Flinging to the left deletes when in vertical bar layout mode.

This mode has the remove icon on the left side, so flinging to the
left makes more sense. But flinging up still works in either case.

Change-Id: I7ab40776b67659026f03f81efd43fae3375b5ba0

4 files changed, 47 insertions, 13 deletions

diff --git a/src/com/android/launcher3/DeleteDropTarget.java b/src/com/android/launcher3/DeleteDropTarget.java
index 9a9b57aed..6d8fa6bd0 100644
--- a/src/com/android/launcher3/DeleteDropTarget.java
+++ b/src/com/android/launcher3/DeleteDropTarget.java
@@ -19,7 +19,6 @@ package com.android.launcher3;
 import android.animation.TimeInterpolator;
 import android.content.Context;
 import android.graphics.PointF;
-import android.os.AsyncTask;
 import android.util.AttributeSet;
 import android.view.View;
 import android.view.animation.AnimationUtils;
diff --git a/src/com/android/launcher3/DeviceProfile.java b/src/com/android/launcher3/DeviceProfile.java
index 66cf2dfea..69ef82683 100644
--- a/src/com/android/launcher3/DeviceProfile.java
+++ b/src/com/android/launcher3/DeviceProfile.java
@@ -372,7 +372,7 @@ public class DeviceProfile {
      * When {@code true}, hotseat is on the bottom row when in landscape mode.
      * If {@code false}, hotseat is on the right column when in landscape mode.
      */
-    boolean isVerticalBarLayout() {
+    public boolean isVerticalBarLayout() {
         return isLandscape && transposeLayoutWithOrientation;
     }
 
diff --git a/src/com/android/launcher3/dragndrop/DragController.java b/src/com/android/launcher3/dragndrop/DragController.java
index e72f3415a..4a39e6be1 100644
--- a/src/com/android/launcher3/dragndrop/DragController.java
+++ b/src/com/android/launcher3/dragndrop/DragController.java
@@ -42,7 +42,6 @@ import com.android.launcher3.ItemInfo;
 import com.android.launcher3.Launcher;
 import com.android.launcher3.PagedView;
 import com.android.launcher3.ShortcutInfo;
-import com.android.launcher3.Utilities;
 import com.android.launcher3.util.Thunk;
 
 import com.android.launcher3.R;
@@ -657,21 +656,29 @@ public class DragController implements DragDriver.EventListener {
 
         ViewConfiguration config = ViewConfiguration.get(mLauncher);
         mVelocityTracker.computeCurrentVelocity(1000, config.getScaledMaximumFlingVelocity());
-
+        PointF vel = new PointF(mVelocityTracker.getXVelocity(), mVelocityTracker.getYVelocity());
+        float theta = MAX_FLING_DEGREES + 1;
         if (mVelocityTracker.getYVelocity() < mFlingToDeleteThresholdVelocity) {
             // Do a quick dot product test to ensure that we are flinging upwards
-            PointF vel = new PointF(mVelocityTracker.getXVelocity(),
-                    mVelocityTracker.getYVelocity());
             PointF upVec = new PointF(0f, -1f);
-            float theta = (float) Math.acos(((vel.x * upVec.x) + (vel.y * upVec.y)) /
-                    (vel.length() * upVec.length()));
-            if (theta <= Math.toRadians(MAX_FLING_DEGREES)) {
-                return vel;
-            }
+            theta = getAngleBetweenVectors(vel, upVec);
+        } else if (mLauncher.getDeviceProfile().isVerticalBarLayout() &&
+                mVelocityTracker.getXVelocity() < mFlingToDeleteThresholdVelocity) {
+            // Remove icon is on left side instead of top, so check if we are flinging to the left.
+            PointF leftVec = new PointF(-1f, 0f);
+            theta = getAngleBetweenVectors(vel, leftVec);
+        }
+        if (theta <= Math.toRadians(MAX_FLING_DEGREES)) {
+            return vel;
         }
         return null;
     }
 
+    private float getAngleBetweenVectors(PointF vec1, PointF vec2) {
+        return (float) Math.acos(((vec1.x * vec2.x) + (vec1.y * vec2.y)) /
+                (vec1.length() * vec2.length()));
+    }
+
     void drop(DropTarget dropTarget, float x, float y, PointF flingVel) {
         final int[] coordinates = mCoordinatesTemp;
 
diff --git a/src/com/android/launcher3/util/FlingAnimation.java b/src/com/android/launcher3/util/FlingAnimation.java
index f82038bf2..da8bae712 100644
--- a/src/com/android/launcher3/util/FlingAnimation.java
+++ b/src/com/android/launcher3/util/FlingAnimation.java
@@ -51,7 +51,7 @@ public class FlingAnimation implements AnimatorUpdateListener {
         mFrom.top += yOffset;
         mFrom.bottom -= yOffset;
 
-        mDuration = initDuration();
+        mDuration = Math.abs(vel.y) > Math.abs(vel.x) ? initFlingUpDuration() : initFlingLeftDuration();
         mAnimationTimeFraction = ((float) mDuration) / (mDuration + DRAG_END_DELAY);
     }
 
@@ -62,7 +62,7 @@ public class FlingAnimation implements AnimatorUpdateListener {
      *   - Calculate a constant acceleration in x direction such that the object reaches
      *     {@link #mIconRect} in the given time.
      */
-    protected int initDuration() {
+    protected int initFlingUpDuration() {
         float sY = -mFrom.bottom;
 
         float d = mUY * mUY + 2 * sY * MAX_ACCELERATION;
@@ -83,6 +83,34 @@ public class FlingAnimation implements AnimatorUpdateListener {
         return (int) Math.round(t);
     }
 
+    /**
+     * The fling animation is based on the following system
+     *   - Apply a constant force in the x direction to causing the fling to decelerate.
+     *   - The animation runs for the time taken by the object to go out of the screen.
+     *   - Calculate a constant acceleration in y direction such that the object reaches
+     *     {@link #mIconRect} in the given time.
+     */
+    protected int initFlingLeftDuration() {
+        float sX = -mFrom.right;
+
+        float d = mUX * mUX + 2 * sX * MAX_ACCELERATION;
+        if (d >= 0) {
+            // sX can be reached under the MAX_ACCELERATION. Use MAX_ACCELERATION for x direction.
+            mAX = MAX_ACCELERATION;
+        } else {
+            // sX is not reachable, decrease the acceleration so that sX is almost reached.
+            d = 0;
+            mAX = mUX * mUX / (2 * -sX);
+        }
+        double t = (-mUX - Math.sqrt(d)) / mAX;
+
+        float sY = -mFrom.exactCenterY() + mIconRect.exactCenterY();
+
+        // Find vertical acceleration such that: u*t + a*t*t/2 = s
+        mAY = (float) ((sY - t * mUY) * 2 / (t * t));
+        return (int) Math.round(t);
+    }
+
     public final int getDuration() {
         return mDuration + DRAG_END_DELAY;
     }