Support drag and drop from Taskbar

- Long clicking a BubbleTextView in Taskbar will start a system drag
  and drop operation, setting the original view invisible meanwhile.
- Defer gesture navigation when starting over a Taskbar item, and
  cancel any started gesture if a Taskbar drag and drop starts.

Bug: 171917176
Change-Id: If5049071fbf1755f545ee937daa4edabd869f00d
diff --git a/quickstep/res/values/dimens.xml b/quickstep/res/values/dimens.xml
index 39a7d09..39cc0b8 100644
--- a/quickstep/res/values/dimens.xml
+++ b/quickstep/res/values/dimens.xml
@@ -124,6 +124,7 @@
     <dimen name="taskbar_size">48dp</dimen>
     <dimen name="taskbar_icon_size">32dp</dimen>
     <dimen name="taskbar_icon_touch_size">48dp</dimen>
+    <dimen name="taskbar_icon_drag_icon_size">54dp</dimen>
     <!-- Note that this applies to both sides of all icons, so visible space is double this. -->
     <dimen name="taskbar_icon_spacing">14dp</dimen>
 </resources>
diff --git a/quickstep/src/com/android/launcher3/taskbar/TaskbarController.java b/quickstep/src/com/android/launcher3/taskbar/TaskbarController.java
index f91bfb7..7608645 100644
--- a/quickstep/src/com/android/launcher3/taskbar/TaskbarController.java
+++ b/quickstep/src/com/android/launcher3/taskbar/TaskbarController.java
@@ -26,6 +26,7 @@
 import android.graphics.PixelFormat;
 import android.graphics.Point;
 import android.view.Gravity;
+import android.view.MotionEvent;
 import android.view.View;
 import android.view.WindowManager;
 
@@ -59,6 +60,7 @@
     private final TaskbarStateHandler mTaskbarStateHandler;
     private final TaskbarVisibilityController mTaskbarVisibilityController;
     private final TaskbarHotseatController mHotseatController;
+    private final TaskbarDragController mDragController;
 
     // Initialized in init().
     private WindowManager.LayoutParams mWindowLayoutParams;
@@ -77,6 +79,7 @@
                 createTaskbarVisibilityControllerCallbacks());
         mHotseatController = new TaskbarHotseatController(mLauncher,
                 createTaskbarHotseatControllerCallbacks());
+        mDragController = new TaskbarDragController(mLauncher);
     }
 
     private TaskbarVisibilityControllerCallbacks createTaskbarVisibilityControllerCallbacks() {
@@ -100,6 +103,11 @@
             public View.OnClickListener getItemOnClickListener() {
                 return ItemClickHandler.INSTANCE;
             }
+
+            @Override
+            public View.OnLongClickListener getItemOnLongClickListener() {
+                return mDragController::startDragOnLongClick;
+            }
         };
     }
 
@@ -227,6 +235,18 @@
     }
 
     /**
+     * @param ev MotionEvent in screen coordinates.
+     * @return Whether any Taskbar item could handle the given MotionEvent if given the chance.
+     */
+    public boolean isEventOverAnyTaskbarItem(MotionEvent ev) {
+        return mTaskbarView.isEventOverAnyItem(ev);
+    }
+
+    public boolean isDraggingItem() {
+        return mTaskbarView.isDraggingItem();
+    }
+
+    /**
      * @return Whether the given View is in the same window as Taskbar.
      */
     public boolean isViewInTaskbar(View v) {
@@ -254,6 +274,7 @@
      */
     protected interface TaskbarViewCallbacks {
         View.OnClickListener getItemOnClickListener();
+        View.OnLongClickListener getItemOnLongClickListener();
     }
 
