The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2009 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package android.widget; |
| 18 | |
| 19 | import android.util.AttributeSet; |
| 20 | import android.graphics.Rect; |
| 21 | import android.view.View; |
| 22 | import android.view.VelocityTracker; |
| 23 | import android.view.ViewConfiguration; |
| 24 | import android.view.ViewGroup; |
| 25 | import android.view.KeyEvent; |
| 26 | import android.view.FocusFinder; |
| 27 | import android.view.MotionEvent; |
| 28 | import android.view.ViewParent; |
| 29 | import android.view.animation.AnimationUtils; |
| 30 | import android.content.Context; |
| 31 | import android.content.res.TypedArray; |
| 32 | |
| 33 | import java.util.List; |
| 34 | |
| 35 | /** |
| 36 | * Layout container for a view hierarchy that can be scrolled by the user, |
| 37 | * allowing it to be larger than the physical display. A HorizontalScrollView |
| 38 | * is a {@link FrameLayout}, meaning you should place one child in it |
| 39 | * containing the entire contents to scroll; this child may itself be a layout |
| 40 | * manager with a complex hierarchy of objects. A child that is often used |
| 41 | * is a {@link LinearLayout} in a horizontal orientation, presenting a horizontal |
| 42 | * array of top-level items that the user can scroll through. |
| 43 | * |
| 44 | * <p>You should never use a HorizontalScrollView with a {@link ListView}, since |
| 45 | * ListView takes care of its own scrolling. Most importantly, doing this |
| 46 | * defeats all of the important optimizations in ListView for dealing with |
| 47 | * large lists, since it effectively forces the ListView to display its entire |
| 48 | * list of items to fill up the infinite container supplied by HorizontalScrollView. |
| 49 | * |
| 50 | * <p>The {@link TextView} class also |
| 51 | * takes care of its own scrolling, so does not require a ScrollView, but |
| 52 | * using the two together is possible to achieve the effect of a text view |
| 53 | * within a larger container. |
| 54 | * |
| 55 | * <p>HorizontalScrollView only supports horizontal scrolling. |
| 56 | */ |
| 57 | public class HorizontalScrollView extends FrameLayout { |
| 58 | private static final int ANIMATED_SCROLL_GAP = ScrollView.ANIMATED_SCROLL_GAP; |
| 59 | |
| 60 | private static final float MAX_SCROLL_FACTOR = ScrollView.MAX_SCROLL_FACTOR; |
| 61 | |
| 62 | |
| 63 | private long mLastScroll; |
| 64 | |
| 65 | private final Rect mTempRect = new Rect(); |
| 66 | private Scroller mScroller; |
| 67 | |
| 68 | /** |
| 69 | * Flag to indicate that we are moving focus ourselves. This is so the |
| 70 | * code that watches for focus changes initiated outside this ScrollView |
| 71 | * knows that it does not have to do anything. |
| 72 | */ |
| 73 | private boolean mScrollViewMovedFocus; |
| 74 | |
| 75 | /** |
| 76 | * Position of the last motion event. |
| 77 | */ |
| 78 | private float mLastMotionX; |
| 79 | |
| 80 | /** |
| 81 | * True when the layout has changed but the traversal has not come through yet. |
| 82 | * Ideally the view hierarchy would keep track of this for us. |
| 83 | */ |
| 84 | private boolean mIsLayoutDirty = true; |
| 85 | |
| 86 | /** |
| 87 | * The child to give focus to in the event that a child has requested focus while the |
| 88 | * layout is dirty. This prevents the scroll from being wrong if the child has not been |
| 89 | * laid out before requesting focus. |
| 90 | */ |
| 91 | private View mChildToScrollTo = null; |
| 92 | |
| 93 | /** |
| 94 | * True if the user is currently dragging this ScrollView around. This is |
| 95 | * not the same as 'is being flinged', which can be checked by |
| 96 | * mScroller.isFinished() (flinging begins when the user lifts his finger). |
| 97 | */ |
| 98 | private boolean mIsBeingDragged = false; |
| 99 | |
| 100 | /** |
| 101 | * Determines speed during touch scrolling |
| 102 | */ |
| 103 | private VelocityTracker mVelocityTracker; |
| 104 | |
| 105 | /** |
| 106 | * When set to true, the scroll view measure its child to make it fill the currently |
| 107 | * visible area. |
| 108 | */ |
| 109 | private boolean mFillViewport; |
| 110 | |
| 111 | /** |
| 112 | * Whether arrow scrolling is animated. |
| 113 | */ |
| 114 | private boolean mSmoothScrollingEnabled = true; |
| 115 | |
| 116 | private int mTouchSlop; |
Romain Guy | 4296fc4 | 2009-07-06 11:48:52 -0700 | [diff] [blame^] | 117 | private int mMinimumVelocity; |
| 118 | private int mMaximumVelocity; |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 119 | |
| 120 | public HorizontalScrollView(Context context) { |
| 121 | this(context, null); |
| 122 | } |
| 123 | |
| 124 | public HorizontalScrollView(Context context, AttributeSet attrs) { |
| 125 | this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); |
| 126 | } |
| 127 | |
| 128 | public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) { |
| 129 | super(context, attrs, defStyle); |
| 130 | initScrollView(); |
| 131 | |
| 132 | TypedArray a = context.obtainStyledAttributes(attrs, |
| 133 | android.R.styleable.HorizontalScrollView, defStyle, 0); |
| 134 | |
| 135 | setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); |
| 136 | |
| 137 | a.recycle(); |
| 138 | } |
| 139 | |
| 140 | @Override |
| 141 | protected float getLeftFadingEdgeStrength() { |
| 142 | if (getChildCount() == 0) { |
| 143 | return 0.0f; |
| 144 | } |
| 145 | |
| 146 | final int length = getHorizontalFadingEdgeLength(); |
| 147 | if (mScrollX < length) { |
| 148 | return mScrollX / (float) length; |
| 149 | } |
| 150 | |
