Updating edge scrolling logic during drag and drop

Activating scroll to left when the either the visualCenter or the touchX
enters the left screen first or right screen.
Previously only the touch point was being considered to activating the scroll
zone. But visual center is used everywhere else for actual drop location. So
depending on the touch point relative to the picked icon, the touch zone could
seem smaller or larger.
Using both points (touch and visualCenter) will increase the scroll zone area
with minimal effect on the drop location calculation.

Bug: 31946075
Change-Id: I4eb5146c0f0a05e8d024313d67f8e040e0b29dec

1 files changed, 44 insertions, 87 deletions

diff --git a/src/com/android/launcher3/Workspace.java b/src/com/android/launcher3/Workspace.java
index cbea7e078..8a423e3a5 100644
--- a/src/com/android/launcher3/Workspace.java
+++ b/src/com/android/launcher3/Workspace.java
@@ -178,7 +178,7 @@ public class Workspace extends PagedView
 
     private final int[] mTempXY = new int[2];
     @Thunk float[] mDragViewVisualCenter = new float[2];
-    private float[] mTempCellLayoutCenterCoordinates = new float[2];
+    private float[] mTempTouchCoordinates = new float[2];
 
     private SpringLoadedDragController mSpringLoadedDragController;
     private float mOverviewModeShrinkFactor;
@@ -2776,7 +2776,8 @@ public class Workspace extends PagedView
         mAddToExistingFolderOnDrop = false;
 
         mDropToLayout = null;
-        setDropLayoutForDragObject(d);
+        mDragViewVisualCenter = d.getVisualCenter(mDragViewVisualCenter);
+        setDropLayoutForDragObject(d, mDragViewVisualCenter[0], mDragViewVisualCenter[1]);
     }
 
     @Override
@@ -2946,68 +2947,6 @@ public class Workspace extends PagedView
        xy[1] += v.getTop();
    }
 
-   static private float squaredDistance(float[] point1, float[] point2) {
-        float distanceX = point1[0] - point2[0];
-        float distanceY = point2[1] - point2[1];
-        return distanceX * distanceX + distanceY * distanceY;
-   }
-
-    /*
-     *
-     * This method returns the CellLayout that is currently being dragged to. In order to drag
-     * to a CellLayout, either the touch point must be directly over the CellLayout, or as a second
-     * strategy, we see if the dragView is overlapping any CellLayout and choose the closest one
-     *
-     * Return null if no CellLayout is currently being dragged over
-     *
-     */
-    private CellLayout findMatchingPageForDragOver(
-            DragView dragView, float originX, float originY, boolean exact) {
-        // We loop through all the screens (ie CellLayouts) and see which ones overlap
-        // with the item being dragged and then choose the one that's closest to the touch point
-        final int screenCount = getChildCount();
-        CellLayout bestMatchingScreen = null;
-        float smallestDistSoFar = Float.MAX_VALUE;
-
-        for (int i = 0; i < screenCount; i++) {
-            // The custom content screen is not a valid drag over option
-            if (mScreenOrder.get(i) == CUSTOM_CONTENT_SCREEN_ID) {
-                continue;
-            }
-
-            CellLayout cl = (CellLayout) getChildAt(i);
-
-            final float[] touchXy = {originX, originY};
-            mapPointFromSelfToChild(cl, touchXy);
-
-            if (touchXy[0] >= 0 && touchXy[0] <= cl.getWidth() &&
-                    touchXy[1] >= 0 && touchXy[1] <= cl.getHeight()) {
-                return cl;
-            }
-
-            if (!exact) {
-                // Get the center of the cell layout in screen coordinates
-                final float[] cellLayoutCenter = mTempCellLayoutCenterCoordinates;
-                cellLayoutCenter[0] = cl.getWidth()/2;
-                cellLayoutCenter[1] = cl.getHeight()/2;
-                mapPointFromChildToSelf(cl, cellLayoutCenter);
-
-                touchXy[0] = originX;
-                touchXy[1] = originY;
-
-                // Calculate the distance between the center of the CellLayout
-                // and the touch point
-                float dist = squaredDistance(touchXy, cellLayoutCenter);
-
-                if (dist < smallestDistSoFar) {
-                    smallestDistSoFar = dist;
-                    bestMatchingScreen = cl;
-                }
-            }
-        }
-        return bestMatchingScreen;
-    }
-
     private boolean isDragWidget(DragObject d) {
         return (d.dragInfo instanceof LauncherAppWidgetInfo ||
                 d.dragInfo instanceof PendingAddWidgetInfo);
@@ -3030,14 +2969,11 @@ public class Workspace extends PagedView
         mDragViewVisualCenter = d.getVisualCenter(mDragViewVisualCenter);
 
