Adding hint text for drop targets.

Bug: 28192178
Change-Id: Id7be5129488622b56082d2dfa328b751311cabd7

5 files changed, 144 insertions, 39 deletions

diff --git a/packages/SystemUI/res/values/dimens.xml b/packages/SystemUI/res/values/dimens.xml
index 03b9837e6175..504361008570 100644
--- a/packages/SystemUI/res/values/dimens.xml
+++ b/packages/SystemUI/res/values/dimens.xml
@@ -640,6 +640,9 @@
     <!-- The amount of overscroll allowed when flinging to the end of the stack. -->
     <dimen name="recents_fling_overscroll_distance">24dp</dimen>
 
+    <!-- The size of the drag hint text. -->
+    <dimen name="recents_drag_hint_text_size">14sp</dimen>
+
     <!-- The min alpha to apply to a task affiliation group color. -->
     <item name="recents_task_affiliation_color_min_alpha_percentage" format="float" type="dimen">0.6</item>
 
diff --git a/packages/SystemUI/res/values/strings.xml b/packages/SystemUI/res/values/strings.xml
index 37b00bbfdc27..a03aa28c47c5 100644
--- a/packages/SystemUI/res/values/strings.xml
+++ b/packages/SystemUI/res/values/strings.xml
@@ -737,6 +737,8 @@
     <string name="recents_stack_action_button_label">Clear all</string>
     <!-- Recents: Incompatible task message. [CHAR LIMIT=NONE] -->
     <string name="recents_incompatible_app_message">App doesn\'t support split screen</string>
+    <!-- Recents: Hint text that shows on the drop targets to start multiwindow. [CHAR LIMIT=NONE] -->
+    <string name="recents_drag_hint_message">Drag here to use split screen</string>
 
     <!-- Recents: MultiStack add stack split horizontal radio button. [CHAR LIMIT=NONE] -->
     <string name="recents_multistack_add_stack_dialog_split_horizontal">Split Horizontal</string>
diff --git a/packages/SystemUI/src/com/android/systemui/recents/model/TaskStack.java b/packages/SystemUI/src/com/android/systemui/recents/model/TaskStack.java
index 95e276f7c8cf..47995c4b73f3 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/model/TaskStack.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/model/TaskStack.java
@@ -30,17 +30,21 @@ import android.animation.Animator;
 import android.animation.AnimatorSet;
 import android.animation.ObjectAnimator;
 import android.animation.PropertyValuesHolder;
-import android.animation.RectEvaluator;
+import android.annotation.IntDef;
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.res.Configuration;
 import android.content.res.Resources;
+import android.graphics.Canvas;
 import android.graphics.Color;
+import android.graphics.Paint;
+import android.graphics.Point;
 import android.graphics.Rect;
 import android.graphics.RectF;
 import android.graphics.drawable.ColorDrawable;
 import android.util.ArrayMap;
 import android.util.ArraySet;
+import android.util.IntProperty;
 import android.util.SparseArray;
 import android.view.animation.Interpolator;
 
@@ -56,6 +60,8 @@ import com.android.systemui.recents.views.DropTarget;
 import com.android.systemui.recents.views.TaskStackLayoutAlgorithm;
 
 import java.io.PrintWriter;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
@@ -240,22 +246,30 @@ public class TaskStack {
      */
     public static class DockState implements DropTarget {
 
+        // The rotation to apply to the hint text
+        @Retention(RetentionPolicy.SOURCE)
+        @IntDef({HORIZONTAL, VERTICAL})
+        public @interface TextOrientation {}
+        private static final int HORIZONTAL = 0;
+        private static final int VERTICAL = 1;
+
         private static final int DOCK_AREA_ALPHA = 192;
-        public static final DockState NONE = new DockState(DOCKED_INVALID, -1, 80, null, null, null);
+        public static final DockState NONE = new DockState(DOCKED_INVALID, -1, 80, 255, HORIZONTAL,
+                null, null, null);
         public static final DockState LEFT = new DockState(DOCKED_LEFT,
-                DOCKED_STACK_CREATE_MODE_TOP_OR_LEFT, DOCK_AREA_ALPHA,
+                DOCKED_STACK_CREATE_MODE_TOP_OR_LEFT, DOCK_AREA_ALPHA, 0, VERTICAL,
                 new RectF(0, 0, 0.125f, 1), new RectF(0, 0, 0.125f, 1),
                 new RectF(0, 0, 0.5f, 1));
         public static final DockState TOP = new DockState(DOCKED_TOP,
-                DOCKED_STACK_CREATE_MODE_TOP_OR_LEFT, DOCK_AREA_ALPHA,
+                DOCKED_STACK_CREATE_MODE_TOP_OR_LEFT, DOCK_AREA_ALPHA, 0, HORIZONTAL,
                 new RectF(0, 0, 1, 0.125f), new RectF(0, 0, 1, 0.125f),
                 new RectF(0, 0, 1, 0.5f));
         public static final DockState RIGHT = new DockState(DOCKED_RIGHT,
-                DOCKED_STACK_CREATE_MODE_BOTTOM_OR_RIGHT, DOCK_AREA_ALPHA,
+                DOCKED_STACK_CREATE_MODE_BOTTOM_OR_RIGHT, DOCK_AREA_ALPHA, 0, VERTICAL,
                 new RectF(0.875f, 0, 1, 1), new RectF(0.875f, 0, 1, 1),
                 new RectF(0.5f, 0, 1, 1));
         public static final DockState BOTTOM = new DockState(DOCKED_BOTTOM,
-                DOCKED_STACK_CREATE_MODE_BOTTOM_OR_RIGHT, DOCK_AREA_ALPHA,
+                DOCKED_STACK_CREATE_MODE_BOTTOM_OR_RIGHT, DOCK_AREA_ALPHA, 0, HORIZONTAL,
                 new RectF(0, 0.875f, 1, 1), new RectF(0, 0.875f, 1, 1),
                 new RectF(0, 0.5f, 1, 1));
 