| 151 | return 1.0f; |
| 152 | } |
| 153 | |
| 154 | @Override |
| 155 | protected float getRightFadingEdgeStrength() { |
| 156 | if (getChildCount() == 0) { |
| 157 | return 0.0f; |
| 158 | } |
| 159 | |
| 160 | final int length = getHorizontalFadingEdgeLength(); |
| 161 | final int rightEdge = getWidth() - mPaddingRight; |
| 162 | final int span = getChildAt(0).getRight() - mScrollX - rightEdge; |
| 163 | if (span < length) { |
| 164 | return span / (float) length; |
| 165 | } |
| 166 | |
| 167 | return 1.0f; |
| 168 | } |
| 169 | |
| 170 | /** |
| 171 | * @return The maximum amount this scroll view will scroll in response to |
| 172 | * an arrow event. |
| 173 | */ |
| 174 | public int getMaxScrollAmount() { |
| 175 | return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); |
| 176 | } |
| 177 | |
| 178 | |
| 179 | private void initScrollView() { |
| 180 | mScroller = new Scroller(getContext()); |
| 181 | setFocusable(true); |
| 182 | setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); |
| 183 | setWillNotDraw(false); |
Romain Guy | 4296fc4 | 2009-07-06 11:48:52 -0700 | [diff] [blame^] | 184 | final ViewConfiguration configuration = ViewConfiguration.get(mContext); |
| 185 | mTouchSlop = configuration.getScaledTouchSlop(); |
| 186 | mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); |
| 187 | mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 188 | } |
| 189 | |
| 190 | @Override |
| 191 | public void addView(View child) { |
| 192 | if (getChildCount() > 0) { |
| 193 | throw new IllegalStateException("HorizontalScrollView can host only one direct child"); |
| 194 | } |
| 195 | |
| 196 | super.addView(child); |
| 197 | } |
| 198 | |
| 199 | @Override |
| 200 | public void addView(View child, int index) { |
| 201 | if (getChildCount() > 0) { |
| 202 | throw new IllegalStateException("HorizontalScrollView can host only one direct child"); |
| 203 | } |
| 204 | |
| 205 | super.addView(child, index); |
| 206 | } |
| 207 | |
| 208 | @Override |
| 209 | public void addView(View child, ViewGroup.LayoutParams params) { |
| 210 | if (getChildCount() > 0) { |
| 211 | throw new IllegalStateException("HorizontalScrollView can host only one direct child"); |
| 212 | } |
| 213 | |
| 214 | super.addView(child, params); |
| 215 | } |
| 216 | |
| 217 | @Override |
| 218 | public void addView(View child, int index, ViewGroup.LayoutParams params) { |
| 219 | if (getChildCount() > 0) { |
| 220 | throw new IllegalStateException("HorizontalScrollView can host only one direct child"); |
| 221 | } |
| 222 | |
| 223 | super.addView(child, index, params); |
| 224 | } |
| 225 | |
| 226 | /** |
| 227 | * @return Returns true this HorizontalScrollView can be scrolled |
| 228 | */ |
| 229 | private boolean canScroll() { |
| 230 | View child = getChildAt(0); |
| 231 | if (child != null) { |
| 232 | int childWidth = child.getWidth(); |
| 233 | return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; |
| 234 | } |
| 235 | return false; |
| 236 | } |
| 237 | |
| 238 | /** |
| 239 | * Indicates whether this ScrollView's content is stretched to fill the viewport. |
| 240 | * |
| 241 | * @return True if the content fills the viewport, false otherwise. |
| 242 | */ |
| 243 | public boolean isFillViewport() { |
| 244 | return mFillViewport; |
| 245 | } |
| 246 | |
| 247 | /** |
| 248 | * Indicates this ScrollView whether it should stretch its content width to fill |
| 249 | * the viewport or not. |
| 250 | * |
| 251 | * @param fillViewport True to stretch the content's width to the viewport's |
| 252 | * boundaries, false otherwise. |
| 253 | */ |
| 254 | public void setFillViewport(boolean fillViewport) { |
| 255 | if (fillViewport != mFillViewport) { |
| 256 | mFillViewport = fillViewport; |
| 257 | requestLayout(); |
| 258 | } |
| 259 | } |
| 260 | |
| 261 | /** |
| 262 | * @return Whether arrow scrolling will animate its transition. |
| 263 | */ |
| 264 | public boolean isSmoothScrollingEnabled() { |
| 265 | return mSmoothScrollingEnabled; |
| 266 | } |
| 267 | |
| 268 | /** |
| 269 | * Set whether arrow scrolling will animate its transition. |
| 270 | * @param smoothScrollingEnabled whether arrow scrolling will animate its transition |
| 271 | */ |
| 272 | public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { |
| 273 | mSmoothScrollingEnabled = smoothScrollingEnabled; |
| 274 | } |
| 275 | |
| 276 | @Override |
| 277 | protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { |
| 278 | super.onMeasure(widthMeasureSpec, heightMeasureSpec); |
| 279 | |
| 280 | if (!mFillViewport) { |
| 281 | return; |
| 282 | } |
| 283 | |
| 284 | final int widthMode = MeasureSpec.getMode(widthMeasureSpec); |
| 285 | if (widthMode == MeasureSpec.UNSPECIFIED) { |
| 286 | return; |
| 287 | } |
| 288 | |
| 289 | final View child = getChildAt(0); |
| 290 | int width = getMeasuredWidth(); |
Romain Guy | f83f59f | 2009-05-04 14:15:23 -0700 | [diff] [blame] | 291 | if (child.getMeasuredWidth() < width) { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 292 | final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); |
| 293 | |
| 294 | int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, mPaddingTop |
| 295 | + mPaddingBottom, lp.height); |
| 296 | width -= mPaddingLeft; |
| 297 | width -= mPaddingRight; |
| 298 | int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); |
| 299 | |
| 300 | child.measure(childWidthMeasureSpec, childHeightMeasureSpec); |
| 301 | } |
| 302 | } |
| 303 | |
| 304 | @Override |
| 305 | public boolean dispatchKeyEvent(KeyEvent event) { |
| 306 | // Let the focused view and/or our descendants get the key first |
