Update tab scale in Android non-overlapping tab switcher

This CL updates the tab sizing in the new Android non-overlapping tab switcher.
We scale the width by 80% when there's one tab open and 60% when there's more
than one open. When there's only one tab open, we crop the bottom to maintain
constant height.

Bug: 828224
Change-Id: I0c8e47bbec01f25a9d54a810b1846f5f7ab0f18b
Reviewed-on: https://chromium-review.googlesource.com/1066993
Commit-Queue: Ryan Landay <rlanday@chromium.org>
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#560803}

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/phone/SimpleAnimationLayout.java

@@ -21,7 +21,6 @@ import org.chromium.chrome.browser.compositor.layouts.content.TabContentManager;
 import org.chromium.chrome.browser.compositor.layouts.eventfilter.BlackHoleEventFilter;
 import org.chromium.chrome.browser.compositor.layouts.eventfilter.EventFilter;
 import org.chromium.chrome.browser.compositor.layouts.phone.stack.Stack;
-import org.chromium.chrome.browser.compositor.layouts.phone.stack.StackAnimation;
 import org.chromium.chrome.browser.compositor.scene_layer.SceneLayer;
 import org.chromium.chrome.browser.compositor.scene_layer.TabListSceneLayer;
 import org.chromium.chrome.browser.fullscreen.ChromeFullscreenManager;
@@ -48,6 +47,9 @@ public class SimpleAnimationLayout extends Layout {
     /** The animation for a tab being created in the background. */
     private AnimatorSet mTabCreatedBackgroundAnimation;
 
+    /** Fraction to scale tabs by during animation. */
+    public static final float SCALE_FRACTION = 0.90f;
+
     /** Duration of the first step of the background animation: zooming out, rotating in */
     private static final long BACKGROUND_STEP1_DURATION = 300;
     /** Duration of the second step of the background animation: pause */
@@ -231,7 +233,7 @@ public class SimpleAnimationLayout extends Layout {
         forceAnimationToFinish();
 
         newLayoutTab.setBorderAlpha(0.0f);
-        final float scale = StackAnimation.SCALE_AMOUNT;
+        final float scale = SCALE_FRACTION;
         final float margin = Math.min(getWidth(), getHeight()) * (1.0f - scale) / 2.0f;
 
         CompositorAnimationHandler handler = getAnimationHandler();

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/phone/stack/NonOverlappingStack.java

@@ -12,6 +12,16 @@ import org.chromium.chrome.browser.compositor.layouts.phone.StackLayoutBase;
  * The non-overlapping tab stack we use when the HorizontalTabSwitcherAndroid flag is enabled.
  */
 public class NonOverlappingStack extends Stack {
+    /**
+     * The scale the tabs should be shown at when there's exactly one tab open.
+     */
+    private static final float SCALE_FRACTION_SINGLE_TAB = 0.80f;
+
+    /**
+     * The scale the tabs should be shown at when there are two or more tabs open.
+     */
+    private static final float SCALE_FRACTION_MULTIPLE_TABS = 0.60f;
+
     /**
      * The percentage of the screen that defines the spacing between tabs by default (no pinch).
      */
@@ -50,6 +60,20 @@ public class NonOverlappingStack extends Stack {
         super(context, layout);
     }
 
+    private int getNonDyingTabCount() {
+        int dyingCount = 0;
+        for (int i = 0; i < mStackTabs.length; i++) {
+            if (mStackTabs[i].isDying()) dyingCount++;
+        }
+        return mStackTabs.length - dyingCount;
+    }
+
+    @Override
+    public float getScaleAmount() {
+        if (getNonDyingTabCount() > 1) return SCALE_FRACTION_MULTIPLE_TABS;
+        return SCALE_FRACTION_SINGLE_TAB;
+    }
+
     @Override
     protected boolean evenOutTabs(float amount, boolean allowReverseDirection) {
         // Nothing to do here; tabs are always a fixed distance apart in NonOverlappingStack (except
@@ -99,8 +123,8 @@ public class NonOverlappingStack extends Stack {
 
     @Override
     protected int computeSpacing(int layoutTabCount) {
-        return (int) Math.round(getScrollDimensionSize() * StackAnimation.SCALE_AMOUNT
-                + EXTRA_SPACE_BETWEEN_TABS_DP);
+        return (int) Math.round(
+                getScrollDimensionSize() * getScaleAmount() + EXTRA_SPACE_BETWEEN_TABS_DP);
     }
 