@@ -267,33 +281,109 @@ public class TaskStack {
         }
 
         // Represents the view state of this dock state
-        public class ViewState {
+        public static class ViewState {
+            private static final IntProperty<ViewState> HINT_ALPHA =
+                    new IntProperty<ViewState>("drawableAlpha") {
+                        @Override
+                        public void setValue(ViewState object, int alpha) {
+                            object.mHintTextAlpha = alpha;
+                            object.dockAreaOverlay.invalidateSelf();
+                        }
+
+                        @Override
+                        public Integer get(ViewState object) {
+                            return object.mHintTextAlpha;
+                        }
+                    };
+
             public final int dockAreaAlpha;
             public final ColorDrawable dockAreaOverlay;
-            private AnimatorSet dockAreaOverlayAnimator;
-
-            private ViewState(int alpha) {
-                dockAreaAlpha = alpha;
+            public final int hintTextAlpha;
+            public final int hintTextOrientation;
+
+            private final int mHintTextResId;
+            private String mHintText;
+            private Paint mHintTextPaint;
+            private Point mHintTextBounds = new Point();
+            private int mHintTextAlpha = 255;
+            private AnimatorSet mDockAreaOverlayAnimator;
+            private Rect mTmpRect = new Rect();
+
+            private ViewState(int areaAlpha, int hintAlpha, @TextOrientation int hintOrientation,
+                    int hintTextResId) {
+                dockAreaAlpha = areaAlpha;
                 dockAreaOverlay = new ColorDrawable(0xFFffffff);
                 dockAreaOverlay.setAlpha(0);
+                hintTextAlpha = hintAlpha;
+                hintTextOrientation = hintOrientation;
+                mHintTextResId = hintTextResId;
+                mHintTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
+                mHintTextPaint.setColor(Color.WHITE);
+            }
+
+            /**
+             * Updates the view state with the given context.
+             */
+            public void update(Context context) {
+                Resources res = context.getResources();
+                mHintText = context.getString(mHintTextResId);
+                mHintTextPaint.setTextSize(res.getDimensionPixelSize(
+                        R.dimen.recents_drag_hint_text_size));
+                mHintTextPaint.getTextBounds(mHintText, 0, mHintText.length(), mTmpRect);
+                mHintTextBounds.set((int) mHintTextPaint.measureText(mHintText), mTmpRect.height());
+            }
+
+            /**
+             * Draws the current view state.
+             */
+            public void draw(Canvas canvas) {
+                // Draw the overlay background
+                if (dockAreaOverlay.getAlpha() > 0) {
+                    dockAreaOverlay.draw(canvas);
+                }
+
+                // Draw the hint text
+                if (mHintTextAlpha > 0) {
+                    Rect bounds = dockAreaOverlay.getBounds();
+                    int x = bounds.left + (bounds.width() - mHintTextBounds.x) / 2;
+                    int y = bounds.top + (bounds.height() + mHintTextBounds.y) / 2;
+                    mHintTextPaint.setAlpha(mHintTextAlpha);
+                    if (hintTextOrientation == VERTICAL) {
+                        canvas.save();
+                        canvas.rotate(-90f, bounds.centerX(), bounds.centerY());
+                    }
+                    canvas.drawText(mHintText, x, y, mHintTextPaint);
+                    if (hintTextOrientation == VERTICAL) {
+                        canvas.restore();
+                    }
+                }
             }
 
