInfo. |
| if (oldCurPosition < curItem.position) { |
| int itemIndex = 0; |
| float offset = oldCurInfo.offset + oldCurInfo.widthFactor + marginOffset; |
| for (int pos = oldCurPosition + 1; pos <= curItem.position && itemIndex < mItems.size(); pos++) { |
| ItemInfo ii = mItems.get(itemIndex); |
| while (pos > ii.position && itemIndex < mItems.size() - 1) { |
| itemIndex++; |
| ii = mItems.get(itemIndex); |
| } |
| |
| while (pos < ii.position) { |
| // We don't have an item populated for this, |
| // ask the adapter for an offset. |
| offset += mAdapter.getPageWidth(pos) + marginOffset; |
| pos++; |
| } |
| |
| ii.offset = offset; |
| offset += ii.widthFactor + marginOffset; |
| } |
| } else if (oldCurPosition > curItem.position) { |
| int itemIndex = mItems.size() - 1; |
| float offset = oldCurInfo.offset; |
| for (int pos = oldCurPosition - 1; pos >= curItem.position && itemIndex >= 0; pos--) { |
| ItemInfo ii = mItems.get(itemIndex); |
| while (pos < ii.position && itemIndex > 0) { |
| itemIndex--; |
| ii = mItems.get(itemIndex); |
| } |
| |
| while (pos > ii.position) { |
| // We don't have an item populated for this, |
| // ask the adapter for an offset. |
| offset -= mAdapter.getPageWidth(pos) + marginOffset; |
| pos--; |
| } |
| |
| offset -= ii.widthFactor + marginOffset; |
| ii.offset = offset; |
| } |
| } |
| } |
| |
| // Base all offsets off of curItem. |
| final int itemCount = mItems.size(); |
| float offset = curItem.offset; |
| int pos = curItem.position - 1; |
| mFirstOffset = curItem.position == 0 ? curItem.offset : -Float.MAX_VALUE; |
| mLastOffset = curItem.position == N - 1 ? |
| curItem.offset + curItem.widthFactor - 1 : Float.MAX_VALUE; |
| |
| // Previous pages |
| for (int i = curIndex - 1; i >= 0; i--, pos--) { |
| final ItemInfo ii = mItems.get(i); |
| while (pos > ii.position) { |
| offset -= mAdapter.getPageWidth(pos--) + marginOffset; |
| } |
| offset -= ii.widthFactor + marginOffset; |
| ii.offset = offset; |
| if (ii.position == 0) mFirstOffset = offset; |
| } |
| |
| offset = curItem.offset + curItem.widthFactor + marginOffset; |
| pos = curItem.position + 1; |
| |
| // Next pages |
| for (int i = curIndex + 1; i < itemCount; i++, pos++) { |
| final ItemInfo ii = mItems.get(i); |
| while (pos < ii.position) { |
| offset += mAdapter.getPageWidth(pos++) + marginOffset; |
| } |
| if (ii.position == N - 1) { |
| mLastOffset = offset + ii.widthFactor - 1; |
| } |
| ii.offset = offset; |
| offset += ii.widthFactor + marginOffset; |
| } |
| } |
| |
| /** |
| * This is the persistent state that is saved by ViewPager. Only needed |
| * if you are creating a sublass of ViewPager that must save its own |
| * state, in which case it should implement a subclass of this which |
| * contains that state. |
| */ |
| public static class SavedState extends BaseSavedState { |
| int position; |
| Parcelable adapterState; |
| ClassLoader loader; |
| |
| public SavedState(Parcel source) { |
| super(source); |
| } |
| |
| public SavedState(Parcelable superState) { |
| super(superState); |
| } |
| |
| @Override |
| public void writeToParcel(Parcel out, int flags) { |
| super.writeToParcel(out, flags); |
| out.writeInt(position); |
| out.writeParcelable(adapterState, flags); |
| } |
| |
| @Override |
| public String toString() { |
| return "FragmentPager.SavedState{" |
| + Integer.toHexString(System.identityHashCode(this)) |
| + " position=" + position + "}"; |
| } |
| |
| public static final Creator<SavedState> CREATOR = new Creator<SavedState>() { |
| @Override |
| public SavedState createFromParcel(Parcel in) { |
| return new SavedState(in); |
| } |
| @Override |
| public SavedState[] newArray(int size) { |
| return new SavedState[size]; |
| } |
| }; |
| |
| SavedState(Parcel in, ClassLoader loader) { |
| super(in); |
| if (loader == null) { |
| loader = getClass().getClassLoader(); |
| } |
| position = in.readInt(); |
| adapterState = in.readParcelable(loader); |
| this.loader = loader; |
| } |
| } |
| |
| @Override |
| public Parcelable onSaveInstanceState() { |
| Parcelable superState = super.onSaveInstanceState(); |
| SavedState ss = new SavedState(superState); |
| ss.position = mCurItem; |
| if (mAdapter != null) { |
| ss.adapterState = mAdapter.saveState(); |
| } |
| return ss; |
| } |
| |
| @Override |
| public void onRestoreInstanceState(Parcelable state) { |
| if (!(state instanceof SavedState)) { |
| super.onRestoreInstanceState(state); |
| return; |
| } |
| |
| SavedState ss = (SavedState)state; |
| super.onRestoreInstanceState(ss.getSuperState()); |
| |
| if (mAdapter != null) { |
| mAdapter.restoreState(ss.adapterState, ss.loader); |
| setCurrentItemInternal(ss.position, false, true); |
| } else { |
| mRestoredCurItem = ss.position; |
| mRestoredAdapterState = ss.adapterState; |
| mRestoredClassLoader = ss.loader; |
| } |
| } |
| |
| @Override |
| public void addView(View child, int index, ViewGroup.LayoutParams params) { |
| if (!checkLayoutParams(params)) { |
| params = generateLayoutParams(params); |
| } |
| final LayoutParams lp = (LayoutParams) params; |
| lp.isDecor |= child instanceof Decor; |
| if (mInLayout) { |
| if (lp != null && lp.isDecor) { |
| throw new IllegalStateException("Cannot add pager decor view during layout"); |
| } |
| lp.needsMeasure = true; |
| addViewInLayout(child, index, params); |
| } else { |
| super.addView(child, index, params); |
| } |
| |
| if (USE_CACHE) { |
| if (child.getVisibility() != GONE) { |
| child.setDrawingCacheEnabled(mScrollingCacheEnabled); |
| } else { |
| child.setDrawingCacheEnabled(false); |
| } |
| } |
| } |
| |
| public Object getCurrent() { |
| final ItemInfo itemInfo = infoForPosition(getCurrentItem()); |
| return itemInfo == null ? null : itemInfo.object; |
| } |
| |
| @Override |
| public void removeView(View view) { |
| if (mInLayout) { |
| removeViewInLayout(view); |
| } else { |
| super.removeView(view); |
| } |
| } |
| |
| ItemInfo infoForChild(View child) { |
| for (int i=0; i<mItems.size(); i++) { |
| ItemInfo ii = mItems.get(i); |
| if (mAdapter.isViewFromObject(child, ii.object)) { |
| return ii; |
| } |
| } |
| return null; |
| } |
| |
| ItemInfo infoForAnyChild(View child) { |
| ViewParent parent; |
| while ((parent=child.getParent()) != this) { |
| if (parent == null || !(parent instanceof View)) { |
| return null; |
| } |
| child = (View)parent; |
| } |
| return infoForChild(child); |
| } |
| |
| ItemInfo infoForPosition(int position) { |
| for (int i = 0; i < mItems.size(); i++) { |
| ItemInfo ii = mItems.get(i); |
| if (ii.position == position) { |
| return ii; |
| } |
| } |
| return null; |
| } |
| |
| @Override |
| protected void onAttachedToWindow() { |
