1/**
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.launcher3.util;
18
19import android.os.Process;
20import android.view.View;
21import android.view.View.OnAttachStateChangeListener;
22import android.view.ViewTreeObserver.OnDrawListener;
23
24import com.android.launcher3.Launcher;
25import com.android.launcher3.LauncherModel;
26
27import java.util.ArrayList;
28import java.util.concurrent.Executor;
29
30/**
31 * An executor which runs all the tasks after the first onDraw is called on the target view.
32 */
33public class ViewOnDrawExecutor implements Executor, OnDrawListener, Runnable,
34        OnAttachStateChangeListener {
35
36    private final ArrayList<Runnable> mTasks = new ArrayList<>();
37    private final Executor mExecutor;
38
39    private Launcher mLauncher;
40    private View mAttachedView;
41    private boolean mCompleted;
42    private boolean mIsExecuting;
43
44    private boolean mLoadAnimationCompleted;
45    private boolean mFirstDrawCompleted;
46
47    public ViewOnDrawExecutor(Executor executor) {
48        mExecutor = executor;
49    }
50
51    public void attachTo(Launcher launcher) {
52        mLauncher = launcher;
53        mAttachedView = launcher.getWorkspace();
54        mAttachedView.addOnAttachStateChangeListener(this);
55
56        attachObserver();
57    }
58
59    private void attachObserver() {
60        if (!mCompleted) {
61            mAttachedView.getViewTreeObserver().addOnDrawListener(this);
62        }
63    }
64
65    @Override
66    public void execute(Runnable command) {
67        mTasks.add(command);
68        LauncherModel.setWorkerPriority(Process.THREAD_PRIORITY_BACKGROUND);
69    }
70
71    @Override
72    public void onViewAttachedToWindow(View v) {
73        attachObserver();
74    }
75
76    @Override
77    public void onViewDetachedFromWindow(View v) { }
78
79    @Override
80    public void onDraw() {
81        mFirstDrawCompleted = true;
82        mAttachedView.post(this);
83    }
84
85    /**
86     * Returns whether the executor is still queuing tasks and hasn't yet executed them.
87     */
88    public boolean canQueue() {
89        return !mIsExecuting && !mCompleted;
90    }
91
92    public void onLoadAnimationCompleted() {
93        mLoadAnimationCompleted = true;
94        if (mAttachedView != null) {
95            mAttachedView.post(this);
96        }
97    }
98
99    @Override
100    public void run() {
101        // Post the pending tasks after both onDraw and onLoadAnimationCompleted have been called.
102        if (mLoadAnimationCompleted && mFirstDrawCompleted && !mCompleted) {
103            mIsExecuting = true;
104            for (final Runnable r : mTasks) {
105                mExecutor.execute(r);
106            }
107            markCompleted();
108        }
109    }
110
111    public void markCompleted() {
112        mTasks.clear();
113        mCompleted = true;
114        mIsExecuting = false;
115        if (mAttachedView != null) {
116            mAttachedView.getViewTreeObserver().removeOnDrawListener(this);
117            mAttachedView.removeOnAttachStateChangeListener(this);
118        }
119        if (mLauncher != null) {
120            mLauncher.clearPendingExecutor(this);
121        }
122        LauncherModel.setWorkerPriority(Process.THREAD_PRIORITY_DEFAULT);
123    }
124}
125