| 307 | boolean handled = super.dispatchKeyEvent(event); |
| 308 | if (handled) { |
| 309 | return true; |
| 310 | } |
| 311 | return executeKeyEvent(event); |
| 312 | } |
| 313 | |
| 314 | /** |
| 315 | * You can call this function yourself to have the scroll view perform |
| 316 | * scrolling from a key event, just as if the event had been dispatched to |
| 317 | * it by the view hierarchy. |
| 318 | * |
| 319 | * @param event The key event to execute. |
| 320 | * @return Return true if the event was handled, else false. |
| 321 | */ |
| 322 | public boolean executeKeyEvent(KeyEvent event) { |
| 323 | mTempRect.setEmpty(); |
| 324 | |
| 325 | if (!canScroll()) { |
| 326 | if (isFocused()) { |
| 327 | View currentFocused = findFocus(); |
| 328 | if (currentFocused == this) currentFocused = null; |
| 329 | View nextFocused = FocusFinder.getInstance().findNextFocus(this, |
| 330 | currentFocused, View.FOCUS_RIGHT); |
| 331 | return nextFocused != null && nextFocused != this && |
| 332 | nextFocused.requestFocus(View.FOCUS_RIGHT); |
| 333 | } |
| 334 | return false; |
| 335 | } |
| 336 | |
| 337 | boolean handled = false; |
| 338 | if (event.getAction() == KeyEvent.ACTION_DOWN) { |
| 339 | switch (event.getKeyCode()) { |
| 340 | case KeyEvent.KEYCODE_DPAD_LEFT: |
| 341 | if (!event.isAltPressed()) { |
| 342 | handled = arrowScroll(View.FOCUS_LEFT); |
| 343 | } else { |
| 344 | handled = fullScroll(View.FOCUS_LEFT); |
| 345 | } |
| 346 | break; |
| 347 | case KeyEvent.KEYCODE_DPAD_RIGHT: |
| 348 | if (!event.isAltPressed()) { |
| 349 | handled = arrowScroll(View.FOCUS_RIGHT); |
| 350 | } else { |
| 351 | handled = fullScroll(View.FOCUS_RIGHT); |
| 352 | } |
| 353 | break; |
| 354 | case KeyEvent.KEYCODE_SPACE: |
| 355 | pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); |
| 356 | break; |
| 357 | } |
| 358 | } |
| 359 | |
| 360 | return handled; |
| 361 | } |
| 362 | |
| 363 | @Override |
| 364 | public boolean onInterceptTouchEvent(MotionEvent ev) { |
| 365 | /* |
| 366 | * This method JUST determines whether we want to intercept the motion. |
| 367 | * If we return true, onMotionEvent will be called and we do the actual |
| 368 | * scrolling there. |
| 369 | */ |
| 370 | |
| 371 | /* |
| 372 | * Shortcut the most recurring case: the user is in the dragging |
| 373 | * state and he is moving his finger. We want to intercept this |
| 374 | * motion. |
| 375 | */ |
| 376 | final int action = ev.getAction(); |
| 377 | if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { |
| 378 | return true; |
| 379 | } |
| 380 | |
| 381 | if (!canScroll()) { |
| 382 | mIsBeingDragged = false; |
| 383 | return false; |
| 384 | } |
| 385 | |
| 386 | final float x = ev.getX(); |
| 387 | |
| 388 | switch (action) { |
| 389 | case MotionEvent.ACTION_MOVE: |
| 390 | /* |
| 391 | * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check |
| 392 | * whether the user has moved far enough from his original down touch. |
| 393 | */ |
| 394 | |
| 395 | /* |
| 396 | * Locally do absolute value. mLastMotionX is set to the x value |
| 397 | * of the down event. |
| 398 | */ |
| 399 | final int xDiff = (int) Math.abs(x - mLastMotionX); |
| 400 | if (xDiff > mTouchSlop) { |
| 401 | mIsBeingDragged = true; |
| 402 | if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); |
| 403 | } |
| 404 | break; |
| 405 | |
| 406 | case MotionEvent.ACTION_DOWN: |
| 407 | /* Remember location of down touch */ |
| 408 | mLastMotionX = x; |
| 409 | |
| 410 | /* |
| 411 | * If being flinged and user touches the screen, initiate drag; |
| 412 | * otherwise don't. mScroller.isFinished should be false when |
| 413 | * being flinged. |
| 414 | */ |
| 415 | mIsBeingDragged = !mScroller.isFinished(); |
| 416 | break; |
| 417 | |
| 418 | case MotionEvent.ACTION_CANCEL: |
| 419 | case MotionEvent.ACTION_UP: |
| 420 | /* Release the drag */ |
| 421 | mIsBeingDragged = false; |
| 422 | break; |
| 423 | } |
| 424 | |
| 425 | /* |
| 426 | * The only time we want to intercept motion events is if we are in the |
| 427 | * drag mode. |
| 428 | */ |
| 429 | return mIsBeingDragged; |
| 430 | } |
| 431 | |
| 432 | @Override |
| 433 | public boolean onTouchEvent(MotionEvent ev) { |
| 434 | |
| 435 | if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) { |
| 436 | // Don't handle edge touches immediately -- they may actually belong to one of our |
| 437 | // descendants. |
| 438 | return false; |
| 439 | } |
| 440 | |
| 441 | if (!canScroll()) { |
| 442 | return false; |
| 443 | } |
| 444 | |
| 445 | if (mVelocityTracker == null) { |
| 446 | mVelocityTracker = VelocityTracker.obtain(); |
| 447 | } |
| 448 | mVelocityTracker.addMovement(ev); |
| 449 | |
| 450 | final int action = ev.getAction(); |
| 451 | final float x = ev.getX(); |
| 452 | |
| 453 | switch (action) { |
| 454 | case MotionEvent.ACTION_DOWN: |
| 455 | /* |
| 456 | * If being flinged and user touches, stop the fling. isFinished |
| 457 | * will be false if being flinged. |
| 458 | */ |
| 459 | if (!mScroller.isFinished()) { |
| 460 | mScroller.abortAnimation(); |
| 461 | } |
| 462 | |
| 463 | // Remember where the motion event started |
| 464 | mLastMotionX = x; |
| 465 | break; |
| 466 | case MotionEvent.ACTION_MOVE: |
| 467 | // Scroll to follow the motion event |
| 468 | final int deltaX = (int) (mLastMotionX - x); |
| 469 | mLastMotionX = x; |
| 470 | |
| 471 | if (deltaX < 0) { |
| 472 | if (mScrollX > 0) { |
| 473 | scrollBy(deltaX, 0); |
| 474 | } |
| 475 | } else if (deltaX > 0) { |
| 476 | final int rightEdge = getWidth() - mPaddingRight; |