     @Override
@@ -135,4 +159,12 @@ public class NonOverlappingStack extends Stack {
     public float scrollToScreen(float scrollSpace) {
         return scrollSpace;
     }
+
+    @Override
+    public float getMaxTabHeight() {
+        // We want to maintain a constant tab height (via cropping) even as the width is changed as
+        // a result of changing the scale.
+        if (getNonDyingTabCount() > 1) return super.getMaxTabHeight();
+        return (SCALE_FRACTION_MULTIPLE_TABS / SCALE_FRACTION_SINGLE_TAB) * super.getMaxTabHeight();
+    }
 }

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/phone/stack/OverlappingStack.java

@@ -19,6 +19,8 @@ import org.chromium.ui.base.LocalizationUtils;
  * The overlapping tab stack we use when the HorizontalTabSwitcherAndroid flag is not enabled.
  */
 public class OverlappingStack extends Stack {
+    private static final float SCALE_AMOUNT = 0.90f;
+
     /**
      * The percentage of the screen that defines the spacing between tabs by default (no pinch).
      */
@@ -71,6 +73,11 @@ public class OverlappingStack extends Stack {
         super(context, layout);
     }
 
+    @Override
+    public float getScaleAmount() {
+        return SCALE_AMOUNT;
+    }
+
     @Override
     protected boolean evenOutTabs(float amount, boolean allowReverseDirection) {
         if (mStackTabs == null || mOverviewAnimationType != OverviewAnimationType.NONE

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/phone/stack/Stack.java

@@ -285,6 +285,11 @@ public abstract class Stack {
         return visibleCount;
     }
 
+    /**
+     * The scale the tabs should be currently shown at (may change based on how many are open).
+     */
+    public abstract float getScaleAmount();
+
     /*
      * Main Interaction Methods for the rest of the application
      *
@@ -1356,13 +1361,11 @@ public abstract class Stack {
             // there will be more space on the bottom than top.
             final float horizontalPadding =
                     (parentWidth
-                            - layoutTab.getOriginalContentWidth() * StackAnimation.SCALE_AMOUNT
-                                    * stackScale)
+                            - layoutTab.getOriginalContentWidth() * getScaleAmount() * stackScale)
                     / 2.0f;
             final float verticalPadding =
                     (parentHeight
-                            - layoutTab.getOriginalContentHeight() * StackAnimation.SCALE_AMOUNT
-                                    * stackScale)
+                            - layoutTab.getOriginalContentHeight() * getScaleAmount() * stackScale)
                     / 2.0f;
 
             if (portrait) {
@@ -1401,8 +1404,7 @@ public abstract class Stack {
                 } else if (LocalizationUtils.isLayoutRtl()) {
                     // On RTL landscape, pos is a distance between tab's right and mLayout's right.
                     float posOffset = mLayout.getWidth()
-                            - layoutTab.getOriginalContentWidth() * StackAnimation.SCALE_AMOUNT
-                                    * stackScale;
+                            - layoutTab.getOriginalContentWidth() * getScaleAmount() * stackScale;
                     pos = -layoutTab.getX() + posOffset;
                     layoutTab.setX(-Math.min(pos, maxStackedPosition) + posOffset);
                 } else {

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/phone/stack/StackAnimation.java

@@ -5,7 +5,9 @@
 package org.chromium.chrome.browser.compositor.layouts.phone.stack;
 
 import static org.chromium.chrome.browser.compositor.layouts.ChromeAnimation.AnimatableAnimation.addAnimation;
+import static org.chromium.chrome.browser.compositor.layouts.components.LayoutTab.Property.MAX_CONTENT_HEIGHT;
 import static org.chromium.chrome.browser.compositor.layouts.phone.stack.StackTab.Property.DISCARD_AMOUNT;
+import static org.chromium.chrome.browser.compositor.layouts.phone.stack.StackTab.Property.SCALE;
 import static org.chromium.chrome.browser.compositor.layouts.phone.stack.StackTab.Property.SCROLL_OFFSET;
 
 import android.view.animation.Interpolator;
@@ -38,8 +40,6 @@ public abstract class StackAnimation {
         NONE,
     }
 