     /**
diff --git a/quickstep/src/com/android/launcher3/taskbar/TaskbarDragController.java b/quickstep/src/com/android/launcher3/taskbar/TaskbarDragController.java
new file mode 100644
index 0000000..2318ff9
--- /dev/null
+++ b/quickstep/src/com/android/launcher3/taskbar/TaskbarDragController.java
@@ -0,0 +1,133 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.launcher3.taskbar;
+
+import static android.view.View.INVISIBLE;
+import static android.view.View.VISIBLE;
+
+import android.content.ClipData;
+import android.content.ClipDescription;
+import android.content.Intent;
+import android.content.pm.LauncherApps;
+import android.content.res.Resources;
+import android.graphics.Canvas;
+import android.graphics.Point;
+import android.view.DragEvent;
+import android.view.View;
+
+import com.android.launcher3.BaseQuickstepLauncher;
+import com.android.launcher3.BubbleTextView;
+import com.android.launcher3.LauncherSettings;
+import com.android.launcher3.R;
+import com.android.launcher3.model.data.WorkspaceItemInfo;
+import com.android.systemui.shared.system.ClipDescriptionCompat;
+import com.android.systemui.shared.system.LauncherAppsCompat;
+
+/**
+ * Handles long click on Taskbar items to start a system drag and drop operation.
+ */
+public class TaskbarDragController {
+
+    private final BaseQuickstepLauncher mLauncher;
+    private final int mDragIconSize;
+
+    public TaskbarDragController(BaseQuickstepLauncher launcher) {
+        mLauncher = launcher;
+        Resources resources = mLauncher.getResources();
+        mDragIconSize = resources.getDimensionPixelSize(R.dimen.taskbar_icon_drag_icon_size);
+    }
+
+    /**
+     * Attempts to start a system drag and drop operation for the given View, using its tag to
+     * generate the ClipDescription and Intent.
+     * @return Whether {@link View#startDragAndDrop} started successfully.
+     */
+    protected boolean startDragOnLongClick(View view) {
+        if (!(view instanceof BubbleTextView)) {
+            return false;
+        }
+
+        BubbleTextView btv = (BubbleTextView) view;
+
+        View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view) {
+            @Override
+            public void onProvideShadowMetrics(Point shadowSize, Point shadowTouchPoint) {
+                shadowSize.set(mDragIconSize, mDragIconSize);
+                // TODO: should be based on last touch point on the icon.
+                shadowTouchPoint.set(shadowSize.x / 2, shadowSize.y / 2);
+            }
+
+            @Override
+            public void onDrawShadow(Canvas canvas) {
+                canvas.save();
+                float scale = (float) mDragIconSize / btv.getIconSize();
+                canvas.scale(scale, scale);
+                btv.getIcon().draw(canvas);
+                canvas.restore();
+            }
+        };
+
+        Object tag = view.getTag();
+        ClipDescription clipDescription = null;
+        Intent intent = null;
+        if (tag instanceof WorkspaceItemInfo) {
+            WorkspaceItemInfo item = (WorkspaceItemInfo) tag;
+            LauncherApps launcherApps = mLauncher.getSystemService(LauncherApps.class);
+            clipDescription = new ClipDescription(item.title,
+                    new String[] {
+                            item.itemType == LauncherSettings.Favorites.ITEM_TYPE_DEEP_SHORTCUT
+                                    ? ClipDescriptionCompat.MIMETYPE_APPLICATION_SHORTCUT
+                                    : ClipDescriptionCompat.MIMETYPE_APPLICATION_ACTIVITY
+                    });
+            intent = new Intent();
+            if (item.itemType == LauncherSettings.Favorites.ITEM_TYPE_DEEP_SHORTCUT) {
+                intent.putExtra(Intent.EXTRA_PACKAGE_NAME, item.getIntent().getPackage());
+                intent.putExtra(Intent.EXTRA_SHORTCUT_ID, item.getDeepShortcutId());
+            } else {
+                intent.putExtra(ClipDescriptionCompat.EXTRA_PENDING_INTENT,
+                        LauncherAppsCompat.getMainActivityLaunchIntent(launcherApps,
+                                item.getIntent().getComponent(), null, item.user));
+            }
+            intent.putExtra(Intent.EXTRA_USER, item.user);
+        }
+
+        if (clipDescription != null && intent != null) {
+            ClipData clipData = new ClipData(clipDescription, new ClipData.Item(intent));
+            view.setOnDragListener(getDraggedViewDragListener());
+            return view.startDragAndDrop(clipData, shadowBuilder, null /* localState */,
+                    View.DRAG_FLAG_GLOBAL | View.DRAG_FLAG_OPAQUE);
+        }
+        return false;
+    }
+
+    /**
+     * Hide the original Taskbar item while it is being dragged.
+     */
+    private View.OnDragListener getDraggedViewDragListener() {
+        return (view, dragEvent) -> {
+            switch (dragEvent.getAction()) {
+                case DragEvent.ACTION_DRAG_STARTED:
+                    view.setVisibility(INVISIBLE);
+                    return true;
+                case DragEvent.ACTION_DRAG_ENDED:
+                    view.setVisibility(VISIBLE);
+                    view.setOnDragListener(null);
+                    return true;
+            }
+            return false;
+        };
+    }
+}
diff --git a/quickstep/src/com/android/launcher3/taskbar/TaskbarView.java b/quickstep/src/com/android/launcher3/taskbar/TaskbarView.java
index adcfaec..c98f09c 100644
--- a/quickstep/src/com/android/launcher3/taskbar/TaskbarView.java
+++ b/quickstep/src/com/android/launcher3/taskbar/TaskbarView.java
@@ -20,6 +20,7 @@
 import android.graphics.RectF;
 import android.graphics.drawable.ColorDrawable;
 import android.util.AttributeSet;
+import android.view.DragEvent;
 import android.view.LayoutInflater;
 import android.view.MotionEvent;
 import android.view.View;
@@ -46,6 +47,7 @@
     private final int mTouchSlop;
     private final RectF mTempDelegateBounds = new RectF();
     private final RectF mDelegateSlopBounds = new RectF();
+    private final int[] mTempOutLocation = new int[2];
 