| super.onAttachedToWindow(); |
| mFirstLayout = true; |
| } |
| |
| @Override |
| protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { |
| // For simple implementation, our internal size is always 0. |
| // We depend on the container to specify the layout size of |
| // our view. We can't really know what it is since we will be |
| // adding and removing different arbitrary views and do not |
| // want the layout to change as this happens. |
| setMeasuredDimension(getDefaultSize(0, widthMeasureSpec), |
| getDefaultSize(0, heightMeasureSpec)); |
| |
| final int measuredWidth = getMeasuredWidth(); |
| final int maxGutterSize = measuredWidth / 10; |
| mGutterSize = Math.min(maxGutterSize, mDefaultGutterSize); |
| |
| // Children are just made to fill our space. |
| int childWidthSize = measuredWidth - getPaddingLeft() - getPaddingRight(); |
| int childHeightSize = getMeasuredHeight() - getPaddingTop() - getPaddingBottom(); |
| |
| /* |
| * Make sure all children have been properly measured. Decor views first. |
| * Right now we cheat and make this less complicated by assuming decor |
| * views won't intersect. We will pin to edges based on gravity. |
| */ |
| int size = getChildCount(); |
| for (int i = 0; i < size; ++i) { |
| final View child = getChildAt(i); |
| if (child.getVisibility() != GONE) { |
| final LayoutParams lp = (LayoutParams) child.getLayoutParams(); |
| if (lp != null && lp.isDecor) { |
| final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK; |
| final int vgrav = lp.gravity & Gravity.VERTICAL_GRAVITY_MASK; |
| int widthMode = MeasureSpec.AT_MOST; |
| int heightMode = MeasureSpec.AT_MOST; |
| boolean consumeVertical = vgrav == Gravity.TOP || vgrav == Gravity.BOTTOM; |
| boolean consumeHorizontal = hgrav == Gravity.LEFT || hgrav == Gravity.RIGHT; |
| |
| if (consumeVertical) { |
| widthMode = MeasureSpec.EXACTLY; |
| } else if (consumeHorizontal) { |
| heightMode = MeasureSpec.EXACTLY; |
| } |
| |
| int widthSize = childWidthSize; |
| int heightSize = childHeightSize; |
| if (lp.width != LayoutParams.WRAP_CONTENT) { |
| widthMode = MeasureSpec.EXACTLY; |
| if (lp.width != LayoutParams.FILL_PARENT) { |
| widthSize = lp.width; |
| } |
| } |
| if (lp.height != LayoutParams.WRAP_CONTENT) { |
| heightMode = MeasureSpec.EXACTLY; |
| if (lp.height != LayoutParams.FILL_PARENT) { |
| heightSize = lp.height; |
| } |
| } |
| final int widthSpec = MeasureSpec.makeMeasureSpec(widthSize, widthMode); |
| final int heightSpec = MeasureSpec.makeMeasureSpec(heightSize, heightMode); |
| child.measure(widthSpec, heightSpec); |
| |
| if (consumeVertical) { |
| childHeightSize -= child.getMeasuredHeight(); |
| } else if (consumeHorizontal) { |
| childWidthSize -= child.getMeasuredWidth(); |
| } |
| } |
| } |
| } |
| |
| mChildWidthMeasureSpec = MeasureSpec.makeMeasureSpec(childWidthSize, MeasureSpec.EXACTLY); |
| mChildHeightMeasureSpec = MeasureSpec.makeMeasureSpec(childHeightSize, MeasureSpec.EXACTLY); |
| |
| // Make sure we have created all fragments that we need to have shown. |
| mInLayout = true; |
| populate(); |
| mInLayout = false; |
| |
| // Page views next. |
| size = getChildCount(); |
| for (int i = 0; i < size; ++i) { |
| final View child = getChildAt(i); |
| if (child.getVisibility() != GONE) { |
| if (DEBUG) Log.v(TAG, "Measuring #" + i + " " + child |
| + ": " + mChildWidthMeasureSpec); |
| |
| final LayoutParams lp = (LayoutParams) child.getLayoutParams(); |
| if (lp == null || !lp.isDecor) { |
| final int widthSpec = MeasureSpec.makeMeasureSpec( |
| (int) (childWidthSize * lp.widthFactor), MeasureSpec.EXACTLY); |
| child.measure(widthSpec, mChildHeightMeasureSpec); |
| } |
| } |
| } |
| } |
| |
| @Override |
| protected void onSizeChanged(int w, int h, int oldw, int oldh) { |
| super.onSizeChanged(w, h, oldw, oldh); |
| |
| // Make sure scroll position is set correctly. |
| if (w != oldw) { |
| recomputeScrollPosition(w, oldw, mPageMargin, mPageMargin); |
| } |
| } |
| |
| private void recomputeScrollPosition(int width, int oldWidth, int margin, int oldMargin) { |
| if (oldWidth > 0 && !mItems.isEmpty()) { |
| final int widthWithMargin = width - getPaddingLeft() - getPaddingRight() + margin; |
| final int oldWidthWithMargin = oldWidth - getPaddingLeft() - getPaddingRight() |
| + oldMargin; |
| final int xpos = getScrollX(); |
| final float pageOffset = (float) xpos / oldWidthWithMargin; |
| final int newOffsetPixels = (int) (pageOffset * widthWithMargin); |
| |
| scrollTo(newOffsetPixels, getScrollY()); |
| if (!mScroller.isFinished()) { |
| // We now return to your regularly scheduled scroll, already in progress. |
| final int newDuration = mScroller.getDuration() - mScroller.timePassed(); |
| ItemInfo targetInfo = infoForPosition(mCurItem); |
| mScroller.startScroll(newOffsetPixels, 0, |
| (int) (targetInfo.offset * width), 0, newDuration); |
| } |
| } else { |
| final ItemInfo ii = infoForPosition(mCurItem); |
| final float scrollOffset = ii != null ? Math.min(ii.offset, mLastOffset) : 0; |
| final int scrollPos = (int) (scrollOffset * |
| (width - getPaddingLeft() - getPaddingRight())); |
| if (scrollPos != getScrollX()) { |
| completeScroll(false); |
| scrollTo(scrollPos, getScrollY()); |
| } |
| } |
| } |
| |
| @Override |
| protected void onLayout(boolean changed, int l, int t, int r, int b) { |
| final int count = getChildCount(); |
| int width = r - l; |
| int height = b - t; |
| int paddingLeft = getPaddingLeft(); |
| int paddingTop = getPaddingTop(); |
| int paddingRight = getPaddingRight(); |
| int paddingBottom = getPaddingBottom(); |
| final int scrollX = getScrollX(); |
| |
| int decorCount = 0; |
| |
| // First pass - decor views. We need to do this in two passes so that |
| // we have the proper offsets for non-decor views later. |
| for (int i = 0; i < count; i++) { |
| final View child = getChildAt(i); |
| if (child.getVisibility() != GONE) { |
| final LayoutParams lp = (LayoutParams) child.getLayoutParams(); |
| int childLeft = 0; |
| int childTop = 0; |
| if (lp.isDecor) { |
| final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK; |
| final int vgrav = lp.gravity & Gravity.VERTICAL_GRAVITY_MASK; |
| switch (hgrav) { |
| default: |
| childLeft = paddingLeft; |
| break; |
| case Gravity.LEFT: |
| childLeft = paddingLeft; |
| paddingLeft += child.getMeasuredWidth(); |
| break; |
| case Gravity.CENTER_HORIZONTAL: |
| childLeft = Math.max((width - child.getMeasuredWidth()) / 2, |
| paddingLeft); |
| break; |
| case Gravity.RIGHT: |
| childLeft = width - paddingRight - child.getMeasuredWidth(); |
| paddingRight += child.getMeasuredWidth(); |
| break; |
| } |
| switch (vgrav) { |
| default: |