| 477 | final int availableToScroll = getChildAt(0).getRight() - mScrollX - rightEdge; |
| 478 | if (availableToScroll > 0) { |
| 479 | scrollBy(Math.min(availableToScroll, deltaX), 0); |
| 480 | } |
| 481 | } |
| 482 | break; |
| 483 | case MotionEvent.ACTION_UP: |
| 484 | final VelocityTracker velocityTracker = mVelocityTracker; |
Romain Guy | 4296fc4 | 2009-07-06 11:48:52 -0700 | [diff] [blame^] | 485 | velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 486 | int initialVelocity = (int) velocityTracker.getXVelocity(); |
| 487 | |
Romain Guy | 4296fc4 | 2009-07-06 11:48:52 -0700 | [diff] [blame^] | 488 | if ((Math.abs(initialVelocity) > mMinimumVelocity) && getChildCount() > 0) { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 489 | fling(-initialVelocity); |
| 490 | } |
| 491 | |
| 492 | if (mVelocityTracker != null) { |
| 493 | mVelocityTracker.recycle(); |
| 494 | mVelocityTracker = null; |
| 495 | } |
| 496 | } |
| 497 | return true; |
| 498 | } |
| 499 | |
| 500 | /** |
| 501 | * <p> |
| 502 | * Finds the next focusable component that fits in this View's bounds |
| 503 | * (excluding fading edges) pretending that this View's left is located at |
| 504 | * the parameter left. |
| 505 | * </p> |
| 506 | * |
| 507 | * @param leftFocus look for a candidate is the one at the left of the bounds |
| 508 | * if leftFocus is true, or at the right of the bounds if leftFocus |
| 509 | * is false |
| 510 | * @param left the left offset of the bounds in which a focusable must be |
| 511 | * found (the fading edge is assumed to start at this position) |
| 512 | * @param preferredFocusable the View that has highest priority and will be |
| 513 | * returned if it is within my bounds (null is valid) |
| 514 | * @return the next focusable component in the bounds or null if none can be found |
| 515 | */ |
| 516 | private View findFocusableViewInMyBounds(final boolean leftFocus, |
| 517 | final int left, View preferredFocusable) { |
| 518 | /* |
| 519 | * The fading edge's transparent side should be considered for focus |
| 520 | * since it's mostly visible, so we divide the actual fading edge length |
| 521 | * by 2. |
| 522 | */ |
| 523 | final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; |
| 524 | final int leftWithoutFadingEdge = left + fadingEdgeLength; |
| 525 | final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; |
| 526 | |
| 527 | if ((preferredFocusable != null) |
| 528 | && (preferredFocusable.getLeft() < rightWithoutFadingEdge) |
| 529 | && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { |
| 530 | return preferredFocusable; |
| 531 | } |
| 532 | |
| 533 | return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, |
| 534 | rightWithoutFadingEdge); |
| 535 | } |
| 536 | |
| 537 | /** |
| 538 | * <p> |
| 539 | * Finds the next focusable component that fits in the specified bounds. |
| 540 | * </p> |
| 541 | * |
| 542 | * @param leftFocus look for a candidate is the one at the left of the bounds |
| 543 | * if leftFocus is true, or at the right of the bounds if |
| 544 | * leftFocus is false |
| 545 | * @param left the left offset of the bounds in which a focusable must be |
| 546 | * found |
| 547 | * @param right the right offset of the bounds in which a focusable must |
| 548 | * be found |
| 549 | * @return the next focusable component in the bounds or null if none can |
| 550 | * be found |
| 551 | */ |
| 552 | private View findFocusableViewInBounds(boolean leftFocus, int left, int right) { |
| 553 | |
| 554 | List<View> focusables = getFocusables(View.FOCUS_FORWARD); |
| 555 | View focusCandidate = null; |
| 556 | |
| 557 | /* |
| 558 | * A fully contained focusable is one where its left is below the bound's |
| 559 | * left, and its right is above the bound's right. A partially |
| 560 | * contained focusable is one where some part of it is within the |
| 561 | * bounds, but it also has some part that is not within bounds. A fully contained |
| 562 | * focusable is preferred to a partially contained focusable. |
| 563 | */ |
| 564 | boolean foundFullyContainedFocusable = false; |
| 565 | |
| 566 | int count = focusables.size(); |
| 567 | for (int i = 0; i < count; i++) { |
| 568 | View view = focusables.get(i); |
| 569 | int viewLeft = view.getLeft(); |
| 570 | int viewRight = view.getRight(); |
| 571 | |
| 572 | if (left < viewRight && viewLeft < right) { |
| 573 | /* |
| 574 | * the focusable is in the target area, it is a candidate for |
| 575 | * focusing |
| 576 | */ |
| 577 | |
| 578 | final boolean viewIsFullyContained = (left < viewLeft) && |
| 579 | (viewRight < right); |
| 580 | |
| 581 | if (focusCandidate == null) { |
| 582 | /* No candidate, take this one */ |
| 583 | focusCandidate = view; |
| 584 | foundFullyContainedFocusable = viewIsFullyContained; |
| 585 | } else { |
| 586 | final boolean viewIsCloserToBoundary = |
| 587 | (leftFocus && viewLeft < focusCandidate.getLeft()) || |
| 588 | (!leftFocus && viewRight > focusCandidate.getRight()); |
| 589 | |
| 590 | if (foundFullyContainedFocusable) { |
| 591 | if (viewIsFullyContained && viewIsCloserToBoundary) { |
| 592 | /* |
| 593 | * We're dealing with only fully contained views, so |
| 594 | * it has to be closer to the boundary to beat our |
| 595 | * candidate |
| 596 | */ |
| 597 | focusCandidate = view; |
| 598 | } |
| 599 | } else { |
| 600 | if (viewIsFullyContained) { |
| 601 | /* Any fully contained view beats a partially contained view */ |
| 602 | focusCandidate = view; |
| 603 | foundFullyContainedFocusable = true; |
| 604 | } else if (viewIsCloserToBoundary) { |
| 605 | /* |
