2

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：如何在 Qt for android 中保持屏幕开启？, 除了我使用callMethod<void>而不是callObjectMethod.

问题是，当应用程序启动时，它会因大量 Java 日志而崩溃，我怀疑这是其中的相关部分：

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

4

3 回答 3

2 
#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

从这里得到它，在 5.1 android 上对我有用

于 2015-12-23T05:52:17.023 回答
1

我最终用 Java 来做这件事。

这是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。

于 2016-02-03T07:34:21.597 回答
0

在 Android 上部署时，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，因此您很难返回该线程以使该代码工作。

最好的办法是使用 aWakeLock来防止系统进入睡眠模式。这是一篇解释如何做的帖子。

这将防止应用程序运行时屏幕变暗。

于 2015-12-26T07:37:17.270 回答