| childTop = paddingTop; |
| break; |
| case Gravity.TOP: |
| childTop = paddingTop; |
| paddingTop += child.getMeasuredHeight(); |
| break; |
| case Gravity.CENTER_VERTICAL: |
| childTop = Math.max((height - child.getMeasuredHeight()) / 2, |
| paddingTop); |
| break; |
| case Gravity.BOTTOM: |
| childTop = height - paddingBottom - child.getMeasuredHeight(); |
| paddingBottom += child.getMeasuredHeight(); |
| break; |
| } |
| childLeft += scrollX; |
| child.layout(childLeft, childTop, |
| childLeft + child.getMeasuredWidth(), |
| childTop + child.getMeasuredHeight()); |
| decorCount++; |
| } |
| } |
| } |
| |
| final int childWidth = width - paddingLeft - paddingRight; |
| // Page views. Do this once we have the right padding offsets from above. |
| for (int i = 0; i < count; i++) { |
| final View child = getChildAt(i); |
| if (child.getVisibility() == GONE) { |
| continue; |
| } |
| |
| final LayoutParams lp = (LayoutParams) child.getLayoutParams(); |
| if (lp.isDecor) { |
| continue; |
| } |
| |
| final ItemInfo ii = infoForChild(child); |
| if (ii == null) { |
| continue; |
| } |
| |
| if (lp.needsMeasure) { |
| // This was added during layout and needs measurement. |
| // Do it now that we know what we're working with. |
| lp.needsMeasure = false; |
| final int widthSpec = MeasureSpec.makeMeasureSpec( |
| (int) (childWidth * lp.widthFactor), |
| MeasureSpec.EXACTLY); |
| final int heightSpec = MeasureSpec.makeMeasureSpec( |
| (int) (height - paddingTop - paddingBottom), |
| MeasureSpec.EXACTLY); |
| child.measure(widthSpec, heightSpec); |
| } |
| |
| final int childMeasuredWidth = child.getMeasuredWidth(); |
| final int startOffset = (int) (childWidth * ii.offset); |
| final int childLeft; |
| if (isLayoutRtl()) { |
| childLeft = MAX_SCROLL_X - paddingRight - startOffset - childMeasuredWidth; |
| } else { |
| childLeft = paddingLeft + startOffset; |
| } |
| |
| final int childTop = paddingTop; |
| child.layout(childLeft, childTop, childLeft + childMeasuredWidth, |
| childTop + child.getMeasuredHeight()); |
| } |
| |
| mTopPageBounds = paddingTop; |
| mBottomPageBounds = height - paddingBottom; |
| mDecorChildCount = decorCount; |
| |
| if (mFirstLayout) { |
| scrollToItem(mCurItem, false, 0, false); |
| } |
| mFirstLayout = false; |
| } |
| |
| @Override |
| public void computeScroll() { |
| if (!mScroller.isFinished() && mScroller.computeScrollOffset()) { |
| final int oldX = getScrollX(); |
| final int oldY = getScrollY(); |
| final int x = mScroller.getCurrX(); |
| final int y = mScroller.getCurrY(); |
| |
| if (oldX != x || oldY != y) { |
| scrollTo(x, y); |
| |
| if (!pageScrolled(x)) { |
| mScroller.abortAnimation(); |
| scrollTo(0, y); |
| } |
| } |
| |
| // Keep on drawing until the animation has finished. |
| postInvalidateOnAnimation(); |
| return; |
| } |
| |
| // Done with scroll, clean up state. |
| completeScroll(true); |
| } |
| |
| private boolean pageScrolled(int scrollX) { |
| if (mItems.size() == 0) { |
| mCalledSuper = false; |
| onPageScrolled(0, 0, 0); |
| if (!mCalledSuper) { |
| throw new IllegalStateException( |
| "onPageScrolled did not call superclass implementation"); |
| } |
| return false; |
| } |
| |
| // Translate to scrollX to scrollStart for RTL. |
| final int scrollStart; |
| if (isLayoutRtl()) { |
| scrollStart = MAX_SCROLL_X - scrollX; |
| } else { |
| scrollStart = scrollX; |
| } |
| |
| final ItemInfo ii = infoForFirstVisiblePage(); |
| final int width = getPaddedWidth(); |
| final int widthWithMargin = width + mPageMargin; |
| final float marginOffset = (float) mPageMargin / width; |
| final int currentPage = ii.position; |
| final float pageOffset = (((float) scrollStart / width) - ii.offset) / |
| (ii.widthFactor + marginOffset); |
| final int offsetPixels = (int) (pageOffset * widthWithMargin); |
| |
| mCalledSuper = false; |
| onPageScrolled(currentPage, pageOffset, offsetPixels); |
| if (!mCalledSuper) { |
| throw new IllegalStateException( |
| "onPageScrolled did not call superclass implementation"); |
| } |
| return true; |
| } |
| |
| /** |
| * This method will be invoked when the current page is scrolled, either as part |
| * of a programmatically initiated smooth scroll or a user initiated touch scroll. |
| * If you override this method you must call through to the superclass implementation |
| * (e.g. super.onPageScrolled(position, offset, offsetPixels)) before onPageScrolled |
| * returns. |
| * |
| * @param position Position index of the first page currently being displayed. |
| * Page position+1 will be visible if positionOffset is nonzero. |
| * @param offset Value from [0, 1) indicating the offset from the page at position. |
| * @param offsetPixels Value in pixels indicating the offset from position. |
| */ |
| protected void onPageScrolled(int position, float offset, int offsetPixels) { |
| // Offset any decor views if needed - keep them on-screen at all times. |
| if (mDecorChildCount > 0) { |
| final int scrollX = getScrollX(); |
| int paddingLeft = getPaddingLeft(); |
| int paddingRight = getPaddingRight(); |
| final int width = getWidth(); |
| final int childCount = getChildCount(); |
| for (int i = 0; i < childCount; i++) { |
| final View child = getChildAt(i); |
| final LayoutParams lp = (LayoutParams) child.getLayoutParams(); |
| if (!lp.isDecor) continue; |
| |
| final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK; |
| int childLeft = 0; |
| switch (hgrav) { |
| default: |
| childLeft = paddingLeft; |
| break; |
| case Gravity.LEFT: |
| childLeft = paddingLeft; |
| paddingLeft += child.getWidth(); |
| break; |
| case Gravity.CENTER_HORIZONTAL: |
| childLeft = Math.max((width - child.getMeasuredWidth()) / 2, |
| paddingLeft); |
| break; |
| case Gravity.RIGHT: |
| childLeft = width - paddingRight - child.getMeasuredWidth(); |
| paddingRight += child.getMeasuredWidth(); |
| break; |
| } |
| childLeft += scrollX; |
| |
| final int childOffset = childLeft - child.getLeft(); |
| if (childOffset != 0) { |
| child.offsetLeftAndRight(childOffset); |
| } |
| } |
| } |
| |
| if (mOnPageChangeListener != null) { |
| mOnPageChangeListener.onPageScrolled(position, offset, offsetPixels); |
| } |
| if (mInternalPageChangeListener != null) { |
| mInternalPageChangeListener.onPageScrolled(position, offset, offsetPixels); |
| } |
| |
| if (mPageTransformer != null) { |
| final int scrollX = getScrollX(); |
| final int childCount = getChildCount(); |
| for (int i = 0; i < childCount; i++) { |
| final View child = getChildAt(i); |
| final LayoutParams lp = (LayoutParams) child.getLayoutParams(); |
| |
| if (lp.isDecor) continue; |
| |
| final float transformPos = (float) (child.getLeft() - scrollX) / getPaddedWidth(); |