| 606 | * Partially contained view beats another partially |
| 607 | * contained view if it's closer |
| 608 | */ |
| 609 | focusCandidate = view; |
| 610 | } |
| 611 | } |
| 612 | } |
| 613 | } |
| 614 | } |
| 615 | |
| 616 | return focusCandidate; |
| 617 | } |
| 618 | |
| 619 | /** |
| 620 | * <p>Handles scrolling in response to a "page up/down" shortcut press. This |
| 621 | * method will scroll the view by one page left or right and give the focus |
| 622 | * to the leftmost/rightmost component in the new visible area. If no |
| 623 | * component is a good candidate for focus, this scrollview reclaims the |
| 624 | * focus.</p> |
| 625 | * |
| 626 | * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} |
| 627 | * to go one page left or {@link android.view.View#FOCUS_RIGHT} |
| 628 | * to go one page right |
| 629 | * @return true if the key event is consumed by this method, false otherwise |
| 630 | */ |
| 631 | public boolean pageScroll(int direction) { |
| 632 | boolean right = direction == View.FOCUS_RIGHT; |
| 633 | int width = getWidth(); |
| 634 | |
| 635 | if (right) { |
| 636 | mTempRect.left = getScrollX() + width; |
| 637 | int count = getChildCount(); |
| 638 | if (count > 0) { |
| 639 | View view = getChildAt(count - 1); |
| 640 | if (mTempRect.left + width > view.getRight()) { |
| 641 | mTempRect.left = view.getRight() - width; |
| 642 | } |
| 643 | } |
| 644 | } else { |
| 645 | mTempRect.left = getScrollX() - width; |
| 646 | if (mTempRect.left < 0) { |
| 647 | mTempRect.left = 0; |
| 648 | } |
| 649 | } |
| 650 | mTempRect.right = mTempRect.left + width; |
| 651 | |
| 652 | return scrollAndFocus(direction, mTempRect.left, mTempRect.right); |
| 653 | } |
| 654 | |
| 655 | /** |
| 656 | * <p>Handles scrolling in response to a "home/end" shortcut press. This |
| 657 | * method will scroll the view to the left or right and give the focus |
| 658 | * to the leftmost/rightmost component in the new visible area. If no |
| 659 | * component is a good candidate for focus, this scrollview reclaims the |
| 660 | * focus.</p> |
| 661 | * |
| 662 | * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} |
| 663 | * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} |
| 664 | * to go the right |
| 665 | * @return true if the key event is consumed by this method, false otherwise |
| 666 | */ |
| 667 | public boolean fullScroll(int direction) { |
| 668 | boolean right = direction == View.FOCUS_RIGHT; |
| 669 | int width = getWidth(); |
| 670 | |
| 671 | mTempRect.left = 0; |
| 672 | mTempRect.right = width; |
| 673 | |
| 674 | if (right) { |
| 675 | int count = getChildCount(); |
| 676 | if (count > 0) { |
| 677 | View view = getChildAt(count - 1); |
| 678 | mTempRect.right = view.getRight(); |
| 679 | mTempRect.left = mTempRect.right - width; |
| 680 | } |
| 681 | } |
| 682 | |
| 683 | return scrollAndFocus(direction, mTempRect.left, mTempRect.right); |
| 684 | } |
| 685 | |
| 686 | /** |
| 687 | * <p>Scrolls the view to make the area defined by <code>left</code> and |
| 688 | * <code>right</code> visible. This method attempts to give the focus |
| 689 | * to a component visible in this area. If no component can be focused in |
| 690 | * the new visible area, the focus is reclaimed by this scrollview.</p> |
| 691 | * |
| 692 | * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} |
| 693 | * to go left {@link android.view.View#FOCUS_RIGHT} to right |
| 694 | * @param left the left offset of the new area to be made visible |
| 695 | * @param right the right offset of the new area to be made visible |
| 696 | * @return true if the key event is consumed by this method, false otherwise |
| 697 | */ |
| 698 | private boolean scrollAndFocus(int direction, int left, int right) { |
| 699 | boolean handled = true; |
| 700 | |
| 701 | int width = getWidth(); |
| 702 | int containerLeft = getScrollX(); |
| 703 | int containerRight = containerLeft + width; |
| 704 | boolean goLeft = direction == View.FOCUS_LEFT; |
| 705 | |
| 706 | View newFocused = findFocusableViewInBounds(goLeft, left, right); |
| 707 | if (newFocused == null) { |
| 708 | newFocused = this; |
| 709 | } |
| 710 | |
| 711 | if (left >= containerLeft && right <= containerRight) { |
| 712 | handled = false; |
| 713 | } else { |
| 714 | int delta = goLeft ? (left - containerLeft) : (right - containerRight); |
| 715 | doScrollX(delta); |
| 716 | } |
| 717 | |
| 718 | if (newFocused != findFocus() && newFocused.requestFocus(direction)) { |
| 719 | mScrollViewMovedFocus = true; |
| 720 | mScrollViewMovedFocus = false; |
| 721 | } |
| 722 | |
| 723 | return handled; |
| 724 | } |
| 725 | |
| 726 | /** |
| 727 | * Handle scrolling in response to a left or right arrow click. |
| 728 | * |
| 729 | * @param direction The direction corresponding to the arrow key that was |
| 730 | * pressed |
| 731 | * @return True if we consumed the event, false otherwise |
| 732 | */ |
| 733 | public boolean arrowScroll(int direction) { |
| 734 | |
| 735 | View currentFocused = findFocus(); |
| 736 | if (currentFocused == this) currentFocused = null; |
| 737 | |
| 738 | View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); |
| 739 | |
| 740 | final int maxJump = getMaxScrollAmount(); |
| 741 | |
| 742 | if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { |
| 743 | nextFocused.getDrawingRect(mTempRect); |
| 744 | offsetDescendantRectToMyCoords(nextFocused, mTempRect); |
| 745 | int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); |
| 746 | doScrollX(scrollDelta); |
| 747 | nextFocused.requestFocus(direction); |
| 748 | } else { |
