当屏幕方向更改时,lockCanvas失败

概述我正在尝试在Android中构建动态壁纸,但是当方向更改时,它会使应用程序崩溃.尝试将Canvas锁定在表面支架上时看起来像崩溃了,但是我不确定该怎么做才能防止它.这是课程：publicclassLiveWallpaperServiceextendsWallpaperService{publicvoidonCreate(){super

我正在尝试在Android中构建动态壁纸,但是当方向更改时,它会使应用程序崩溃.尝试将Canvas锁定在表面支架上时看起来像崩溃了,但是我不确定该怎么做才能防止它.

这是课程：

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异常：

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$Engine.lockCanvas(WallpaperService.java:262)           at greencell.bitpatternswallpaper.liveWallpaperService$MyWallpaperEngine.draw(liveWallpaperService.java:206)           at greencell.bitpatternswallpaper.liveWallpaperService$MyWallpaperEngine.run(liveWallpaperService.java:51)           at androID.os.Handler.handleCallback(Handler.java:790)           at androID.os.Handler.dispatchMessage(Handler.java:99)           at androID.os.Looper.loop(Looper.java:164)           at androID.app.ActivityThread.main(ActivityThread.java:6494)           at java.lang.reflect.Method.invoke(Native Method)           at com.androID.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)           at com.androID.internal.os.ZygoteInit.main(ZygoteInit.java:807)

更新：

我检查了许多其他线程,它们似乎都存在相同的问题,但是到目前为止,我唯一能做的就是在尝试捕获中包装unlockCanvasAndPost和lockCanvas来忽略IllegalArgumentException.

@H_404_22@解决方法:

在draw()中,我尝试移动handler.removeCallbacks(drawRunner);在try块之前.可能是在方向更改时调用了onOffsetsChanged(),并且处理程序上的上一个线程可能尚未调用unlockCanvasAndPost(c),这解释了为什么此时出现lockCanvas()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,则情况并非如此,因为您没有覆盖onOffsetsChanged().

您可以尝试的另一件事是重写onSurfaceChanged()并清除处理程序队列,如下所示：

@OverrIDepublic voID onSurfaceChanged(SurfaceHolder holder, int format, int wIDth, int height) {    handler.removeCallbacks(drawRunner);    super.onSurfaceChanged(holder, format, wIDth, height);}

最终,我在网上阅读的所有与WallpaperService有关的示例都具有一个try-finally块,该块具有锁定/解锁画布逻辑,因此我不必担心.

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