java - 绘图表面、unlockCanvasAndPost 和 IllegalArgumentException

Question

我的绘图应用程序有问题。当我离开绘图 Activity 时出现以下错误(例如使用返回按钮)。我看过这些帖子，但似乎没有任何帮助。拜托，如果你能看看我的绘图表面 Activity ，那将意义重大，因为我已经尝试让它工作了一段时间!非常感谢:)

错误:

03-25 13:41:36.760: E/AndroidRuntime(6642): FATAL EXCEPTION: Thread-423
03-25 13:41:36.760: E/AndroidRuntime(6642): java.lang.IllegalArgumentException
03-25 13:41:36.760: E/AndroidRuntime(6642):     at android.view.Surface.nativeUnlockCanvasAndPost(Native Method)
03-25 13:41:36.760: E/AndroidRuntime(6642):     at android.view.Surface.unlockCanvasAndPost(Surface.java:457)
03-25 13:41:36.760: E/AndroidRuntime(6642):     at android.view.SurfaceView$4.unlockCanvasAndPost(SurfaceView.java:812)
03-25 13:41:36.760: E/AndroidRuntime(6642):     at com.ecp.drawing.DrawingSurface$DrawThread.run(DrawingSurface.java:80)

DrawingSurface主要代码:

    public void run() {
        Canvas canvas = null;
        while (_run){
            if(isDrawing == true){
                try{
                    canvas = mSurfaceHolder.lockCanvas(null);
                    if(mBitmap == null){
                        mBitmap =  Bitmap.createBitmap (1, 1, Bitmap.Config.ARGB_8888);
                    }
                    final Canvas c = new Canvas (mBitmap);

                    c.drawColor(0, PorterDuff.Mode.CLEAR);
                    canvas.drawColor(0, PorterDuff.Mode.CLEAR);


                    commandManager.executeAll(c,previewDoneHandler);
                    previewPath.draw(c);

                    canvas.drawBitmap (mBitmap, 0,  0,null);
                } finally {
                    mSurfaceHolder.unlockCanvasAndPost(canvas);
                }


            }

        }

    }

已经有一个surface destroyed函数:

public void surfaceDestroyed(SurfaceHolder holder) {
    // TODO Auto-generated method stub
    boolean retry = true;
    thread.setRunning(false);
    while (retry) {
        try {
            thread.join();
            retry = false;
        } catch (InterruptedException e) {
            // we will try it again and again...
        }
    }
}

Answer 1

我猜想 lockCanvas 抛出了一个异常，它使 canvas 设置为空。该异常将执行发送到 finally 子句，该子句调用了 unlockCanvasAndPost，它引发了一个新的异常。新异常掩盖了旧异常。

(这看起来有点像 4.3 中的错误，但这是在 4.3 出来之前发布的。)