| mPageTransformer.transformPage(child, transformPos); |
| } |
| } |
| |
| mCalledSuper = true; |
| } |
| |
| private void completeScroll(boolean postEvents) { |
| boolean needPopulate = mScrollState == SCROLL_STATE_SETTLING; |
| if (needPopulate) { |
| // Done with scroll, no longer want to cache view drawing. |
| setScrollingCacheEnabled(false); |
| mScroller.abortAnimation(); |
| int oldX = getScrollX(); |
| int oldY = getScrollY(); |
| int x = mScroller.getCurrX(); |
| int y = mScroller.getCurrY(); |
| if (oldX != x || oldY != y) { |
| scrollTo(x, y); |
| } |
| } |
| mPopulatePending = false; |
| for (int i=0; i<mItems.size(); i++) { |
| ItemInfo ii = mItems.get(i); |
| if (ii.scrolling) { |
| needPopulate = true; |
| ii.scrolling = false; |
| } |
| } |
| if (needPopulate) { |
| if (postEvents) { |
| postOnAnimation(mEndScrollRunnable); |
| } else { |
| mEndScrollRunnable.run(); |
| } |
| } |
| } |
| |
| private boolean isGutterDrag(float x, float dx) { |
| return (x < mGutterSize && dx > 0) || (x > getWidth() - mGutterSize && dx < 0); |
| } |
| |
| private void enableLayers(boolean enable) { |
| final int childCount = getChildCount(); |
| for (int i = 0; i < childCount; i++) { |
| final int layerType = enable ? LAYER_TYPE_HARDWARE : LAYER_TYPE_NONE; |
| getChildAt(i).setLayerType(layerType, null); |
| } |
| } |
| |
| @Override |
| public boolean onInterceptTouchEvent(MotionEvent ev) { |
| /* |
| * This method JUST determines whether we want to intercept the motion. |
| * If we return true, onMotionEvent will be called and we do the actual |
| * scrolling there. |
| */ |
| |
| final int action = ev.getAction() & MotionEvent.ACTION_MASK; |
| |
| // Always take care of the touch gesture being complete. |
| if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) { |
| // Release the drag. |
| if (DEBUG) Log.v(TAG, "Intercept done!"); |
| mIsBeingDragged = false; |
| mIsUnableToDrag = false; |
| mActivePointerId = INVALID_POINTER; |
| if (mVelocityTracker != null) { |
| mVelocityTracker.recycle(); |
| mVelocityTracker = null; |
| } |
| return false; |
| } |
| |
| // Nothing more to do here if we have decided whether or not we |
| // are dragging. |
| if (action != MotionEvent.ACTION_DOWN) { |
| if (mIsBeingDragged) { |
| if (DEBUG) Log.v(TAG, "Being dragged, intercept returning true!"); |
| return true; |
| } |
| if (mIsUnableToDrag) { |
| if (DEBUG) Log.v(TAG, "Unable to drag, intercept returning false!"); |
| return false; |
| } |
| } |
| |
| switch (action) { |
| case MotionEvent.ACTION_MOVE: { |
| /* |
| * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check |
| * whether the user has moved far enough from his original down touch. |
| */ |
| |
| /* |
| * Locally do absolute value. mLastMotionY is set to the y value |
| * of the down event. |
| */ |
| final int activePointerId = mActivePointerId; |
| if (activePointerId == INVALID_POINTER) { |
| // If we don't have a valid id, the touch down wasn't on content. |
| break; |
| } |
| |
| final int pointerIndex = ev.findPointerIndex(activePointerId); |
| final float x = ev.getX(pointerIndex); |
| final float dx = x - mLastMotionX; |
| final float xDiff = Math.abs(dx); |
| final float y = ev.getY(pointerIndex); |
| final float yDiff = Math.abs(y - mInitialMotionY); |
| if (DEBUG) Log.v(TAG, "Moved x to " + x + "," + y + " diff=" + xDiff + "," + yDiff); |
| |
| if (dx != 0 && !isGutterDrag(mLastMotionX, dx) && |
| canScroll(this, false, (int) dx, (int) x, (int) y)) { |
| // Nested view has scrollable area under this point. Let it be handled there. |
| mLastMotionX = x; |
| mLastMotionY = y; |
| mIsUnableToDrag = true; |
| return false; |
| } |
| if (xDiff > mTouchSlop && xDiff * 0.5f > yDiff) { |
| if (DEBUG) Log.v(TAG, "Starting drag!"); |
| mIsBeingDragged = true; |
| requestParentDisallowInterceptTouchEvent(true); |
| setScrollState(SCROLL_STATE_DRAGGING); |
| mLastMotionX = dx > 0 ? mInitialMotionX + mTouchSlop : |
| mInitialMotionX - mTouchSlop; |
| mLastMotionY = y; |
| setScrollingCacheEnabled(true); |
| } else if (yDiff > mTouchSlop) { |
| // The finger has moved enough in the vertical |
| // direction to be counted as a drag... abort |
| // any attempt to drag horizontally, to work correctly |
| // with children that have scrolling containers. |
| if (DEBUG) Log.v(TAG, "Starting unable to drag!"); |
| mIsUnableToDrag = true; |
| } |
| if (mIsBeingDragged) { |
| // Scroll to follow the motion event |
| if (performDrag(x)) { |
| postInvalidateOnAnimation(); |
| } |
| } |
| break; |
| } |
| |
| case MotionEvent.ACTION_DOWN: { |
| /* |
| * Remember location of down touch. |
| * ACTION_DOWN always refers to pointer index 0. |
| */ |
| mLastMotionX = mInitialMotionX = ev.getX(); |
| mLastMotionY = mInitialMotionY = ev.getY(); |
| mActivePointerId = ev.getPointerId(0); |
| mIsUnableToDrag = false; |
| |
| mScroller.computeScrollOffset(); |
| if (mScrollState == SCROLL_STATE_SETTLING && |
| Math.abs(mScroller.getFinalX() - mScroller.getCurrX()) > mCloseEnough) { |
| // Let the user 'catch' the pager as it animates. |
| mScroller.abortAnimation(); |
| mPopulatePending = false; |
| populate(); |
| mIsBeingDragged = true; |
| requestParentDisallowInterceptTouchEvent(true); |
| setScrollState(SCROLL_STATE_DRAGGING); |
| } else { |
| completeScroll(false); |
| mIsBeingDragged = false; |
| } |
| |
| if (DEBUG) Log.v(TAG, "Down at " + mLastMotionX + "," + mLastMotionY |
| + " mIsBeingDragged=" + mIsBeingDragged |
| + "mIsUnableToDrag=" + mIsUnableToDrag); |
| break; |
| } |
| |
| case MotionEvent.ACTION_POINTER_UP: |
| onSecondaryPointerUp(ev); |
| break; |
| } |
| |
| if (mVelocityTracker == null) { |
| mVelocityTracker = VelocityTracker.obtain(); |
| } |
| mVelocityTracker.addMovement(ev); |
| |
| /* |
| * The only time we want to intercept motion events is if we are in the |
| * drag mode. |
| */ |
| return mIsBeingDragged; |
| } |
| |
| @Override |
| public boolean onTouchEvent(MotionEvent ev) { |
| if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) { |
| // Don't handle edge touches immediately -- they may actually belong to one of our |
| // descendants. |
| return false; |
| } |
| |
| if (mAdapter == null || mAdapter.getCount() == 0) { |
| // Nothing to present or scroll; nothing to touch. |
| return false; |
| } |
| |
| if (mVelocityTracker == null) { |
| mVelocityTracker = VelocityTracker.obtain(); |
| } |
| mVelocityTracker.addMovement(ev); |
| |
| final int action = ev.getAction(); |
| boolean needsInvalidate = false; |
| |
| switch (action & MotionEvent.ACTION_MASK) { |
| case MotionEvent.ACTION_DOWN: { |
| mScroller.abortAnimation(); |