-    public static final float SCALE_AMOUNT = 0.90f;
-
     protected static final int ENTER_STACK_TOOLBAR_ALPHA_DURATION = 100;
     protected static final int ENTER_STACK_TOOLBAR_ALPHA_DELAY = 100;
     protected static final int ENTER_STACK_ANIMATION_DURATION = 300;
@@ -308,6 +308,12 @@ public abstract class StackAnimation {
                     addAnimation(set, tab, DISCARD_AMOUNT, tab.getDiscardAmount(), 0.0f,
                             UNDISCARD_ANIMATION_DURATION, 0);
                 }
+                addAnimation(set, tab, SCALE, tab.getScale(), mStack.getScaleAmount(),
+                        DISCARD_ANIMATION_DURATION, 0);
+
+                addAnimation(set, tab.getLayoutTab(), MAX_CONTENT_HEIGHT,
+                        tab.getLayoutTab().getMaxContentHeight(), mStack.getMaxTabHeight(),
+                        DISCARD_ANIMATION_DURATION, 0);
 
                 float newScrollOffset = mStack.screenToScroll(spacing * newIndex);
 
@@ -316,7 +322,7 @@ public abstract class StackAnimation {
                 // put it in the right place.
                 if (tab.getDiscardAmount() >= discardRange) {
                     tab.setScrollOffset(newScrollOffset);
-                    tab.setScale(SCALE_AMOUNT);
+                    tab.setScale(mStack.getScaleAmount());
                 } else {
                     float start = tab.getScrollOffset();
                     if (start != newScrollOffset) {

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/phone/stack/StackAnimationLandscape.java

@@ -45,7 +45,7 @@ class StackAnimationLandscape extends StackAnimation {
             StackTab tab = tabs[i];
 
             tab.resetOffset();
-            tab.setScale(SCALE_AMOUNT);
+            tab.setScale(mStack.getScaleAmount());
             tab.setAlpha(1.f);
             tab.getLayoutTab().setToolbarAlpha(0.f);
             tab.getLayoutTab().setBorderScale(1.f);
@@ -67,8 +67,8 @@ class StackAnimationLandscape extends StackAnimation {
                 tab.setScrollOffset(scrollOffset);
                 addAnimation(set, tab, X_IN_STACK_INFLUENCE, 0.0f, 1.0f,
                         ENTER_STACK_BORDER_ALPHA_DURATION, 0);
-                addAnimation(
-                        set, tab, SCALE, 1.0f, SCALE_AMOUNT, ENTER_STACK_BORDER_ALPHA_DURATION, 0);
+                addAnimation(set, tab, SCALE, 1.0f, mStack.getScaleAmount(),
+                        ENTER_STACK_BORDER_ALPHA_DURATION, 0);
                 addAnimation(set, tab.getLayoutTab(), TOOLBAR_ALPHA, 1.f, 0.f,
                         ENTER_STACK_TOOLBAR_ALPHA_DURATION, ENTER_STACK_TOOLBAR_ALPHA_DELAY);
                 addAnimation(set, tab.getLayoutTab(), TOOLBAR_Y_OFFSET, 0.f,

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/phone/stack/StackAnimationPortrait.java

@@ -54,7 +54,7 @@ class StackAnimationPortrait extends StackAnimation {
             StackTab tab = tabs[i];
 
             tab.resetOffset();
-            tab.setScale(SCALE_AMOUNT);
+            tab.setScale(mStack.getScaleAmount());
             tab.setAlpha(1.f);
             tab.getLayoutTab().setToolbarAlpha(0.f);
             tab.getLayoutTab().setBorderScale(1.f);
@@ -79,8 +79,8 @@ class StackAnimationPortrait extends StackAnimation {
                         ENTER_STACK_RESIZE_DELAY);
                 addAnimation(set, tab, Y_IN_STACK_INFLUENCE, 0.0f, 1.0f,
                         ENTER_STACK_BORDER_ALPHA_DURATION, 0);
-                addAnimation(
-                        set, tab, SCALE, 1.0f, SCALE_AMOUNT, ENTER_STACK_BORDER_ALPHA_DURATION, 0);
+                addAnimation(set, tab, SCALE, 1.0f, mStack.getScaleAmount(),
+                        ENTER_STACK_BORDER_ALPHA_DURATION, 0);
                 addAnimation(set, tab.getLayoutTab(), TOOLBAR_ALPHA, 1.f, 0.f,
                         ENTER_STACK_BORDER_ALPHA_DURATION, ENTER_STACK_TOOLBAR_ALPHA_DELAY);
                 addAnimation(set, tab.getLayoutTab(), TOOLBAR_Y_OFFSET, 0.f,