Qt android屏幕锁定java问题

Question

我有 Qt 应用程序，需要在应用程序运行时防止屏幕变暗。我在 main.cpp 的 main() 开头放置了以下代码：

#ifdef ANDROID
    // disable screen lock on android devices
    QAndroidJniObject activity = QtAndroid::androidActivity();
    if (activity.isValid()) {
        QAndroidJniObject window = activity.callObjectMethod("getWindow", "()Landroid/view/Window;");

        if (window.isValid()) {
            const int FLAG_KEEP_SCREEN_ON = 128;
            window.callMethod<void>("addFlags", "(I)V", FLAG_KEEP_SCREEN_ON);
        }
    }
#endif

这几乎来自：How to keep the screen on in Qt for android?，除了我使用callMethod<void> 而不是callObjectMethod。

问题是，当应用程序启动时，它会因巨大的 Java 日志而崩溃，我怀疑这是它的相关部分：

F/art     (26455): art/runtime/runtime.cc:289] Pending exception android.view.ViewRootImpl$CalledFromWrongThreadException thrown by 'unknown throw location'
F/art     (26455): art/runtime/runtime.cc:289] android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
F/art     (26455): art/runtime/runtime.cc:289]   at void android.view.ViewRootImpl.checkThread() (ViewRootImpl.java:6357)
F/art     (26455): art/runtime/runtime.cc:289]   at void android.view.ViewRootImpl.requestLayout() (ViewRootImpl.java:874)
F/art     (26455): art/runtime/runtime.cc:289]   at void android.view.View.requestLayout() (View.java:17476)
F/art     (26455): art/runtime/runtime.cc:289]   at void android.view.View.setLayoutParams(android.view.ViewGroup$LayoutParams) (View.java:11477)
F/art     (26455): art/runtime/runtime.cc:289]   at void android.view.WindowManagerGlobal.updateViewLayout(android.view.View, android.view.ViewGroup$LayoutParams) (WindowManagerGlobal.java:305)
F/art     (26455): art/runtime/runtime.cc:289]   at void android.view.WindowManagerImpl.updateViewLayout(android.view.View, android.view.ViewGroup$LayoutParams) (WindowManagerImpl.java:91)
F/art     (26455): art/runtime/runtime.cc:289]   at void android.app.Activity.onWindowAttributesChanged(android.view.WindowManager$LayoutParams) (Activity.java:2596)
F/art     (26455): art/runtime/runtime.cc:289]   at void org.qtproject.qt5.android.bindings.QtActivity.onWindowAttributesChanged(android.view.WindowManager$LayoutParams) (QtActivity.java:1385)
F/art     (26455): art/runtime/runtime.cc:289]   at void android.view.Window.dispatchWindowAttributesChanged(android.view.WindowManager$LayoutParams) (Window.java:836)
F/art     (26455): art/runtime/runtime.cc:289]   at void com.android.internal.policy.impl.PhoneWindow.dispatchWindowAttributesChanged(android.view.WindowManager$LayoutParams) (PhoneWindow.java:3993)
F/art     (26455): art/runtime/runtime.cc:289]   at void android.view.Window.setFlags(int, int) (Window.java:813)
F/art     (26455): art/runtime/runtime.cc:289]   at void android.view.Window.addFlags(int) (Window.java:771)

我向 AndroidManifest.xml 添加了适当的权限 (android.permission.WAKE_LOCK)。问题似乎是由于 addFlags() 在其主视图之外运行引起的？我用谷歌搜索了很多，找不到其他人有同样的问题。

谢谢， 伊万

Answer 1

#if defined(Q_OS_ANDROID)
QAndroidJniObject activity = QtAndroid::androidActivity();
if (activity.isValid()) {
    QAndroidJniObject window = activity.callObjectMethod("getWindow", "()Landroid/view/Window;");

    if (window.isValid()) {
        const int FLAG_KEEP_SCREEN_ON = 128;
        window.callMethod<void>("addFlags", "(I)V", FLAG_KEEP_SCREEN_ON);
    }
    QAndroidJniEnvironment env; if (env->ExceptionCheck()) { env->ExceptionClear(); } //Clear any possible pending exceptions.
}
#endif

从here 获得，适用于我的 5.1 android 系统

Answer 2

我最终改用 Java 来做这个。

这里是java代码：

package org.qtproject.visualization;

import org.qtproject.qt5.android.bindings.*;
import android.os.Bundle;
import android.view.WindowManager;

public class ScreenOnActivity extends QtActivity
{
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        getWindow().addFlags( WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON );
        super.onCreate(savedInstanceState);
    }
}

然后将其集成到应用程序的其余部分中。

Answer 3

当部署在 Android 上时，Qt 实际上并不在主应用程序 (Java) 线程中运行。由于android.view.Window.addFlags必须从Java主线程调用，你很难回到这个线程让这段代码工作。

最好使用WakeLock 来防止系统进入睡眠模式。 here is a post explaining how to do it.

这将防止屏幕在应用程序运行时变暗。