Implement ViewDragHelper to pull down history.
Bug: 31623549
Change-Id: Ie5c9bc0afef59f0922bd87bee709d04d294f24b9
diff --git a/src/com/android/calculator2/DragLayout.java b/src/com/android/calculator2/DragLayout.java
new file mode 100644
index 0000000..93a5974
--- /dev/null
+++ b/src/com/android/calculator2/DragLayout.java
@@ -0,0 +1,247 @@
+/*
+ * Copyright (C) 2016 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.calculator2;
+
+import android.content.Context;
+import android.graphics.Rect;
+import android.os.Bundle;
+import android.os.Parcelable;
+import android.support.v4.view.ViewCompat;
+import android.support.v4.widget.ViewDragHelper;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.view.View;
+import android.widget.FrameLayout;
+import android.widget.RelativeLayout;
+
+public class DragLayout extends RelativeLayout {
+
+ private static final double AUTO_OPEN_SPEED_LIMIT = 800.0;
+ private static final String KEY_IS_OPEN = "IS_OPEN";
+ private static final String KEY_SUPER_STATE = "SUPER_STATE";
+
+ private final Rect mHitRect = new Rect();
+
+ private CalculatorDisplay mCalculatorDisplay;
+ private FrameLayout mHistoryFrame;
+ private ViewDragHelper mDragHelper;
+
+ private OnDragCallback mOnDragCallback;
+
+ private int mDraggingState = ViewDragHelper.STATE_IDLE;
+ private int mDraggingBorder;
+ private int mVerticalRange;
+ private boolean mIsOpen;
+
+ public DragLayout(Context context, AttributeSet attrs) {
+ super(context, attrs);
+ }
+
+ @Override
+ protected void onFinishInflate() {
+ mDragHelper = ViewDragHelper.create(this, 1.0f, new DragHelperCallback());
+ mHistoryFrame = (FrameLayout) findViewById(R.id.history_frame);
+ mCalculatorDisplay = (CalculatorDisplay) findViewById(R.id.display);
+ super.onFinishInflate();
+ }
+
+ @Override
+ protected void onLayout(boolean changed, int l, int t, int r, int b) {
+ super.onLayout(changed, l, t, r, b);
+ if (changed) {
+ mHistoryFrame.setTranslationY(-(b - t) + mCalculatorDisplay.getBottom());
+
+ if (mIsOpen) {
+ setOpen();
+ }
+ }
+ }
+
+ @Override
+ protected void onSizeChanged(int w, int h, int oldw, int oldh) {
+ mVerticalRange = h - mCalculatorDisplay.getMeasuredHeight();
+ super.onSizeChanged(w, h, oldw, oldh);
+ }
+
+ @Override
+ protected Parcelable onSaveInstanceState() {
+ final Bundle bundle = new Bundle();
+ bundle.putParcelable(KEY_SUPER_STATE, super.onSaveInstanceState());
+ bundle.putBoolean(KEY_IS_OPEN, mIsOpen);
+ return bundle;
+ }
+
+ @Override
+ protected void onRestoreInstanceState(Parcelable state) {
+ if (state instanceof Bundle) {
+ final Bundle bundle = (Bundle) state;
+ mIsOpen = bundle.getBoolean(KEY_IS_OPEN);
+ state = bundle.getParcelable(KEY_SUPER_STATE);
+ }
+ super.onRestoreInstanceState(state);
+ }
+
+ @Override
+ public boolean onInterceptTouchEvent(MotionEvent event) {
+ return (isDisplayTarget(event) || isHistoryTarget(event))
+ && mDragHelper.shouldInterceptTouchEvent(event);
+ }
+
+ @Override
+ public boolean onTouchEvent(MotionEvent event) {
+ if (isDisplayTarget(event) || isHistoryTarget(event) || isMoving()) {
+ mDragHelper.processTouchEvent(event);
+ return true;
+ } else {
+ return super.onTouchEvent(event);
+ }
+ }
+
+ @Override
+ public void computeScroll() {
+ if (mDragHelper.continueSettling(true)) {
+ ViewCompat.postInvalidateOnAnimation(this);
+ }
+ }