     // Initialized in init().
     private int mHotseatStartIndex;
@@ -57,6 +59,8 @@
     private boolean mDelegateTargeted;
     private View mDelegateView;
 
+    private boolean mIsDraggingItem;
+
     public TaskbarView(@NonNull Context context) {
         this(context, null);
     }
@@ -135,9 +139,12 @@
                         (WorkspaceItemInfo) hotseatItemInfo);
                 hotseatView.setVisibility(VISIBLE);
                 hotseatView.setOnClickListener(mControllerCallbacks.getItemOnClickListener());
+                hotseatView.setOnLongClickListener(
+                        mControllerCallbacks.getItemOnLongClickListener());
             } else {
                 hotseatView.setVisibility(GONE);
                 hotseatView.setOnClickListener(null);
+                hotseatView.setOnLongClickListener(null);
             }
         }
     }
@@ -157,25 +164,12 @@
         final float x = event.getX();
         final float y = event.getY();
         if (mDelegateView == null && event.getAction() == MotionEvent.ACTION_DOWN) {
-            for (int i = 0; i < getChildCount(); i++) {
-                View child = getChildAt(i);
-                if (!child.isShown() || !child.isClickable()) {
-                    continue;
-                }
-                int childCenterX = child.getLeft() + child.getWidth() / 2;
-                int childCenterY = child.getTop() + child.getHeight() / 2;
-                mTempDelegateBounds.set(
-                        childCenterX - mIconTouchSize / 2f,
-                        childCenterY - mIconTouchSize / 2f,
-                        childCenterX + mIconTouchSize / 2f,
-                        childCenterY + mIconTouchSize / 2f);
-                mDelegateTargeted = mTempDelegateBounds.contains(x, y);
-                if (mDelegateTargeted) {
-                    mDelegateView = child;
-                    mDelegateSlopBounds.set(mTempDelegateBounds);
-                    mDelegateSlopBounds.inset(-mTouchSlop, -mTouchSlop);
-                    break;
-                }
+            View delegateView = findDelegateView(x, y);
+            if (delegateView != null) {
+                mDelegateTargeted = true;
+                mDelegateView = delegateView;
+                mDelegateSlopBounds.set(mTempDelegateBounds);
+                mDelegateSlopBounds.inset(-mTouchSlop, -mTouchSlop);
             }
         }
 