| mPopulatePending = false; |
| populate(); |
| |
| // Remember where the motion event started |
| mLastMotionX = mInitialMotionX = ev.getX(); |
| mLastMotionY = mInitialMotionY = ev.getY(); |
| mActivePointerId = ev.getPointerId(0); |
| break; |
| } |
| case MotionEvent.ACTION_MOVE: |
| if (!mIsBeingDragged) { |
| final int pointerIndex = ev.findPointerIndex(mActivePointerId); |
| final float x = ev.getX(pointerIndex); |
| final float xDiff = Math.abs(x - mLastMotionX); |
| final float y = ev.getY(pointerIndex); |
| final float yDiff = Math.abs(y - mLastMotionY); |
| if (DEBUG) Log.v(TAG, "Moved x to " + x + "," + y + " diff=" + xDiff + "," + yDiff); |
| if (xDiff > mTouchSlop && xDiff > yDiff) { |
| if (DEBUG) Log.v(TAG, "Starting drag!"); |
| mIsBeingDragged = true; |
| requestParentDisallowInterceptTouchEvent(true); |
| mLastMotionX = x - mInitialMotionX > 0 ? mInitialMotionX + mTouchSlop : |
| mInitialMotionX - mTouchSlop; |
| mLastMotionY = y; |
| setScrollState(SCROLL_STATE_DRAGGING); |
| setScrollingCacheEnabled(true); |
| |
| // Disallow Parent Intercept, just in case |
| ViewParent parent = getParent(); |
| if (parent != null) { |
| parent.requestDisallowInterceptTouchEvent(true); |
| } |
| } |
| } |
| // Not else! Note that mIsBeingDragged can be set above. |
| if (mIsBeingDragged) { |
| // Scroll to follow the motion event |
| final int activePointerIndex = ev.findPointerIndex(mActivePointerId); |
| final float x = ev.getX(activePointerIndex); |
| needsInvalidate |= performDrag(x); |
| } |
| break; |
| case MotionEvent.ACTION_UP: |
| if (mIsBeingDragged) { |
| final VelocityTracker velocityTracker = mVelocityTracker; |
| velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); |
| final int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId); |
| |
| mPopulatePending = true; |
| |
| final float scrollStart = getScrollStart(); |
| final float scrolledPages = scrollStart / getPaddedWidth(); |
| final ItemInfo ii = infoForFirstVisiblePage(); |
| final int currentPage = ii.position; |
| final float nextPageOffset; |
| if (isLayoutRtl()) { |
| nextPageOffset = (ii.offset - scrolledPages) / ii.widthFactor; |
| } else { |
| nextPageOffset = (scrolledPages - ii.offset) / ii.widthFactor; |
| } |
| |
| final int activePointerIndex = ev.findPointerIndex(mActivePointerId); |
| final float x = ev.getX(activePointerIndex); |
| final int totalDelta = (int) (x - mInitialMotionX); |
| final int nextPage = determineTargetPage( |
| currentPage, nextPageOffset, initialVelocity, totalDelta); |
| setCurrentItemInternal(nextPage, true, true, initialVelocity); |
| |
| mActivePointerId = INVALID_POINTER; |
| endDrag(); |
| mLeftEdge.onRelease(); |
| mRightEdge.onRelease(); |
| needsInvalidate = true; |
| } |
| break; |
| case MotionEvent.ACTION_CANCEL: |
| if (mIsBeingDragged) { |
| scrollToItem(mCurItem, true, 0, false); |
| mActivePointerId = INVALID_POINTER; |
| endDrag(); |
| mLeftEdge.onRelease(); |
| mRightEdge.onRelease(); |
| needsInvalidate = true; |
| } |
| break; |
| case MotionEvent.ACTION_POINTER_DOWN: { |
| final int index = ev.getActionIndex(); |
| final float x = ev.getX(index); |
| mLastMotionX = x; |
| mActivePointerId = ev.getPointerId(index); |
| break; |
| } |
| case MotionEvent.ACTION_POINTER_UP: |
| onSecondaryPointerUp(ev); |
| mLastMotionX = ev.getX(ev.findPointerIndex(mActivePointerId)); |
| break; |
| } |
| if (needsInvalidate) { |
| postInvalidateOnAnimation(); |
| } |
| return true; |
| } |
| |
| private void requestParentDisallowInterceptTouchEvent(boolean disallowIntercept) { |
| final ViewParent parent = getParent(); |
| if (parent != null) { |
| parent.requestDisallowInterceptTouchEvent(disallowIntercept); |
| } |
| } |
| |
| private boolean performDrag(float x) { |
| boolean needsInvalidate = false; |
| |
| final int width = getPaddedWidth(); |
| final float deltaX = mLastMotionX - x; |
| mLastMotionX = x; |
| |
| final EdgeEffect startEdge; |
| final EdgeEffect endEdge; |
| if (isLayoutRtl()) { |
| startEdge = mRightEdge; |
| endEdge = mLeftEdge; |
| } else { |
| startEdge = mLeftEdge; |
| endEdge = mRightEdge; |
| } |
| |
| // Translate scroll to relative coordinates. |
| final float nextScrollX = getScrollX() + deltaX; |
| final float scrollStart; |
| if (isLayoutRtl()) { |
| scrollStart = MAX_SCROLL_X - nextScrollX; |
| } else { |
| scrollStart = nextScrollX; |
| } |
| |
| final float startBound; |
| final ItemInfo startItem = mItems.get(0); |
| final boolean startAbsolute = startItem.position == 0; |
| if (startAbsolute) { |
| startBound = startItem.offset * width; |
| } else { |
| startBound = width * mFirstOffset; |
| } |
| |
| final float endBound; |
| final ItemInfo endItem = mItems.get(mItems.size() - 1); |
| final boolean endAbsolute = endItem.position == mAdapter.getCount() - 1; |
| if (endAbsolute) { |
| endBound = endItem.offset * width; |
| } else { |
| endBound = width * mLastOffset; |
| } |
| |
| final float clampedScrollStart; |
| if (scrollStart < startBound) { |
| if (startAbsolute) { |
| final float over = startBound - scrollStart; |
| startEdge.onPull(Math.abs(over) / width); |
| needsInvalidate = true; |
| } |
| clampedScrollStart = startBound; |
| } else if (scrollStart > endBound) { |
| if (endAbsolute) { |
| final float over = scrollStart - endBound; |
| endEdge.onPull(Math.abs(over) / width); |
| needsInvalidate = true; |
| } |
| clampedScrollStart = endBound; |
| } else { |
| clampedScrollStart = scrollStart; |
| } |
| |
| // Translate back to absolute coordinates. |
| final float targetScrollX; |
| if (isLayoutRtl()) { |
| targetScrollX = MAX_SCROLL_X - clampedScrollStart; |
| } else { |
| targetScrollX = clampedScrollStart; |
| } |
| |
| // Don't lose the rounded component. |
| mLastMotionX += targetScrollX - (int) targetScrollX; |
| |
| scrollTo((int) targetScrollX, getScrollY()); |
| pageScrolled((int) targetScrollX); |
| |
| return needsInvalidate; |
| } |
| |
| /** |
| * @return Info about the page at the current scroll position. |
| * This can be synthetic for a missing middle page; the 'object' field can be null. |
| */ |
| private ItemInfo infoForFirstVisiblePage() { |
| final int startOffset = getScrollStart(); |
| final int width = getPaddedWidth(); |
| final float scrollOffset = width > 0 ? (float) startOffset / width : 0; |
| final float marginOffset = width > 0 ? (float) mPageMargin / width : 0; |
| |
| int lastPos = -1; |
| float lastOffset = 0.f; |
| float lastWidth = 0.f; |
| boolean first = true; |
| ItemInfo lastItem = null; |
| |
| final int N = mItems.size(); |
| for (int i = 0; i < N; i++) { |
| ItemInfo ii = mItems.get(i); |
| |
| // Seek to position. |
