Merge "Add carousel curve effect to RecentsView." into ub-launcher3-master

quickstep/src/com/android/quickstep/RecentsView.java

@@ -16,10 +16,12 @@
 
 package com.android.quickstep;
 
+import android.animation.TimeInterpolator;
 import android.content.Context;
 import android.graphics.Rect;
 import android.util.AttributeSet;
 import android.view.LayoutInflater;
+import android.view.View;
 
 import com.android.launcher3.DeviceProfile;
 import com.android.launcher3.Launcher;
@@ -41,6 +43,12 @@ import java.util.ArrayList;
  */
 public class RecentsView extends PagedView {
 
+    /** Designates how "curvy" the carousel is from 0 to 1, where 0 is a straight line. */
+    private static final float CURVE_FACTOR = 0.25f;
+    /** A circular curve of x from 0 to 1, where 0 is the center of the screen and 1 is the edge. */
+    private static final TimeInterpolator CURVE_INTERPOLATOR
+        = x -> (float) (1 - Math.sqrt(1 - Math.pow(x, 2)));
+
     private boolean mOverviewStateEnabled;
     private boolean mTaskStackListenerRegistered;
 
@@ -69,6 +77,7 @@ public class RecentsView extends PagedView {
         super(context, attrs, defStyleAttr);
         setWillNotDraw(false);
         setPageSpacing((int) getResources().getDimension(R.dimen.recents_page_spacing));
+        enableFreeScroll(true);
     }
 
     @Override
@@ -170,4 +179,39 @@ public class RecentsView extends PagedView {
         padding.left = padding.right = (int) ((profile.availableWidthPx - overviewWidth) / 2);
         return padding;
     }
+
+    @Override
+    public void scrollTo(int x, int y) {
+        super.scrollTo(x, y);
+        updateCurveProperties();
+    }
+
+    /**
+     * Scales and adjusts translation of adjacent pages as if on a curved carousel.
+     */
+    private void updateCurveProperties() {
+        if (getPageCount() == 0 || getPageAt(0).getMeasuredWidth() == 0) {
+            return;
+        }
+        final int halfScreenWidth = getMeasuredWidth() / 2;
+        final int screenCenter = halfScreenWidth + getScrollX();
+        final int pageSpacing = getResources().getDimensionPixelSize(R.dimen.recents_page_spacing);
+        final int pageCount = getPageCount();
+        for (int i = 0; i < pageCount; i++) {
+            View page = getPageAt(i);
+            int pageWidth = page.getMeasuredWidth();
+            int halfPageWidth = pageWidth / 2;
+            int pageCenter = page.getLeft() + halfPageWidth;
+            float distanceFromScreenCenter = Math.abs(pageCenter - screenCenter);
+            float distanceToReachEdge = halfScreenWidth + halfPageWidth + pageSpacing;
+            float linearInterpolation = Math.min(1, distanceFromScreenCenter / distanceToReachEdge);
+            float curveInterpolation = CURVE_INTERPOLATOR.getInterpolation(linearInterpolation);
+            float scale = 1 - curveInterpolation * CURVE_FACTOR;
+            page.setScaleX(scale);
+            page.setScaleY(scale);
+            // Make sure the biggest card (i.e. the one in front) shows on top of the adjacent ones.
+            page.setTranslationZ(scale);
+            page.setTranslationX((screenCenter - pageCenter) * curveInterpolation * CURVE_FACTOR);
+        }
+    }
 }

src/com/android/launcher3/PagedView.java

@@ -30,7 +30,6 @@ import android.os.Bundle;
 import android.os.Parcel;
 import android.os.Parcelable;
 import android.util.AttributeSet;
-import android.util.DisplayMetrics;
 import android.util.Log;
 import android.view.InputDevice;
 import android.view.KeyEvent;
@@ -87,6 +86,7 @@ public abstract class PagedView extends ViewGroup implements ViewGroup.OnHierarc
     public static final int INVALID_RESTORE_PAGE = -1001;
 
     private boolean mFreeScroll = false;
+    private boolean mSettleOnPageInFreeScroll = false;
 
     protected int mFlingThresholdVelocity;
     protected int mMinFlingVelocity;
@@ -1170,7 +1170,12 @@ public abstract class PagedView extends ViewGroup implements ViewGroup.OnHierarc
      * return true if freescroll has been enabled, false otherwise
      */
     protected void enableFreeScroll() {
+        enableFreeScroll(false);
+    }
+
+    protected void enableFreeScroll(boolean settleOnPageInFreeScroll) {
         setEnableFreeScroll(true);
+        mSettleOnPageInFreeScroll = settleOnPageInFreeScroll;
     }
 
     protected void disableFreeScroll() {
@@ -1414,7 +1419,22 @@ public abstract class PagedView extends ViewGroup implements ViewGroup.OnHierarc
                     mScroller.setInterpolator(mDefaultInterpolator);
                     mScroller.fling(initialScrollX,
                             getScrollY(), vX, 0, Integer.MIN_VALUE, Integer.MAX_VALUE, 0, 0);
-                    mNextPage = getPageNearestToCenterOfScreen((int) (mScroller.getFinalX() / scaleX));
+                    int unscaledScrollX = (int) (mScroller.getFinalX() / scaleX);
+                    mNextPage = getPageNearestToCenterOfScreen(unscaledScrollX);
+                    int firstPageScroll = getScrollForPage(!mIsRtl ? 0 : getPageCount() - 1);
+                    int lastPageScroll = getScrollForPage(!mIsRtl ? getPageCount() - 1 : 0);
+                    if (mSettleOnPageInFreeScroll && unscaledScrollX > firstPageScroll
+                            && unscaledScrollX < lastPageScroll) {
+                        // Make sure we land directly on a page. If flinging past one of the ends,
+                        // don't change the velocity as it will get stopped at the end anyway.
+                        mScroller.setFinalX((int) (getScrollForPage(mNextPage) * getScaleX()));
+                        // Ensure the scroll/snap doesn't happen too fast;
+                        int extraScrollDuration = OVERSCROLL_PAGE_SNAP_ANIMATION_DURATION
+                                - mScroller.getDuration();
+                        if (extraScrollDuration > 0) {
+                            mScroller.extendDuration(extraScrollDuration);
+                        }
+                    }
                     invalidate();
                 }
                 onScrollInteractionEnd();