Adding dampened snap back overscroll to Workspace and AppsCustomizePagedView

issue 15475254

Change-Id: I5eb9fc480167faf4be16bd17bf18e2d103f40f47

4 files changed, 43 insertions, 132 deletions

diff --git a/src/com/android/launcher3/AppsCustomizePagedView.java b/src/com/android/launcher3/AppsCustomizePagedView.java
index d23e65f81..a47f1dbf9 100644
--- a/src/com/android/launcher3/AppsCustomizePagedView.java
+++ b/src/com/android/launcher3/AppsCustomizePagedView.java
@@ -190,16 +190,6 @@ public class AppsCustomizePagedView extends PagedViewWithDraggableItems implemen
     private int mNumWidgetPages;
     private Rect mAllAppsPadding = new Rect();
 
-    // Relating to the scroll and overscroll effects
-    Workspace.ZInterpolator mZInterpolator = new Workspace.ZInterpolator(0.5f);
-    private static float CAMERA_DISTANCE = 6500;
-    private static float TRANSITION_SCALE_FACTOR = 0.74f;
-    private static float TRANSITION_PIVOT = 0.65f;
-    private static float TRANSITION_MAX_ROTATION = 22;
-    private static final boolean PERFORM_OVERSCROLL_ROTATION = false;
-    private AccelerateInterpolator mAlphaInterpolator = new AccelerateInterpolator(0.9f);
-    private DecelerateInterpolator mLeftScreenAlphaInterpolator = new DecelerateInterpolator(4);
-
     // Previews & outlines
     ArrayList<AppsCustomizeAsyncTask> mRunningTasks;
     private static final int sPageSleepDelay = 200;
@@ -1365,73 +1355,7 @@ public class AppsCustomizePagedView extends PagedViewWithDraggableItems implemen
     // In apps customize, we have a scrolling effect which emulates pulling cards off of a stack.
     @Override
     protected void screenScrolled(int screenCenter) {
-        final boolean isRtl = isLayoutRtl();
         super.screenScrolled(screenCenter);
-
-        for (int i = 0; i < getChildCount(); i++) {
-            View v = getPageAt(i);
-            if (v != null) {
-                float scrollProgress = getScrollProgress(screenCenter, v, i);
-
-                float interpolatedProgress;
-                float translationX;
-                float maxScrollProgress = Math.max(0, scrollProgress);
-                float minScrollProgress = Math.min(0, scrollProgress);
-
-                if (isRtl) {
-                    translationX = maxScrollProgress * v.getMeasuredWidth();
-                    interpolatedProgress = mZInterpolator.getInterpolation(Math.abs(maxScrollProgress));
-                } else {
-                    translationX = minScrollProgress * v.getMeasuredWidth();
-                    interpolatedProgress = mZInterpolator.getInterpolation(Math.abs(minScrollProgress));
-                }
-                float scale = (1 - interpolatedProgress) +
-                        interpolatedProgress * TRANSITION_SCALE_FACTOR;
-
-                float alpha;
-                if (isRtl && (scrollProgress > 0)) {
-                    alpha = mAlphaInterpolator.getInterpolation(1 - Math.abs(maxScrollProgress));
-                } else if (!isRtl && (scrollProgress < 0)) {
-                    alpha = mAlphaInterpolator.getInterpolation(1 - Math.abs(scrollProgress));
-                } else {
-                    //  On large screens we need to fade the page as it nears its leftmost position
-                    alpha = mLeftScreenAlphaInterpolator.getInterpolation(1 - scrollProgress);
-                }
-
-                v.setCameraDistance(mDensity * CAMERA_DISTANCE);
-                int pageWidth = v.getMeasuredWidth();
-                int pageHeight = v.getMeasuredHeight();
-
-                if (PERFORM_OVERSCROLL_ROTATION) {
-                    float xPivot = isRtl ? 1f - TRANSITION_PIVOT : TRANSITION_PIVOT;
-                    boolean isOverscrollingFirstPage = isRtl ? scrollProgress > 0 : scrollProgress < 0;
-                    boolean isOverscrollingLastPage = isRtl ? scrollProgress < 0 : scrollProgress > 0;
-
-                    if (i == 0 && isOverscrollingFirstPage) {
-                        // Overscroll to the left
-                        v.setPivotX(xPivot * pageWidth);
-                        v.setRotationY(-TRANSITION_MAX_ROTATION * scrollProgress);
-                        scale = 1.0f;
-                        alpha = 1.0f;
-                        // On the first page, we don't want the page to have any lateral motion
-                        translationX = 0;
-                    } else if (i == getChildCount() - 1 && isOverscrollingLastPage) {
-                        // Overscroll to the right
-                        v.setPivotX((1 - xPivot) * pageWidth);
-                        v.setRotationY(-TRANSITION_MAX_ROTATION * scrollProgress);
-                        scale = 1.0f;
-                        alpha = 1.0f;
-                        // On the last page, we don't want the page to have any lateral motion.
-                        translationX = 0;
-                    } else {
-                        v.setPivotY(pageHeight / 2.0f);
-                        v.setPivotX(pageWidth / 2.0f);
-                        v.setRotationY(0f);
-                    }
-                }
-            }
-        }
-
         enableHwLayersOnVisiblePages();
     }
 