| if (!first && ii.position != lastPos + 1) { |
| // Create a synthetic item for a missing page. |
| ii = mTempItem; |
| ii.offset = lastOffset + lastWidth + marginOffset; |
| ii.position = lastPos + 1; |
| ii.widthFactor = mAdapter.getPageWidth(ii.position); |
| i--; |
| } |
| |
| final float offset = ii.offset; |
| final float startBound = offset; |
| if (first || scrollOffset >= startBound) { |
| final float endBound = offset + ii.widthFactor + marginOffset; |
| if (scrollOffset < endBound || i == mItems.size() - 1) { |
| return ii; |
| } |
| } else { |
| return lastItem; |
| } |
| |
| first = false; |
| lastPos = ii.position; |
| lastOffset = offset; |
| lastWidth = ii.widthFactor; |
| lastItem = ii; |
| } |
| |
| return lastItem; |
| } |
| |
| private int getScrollStart() { |
| if (isLayoutRtl()) { |
| return MAX_SCROLL_X - getScrollX(); |
| } else { |
| return getScrollX(); |
| } |
| } |
| |
| /** |
| * @param currentPage the position of the page with the first visible starting edge |
| * @param pageOffset the fraction of the right-hand page that's visible |
| * @param velocity the velocity of the touch event stream |
| * @param deltaX the distance of the touch event stream |
| * @return the position of the target page |
| */ |
| private int determineTargetPage(int currentPage, float pageOffset, int velocity, int deltaX) { |
| int targetPage; |
| if (Math.abs(deltaX) > mFlingDistance && Math.abs(velocity) > mMinimumVelocity) { |
| targetPage = currentPage - (velocity < 0 ? mLeftIncr : 0); |
| } else { |
| final float truncator = currentPage >= mCurItem ? 0.4f : 0.6f; |
| targetPage = (int) (currentPage - mLeftIncr * (pageOffset + truncator)); |
| } |
| |
| if (mItems.size() > 0) { |
| final ItemInfo firstItem = mItems.get(0); |
| final ItemInfo lastItem = mItems.get(mItems.size() - 1); |
| |
| // Only let the user target pages we have items for |
| targetPage = MathUtils.constrain(targetPage, firstItem.position, lastItem.position); |
| } |
| |
| return targetPage; |
| } |
| |
| @Override |
| public void draw(Canvas canvas) { |
| super.draw(canvas); |
| boolean needsInvalidate = false; |
| |
| final int overScrollMode = getOverScrollMode(); |
| if (overScrollMode == View.OVER_SCROLL_ALWAYS || |
| (overScrollMode == View.OVER_SCROLL_IF_CONTENT_SCROLLS && |
| mAdapter != null && mAdapter.getCount() > 1)) { |
| if (!mLeftEdge.isFinished()) { |
| final int restoreCount = canvas.save(); |
| final int height = getHeight() - getPaddingTop() - getPaddingBottom(); |
| final int width = getWidth(); |
| |
| canvas.rotate(270); |
| canvas.translate(-height + getPaddingTop(), mFirstOffset * width); |
| mLeftEdge.setSize(height, width); |
| needsInvalidate |= mLeftEdge.draw(canvas); |
| canvas.restoreToCount(restoreCount); |
| } |
| if (!mRightEdge.isFinished()) { |
| final int restoreCount = canvas.save(); |
| final int width = getWidth(); |
| final int height = getHeight() - getPaddingTop() - getPaddingBottom(); |
| |
| canvas.rotate(90); |
| canvas.translate(-getPaddingTop(), -(mLastOffset + 1) * width); |
| mRightEdge.setSize(height, width); |
| needsInvalidate |= mRightEdge.draw(canvas); |
| canvas.restoreToCount(restoreCount); |
| } |
| } else { |
| mLeftEdge.finish(); |
| mRightEdge.finish(); |
| } |
| |
| if (needsInvalidate) { |
| // Keep animating |
| postInvalidateOnAnimation(); |
| } |
| } |
| |
| @Override |
| protected void onDraw(Canvas canvas) { |
| super.onDraw(canvas); |
| |
| // Draw the margin drawable between pages if needed. |
| if (mPageMargin > 0 && mMarginDrawable != null && mItems.size() > 0 && mAdapter != null) { |
| final int scrollX = getScrollX(); |
| final int width = getWidth(); |
| |
| final float marginOffset = (float) mPageMargin / width; |
| int itemIndex = 0; |
| ItemInfo ii = mItems.get(0); |
| float offset = ii.offset; |
| |
| final int itemCount = mItems.size(); |
| final int firstPos = ii.position; |
| final int lastPos = mItems.get(itemCount - 1).position; |
| for (int pos = firstPos; pos < lastPos; pos++) { |
| while (pos > ii.position && itemIndex < itemCount) { |
| ii = mItems.get(++itemIndex); |
| } |
| |
| final float itemOffset; |
| final float widthFactor; |
| if (pos == ii.position) { |
| itemOffset = ii.offset; |
| widthFactor = ii.widthFactor; |
| } else { |
| itemOffset = offset; |
| widthFactor = mAdapter.getPageWidth(pos); |
| } |
| |
| final float left; |
| final float scaledOffset = itemOffset * width; |
| if (isLayoutRtl()) { |
| left = MAX_SCROLL_X - scaledOffset; |
| } else { |
| left = scaledOffset + widthFactor * width; |
| } |
| |
| offset = itemOffset + widthFactor + marginOffset; |
| |
| if (left + mPageMargin > scrollX) { |
| mMarginDrawable.setBounds((int) left, mTopPageBounds, |
| (int) (left + mPageMargin + 0.5f), mBottomPageBounds); |
| mMarginDrawable.draw(canvas); |
| } |
| |
| if (left > scrollX + width) { |
| break; // No more visible, no sense in continuing |
| } |
| } |
| } |
| } |
| |
| private void onSecondaryPointerUp(MotionEvent ev) { |
| final int pointerIndex = ev.getActionIndex(); |
| final int pointerId = ev.getPointerId(pointerIndex); |
| if (pointerId == mActivePointerId) { |
| // This was our active pointer going up. Choose a new |
| // active pointer and adjust accordingly. |
| final int newPointerIndex = pointerIndex == 0 ? 1 : 0; |
| mLastMotionX = ev.getX(newPointerIndex); |
| mActivePointerId = ev.getPointerId(newPointerIndex); |
| if (mVelocityTracker != null) { |
| mVelocityTracker.clear(); |
| } |
| } |
| } |
| |
| private void endDrag() { |
| mIsBeingDragged = false; |
| mIsUnableToDrag = false; |
| |
| if (mVelocityTracker != null) { |
| mVelocityTracker.recycle(); |
| mVelocityTracker = null; |
| } |
| } |
| |
| private void setScrollingCacheEnabled(boolean enabled) { |
| if (mScrollingCacheEnabled != enabled) { |
| mScrollingCacheEnabled = enabled; |
| if (USE_CACHE) { |
| final int size = getChildCount(); |
| for (int i = 0; i < size; ++i) { |
| final View child = getChildAt(i); |
| if (child.getVisibility() != GONE) { |
| child.setDrawingCacheEnabled(enabled); |
| } |
| } |
| } |
| } |
| } |
| |
| public boolean canScrollHorizontally(int direction) { |
| if (mAdapter == null) { |
| return false; |
| } |
| |
| final int width = getPaddedWidth(); |
| final int scrollX = getScrollX(); |
| if (direction < 0) { |
| return (scrollX > (int) (width * mFirstOffset)); |
| } else if (direction > 0) { |
| return (scrollX < (int) (width * mLastOffset)); |
| } else { |
| return false; |
| } |
| } |
| |
| /** |
| * Tests scrollability within child views of v given a delta of dx. |
| * |
| * @param v View to test for horizontal scrollability |
