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

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;
+        };
+    }
+}