@@ -1476,7 +1400,7 @@ public class AppsCustomizePagedView extends PagedViewWithDraggableItems implemen
     }
 
     protected void overScroll(float amount) {
-        acceleratedOverScroll(amount);
+        dampedOverScroll(amount);
     }
 
     /**
diff --git a/src/com/android/launcher3/CellLayout.java b/src/com/android/launcher3/CellLayout.java
index 107376482..afe9619fb 100644
--- a/src/com/android/launcher3/CellLayout.java
+++ b/src/com/android/launcher3/CellLayout.java
@@ -71,7 +71,6 @@ public class CellLayout extends ViewGroup {
     private int mWidthGap;
     private int mHeightGap;
     private int mMaxGap;
-    private boolean mScrollingTransformsDirty = false;
     private boolean mDropPending = false;
 
     // These are temporary variables to prevent having to allocate a new object just to
@@ -388,23 +387,6 @@ public class CellLayout extends ViewGroup {
         return mIsDragOverlapping;
     }
 
-    protected void setOverscrollTransformsDirty(boolean dirty) {
-        mScrollingTransformsDirty = dirty;
-    }
-
-    protected void resetOverscrollTransforms() {
-        if (mScrollingTransformsDirty) {
-            setOverscrollTransformsDirty(false);
-            setTranslationX(0);
-            setRotationY(0);
-            // It doesn't matter if we pass true or false here, the important thing is that we
-            // pass 0, which results in the overscroll drawable not being drawn any more.
-            setOverScrollAmount(0, false);
-            setPivotX(getMeasuredWidth() / 2);
-            setPivotY(getMeasuredHeight() / 2);
-        }
-    }
-
     @Override
     protected void onDraw(Canvas canvas) {
         // When we're large, we are either drawn in a "hover" state (ie when dragging an item to
diff --git a/src/com/android/launcher3/PagedView.java b/src/com/android/launcher3/PagedView.java
index 0dbcd97f0..54aa24ef6 100644
--- a/src/com/android/launcher3/PagedView.java
+++ b/src/com/android/launcher3/PagedView.java
@@ -74,11 +74,12 @@ public abstract class PagedView extends ViewGroup implements ViewGroup.OnHierarc
     private static final int MIN_LENGTH_FOR_FLING = 25;
 
     protected static final int PAGE_SNAP_ANIMATION_DURATION = 750;
+    protected static final int OVER_SCROLL_PAGE_SNAP_ANIMATION_DURATION = 350;
     protected static final int SLOW_PAGE_SNAP_ANIMATION_DURATION = 950;
     protected static final float NANOTIME_DIV = 1000000000.0f;
 
     private static final float OVERSCROLL_ACCELERATE_FACTOR = 2;
-    private static final float OVERSCROLL_DAMP_FACTOR = 0.14f;
+    private static final float OVERSCROLL_DAMP_FACTOR = 0.07f;
 
     private static final float RETURN_TO_ORIGINAL_PAGE_THRESHOLD = 0.33f;
     // The page is moved more than halfway, automatically move to the next page on touch up.
@@ -1601,29 +1602,20 @@ public abstract class PagedView extends ViewGroup implements ViewGroup.OnHierarc
         return f * f * f + 1.0f;
     }
 