             /**
              * Creates a new bounds and alpha animation.
              */
-            public void startAnimation(Rect bounds, int alpha, int duration,
+            public void startAnimation(Rect bounds, int areaAlpha, int hintAlpha, int duration,
                     Interpolator interpolator, boolean animateAlpha, boolean animateBounds) {
-                if (dockAreaOverlayAnimator != null) {
-                    dockAreaOverlayAnimator.cancel();
+                if (mDockAreaOverlayAnimator != null) {
+                    mDockAreaOverlayAnimator.cancel();
                 }
 
                 ArrayList<Animator> animators = new ArrayList<>();
-                if (dockAreaOverlay.getAlpha() != alpha) {
+                if (dockAreaOverlay.getAlpha() != areaAlpha) {
                     if (animateAlpha) {
                         animators.add(ObjectAnimator.ofInt(dockAreaOverlay,
-                                Utilities.DRAWABLE_ALPHA, dockAreaOverlay.getAlpha(), alpha));
+                                Utilities.DRAWABLE_ALPHA, dockAreaOverlay.getAlpha(), areaAlpha));
                     } else {
-                        dockAreaOverlay.setAlpha(alpha);
+                        dockAreaOverlay.setAlpha(areaAlpha);
+                    }
+                }
+                if (mHintTextAlpha != hintAlpha) {
+                    if (animateAlpha) {
+                        animators.add(ObjectAnimator.ofInt(this, HINT_ALPHA, mHintTextAlpha,
+                                hintAlpha));
+                    } else {
+                        mHintTextAlpha = hintAlpha;
+                        dockAreaOverlay.invalidateSelf();
                     }
                 }
                 if (bounds != null && !dockAreaOverlay.getBounds().equals(bounds)) {
@@ -307,11 +397,11 @@ public class TaskStack {
                     }
                 }
                 if (!animators.isEmpty()) {
-                    dockAreaOverlayAnimator = new AnimatorSet();
-                    dockAreaOverlayAnimator.playTogether(animators);
-                    dockAreaOverlayAnimator.setDuration(duration);
-                    dockAreaOverlayAnimator.setInterpolator(interpolator);
-                    dockAreaOverlayAnimator.start();
+                    mDockAreaOverlayAnimator = new AnimatorSet();
+                    mDockAreaOverlayAnimator.playTogether(animators);
+                    mDockAreaOverlayAnimator.setDuration(duration);
+                    mDockAreaOverlayAnimator.setInterpolator(interpolator);
+                    mDockAreaOverlayAnimator.start();
                 }
             }
         }
@@ -331,17 +421,26 @@ public class TaskStack {
          *                              the initial touch area.  This is also the new dock area to
          *                              draw.
          */
-        DockState(int dockSide, int createMode, int dockAreaAlpha, RectF touchArea, RectF dockArea,
+        DockState(int dockSide, int createMode, int dockAreaAlpha, int hintTextAlpha,
+                  @TextOrientation int hintTextOrientation, RectF touchArea, RectF dockArea,
                   RectF expandedTouchDockArea) {
             this.dockSide = dockSide;
             this.createMode = createMode;
-            this.viewState = new ViewState(dockAreaAlpha);
+            this.viewState = new ViewState(dockAreaAlpha, hintTextAlpha, hintTextOrientation,
+                    R.string.recents_drag_hint_message);
             this.dockArea = dockArea;
             this.touchArea = touchArea;
             this.expandedTouchDockArea = expandedTouchDockArea;
         }
 
         /**
+         * Updates the dock state with the given context.
+         */
+        public void update(Context context) {
+            viewState.update(context);
+        }
+
+        /**
          * Returns whether {@param x} and {@param y} are contained in the area scaled to the
          * given {@param width} and {@param height}.
          */
diff --git a/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java b/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java
index 6604cccdb93d..a5ca302bac2f 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java
@@ -426,10 +426,7 @@ public class RecentsView extends FrameLayout {
 
         ArrayList<TaskStack.DockState> visDockStates = mTouchHandler.getVisibleDockStates();
         for (int i = visDockStates.size() - 1; i >= 0; i--) {
-            Drawable d = visDockStates.get(i).viewState.dockAreaOverlay;
-            if (d.getAlpha() > 0) {
-                d.draw(canvas);
-            }
+            visDockStates.get(i).viewState.draw(canvas);
         }
     }
 
@@ -465,6 +462,7 @@ public class RecentsView extends FrameLayout {
     public final void onBusEvent(DragStartEvent event) {
         updateVisibleDockRegions(mTouchHandler.getDockStatesForCurrentOrientation(),
                 true /* isDefaultDockState */, TaskStack.DockState.NONE.viewState.dockAreaAlpha,
+                TaskStack.DockState.NONE.viewState.hintTextAlpha,
                 true /* animateAlpha */, false /* animateBounds */);
     }
 