+
+ private void onStartDragging() {
+ mOnDragCallback.onStartDragging();
+ mHistoryFrame.setVisibility(VISIBLE);
+ }
+
+ private boolean isViewTarget(View view, MotionEvent event) {
+ view.getHitRect(mHitRect);
+ offsetDescendantRectToMyCoords(view, mHitRect);
+ return mHitRect.contains((int) event.getRawX(), (int) event.getRawY());
+ }
+
+ private boolean isDisplayTarget(MotionEvent event) {
+ return isViewTarget(mCalculatorDisplay, event);
+ }
+
+ private boolean isHistoryTarget(MotionEvent event) {
+ return isViewTarget(mHistoryFrame, event);
+ }
+
+ public boolean isMoving() {
+ return mDraggingState == ViewDragHelper.STATE_DRAGGING
+ || mDraggingState == ViewDragHelper.STATE_SETTLING;
+ }
+
+ public boolean isOpen() {
+ return mIsOpen;
+ }
+
+ public void setOpen() {
+ mDragHelper.smoothSlideViewTo(mHistoryFrame, 0, mVerticalRange);
+ mIsOpen = true;
+ mHistoryFrame.setVisibility(VISIBLE);
+ }
+
+ public void setClosed() {
+ mDragHelper.smoothSlideViewTo(mHistoryFrame, 0, 0);
+ mIsOpen = false;
+ mOnDragCallback.onDragToClose();
+ mHistoryFrame.setVisibility(GONE);
+ }
+
+ public void setOnDragCallback(OnDragCallback callback) {
+ mOnDragCallback = callback;
+ }
+
+ public interface OnDragCallback {
+ // Callback when a drag in any direction begins.
+ void onStartDragging();
+
+ // Callback when a drag is used to close.
+ void onDragToClose();
+ }
+
+ public class DragHelperCallback extends ViewDragHelper.Callback {
+ @Override
+ public void onViewDragStateChanged(int state) {
+ if (state == mDraggingState) {
+ // No change.
+ return;
+ }
+ if ((mDraggingState == ViewDragHelper.STATE_DRAGGING
+ || mDraggingState == ViewDragHelper.STATE_SETTLING)
+ && state == ViewDragHelper.STATE_IDLE) {
+ // The view stopped moving.
+ if (mDraggingBorder == 0) {
+ setClosed();
+ } else if (mDraggingBorder == mVerticalRange) {
+ setOpen();
+ }
+ }
+ if (state == ViewDragHelper.STATE_DRAGGING) {
+ onStartDragging();
+ }
+ mDraggingState = state;
+ }
+
+ @Override
+ public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {
+ mDraggingBorder = top;
+ }
+
+ @Override
+ public int getViewVerticalDragRange(View child) {
+ return mVerticalRange;
+ }
+
+ @Override
+ public boolean tryCaptureView(View view, int i) {
+ return view.getId() == R.id.history_frame;
+ }
+
+ @Override
+ public int clampViewPositionVertical(View child, int top, int dy) {
+ final int topBound = getPaddingTop();
+ final int bottomBound = mVerticalRange;
+ return Math.min(Math.max(top, topBound), bottomBound);
+ }
+
+ @Override
+ public void onViewReleased(View releasedChild, float xvel, float yvel) {
+ if (mDraggingBorder == 0) {
+ setClosed();
+ return;
+ }
+ if (mDraggingBorder == mVerticalRange) {
+ setOpen();
+ return;
+ }
+ boolean settleToOpen = false;
+ final float threshold = mVerticalRange / 2;
+ if (yvel > AUTO_OPEN_SPEED_LIMIT) {
+ // Speed has priority over position.
+ settleToOpen = true;
+ } else if (yvel < -AUTO_OPEN_SPEED_LIMIT) {
+ settleToOpen = false;
+ } else if (mDraggingBorder > threshold) {
+ settleToOpen = true;
+ } else if (mDraggingBorder < threshold) {
+ settleToOpen = false;
+ }
+
+ if (mDragHelper.settleCapturedViewAt(0, settleToOpen ? mVerticalRange : 0)) {
+ ViewCompat.postInvalidateOnAnimation(DragLayout.this);
+ }
+ }
+ }
+}
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