         final View child = (mDragInfo == null) ? null : mDragInfo.cell;
-        if (setDropLayoutForDragObject(d)) {
-            boolean isInSpringLoadedMode = (mState == State.SPRING_LOADED);
-            if (isInSpringLoadedMode) {
-                if (mLauncher.isHotseatLayout(mDragTargetLayout)) {
-                    mSpringLoadedDragController.cancel();
-                } else {
-                    mSpringLoadedDragController.setAlarm(mDragTargetLayout);
-                }
+        if (setDropLayoutForDragObject(d, mDragViewVisualCenter[0], mDragViewVisualCenter[1])) {
+            if (mLauncher.isHotseatLayout(mDragTargetLayout)) {
+                mSpringLoadedDragController.cancel();
+            } else {
+                mSpringLoadedDragController.setAlarm(mDragTargetLayout);
             }
         }
 
@@ -3114,7 +3050,7 @@ public class Workspace extends PagedView
      *
      * @return whether the layout is different from the current {@link #mDragTargetLayout}.
      */
-    private boolean setDropLayoutForDragObject(DragObject d) {
+    private boolean setDropLayoutForDragObject(DragObject d, float centerX, float centerY) {
         CellLayout layout = null;
         // Test to see if we are over the hotseat first
         if (mLauncher.getHotseat() != null && !isDragWidget(d)) {
@@ -3122,12 +3058,25 @@ public class Workspace extends PagedView
                 layout = mLauncher.getHotseat().getLayout();
             }
         }
-        if (layout == null) {
-            // Identify whether we have dragged over a side page,
-            // otherwise just use the current page
-            layout = workspaceInModalState() ?
-                    findMatchingPageForDragOver(d.dragView, d.x, d.y, false)
-                    : getCurrentDropLayout();
+
+        int nextPage = getNextPage();
+        if (layout == null && !isPageInTransition()) {
+            // Check if the item is dragged over left page
+            mTempTouchCoordinates[0] = Math.min(centerX, d.x);
+            mTempTouchCoordinates[1] = d.y;
+            layout = verifyInsidePage(nextPage + (mIsRtl ? 1 : -1), mTempTouchCoordinates);
+        }
+
+        if (layout == null && !isPageInTransition()) {
+            // Check if the item is dragged over right page
+            mTempTouchCoordinates[0] = Math.max(centerX, d.x);
+            mTempTouchCoordinates[1] = d.y;
+            layout = verifyInsidePage(nextPage + (mIsRtl ? -1 : 1), mTempTouchCoordinates);
+        }
+
+        // Always pick the current page.
+        if (layout == null && nextPage >= numCustomPages() && nextPage < getPageCount()) {
+            layout = (CellLayout) getChildAt(nextPage);
         }
         if (layout != mDragTargetLayout) {
             setCurrentDropLayout(layout);
@@ -3137,6 +3086,22 @@ public class Workspace extends PagedView
         return false;
     }
 
+    /**
+     * Returns the child CellLayout if the point is inside the page coordinates, null otherwise.
+     */
+    private CellLayout verifyInsidePage(int pageNo, float[] touchXy)  {
+        if (pageNo >= numCustomPages() && pageNo < getPageCount()) {
+            CellLayout cl = (CellLayout) getChildAt(pageNo);
+            mapPointFromSelfToChild(cl, touchXy);
+            if (touchXy[0] >= 0 && touchXy[0] <= cl.getWidth() &&
+                    touchXy[1] >= 0 && touchXy[1] <= cl.getHeight()) {
+                // This point is inside the cell layout
+                return cl;
+            }
+        }
+        return null;
+    }
+
     private void manageFolderFeedback(CellLayout targetLayout,
             int[] targetCell, float distance, DragObject dragObject) {
         if (distance > mMaxDistanceForFolderCreation) return;
@@ -3571,14 +3536,6 @@ public class Workspace extends PagedView
     }
 
     /**
-     * Return the current {@link CellLayout}, correctly picking the destination
-     * screen while a scroll is in progress.
-     */
-    public CellLayout getCurrentDropLayout() {
-        return (CellLayout) getChildAt(getNextPage());
-    }
-
-    /**
      * Return the current CellInfo describing our current drag; this method exists
      * so that Launcher can sync this object with the correct info when the activity is created/
      * destroyed