Java 当屏幕方向改变时lockCanvas失败
我正试图在安卓系统中制作一张实时壁纸,但当方向改变时,它会使应用程序崩溃。当试图将画布锁定在曲面支架上时,它看起来像是在崩溃,但我不确定我能做些什么来防止它 下面是课程:Java 当屏幕方向改变时lockCanvas失败,java,android,surfaceholder,Java,Android,Surfaceholder,我正试图在安卓系统中制作一张实时壁纸,但当方向改变时,它会使应用程序崩溃。当试图将画布锁定在曲面支架上时,它看起来像是在崩溃,但我不确定我能做些什么来防止它 下面是课程: public class LiveWallpaperService extends WallpaperService { public void onCreate() { super.onCreate(); } public void onDestroy() { sup
public class LiveWallpaperService extends WallpaperService
{
public void onCreate() {
super.onCreate();
}
public void onDestroy() {
super.onDestroy();
}
public Engine onCreateEngine() {
return new MyWallpaperEngine();
}
class MyWallpaperEngine extends Engine
{
private final Handler handler = new Handler();
private final Runnable drawRunner = new Runnable() {
@Override
public void run() {
draw();
}
};
private boolean visible = true;
Paint paint;
MyWallpaperEngine() {
paint = new Paint();
}
public void onCreate(SurfaceHolder surfaceHolder) {
super.onCreate(surfaceHolder);
}
@Override
public void onVisibilityChanged(boolean visible) {
this.visible = visible;
if (visible) {
handler.post(drawRunner);
}
else {
handler.removeCallbacks(drawRunner);
}
}
@Override
public void onSurfaceDestroyed(SurfaceHolder holder) {
super.onSurfaceDestroyed(holder);
this.visible = false;
handler.removeCallbacks(drawRunner);
}
public void onOffsetsChanged(float xOffset, float yOffset, float xStep, float yStep, int xPixels, int yPixels) {
draw();
}
void draw() {
final SurfaceHolder holder = getSurfaceHolder();
Canvas c = null;
try {
c = holder.lockCanvas();
if (c != null) {
// Paint stuff here.
}
}
finally {
if (c != null) {
holder.unlockCanvasAndPost(c);
}
}
handler.removeCallbacks(drawRunner);
if (visible) {
handler.postDelayed(drawRunner, 10);
}
}
}
}
这是方向改变时发生的例外情况:
E/StudioProfiler: JVMTI error: 15(JVMTI_ERROR_THREAD_NOT_ALIVE)
E/Surface: dequeueBuffer failed (No such device)
E/BaseSurfaceHolder: Exception locking surface
java.lang.IllegalArgumentException
at android.view.Surface.nativeLockCanvas(Native Method)
at android.view.Surface.lockCanvas(Surface.java:318)
at com.android.internal.view.BaseSurfaceHolder.internalLockCanvas(BaseSurfaceHolder.java:194)
at com.android.internal.view.BaseSurfaceHolder.lockCanvas(BaseSurfaceHolder.java:158)
at android.service.wallpaper.WallpaperService$Engine$1.lockCanvas(WallpaperService.java:262)
at greencell.bitpatternswallpaper.LiveWallpaperService$MyWallpaperEngine.draw(LiveWallpaperService.java:206)
at greencell.bitpatternswallpaper.LiveWallpaperService$MyWallpaperEngine$1.run(LiveWallpaperService.java:51)
at android.os.Handler.handleCallback(Handler.java:790)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
更新:
我已经检查了许多其他线程,这些线程似乎都有相同的问题,但到目前为止,我唯一能做的就是在try catch中包装unlockCanvasAndPost
和lockCanvas
,以忽略IllegalArgumentException
,在draw()
中,我会尝试移动处理程序。removeCallbacks(drawRunner)代码>就在块之前,请尝试块。可能是onOffsetChanged()
在方向更改时被调用,并且处理程序上的前一个线程可能还没有调用unlockCanvasAndPost(c)
,这就解释了为什么此时lockCanvas()
会出现错误。但是,如果您在此处发布的代码与您在本地运行的代码完全匹配,则不应出现这种情况,因为您没有重写onOffsetChanged()
您可以尝试的另一件事是重写onSurfaceChanged()
,并按如下方式清除处理程序队列:
@Override
public void onSurfaceChanged(SurfaceHolder holder, int format, int width, int height) {
handler.removeCallbacks(drawRunner);
super.onSurfaceChanged(holder, format, width, height);
}
最后,我在网上读到的所有关于壁纸服务的例子都有一个try
-最后用锁定/解锁画布逻辑阻塞,所以我不会担心。在你的桌面上尝试安卓:configChanges=“orientation”
清单中的
例如:
检查一下,我不懂。链接中的问题与这里发生的完全不同。我试图用您提供的代码重现这个问题,但我做不到。这会发生在任何特定的Android版本/设备上吗?现在我正在使用Android版本8.1.0的Pixel 2进行测试。这个错误仍然会偶尔触发一次,但感觉更稳定。是的,我注意到所有的例子都以试抓结束,只是感觉很脏,但我想我需要接受它:)。非常感谢。这很奇怪,但我很高兴能帮上忙!:)谢谢你的回答,不过我没注意到有什么不同。