| 749 | // no new focus |
| 750 | int scrollDelta = maxJump; |
| 751 | |
| 752 | if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { |
| 753 | scrollDelta = getScrollX(); |
| 754 | } else if (direction == View.FOCUS_RIGHT) { |
| 755 | |
| 756 | int daRight = getChildAt(getChildCount() - 1).getRight(); |
| 757 | |
| 758 | int screenRight = getScrollX() + getWidth(); |
| 759 | |
| 760 | if (daRight - screenRight < maxJump) { |
| 761 | scrollDelta = daRight - screenRight; |
| 762 | } |
| 763 | } |
| 764 | if (scrollDelta == 0) { |
| 765 | return false; |
| 766 | } |
| 767 | doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); |
| 768 | } |
| 769 | |
| 770 | if (currentFocused != null && currentFocused.isFocused() |
| 771 | && isOffScreen(currentFocused)) { |
| 772 | // previously focused item still has focus and is off screen, give |
| 773 | // it up (take it back to ourselves) |
| 774 | // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are |
| 775 | // sure to |
| 776 | // get it) |
| 777 | final int descendantFocusability = getDescendantFocusability(); // save |
| 778 | setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); |
| 779 | requestFocus(); |
| 780 | setDescendantFocusability(descendantFocusability); // restore |
| 781 | } |
| 782 | return true; |
| 783 | } |
| 784 | |
| 785 | /** |
| 786 | * @return whether the descendant of this scroll view is scrolled off |
| 787 | * screen. |
| 788 | */ |
| 789 | private boolean isOffScreen(View descendant) { |
| 790 | return !isWithinDeltaOfScreen(descendant, 0); |
| 791 | } |
| 792 | |
| 793 | /** |
| 794 | * @return whether the descendant of this scroll view is within delta |
| 795 | * pixels of being on the screen. |
| 796 | */ |
| 797 | private boolean isWithinDeltaOfScreen(View descendant, int delta) { |
| 798 | descendant.getDrawingRect(mTempRect); |
| 799 | offsetDescendantRectToMyCoords(descendant, mTempRect); |
| 800 | |
| 801 | return (mTempRect.right + delta) >= getScrollX() |
| 802 | && (mTempRect.left - delta) <= (getScrollX() + getWidth()); |
| 803 | } |
| 804 | |
| 805 | /** |
| 806 | * Smooth scroll by a X delta |
| 807 | * |
| 808 | * @param delta the number of pixels to scroll by on the X axis |
| 809 | */ |
| 810 | private void doScrollX(int delta) { |
| 811 | if (delta != 0) { |
| 812 | if (mSmoothScrollingEnabled) { |
| 813 | smoothScrollBy(delta, 0); |
| 814 | } else { |
| 815 | scrollBy(delta, 0); |
| 816 | } |
| 817 | } |
| 818 | } |
| 819 | |
| 820 | /** |
| 821 | * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. |
| 822 | * |
| 823 | * @param dx the number of pixels to scroll by on the X axis |
| 824 | * @param dy the number of pixels to scroll by on the Y axis |
| 825 | */ |
| 826 | public final void smoothScrollBy(int dx, int dy) { |
| 827 | long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; |
| 828 | if (duration > ANIMATED_SCROLL_GAP) { |
| 829 | mScroller.startScroll(mScrollX, mScrollY, dx, dy); |
| 830 | invalidate(); |
| 831 | } else { |
| 832 | if (!mScroller.isFinished()) { |
| 833 | mScroller.abortAnimation(); |
| 834 | } |
| 835 | scrollBy(dx, dy); |
| 836 | } |
| 837 | mLastScroll = AnimationUtils.currentAnimationTimeMillis(); |
| 838 | } |
| 839 | |
| 840 | /** |
| 841 | * Like {@link #scrollTo}, but scroll smoothly instead of immediately. |
| 842 | * |
| 843 | * @param x the position where to scroll on the X axis |
| 844 | * @param y the position where to scroll on the Y axis |
| 845 | */ |
| 846 | public final void smoothScrollTo(int x, int y) { |
| 847 | smoothScrollBy(x - mScrollX, y - mScrollY); |
| 848 | } |
| 849 | |
| 850 | /** |
| 851 | * <p>The scroll range of a scroll view is the overall width of all of its |
| 852 | * children.</p> |
| 853 | */ |
| 854 | @Override |
| 855 | protected int computeHorizontalScrollRange() { |
| 856 | int count = getChildCount(); |
| 857 | return count == 0 ? getWidth() : getChildAt(0).getRight(); |
| 858 | } |
| 859 | |
| 860 | |
| 861 | @Override |
| 862 | protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { |
| 863 | ViewGroup.LayoutParams lp = child.getLayoutParams(); |
| 864 | |
| 865 | int childWidthMeasureSpec; |
| 866 | int childHeightMeasureSpec; |
| 867 | |
| 868 | childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop |
| 869 | + mPaddingBottom, lp.height); |
| 870 | |
| 871 | childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); |
| 872 | |
| 873 | child.measure(childWidthMeasureSpec, childHeightMeasureSpec); |
| 874 | } |
| 875 | |
| 876 | @Override |
| 877 | protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, |
| 878 | int parentHeightMeasureSpec, int heightUsed) { |
| 879 | final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); |
| 880 | |
| 881 | final int childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, |
| 882 | mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin |
| 883 | + heightUsed, lp.height); |
| 884 | final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( |
| 885 | lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); |
| 886 | |
| 887 | child.measure(childWidthMeasureSpec, childHeightMeasureSpec); |
| 888 | } |
| 889 | |
| 890 | @Override |
| 891 | public void computeScroll() { |
| 892 | if (mScroller.computeScrollOffset()) { |
| 893 | // This is called at drawing time by ViewGroup. We don't want to |
| 894 | // re-show the scrollbars at this point, which scrollTo will do, |
| 895 | // so we replicate most of scrollTo here. |
| 896 | // |
| 897 | // It's a little odd to call onScrollChanged from inside the drawing. |
| 898 | // |
