added scale animation for context menu

chrome/android/java/src/org/chromium/chrome/browser/widget/ContextMenuDialog.java

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.widget;
+
+import android.app.Activity;
+import android.support.v4.view.animation.LinearOutSlowInInterpolator;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.animation.Animation;
+import android.view.animation.Animation.AnimationListener;
+import android.view.animation.ScaleAnimation;
+
+/**
+ * AlwaysDismissedDialog that ensures that the dialog animates when it's being dismissed.

[Theresa, 2017/05/24 20:16:33]

nit: The class comment and class name don't really match. I think the comment
should talk about the context menu.

[Daniel Park, 2017/05/24 22:34:31]

Done.

+ */
+public class ContextMenuDialog extends AlwaysDismissedDialog {
+    private View mPagerView;
+    private float mContextMenuDestinationX;
+    private float mContextMenuDestinationY;
+    private int mContextMenuFirstLocationY;
+
+    private static final int ANIMATION_IN_DURATION = 250;
+    // Animation out duration should be set to 60% of the animation in duration.
+    private static final int ANIMATION_OUT_DURATION = 150;
+
+    public ContextMenuDialog(Activity ownerActivity, int theme) {
+        super(ownerActivity, theme);
+    }
+
+    public void setExitAnimationParameters(View pagerView, float contextMenuDestinationX,

[Theresa, 2017/05/24 20:16:33]

nit: JavaDocs for this. Also, does it matter that this is the pagerView or
should we call it contentView or something else more generic?

[Daniel Park, 2017/05/24 22:34:31]

Done.

+            float contextMenuDestinationY, int contextMenuFirstLocationY) {
+        mPagerView = pagerView;
+        mContextMenuDestinationX = contextMenuDestinationX;
+        mContextMenuDestinationY = contextMenuDestinationY;
+        mContextMenuFirstLocationY = contextMenuFirstLocationY;
+    }
+
+    @Override
+    public void dismiss() {
+        int[] contextMenuFinalLocation = new int[2];
+        mPagerView.getLocationOnScreen(contextMenuFinalLocation);
+        // Recalculate mContextMenuDestinationY because the final tab shown may have caused the view
+        // height to change
+        mContextMenuDestinationY = mContextMenuDestinationY
+                + (mContextMenuFirstLocationY - contextMenuFinalLocation[1]);
+
+        Animation exitAnimation =
+                getScaleAnimation(false, mContextMenuDestinationX, mContextMenuDestinationY);
+        exitAnimation.setAnimationListener(new AnimationListener() {
+
+            @Override
+            public void onAnimationStart(Animation animation) {}
+
+            @Override
+            public void onAnimationRepeat(Animation animation) {}
+
+            @Override
+            public void onAnimationEnd(Animation animation) {
+                ContextMenuDialog.super.dismiss();
+            }
+        });
+        mPagerView.startAnimation(exitAnimation);
+    }
+
+    @Override
+    public boolean onTouchEvent(MotionEvent event) {
+        if (event.getAction() == MotionEvent.ACTION_DOWN) {
+            this.dismiss();
+        }
+        return true;
+    }
+
+    /**
+     * @param isEnterAnimation Whether or not the animation will be for when the context menu enters
+     *                         or not.
+     * @param pivotX The X coordinate of the point about which the object is being scaled, specified
+     *               as an absolute number where 0 is the left edge.
+     * @param pivotY The Y coordinate of the point about which the object is being scaled, specified
+     *               as an absolute number where 0 is the top edge.
+     * @return Returns the scale animation for the context menu.
+     */
+
+    public Animation getScaleAnimation(boolean isEnterAnimation, float pivotX, float pivotY) {
+        float fromX = isEnterAnimation ? 0f : 1f;
+        float toX = isEnterAnimation ? 1f : 0f;
+        float fromY = fromX;
+        float toY = toX;
+
+        ScaleAnimation animation = new ScaleAnimation(
+                fromX, toX, fromY, toY, Animation.ABSOLUTE, pivotX, Animation.ABSOLUTE, pivotY);
+
+        long duration = isEnterAnimation ? ANIMATION_IN_DURATION : ANIMATION_OUT_DURATION;
+
+        animation.setDuration(duration);
+        animation.setInterpolator(new LinearOutSlowInInterpolator());
+        return animation;
+    }
+}