[Custom Tabs]Introduce the url scaling animation

chrome/android/java/src/org/chromium/chrome/browser/toolbar/CustomTabToolbarAnimationDelegate.java

Index: chrome/android/java/src/org/chromium/chrome/browser/toolbar/CustomTabToolbarAnimationDelegate.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/toolbar/CustomTabToolbarAnimationDelegate.java b/chrome/android/java/src/org/chromium/chrome/browser/toolbar/CustomTabToolbarAnimationDelegate.java
index 31a8b33ca9f5ea1facc8ac87319da5733688342e..f2f10ffcdd896092f9d0746b910b600928037277 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/toolbar/CustomTabToolbarAnimationDelegate.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/toolbar/CustomTabToolbarAnimationDelegate.java
@@ -8,13 +8,25 @@ import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
 import android.animation.AnimatorSet;
 import android.animation.ObjectAnimator;
+import android.content.Context;
+import android.util.TypedValue;
 import android.view.View;
+import android.widget.TextView;
 
 import org.chromium.chrome.R;
 import org.chromium.ui.interpolators.BakedBezierInterpolator;
 
 /**
- * A delegate class to handle animations in {@link CustomTabToolbar}.
+ * A delegate class to handle the title animation and security icon fading animation in
+ * {@link CustomTabToolbar}.
+ * <p>
+ * How does the title animation work?
+ * <p>
+ * 1. The title bar is set from {@link View#GONE} to {@link View#VISIBLE}, which triggers a relayout
+ * of the location bar. 2. On relayout, the newly positioned urlbar will be moved&scaled to look
+ * exactly the same as before the relayout. (Note the scale factor is calculated based on
+ * {@link TextView#getTextSize()}, not height or width.) 3. Finally the urlbar will be animated to
+ * its new position.
  */
 class CustomTabToolbarAnimationDelegate {
     private static final int CUSTOM_TAB_TOOLBAR_SLIDE_DURATION_MS = 200;
@@ -24,6 +36,11 @@ class CustomTabToolbarAnimationDelegate {
     private final AnimatorSet mSecurityButtonShowAnimator;
     private final AnimatorSet mSecurityButtonHideAnimator;
 
+    private TextView mUrlBar;
+    private TextView mTitleBar;
+    // A flag controlling whether the animation has run before.
+    private boolean mShouldRunTitleAnimation;
+
     /**
      * Constructs an instance of {@link CustomTabToolbarAnimationDelegate}.
      */
@@ -70,6 +87,66 @@ class CustomTabToolbarAnimationDelegate {
         mSecurityButtonHideAnimator.playSequentially(fadeOut, translateLeft);
     }
 
+    void prepareTitleAnim(TextView urlBar, TextView titleBar) {
+        mTitleBar = titleBar;
+        mUrlBar = urlBar;
+        mUrlBar.setPivotX(0f);
+        mUrlBar.setPivotY(0f);
+        mShouldRunTitleAnimation = true;
+    }
+
+    /**
+     * Starts animation for urlbar scaling and title fading-in. If this animation has already run
+     * once, does nothing.
+     */
+    void startTitleAnimation(Context context) {
+        if (!mShouldRunTitleAnimation) return;
+        mShouldRunTitleAnimation = false;
+
+        mTitleBar.setVisibility(View.VISIBLE);
+        mTitleBar.setAlpha(0f);
+
+        float newSizeSp = context.getResources().getDimension(R.dimen.custom_tabs_url_text_size);
+
+        float oldSizePx = mUrlBar.getTextSize();
+        mUrlBar.setTextSize(TypedValue.COMPLEX_UNIT_PX, newSizeSp);
+        float newSizePx = mUrlBar.getTextSize();
+        final float scale = oldSizePx / newSizePx;
+
+        // View#getY() cannot be used because the boundary of the parent will change after relayout.
+        final int[] oldLoc = new int[2];
+        mUrlBar.getLocationInWindow(oldLoc);
+
+        mUrlBar.requestLayout();
+        mUrlBar.addOnLayoutChangeListener(new View.OnLayoutChangeListener() {
+            @Override
+            public void onLayoutChange(View v, int left, int top, int right, int bottom,
+                    int oldLeft, int oldTop, int oldRight, int oldBottom) {
+                mUrlBar.removeOnLayoutChangeListener(this);
+
+                int[] newLoc = new int[2];
+                mUrlBar.getLocationInWindow(newLoc);
+
+                mUrlBar.setScaleX(scale);
+                mUrlBar.setScaleY(scale);
+                mUrlBar.setTranslationX(oldLoc[0] - newLoc[0]);
+                mUrlBar.setTranslationY(oldLoc[1] - newLoc[1]);
+
+                mUrlBar.animate().scaleX(1f).scaleY(1f).translationX(0).translationY(0)
+                        .setDuration(CUSTOM_TAB_TOOLBAR_SLIDE_DURATION_MS)
+                        .setInterpolator(BakedBezierInterpolator.TRANSFORM_CURVE)
+                        .setListener(new AnimatorListenerAdapter() {
+                            @Override
+                            public void onAnimationEnd(Animator animation) {
+                                mTitleBar.animate().alpha(1f)
+                                    .setInterpolator(BakedBezierInterpolator.FADE_IN_CURVE)
+                                    .setDuration(CUSTOM_TAB_TOOLBAR_FADE_DURATION_MS).start();
+                            }
+                        }).start();
+            }
+        });
+    }
+
     /**
      * Starts the animation to show the security button. Will do nothing if the button is already
      * visible.