-    protected void acceleratedOverScroll(float amount) {
+    protected float acceleratedOverFactor(float amount) {
         int screenSize = getViewportWidth();
 
         // We want to reach the max over scroll effect when the user has
         // over scrolled half the size of the screen
         float f = OVERSCROLL_ACCELERATE_FACTOR * (amount / screenSize);
 
-        if (f == 0) return;
+        if (f == 0) return 0;
 
         // Clamp this factor, f, to -1 < f < 1
         if (Math.abs(f) >= 1) {
             f /= Math.abs(f);
         }
-
-        int overScrollAmount = (int) Math.round(f * screenSize);
-        if (amount < 0) {
-            mOverScrollX = overScrollAmount;
-            super.scrollTo(0, getScrollY());
-        } else {
-            mOverScrollX = mMaxScrollX + overScrollAmount;
-            super.scrollTo(mMaxScrollX, getScrollY());
-        }
-        invalidate();
+        return f;
     }
 
     protected void dampedOverScroll(float amount) {
@@ -1642,10 +1634,10 @@ public abstract class PagedView extends ViewGroup implements ViewGroup.OnHierarc
         int overScrollAmount = (int) Math.round(OVERSCROLL_DAMP_FACTOR * f * screenSize);
         if (amount < 0) {
             mOverScrollX = overScrollAmount;
-            super.scrollTo(0, getScrollY());
+            super.scrollTo(mOverScrollX, getScrollY());
         } else {
             mOverScrollX = mMaxScrollX + overScrollAmount;
-            super.scrollTo(mMaxScrollX, getScrollY());
+            super.scrollTo(mOverScrollX, getScrollY());
         }
         invalidate();
     }
@@ -2145,8 +2137,20 @@ public abstract class PagedView extends ViewGroup implements ViewGroup.OnHierarc
         return minDistanceFromScreenCenterIndex;
     }
 
+    protected boolean isInOverScroll() {
+        return (mOverScrollX > mMaxScrollX || mOverScrollX < 0);
+    }
+
+    protected int getPageSnapDuration() {
+        if (isInOverScroll()) {
+            return OVER_SCROLL_PAGE_SNAP_ANIMATION_DURATION;
+        }
+        return PAGE_SNAP_ANIMATION_DURATION;
+
+    }
+
     protected void snapToDestination() {
-        snapToPage(getPageNearestToCenterOfScreen(), PAGE_SNAP_ANIMATION_DURATION);
+        snapToPage(getPageNearestToCenterOfScreen(), getPageSnapDuration());
     }
 
     private static class ScrollInterpolator implements Interpolator {
@@ -2177,10 +2181,10 @@ public abstract class PagedView extends ViewGroup implements ViewGroup.OnHierarc
         int delta = newX - mUnboundedScrollX;
         int duration = 0;
 
-        if (Math.abs(velocity) < mMinFlingVelocity) {
+        if (Math.abs(velocity) < mMinFlingVelocity || isInOverScroll()) {
             // If the velocity is low enough, then treat this more as an automatic page advance
             // as opposed to an apparent physical response to flinging
-            snapToPage(whichPage, PAGE_SNAP_ANIMATION_DURATION);
+            snapToPage(whichPage, getPageSnapDuration());
             return;
         }
 