| * @param checkV Whether the view v passed should itself be checked for scrollability (true), |
| * or just its children (false). |
| * @param dx Delta scrolled in pixels |
| * @param x X coordinate of the active touch point |
| * @param y Y coordinate of the active touch point |
| * @return true if child views of v can be scrolled by delta of dx. |
| */ |
| protected boolean canScroll(View v, boolean checkV, int dx, int x, int y) { |
| if (v instanceof ViewGroup) { |
| final ViewGroup group = (ViewGroup) v; |
| final int scrollX = v.getScrollX(); |
| final int scrollY = v.getScrollY(); |
| final int count = group.getChildCount(); |
| // Count backwards - let topmost views consume scroll distance first. |
| for (int i = count - 1; i >= 0; i--) { |
| // TODO: Add support for transformed views. |
| final View child = group.getChildAt(i); |
| if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() |
| && y + scrollY >= child.getTop() && y + scrollY < child.getBottom() |
| && canScroll(child, true, dx, x + scrollX - child.getLeft(), |
| y + scrollY - child.getTop())) { |
| return true; |
| } |
| } |
| } |
| |
| return checkV && v.canScrollHorizontally(-dx); |
| } |
| |
| @Override |
| public boolean dispatchKeyEvent(KeyEvent event) { |
| // Let the focused view and/or our descendants get the key first |
| return super.dispatchKeyEvent(event) || executeKeyEvent(event); |
| } |
| |
| /** |
| * You can call this function yourself to have the scroll view perform |
| * scrolling from a key event, just as if the event had been dispatched to |
| * it by the view hierarchy. |
| * |
| * @param event The key event to execute. |
| * @return Return true if the event was handled, else false. |
| */ |
| public boolean executeKeyEvent(KeyEvent event) { |
| boolean handled = false; |
| if (event.getAction() == KeyEvent.ACTION_DOWN) { |
| switch (event.getKeyCode()) { |
| case KeyEvent.KEYCODE_DPAD_LEFT: |
| handled = arrowScroll(FOCUS_LEFT); |
| break; |
| case KeyEvent.KEYCODE_DPAD_RIGHT: |
| handled = arrowScroll(FOCUS_RIGHT); |
| break; |
| case KeyEvent.KEYCODE_TAB: |
| if (event.hasNoModifiers()) { |
| handled = arrowScroll(FOCUS_FORWARD); |
| } else if (event.hasModifiers(KeyEvent.META_SHIFT_ON)) { |
| handled = arrowScroll(FOCUS_BACKWARD); |
| } |
| break; |
| } |
| } |
| return handled; |
| } |
| |
| public boolean arrowScroll(int direction) { |
| View currentFocused = findFocus(); |
| if (currentFocused == this) { |
| currentFocused = null; |
| } else if (currentFocused != null) { |
| boolean isChild = false; |
| for (ViewParent parent = currentFocused.getParent(); parent instanceof ViewGroup; |
| parent = parent.getParent()) { |
| if (parent == this) { |
| isChild = true; |
| break; |
| } |
| } |
| if (!isChild) { |
| // This would cause the focus search down below to fail in fun ways. |
| final StringBuilder sb = new StringBuilder(); |
| sb.append(currentFocused.getClass().getSimpleName()); |
| for (ViewParent parent = currentFocused.getParent(); parent instanceof ViewGroup; |
| parent = parent.getParent()) { |
| sb.append(" => ").append(parent.getClass().getSimpleName()); |
| } |
| Log.e(TAG, "arrowScroll tried to find focus based on non-child " + |
| "current focused view " + sb.toString()); |
| currentFocused = null; |
| } |
| } |
| |
| boolean handled = false; |
| |
| View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, |
| direction); |
| if (nextFocused != null && nextFocused != currentFocused) { |
| if (direction == View.FOCUS_LEFT) { |
| // If there is nothing to the left, or this is causing us to |
| // jump to the right, then what we really want to do is page left. |
| final int nextLeft = getChildRectInPagerCoordinates(mTempRect, nextFocused).left; |
| final int currLeft = getChildRectInPagerCoordinates(mTempRect, currentFocused).left; |
| if (currentFocused != null && nextLeft >= currLeft) { |
| handled = pageLeft(); |
| } else { |
| handled = nextFocused.requestFocus(); |
| } |
| } else if (direction == View.FOCUS_RIGHT) { |
| // If there is nothing to the right, or this is causing us to |
| // jump to the left, then what we really want to do is page right. |
| final int nextLeft = getChildRectInPagerCoordinates(mTempRect, nextFocused).left; |
| final int currLeft = getChildRectInPagerCoordinates(mTempRect, currentFocused).left; |
| if (currentFocused != null && nextLeft <= currLeft) { |
| handled = pageRight(); |
| } else { |
| handled = nextFocused.requestFocus(); |
| } |
| } |
| } else if (direction == FOCUS_LEFT || direction == FOCUS_BACKWARD) { |
| // Trying to move left and nothing there; try to page. |
| handled = pageLeft(); |
| } else if (direction == FOCUS_RIGHT || direction == FOCUS_FORWARD) { |
| // Trying to move right and nothing there; try to page. |
| handled = pageRight(); |
| } |
| if (handled) { |
| playSoundEffect(SoundEffectConstants.getContantForFocusDirection(direction)); |
| } |
| return handled; |
| } |
| |
| private Rect getChildRectInPagerCoordinates(Rect outRect, View child) { |
| if (outRect == null) { |
| outRect = new Rect(); |
| } |
| if (child == null) { |
| outRect.set(0, 0, 0, 0); |
| return outRect; |
| } |
| outRect.left = child.getLeft(); |
| outRect.right = child.getRight(); |
| outRect.top = child.getTop(); |
| outRect.bottom = child.getBottom(); |
| |
| ViewParent parent = child.getParent(); |
| while (parent instanceof ViewGroup && parent != this) { |
| final ViewGroup group = (ViewGroup) parent; |
| outRect.left += group.getLeft(); |
| outRect.right += group.getRight(); |
| outRect.top += group.getTop(); |
| outRect.bottom += group.getBottom(); |
| |
| parent = group.getParent(); |
| } |
| return outRect; |
| } |
| |
| boolean pageLeft() { |
| return setCurrentItemInternal(mCurItem + mLeftIncr, true, false); |
| } |
| |
| boolean pageRight() { |
| return setCurrentItemInternal(mCurItem - mLeftIncr, true, false); |
| } |
| |
| @Override |
| public void onRtlPropertiesChanged(@ResolvedLayoutDir int layoutDirection) { |
| super.onRtlPropertiesChanged(layoutDirection); |
| |
| if (layoutDirection == LAYOUT_DIRECTION_LTR) { |
| mLeftIncr = -1; |
| } else { |
| mLeftIncr = 1; |
| } |
| } |
| |
| /** |
| * We only want the current page that is being shown to be focusable. |
| */ |
| @Override |
| public void addFocusables(ArrayList<View> views, int direction, int focusableMode) { |
| final int focusableCount = views.size(); |
| |
| final int descendantFocusability = getDescendantFocusability(); |
| |
| if (descendantFocusability != FOCUS_BLOCK_DESCENDANTS) { |
| for (int i = 0; i < getChildCount(); i++) { |
| final View child = getChildAt(i); |
| if (child.getVisibility() == VISIBLE) { |
| ItemInfo ii = infoForChild(child); |
