Add recent tasks to Taskbar

- Also adds a divider between Hotseat and Recents
- Dedupes Recents from Hotseat

Test: Open some recent tasks, ensure they are deduped
from Hotseat and also handle < 2 tasks.

Bug: 171917176
Change-Id: Ia782c6ccbcda94cfd844aad04dc3d25a3f072c2b

1 files changed, 114 insertions, 0 deletions

diff --git a/quickstep/src/com/android/launcher3/taskbar/TaskbarRecentsController.java b/quickstep/src/com/android/launcher3/taskbar/TaskbarRecentsController.java
new file mode 100644
index 0000000000..9d4e000da0
--- /dev/null
+++ b/quickstep/src/com/android/launcher3/taskbar/TaskbarRecentsController.java
@@ -0,0 +1,114 @@
+/*
+ * 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 com.android.launcher3.BaseQuickstepLauncher;
+import com.android.quickstep.RecentsModel;
+import com.android.quickstep.util.CancellableTask;
+import com.android.systemui.shared.recents.model.Task;
+import com.android.systemui.shared.system.TaskStackChangeListener;
+import com.android.systemui.shared.system.TaskStackChangeListeners;
+
+import java.util.ArrayList;
+
+/**
+ * Works with TaskbarController to update the TaskbarView's Recent items.
+ */
+public class TaskbarRecentsController {
+
+    private final int mNumRecentIcons = 2;
+    private final BaseQuickstepLauncher mLauncher;
+    private final TaskbarController.TaskbarRecentsControllerCallbacks mTaskbarCallbacks;
+    private final RecentsModel mRecentsModel;
+
+    private final TaskStackChangeListener mTaskStackChangeListener = new TaskStackChangeListener() {
+        @Override
+        public void onTaskStackChanged() {
+            reloadRecentTasksIfNeeded();
+        }
+    };
+
+    // TODO: add TaskbarVisualsChangedListener as well (for calendar/clock?)
+
+    // Used to keep track of the last requested task list id, so that we do not request to load the
+    // tasks again if we have already requested it and the task list has not changed
+    private int mTaskListChangeId = -1;
+
+    // The current background requests to load the task icons
+    private CancellableTask[] mIconLoadRequests = new CancellableTask[mNumRecentIcons];
+
+    public TaskbarRecentsController(BaseQuickstepLauncher launcher,
+            TaskbarController.TaskbarRecentsControllerCallbacks taskbarCallbacks) {
+        mLauncher = launcher;
+        mTaskbarCallbacks = taskbarCallbacks;
+        mRecentsModel = RecentsModel.INSTANCE.get(mLauncher);
+    }
+
+    protected void init() {
+        TaskStackChangeListeners.getInstance().registerTaskStackListener(mTaskStackChangeListener);
+        reloadRecentTasksIfNeeded();
+    }
+
+    protected void cleanup() {
+        TaskStackChangeListeners.getInstance().unregisterTaskStackListener(
+                mTaskStackChangeListener);
+        cancelAllPendingIconLoadTasks();
+    }
+
+    private void reloadRecentTasksIfNeeded() {
+        if (!mRecentsModel.isTaskListValid(mTaskListChangeId)) {
+            mTaskListChangeId = mRecentsModel.getTasks(this::onRecentTasksChanged);
+        }
+    }
+
+    private void cancelAllPendingIconLoadTasks() {
+        for (int i = 0; i < mIconLoadRequests.length; i++) {
+            if (mIconLoadRequests[i] != null) {
+                mIconLoadRequests[i].cancel();
+            }
+            mIconLoadRequests[i] = null;
+        }
+    }
+
+    private void onRecentTasksChanged(ArrayList<Task> tasks) {
+        mTaskbarCallbacks.updateRecentItems(tasks);
+    }
+
+    /**
+     * For each Task, loads its icon from the cache in the background, then calls
+     * {@link TaskbarController.TaskbarRecentsControllerCallbacks#updateRecentTaskAtIndex}.
+     */
+    protected void loadIconsForTasks(Task[] tasks) {
+        cancelAllPendingIconLoadTasks();
+        for (int i = 0; i < tasks.length; i++) {
+            Task task = tasks[i];
+            if (task == null) {
+                continue;
+            }
+            final int taskIndex = i;
+            mIconLoadRequests[i] = mRecentsModel.getIconCache().updateIconInBackground(
+                    task, updatedTask -> onTaskIconLoaded(task, taskIndex));
+        }
+    }
+
+    private void onTaskIconLoaded(Task task, int taskIndex) {
+        mTaskbarCallbacks.updateRecentTaskAtIndex(taskIndex, task);
+    }
+
+    protected int getNumRecentIcons() {
+        return mNumRecentIcons;
+    }
+}