| 899 | // It is, except when you remember that computeScroll() is used to |
| 900 | // animate scrolling. So unless we want to defer the onScrollChanged() |
| 901 | // until the end of the animated scrolling, we don't really have a |
| 902 | // choice here. |
| 903 | // |
| 904 | // I agree. The alternative, which I think would be worse, is to post |
| 905 | // something and tell the subclasses later. This is bad because there |
| 906 | // will be a window where mScrollX/Y is different from what the app |
| 907 | // thinks it is. |
| 908 | // |
| 909 | int oldX = mScrollX; |
| 910 | int oldY = mScrollY; |
| 911 | int x = mScroller.getCurrX(); |
| 912 | int y = mScroller.getCurrY(); |
| 913 | if (getChildCount() > 0) { |
| 914 | View child = getChildAt(0); |
| 915 | mScrollX = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); |
| 916 | mScrollY = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); |
| 917 | } else { |
| 918 | mScrollX = x; |
| 919 | mScrollY = y; |
| 920 | } |
| 921 | if (oldX != mScrollX || oldY != mScrollY) { |
| 922 | onScrollChanged(mScrollX, mScrollY, oldX, oldY); |
| 923 | } |
| 924 | |
| 925 | // Keep on drawing until the animation has finished. |
| 926 | postInvalidate(); |
| 927 | } |
| 928 | } |
| 929 | |
| 930 | /** |
| 931 | * Scrolls the view to the given child. |
| 932 | * |
| 933 | * @param child the View to scroll to |
| 934 | */ |
| 935 | private void scrollToChild(View child) { |
| 936 | child.getDrawingRect(mTempRect); |
| 937 | |
| 938 | /* Offset from child's local coordinates to ScrollView coordinates */ |
| 939 | offsetDescendantRectToMyCoords(child, mTempRect); |
| 940 | |
| 941 | int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); |
| 942 | |
| 943 | if (scrollDelta != 0) { |
| 944 | scrollBy(scrollDelta, 0); |
| 945 | } |
| 946 | } |
| 947 | |
| 948 | /** |
| 949 | * If rect is off screen, scroll just enough to get it (or at least the |
| 950 | * first screen size chunk of it) on screen. |
| 951 | * |
| 952 | * @param rect The rectangle. |
| 953 | * @param immediate True to scroll immediately without animation |
| 954 | * @return true if scrolling was performed |
| 955 | */ |
| 956 | private boolean scrollToChildRect(Rect rect, boolean immediate) { |
| 957 | final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); |
| 958 | final boolean scroll = delta != 0; |
| 959 | if (scroll) { |
| 960 | if (immediate) { |
| 961 | scrollBy(delta, 0); |
| 962 | } else { |
| 963 | smoothScrollBy(delta, 0); |
| 964 | } |
| 965 | } |
| 966 | return scroll; |
| 967 | } |
| 968 | |
| 969 | /** |
| 970 | * Compute the amount to scroll in the X direction in order to get |
| 971 | * a rectangle completely on the screen (or, if taller than the screen, |
| 972 | * at least the first screen size chunk of it). |
| 973 | * |
| 974 | * @param rect The rect. |
| 975 | * @return The scroll delta. |
| 976 | */ |
| 977 | protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { |
| 978 | |
| 979 | int width = getWidth(); |
| 980 | int screenLeft = getScrollX(); |
| 981 | int screenRight = screenLeft + width; |
| 982 | |
| 983 | int fadingEdge = getHorizontalFadingEdgeLength(); |
| 984 | |
| 985 | // leave room for left fading edge as long as rect isn't at very left |
| 986 | if (rect.left > 0) { |
| 987 | screenLeft += fadingEdge; |
| 988 | } |
| 989 | |
| 990 | // leave room for right fading edge as long as rect isn't at very right |
| 991 | if (rect.right < getChildAt(0).getWidth()) { |
| 992 | screenRight -= fadingEdge; |
| 993 | } |
| 994 | |
| 995 | int scrollXDelta = 0; |
| 996 | |
| 997 | if (rect.right > screenRight && rect.left > screenLeft) { |
| 998 | // need to move right to get it in view: move right just enough so |
| 999 | // that the entire rectangle is in view (or at least the first |
| 1000 | // screen size chunk). |
| 1001 | |
| 1002 | if (rect.width() > width) { |
| 1003 | // just enough to get screen size chunk on |
| 1004 | scrollXDelta += (rect.left - screenLeft); |
| 1005 | } else { |
| 1006 | // get entire rect at right of screen |
| 1007 | scrollXDelta += (rect.right - screenRight); |
| 1008 | } |
| 1009 | |
| 1010 | // make sure we aren't scrolling beyond the end of our content |
| 1011 | int right = getChildAt(getChildCount() - 1).getRight(); |
| 1012 | int distanceToRight = right - screenRight; |
| 1013 | scrollXDelta = Math.min(scrollXDelta, distanceToRight); |
| 1014 | |
| 1015 | } else if (rect.left < screenLeft && rect.right < screenRight) { |
| 1016 | // need to move right to get it in view: move right just enough so that |
| 1017 | // entire rectangle is in view (or at least the first screen |
| 1018 | // size chunk of it). |
| 1019 | |
| 1020 | if (rect.width() > width) { |
| 1021 | // screen size chunk |
| 1022 | scrollXDelta -= (screenRight - rect.right); |
| 1023 | } else { |
| 1024 | // entire rect at left |
| 1025 | scrollXDelta -= (screenLeft - rect.left); |
| 1026 | } |
| 1027 | |
| 1028 | // make sure we aren't scrolling any further than the left our content |
| 1029 | scrollXDelta = Math.max(scrollXDelta, -getScrollX()); |
| 1030 | } |
| 1031 | return scrollXDelta; |
| 1032 | } |
| 1033 | |
| 1034 | @Override |
| 1035 | public void requestChildFocus(View child, View focused) { |
| 1036 | if (!mScrollViewMovedFocus) { |
| 1037 | if (!mIsLayoutDirty) { |
| 1038 | scrollToChild(focused); |
| 1039 | } else { |
| 1040 | // The child may not be laid out yet, we can't compute the scroll yet |
| 1041 | mChildToScrollTo = focused; |
| 1042 | } |
| 1043 | } |
| 1044 | super.requestChildFocus(child, focused); |
| 1045 | } |
| 1046 | |
| 1047 | |
| 1048 | /** |