@@ -472,11 +470,12 @@ public class RecentsView extends FrameLayout {
         if (event.dropTarget == null || !(event.dropTarget instanceof TaskStack.DockState)) {
             updateVisibleDockRegions(mTouchHandler.getDockStatesForCurrentOrientation(),
                     true /* isDefaultDockState */, TaskStack.DockState.NONE.viewState.dockAreaAlpha,
+                    TaskStack.DockState.NONE.viewState.hintTextAlpha,
                     true /* animateAlpha */, true /* animateBounds */);
         } else {
             final TaskStack.DockState dockState = (TaskStack.DockState) event.dropTarget;
             updateVisibleDockRegions(new TaskStack.DockState[] {dockState},
-                    false /* isDefaultDockState */, -1, true /* animateAlpha */,
+                    false /* isDefaultDockState */, -1, -1, true /* animateAlpha */,
                     true /* animateBounds */);
         }
         if (mStackActionButton != null) {
@@ -498,13 +497,9 @@ public class RecentsView extends FrameLayout {
             final TaskStack.DockState dockState = (TaskStack.DockState) event.dropTarget;
 
             // Hide the dock region
-            updateVisibleDockRegions(null, false /* isDefaultDockState */, -1,
+            updateVisibleDockRegions(null, false /* isDefaultDockState */, -1, -1,
                     false /* animateAlpha */, false /* animateBounds */);
 
-            TaskStackLayoutAlgorithm stackLayout = mTaskStackView.getStackAlgorithm();
-            TaskStackViewScroller stackScroller = mTaskStackView.getScroller();
-            TaskViewTransform tmpTransform = new TaskViewTransform();
-
             // We translated the view but we need to animate it back from the current layout-space
             // rect to its final layout-space rect
             int x = (int) event.taskView.getTranslationX();
@@ -548,7 +543,7 @@ public class RecentsView extends FrameLayout {
                     event.task.getTopComponent().flattenToShortString());
         } else {
             // Animate the overlay alpha back to 0
-            updateVisibleDockRegions(null, true /* isDefaultDockState */, -1,
+            updateVisibleDockRegions(null, true /* isDefaultDockState */, -1, -1,
                     true /* animateAlpha */, false /* animateBounds */);
         }
     }
@@ -710,8 +705,8 @@ public class RecentsView extends FrameLayout {
      * Updates the dock region to match the specified dock state.
      */
     private void updateVisibleDockRegions(TaskStack.DockState[] newDockStates,
-            boolean isDefaultDockState, int overrideAlpha, boolean animateAlpha,
-            boolean animateBounds) {
+            boolean isDefaultDockState, int overrideAreaAlpha, int overrideHintAlpha,
+            boolean animateAlpha, boolean animateBounds) {
         ArraySet<TaskStack.DockState> newDockStatesSet = Utilities.arrayToSet(newDockStates,
                 new ArraySet<TaskStack.DockState>());
         ArrayList<TaskStack.DockState> visDockStates = mTouchHandler.getVisibleDockStates();
@@ -720,11 +715,16 @@ public class RecentsView extends FrameLayout {
             TaskStack.DockState.ViewState viewState = dockState.viewState;
             if (newDockStates == null || !newDockStatesSet.contains(dockState)) {
                 // This is no longer visible, so hide it
-                viewState.startAnimation(null, 0, DOCK_AREA_OVERLAY_TRANSITION_DURATION,
+                viewState.startAnimation(null, 0, 0, DOCK_AREA_OVERLAY_TRANSITION_DURATION,
                         Interpolators.ALPHA_OUT, animateAlpha, animateBounds);
             } else {
                 // This state is now visible, update the bounds and show it
-                int alpha = (overrideAlpha != -1 ? overrideAlpha : viewState.dockAreaAlpha);
+                int areaAlpha = overrideAreaAlpha != -1
+                        ? overrideAreaAlpha
+                        : viewState.dockAreaAlpha;
+                int hintAlpha = overrideHintAlpha != -1
+                        ? overrideHintAlpha
+                        : viewState.hintTextAlpha;
                 Rect bounds = isDefaultDockState
                         ? dockState.getPreDockedBounds(getMeasuredWidth(), getMeasuredHeight())
                         : dockState.getDockedBounds(getMeasuredWidth(), getMeasuredHeight(),
diff --git a/packages/SystemUI/src/com/android/systemui/recents/views/RecentsViewTouchHandler.java b/packages/SystemUI/src/com/android/systemui/recents/views/RecentsViewTouchHandler.java
index 70c4dbdc9665..214ec90fe5ee 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/views/RecentsViewTouchHandler.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/views/RecentsViewTouchHandler.java
@@ -171,6 +171,7 @@ public class RecentsViewTouchHandler {
                 TaskStack.DockState[] dockStates = getDockStatesForCurrentOrientation();
                 for (TaskStack.DockState dockState : dockStates) {
                     registerDropTargetForCurrentDrag(dockState);
+                    dockState.update(mRv.getContext());
                     mVisibleDockStates.add(dockState);
                 }
             }