@@ -2204,11 +2208,11 @@ public abstract class PagedView extends ViewGroup implements ViewGroup.OnHierarc
     }
 
     protected void snapToPage(int whichPage) {
-        snapToPage(whichPage, PAGE_SNAP_ANIMATION_DURATION);
+        snapToPage(whichPage, getPageSnapDuration());
     }
 
     protected void snapToPageImmediately(int whichPage) {
-        snapToPage(whichPage, PAGE_SNAP_ANIMATION_DURATION, true, null);
+        snapToPage(whichPage, getPageSnapDuration(), true, null);
     }
 
     protected void snapToPage(int whichPage, int duration) {
diff --git a/src/com/android/launcher3/Workspace.java b/src/com/android/launcher3/Workspace.java
index 733923d24..53a3f948d 100644
--- a/src/com/android/launcher3/Workspace.java
+++ b/src/com/android/launcher3/Workspace.java
@@ -215,7 +215,7 @@ public class Workspace extends SmoothPagedView
     private final Rect mTempRect = new Rect();
     private final int[] mTempXY = new int[2];
     private int[] mTempVisiblePagesRange = new int[2];
-    private boolean mOverscrollTransformsSet;
+    private boolean mOverscrollEffectSet;
     public static final int DRAG_BITMAP_PADDING = 2;
     private boolean mWorkspaceFadeInAdjacentScreens;
 
@@ -281,6 +281,8 @@ public class Workspace extends SmoothPagedView
     private int mLastChildCount = -1;
     private float mTransitionProgress;
 
+    float mOverScrollEffect = 0f;
+
     private Runnable mDeferredAction;
     private boolean mDeferDropAfterUninstall;
     private boolean mUninstallSuccessful;
@@ -1683,14 +1685,11 @@ public class Workspace extends SmoothPagedView
         updateStateForCustomContent(screenCenter);
         enableHwLayersOnVisiblePages();
 
-        boolean shouldOverScroll = (mOverScrollX < 0 && (!hasCustomContent() || isLayoutRtl())) ||
-                (mOverScrollX > mMaxScrollX && (!hasCustomContent() || !isLayoutRtl()));
+        boolean shouldOverScroll = (mOverScrollEffect < 0 && (!hasCustomContent() || isLayoutRtl())) ||
+                (mOverScrollEffect > 0 && (!hasCustomContent() || !isLayoutRtl()));
 
         if (shouldOverScroll) {
             int index = 0;
-            float pivotX = 0f;
-            final float leftBiasedPivot = 0.25f;
-            final float rightBiasedPivot = 0.75f;
             final int lowerIndex = 0;
             final int upperIndex = getChildCount() - 1;
 
@@ -1698,25 +1697,27 @@ public class Workspace extends SmoothPagedView
             index = (!isRtl && isLeftPage) || (isRtl && !isLeftPage) ? lowerIndex : upperIndex;
 
             CellLayout cl = (CellLayout) getChildAt(index);
-            float scrollProgress = getScrollProgress(screenCenter, cl, index);
-            cl.setOverScrollAmount(Math.abs(scrollProgress), isLeftPage);
+            float effect = Math.abs(mOverScrollEffect);
+            cl.setOverScrollAmount(Math.abs(effect), isLeftPage);
 
-            if (!mOverscrollTransformsSet) {
-                mOverscrollTransformsSet = true;
-                cl.setOverscrollTransformsDirty(true);
-            }
+            mOverscrollEffectSet = true;
         } else {
-            if (mOverscrollTransformsSet && getChildCount() > 0) {
-                mOverscrollTransformsSet = false;
-                ((CellLayout) getChildAt(0)).resetOverscrollTransforms();
-                ((CellLayout) getChildAt(getChildCount() - 1)).resetOverscrollTransforms();
+            if (mOverscrollEffectSet && getChildCount() > 0) {
+                mOverscrollEffectSet = false;
+                ((CellLayout) getChildAt(0)).setOverScrollAmount(0, false);
+                ((CellLayout) getChildAt(getChildCount() - 1)).setOverScrollAmount(0, false);
             }
         }
     }
 
+    private void computeOverScrollEffect(float amount) {
+        mOverScrollEffect = acceleratedOverFactor(amount);
+    }
+
     @Override
     protected void overScroll(float amount) {
-        acceleratedOverScroll(amount);
+        computeOverScrollEffect(amount);
+        dampedOverScroll(amount);
     }
 
     protected void onAttachedToWindow() {