| 1049 | * When looking for focus in children of a scroll view, need to be a little |
| 1050 | * more careful not to give focus to something that is scrolled off screen. |
| 1051 | * |
| 1052 | * This is more expensive than the default {@link android.view.ViewGroup} |
| 1053 | * implementation, otherwise this behavior might have been made the default. |
| 1054 | */ |
| 1055 | @Override |
| 1056 | protected boolean onRequestFocusInDescendants(int direction, |
| 1057 | Rect previouslyFocusedRect) { |
| 1058 | |
| 1059 | // convert from forward / backward notation to up / down / left / right |
| 1060 | // (ugh). |
| 1061 | if (direction == View.FOCUS_FORWARD) { |
| 1062 | direction = View.FOCUS_RIGHT; |
| 1063 | } else if (direction == View.FOCUS_BACKWARD) { |
| 1064 | direction = View.FOCUS_LEFT; |
| 1065 | } |
| 1066 | |
| 1067 | final View nextFocus = previouslyFocusedRect == null ? |
| 1068 | FocusFinder.getInstance().findNextFocus(this, null, direction) : |
| 1069 | FocusFinder.getInstance().findNextFocusFromRect(this, |
| 1070 | previouslyFocusedRect, direction); |
| 1071 | |
| 1072 | if (nextFocus == null) { |
| 1073 | return false; |
| 1074 | } |
| 1075 | |
| 1076 | if (isOffScreen(nextFocus)) { |
| 1077 | return false; |
| 1078 | } |
| 1079 | |
| 1080 | return nextFocus.requestFocus(direction, previouslyFocusedRect); |
| 1081 | } |
| 1082 | |
| 1083 | @Override |
| 1084 | public boolean requestChildRectangleOnScreen(View child, Rect rectangle, |
| 1085 | boolean immediate) { |
| 1086 | // offset into coordinate space of this scroll view |
| 1087 | rectangle.offset(child.getLeft() - child.getScrollX(), |
| 1088 | child.getTop() - child.getScrollY()); |
| 1089 | |
| 1090 | return scrollToChildRect(rectangle, immediate); |
| 1091 | } |
| 1092 | |
| 1093 | @Override |
| 1094 | public void requestLayout() { |
| 1095 | mIsLayoutDirty = true; |
| 1096 | super.requestLayout(); |
| 1097 | } |
| 1098 | |
| 1099 | @Override |
| 1100 | protected void onLayout(boolean changed, int l, int t, int r, int b) { |
| 1101 | super.onLayout(changed, l, t, r, b); |
| 1102 | mIsLayoutDirty = false; |
| 1103 | // Give a child focus if it needs it |
| 1104 | if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { |
| 1105 | scrollToChild(mChildToScrollTo); |
| 1106 | } |
| 1107 | mChildToScrollTo = null; |
| 1108 | |
| 1109 | // Calling this with the present values causes it to re-clam them |
| 1110 | scrollTo(mScrollX, mScrollY); |
| 1111 | } |
| 1112 | |
| 1113 | @Override |
| 1114 | protected void onSizeChanged(int w, int h, int oldw, int oldh) { |
| 1115 | super.onSizeChanged(w, h, oldw, oldh); |
| 1116 | |
| 1117 | View currentFocused = findFocus(); |
| 1118 | if (null == currentFocused || this == currentFocused) |
| 1119 | return; |
| 1120 | |
| 1121 | final int maxJump = mRight - mLeft; |
| 1122 | |
| 1123 | if (isWithinDeltaOfScreen(currentFocused, maxJump)) { |
| 1124 | currentFocused.getDrawingRect(mTempRect); |
| 1125 | offsetDescendantRectToMyCoords(currentFocused, mTempRect); |
| 1126 | int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); |
| 1127 | doScrollX(scrollDelta); |
| 1128 | } |
| 1129 | } |
| 1130 | |
| 1131 | /** |
| 1132 | * Return true if child is an descendant of parent, (or equal to the parent). |
| 1133 | */ |
| 1134 | private boolean isViewDescendantOf(View child, View parent) { |
| 1135 | if (child == parent) { |
| 1136 | return true; |
| 1137 | } |
| 1138 | |
| 1139 | final ViewParent theParent = child.getParent(); |
| 1140 | return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); |
| 1141 | } |
| 1142 | |
| 1143 | /** |
| 1144 | * Fling the scroll view |
| 1145 | * |
| 1146 | * @param velocityX The initial velocity in the X direction. Positive |
| 1147 | * numbers mean that the finger/curor is moving down the screen, |
| 1148 | * which means we want to scroll towards the left. |
| 1149 | */ |
| 1150 | public void fling(int velocityX) { |
| 1151 | int width = getWidth() - mPaddingRight - mPaddingLeft; |
| 1152 | int right = getChildAt(0).getWidth(); |
| 1153 | |
| 1154 | mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, right - width, 0, 0); |
| 1155 | |
| 1156 | final boolean movingRight = velocityX > 0; |
| 1157 | |
| 1158 | View newFocused = findFocusableViewInMyBounds(movingRight, |
| 1159 | mScroller.getFinalX(), findFocus()); |
| 1160 | |
| 1161 | if (newFocused == null) { |
| 1162 | newFocused = this; |
| 1163 | } |
| 1164 | |
| 1165 | if (newFocused != findFocus() |
| 1166 | && newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT)) { |
| 1167 | mScrollViewMovedFocus = true; |
| 1168 | mScrollViewMovedFocus = false; |
| 1169 | } |
| 1170 | |
| 1171 | invalidate(); |
| 1172 | } |
| 1173 | |
| 1174 | /** |
| 1175 | * {@inheritDoc} |
| 1176 | * |
| 1177 | * <p>This version also clamps the scrolling to the bounds of our child. |
| 1178 | */ |
| 1179 | public void scrollTo(int x, int y) { |
| 1180 | // we rely on the fact the View.scrollBy calls scrollTo. |
| 1181 | if (getChildCount() > 0) { |
| 1182 | View child = getChildAt(0); |
| 1183 | x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth()); |
| 1184 | y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight()); |
| 1185 | if (x != mScrollX || y != mScrollY) { |
| 1186 | super.scrollTo(x, y); |
| 1187 | } |
| 1188 | } |
| 1189 | } |
| 1190 | |
| 1191 | private int clamp(int n, int my, int child) { |
| 1192 | if (my >= child || n < 0) { |
| 1193 | return 0; |
| 1194 | } |
| 1195 | if ((my + n) > child) { |
| 1196 | return child - my; |
| 1197 | } |
| 1198 | return n; |
| 1199 | } |
| 1200 | } |