| if (ii != null && ii.position == mCurItem) { |
| child.addFocusables(views, direction, focusableMode); |
| } |
| } |
| } |
| } |
| |
| // we add ourselves (if focusable) in all cases except for when we are |
| // FOCUS_AFTER_DESCENDANTS and there are some descendants focusable. this is |
| // to avoid the focus search finding layouts when a more precise search |
| // among the focusable children would be more interesting. |
| if ( |
| descendantFocusability != FOCUS_AFTER_DESCENDANTS || |
| // No focusable descendants |
| (focusableCount == views.size())) { |
| // Note that we can't call the superclass here, because it will |
| // add all views in. So we need to do the same thing View does. |
| if (!isFocusable()) { |
| return; |
| } |
| if ((focusableMode & FOCUSABLES_TOUCH_MODE) == FOCUSABLES_TOUCH_MODE && |
| isInTouchMode() && !isFocusableInTouchMode()) { |
| return; |
| } |
| if (views != null) { |
| views.add(this); |
| } |
| } |
| } |
| |
| /** |
| * We only want the current page that is being shown to be touchable. |
| */ |
| @Override |
| public void addTouchables(ArrayList<View> views) { |
| // Note that we don't call super.addTouchables(), which means that |
| // we don't call View.addTouchables(). This is okay because a ViewPager |
| // is itself not touchable. |
| for (int i = 0; i < getChildCount(); i++) { |
| final View child = getChildAt(i); |
| if (child.getVisibility() == VISIBLE) { |
| ItemInfo ii = infoForChild(child); |
| if (ii != null && ii.position == mCurItem) { |
| child.addTouchables(views); |
| } |
| } |
| } |
| } |
| |
| /** |
| * We only want the current page that is being shown to be focusable. |
| */ |
| @Override |
| protected boolean onRequestFocusInDescendants(int direction, |
| Rect previouslyFocusedRect) { |
| int index; |
| int increment; |
| int end; |
| int count = getChildCount(); |
| if ((direction & FOCUS_FORWARD) != 0) { |
| index = 0; |
| increment = 1; |
| end = count; |
| } else { |
| index = count - 1; |
| increment = -1; |
| end = -1; |
| } |
| for (int i = index; i != end; i += increment) { |
| View child = getChildAt(i); |
| if (child.getVisibility() == VISIBLE) { |
| ItemInfo ii = infoForChild(child); |
| if (ii != null && ii.position == mCurItem) { |
| if (child.requestFocus(direction, previouslyFocusedRect)) { |
| return true; |
| } |
| } |
| } |
| } |
| return false; |
| } |
| |
| @Override |
| protected ViewGroup.LayoutParams generateDefaultLayoutParams() { |
| return new LayoutParams(); |
| } |
| |
| @Override |
| protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) { |
| return generateDefaultLayoutParams(); |
| } |
| |
| @Override |
| protected boolean checkLayoutParams(ViewGroup.LayoutParams p) { |
| return p instanceof LayoutParams && super.checkLayoutParams(p); |
| } |
| |
| @Override |
| public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs) { |
| return new LayoutParams(getContext(), attrs); |
| } |
| |
| |
| @Override |
| public void onInitializeAccessibilityEvent(AccessibilityEvent event) { |
| super.onInitializeAccessibilityEvent(event); |
| |
| event.setClassName(ViewPager.class.getName()); |
| event.setScrollable(canScroll()); |
| |
| if (event.getEventType() == AccessibilityEvent.TYPE_VIEW_SCROLLED && mAdapter != null) { |
| event.setItemCount(mAdapter.getCount()); |
| event.setFromIndex(mCurItem); |
| event.setToIndex(mCurItem); |
| } |
| } |
| |
| @Override |
| public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { |
| super.onInitializeAccessibilityNodeInfo(info); |
| |
| info.setClassName(ViewPager.class.getName()); |
| info.setScrollable(canScroll()); |
| |
| if (canScrollHorizontally(1)) { |
| info.addAction(AccessibilityAction.ACTION_SCROLL_FORWARD); |
| info.addAction(AccessibilityAction.ACTION_SCROLL_RIGHT); |
| } |
| |
| if (canScrollHorizontally(-1)) { |
| info.addAction(AccessibilityAction.ACTION_SCROLL_BACKWARD); |
| info.addAction(AccessibilityAction.ACTION_SCROLL_LEFT); |
| } |
| } |
| |
| @Override |
| public boolean performAccessibilityAction(int action, Bundle args) { |
| if (super.performAccessibilityAction(action, args)) { |
| return true; |
| } |
| |
| switch (action) { |
| case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: |
| case R.id.accessibilityActionScrollRight: |
| if (canScrollHorizontally(1)) { |
| setCurrentItem(mCurItem + 1); |
| return true; |
| } |
| return false; |
| case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: |
| case R.id.accessibilityActionScrollLeft: |
| if (canScrollHorizontally(-1)) { |
| setCurrentItem(mCurItem - 1); |
| return true; |
| } |
| return false; |
| } |
| |
| return false; |
| } |
| |
| private boolean canScroll() { |
| return mAdapter != null && mAdapter.getCount() > 1; |
| } |
| |
| private class PagerObserver extends DataSetObserver { |
| @Override |
| public void onChanged() { |
| dataSetChanged(); |
| } |
| @Override |
| public void onInvalidated() { |
| dataSetChanged(); |
| } |
| } |
| |
| /** |
| * Layout parameters that should be supplied for views added to a |
| * ViewPager. |
| */ |
| public static class LayoutParams extends ViewGroup.LayoutParams { |
| /** |
| * true if this view is a decoration on the pager itself and not |
| * a view supplied by the adapter. |
| */ |
| public boolean isDecor; |
| |
| /** |
| * Gravity setting for use on decor views only: |
| * Where to position the view page within the overall ViewPager |
| * container; constants are defined in {@link android.view.Gravity}. |
| */ |
| public int gravity; |
| |
| /** |
| * Width as a 0-1 multiplier of the measured pager width |
| */ |
| float widthFactor = 0.f; |
| |
| /** |
| * true if this view was added during layout and needs to be measured |
| * before being positioned. |
| */ |
| boolean needsMeasure; |
| |
| /** |
| * Adapter position this view is for if !isDecor |
| */ |
| int position; |
| |
| /** |
| * Current child index within the ViewPager that this view occupies |
| */ |
| int childIndex; |
| |
| public LayoutParams() { |
| super(FILL_PARENT, FILL_PARENT); |
| } |
| |
| public LayoutParams(Context context, AttributeSet attrs) { |
| super(context, attrs); |
| |
| final TypedArray a = context.obtainStyledAttributes(attrs, LAYOUT_ATTRS); |
| gravity = a.getInteger(0, Gravity.TOP); |
| a.recycle(); |
| } |
| } |
| |
| static class ViewPositionComparator implements Comparator<View> { |
| @Override |
| public int compare(View lhs, View rhs) { |
| final LayoutParams llp = (LayoutParams) lhs.getLayoutParams(); |
| final LayoutParams rlp = (LayoutParams) rhs.getLayoutParams(); |
| if (llp.isDecor != rlp.isDecor) { |
| return llp.isDecor ? 1 : -1; |
| } |
| return llp.position - rlp.position; |
| } |
| } |
| } |