@@ -210,6 +204,60 @@
         return handled;
     }
 
+    /**
+     * Return an item whose touch bounds contain the given coordinates,
+     * or null if no such item exists.
+     *
+     * Also sets {@link #mTempDelegateBounds} to be the touch bounds of the chosen delegate view.
+     */
+    private @Nullable View findDelegateView(float x, float y) {
+        for (int i = 0; i < getChildCount(); i++) {
+            View child = getChildAt(i);
+            if (!child.isShown() || !child.isClickable()) {
+                continue;
+            }
+            int childCenterX = child.getLeft() + child.getWidth() / 2;
+            int childCenterY = child.getTop() + child.getHeight() / 2;
+            mTempDelegateBounds.set(
+                    childCenterX - mIconTouchSize / 2f,
+                    childCenterY - mIconTouchSize / 2f,
+                    childCenterX + mIconTouchSize / 2f,
+                    childCenterY + mIconTouchSize / 2f);
+            if (mTempDelegateBounds.contains(x, y)) {
+                return child;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Returns whether the given MotionEvent, *in screen coorindates*, is within any Taskbar item's
+     * touch bounds.
+     */
+    public boolean isEventOverAnyItem(MotionEvent ev) {
+        getLocationOnScreen(mTempOutLocation);
+        float xInOurCoordinates = ev.getX() - mTempOutLocation[0];
+        float yInOurCoorindates = ev.getY() - mTempOutLocation[1];
+        return findDelegateView(xInOurCoordinates, yInOurCoorindates) != null;
+    }
+
+    @Override
+    public boolean onDragEvent(DragEvent event) {
+        switch (event.getAction()) {
+            case DragEvent.ACTION_DRAG_STARTED:
+                mIsDraggingItem = true;
+                return true;
+            case DragEvent.ACTION_DRAG_ENDED:
+                mIsDraggingItem = false;
+                break;
+        }
+        return super.onDragEvent(event);
+    }
+
+    public boolean isDraggingItem() {
+        return mIsDraggingItem;
+    }
+
     private View inflate(@LayoutRes int layoutResId) {
         return LayoutInflater.from(getContext()).inflate(layoutResId, this, false);
     }
diff --git a/quickstep/src/com/android/quickstep/BaseActivityInterface.java b/quickstep/src/com/android/quickstep/BaseActivityInterface.java
index 5f6e59f..ce14197 100644
--- a/quickstep/src/com/android/quickstep/BaseActivityInterface.java
+++ b/quickstep/src/com/android/quickstep/BaseActivityInterface.java
@@ -153,6 +153,13 @@
         return deviceState.isInDeferredGestureRegion(ev);
     }
 
+    /**
+     * @return Whether the gesture in progress should be cancelled.
+     */
+    public boolean shouldCancelCurrentGesture() {
+        return false;
+    }
+
     public abstract void onExitOverview(RotationTouchHelper deviceState,
             Runnable exitRunnable);
 
diff --git a/quickstep/src/com/android/quickstep/LauncherActivityInterface.java b/quickstep/src/com/android/quickstep/LauncherActivityInterface.java
index deb86ec..8b0d782 100644
--- a/quickstep/src/com/android/quickstep/LauncherActivityInterface.java
+++ b/quickstep/src/com/android/quickstep/LauncherActivityInterface.java
@@ -26,6 +26,7 @@
 import android.content.res.Resources;
 import android.graphics.Rect;
 import android.util.Log;
+import android.view.MotionEvent;
 
 import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
@@ -311,4 +312,22 @@
         boolean isImeVisible = (systemUiStateFlags & SYSUI_STATE_IME_SHOWING) != 0;
         taskbarController.setIsImeVisible(isImeVisible);
     }
+
+    @Override
+    public boolean deferStartingActivity(RecentsAnimationDeviceState deviceState, MotionEvent ev) {
+        TaskbarController taskbarController = getTaskbarController();
+        if (taskbarController == null) {
+            return super.deferStartingActivity(deviceState, ev);
+        }
+        return taskbarController.isEventOverAnyTaskbarItem(ev);
+    }
+
+    @Override
+    public boolean shouldCancelCurrentGesture() {
+        TaskbarController taskbarController = getTaskbarController();
+        if (taskbarController == null) {
+            return super.shouldCancelCurrentGesture();
+        }
+        return taskbarController.isDraggingItem();
+    }
 }
diff --git a/quickstep/src/com/android/quickstep/TouchInteractionService.java b/quickstep/src/com/android/quickstep/TouchInteractionService.java
index a98fc1c..8ebea33 100644
--- a/quickstep/src/com/android/quickstep/TouchInteractionService.java
+++ b/quickstep/src/com/android/quickstep/TouchInteractionService.java
@@ -514,9 +514,14 @@
             }
         }
 
-        boolean cleanUpConsumer = (action == ACTION_UP || action == ACTION_CANCEL)
+        boolean cancelGesture = mGestureState.getActivityInterface() != null
+                && mGestureState.getActivityInterface().shouldCancelCurrentGesture();
+        boolean cleanUpConsumer = (action == ACTION_UP || action == ACTION_CANCEL || cancelGesture)
                 && mConsumer != null
                 && !mConsumer.getActiveConsumerInHierarchy().isConsumerDetachedFromGesture();
+        if (cancelGesture) {
+            event.setAction(ACTION_CANCEL);
+        }
         mUncheckedConsumer.onMotionEvent(event);
 
         if (cleanUpConsumer) {