Question

我从opencv4android（面部检测）复制了示例代码。我通过了NDK部分。并在手机上运行应用程序。但SurfaceView仅显示相机预览。似乎OnCameraFrame中的任何操作都不会影响SurfaceView上的Canvas。所以我追溯到他们的SDK。问题出在deliverAndDrawFrame函数中。以前有人遇到过同样的问题吗？

Canvas canvas = getHolder().lockCanvas();
if (canvas != null) {
canvas.drawColor(0, android.graphics.PorterDuff.Mode.CLEAR);
Log.d(TAG, "mStretch value: " + mScale);

if (mScale != 0) {
    canvas.drawBitmap(mCacheBitmap, new Rect(0,0,mCacheBitmap.getWidth(), mCacheBitmap.getHeight()),
                     new Rect((int)((canvas.getWidth() - mScale*mCacheBitmap.getWidth()) / 2),
                     (int)((canvas.getHeight() - mScale*mCacheBitmap.getHeight()) / 2),
                     (int)((canvas.getWidth() - mScale*mCacheBitmap.getWidth()) / 2 + mScale*mCacheBitmap.getWidth()),
                     (int)((canvas.getHeight() - mScale*mCacheBitmap.getHeight()) / 2 + mScale*mCacheBitmap.getHeight())), null);
} else {
    canvas.drawBitmap(mCacheBitmap, new Rect(0,0,mCacheBitmap.getWidth(), mCacheBitmap.getHeight()),
                     new Rect((canvas.getWidth() - mCacheBitmap.getWidth()) / 2,
                     (canvas.getHeight() - mCacheBitmap.getHeight()) / 2,
                     (canvas.getWidth() - mCacheBitmap.getWidth()) / 2 + mCacheBitmap.getWidth(),
                     (canvas.getHeight() - mCacheBitmap.getHeight()) / 2 + mCacheBitmap.getHeight()), null);
}

if (mFpsMeter != null) {
    mFpsMeter.measure();
    mFpsMeter.draw(canvas, 20, 30);
}
getHolder().unlockCanvasAndPost(canvas);
}

错误：

10-09 21:57:47.485  28018-28088/com.example.tim.r3dmobileclient E/SurfaceHolder﹕ Exception locking surface
java.lang.IllegalArgumentException
        at android.view.Surface.nativeLockCanvas(Native Method)
        at android.view.Surface.lockCanvas(Surface.java:253)
        at android.view.SurfaceView$4.internalLockCanvas(SurfaceView.java:848)
        at android.view.SurfaceView$4.lockCanvas(SurfaceView.java:816)
        at org.opencv.android.CameraBridgeViewBase.deliverAndDrawFrame(CameraBridgeViewBase.java:412)
        at org.opencv.android.JavaCameraView$CameraWorker.run(JavaCameraView.java:348)
        at java.lang.Thread.run(Thread.java:841)

Answer 1

在尝试锁定画布之前，您是否尝试检查表面是否有效？如果所有这些代码都在一个循环中，请在锁定画布之前将其放入：

if(!getHolder().getSurface().isValid()){
continue;
}

如果它不在循环中，请尝试将所有代码（从锁定画布及其下方）放入此if语句中：

if(getHolder().getSurface().isValid()){
//code goes here
}

Answer 2

我遇到了相同的问题，要解决它，请相信或不注释，只需注释掉这部分即可！当您调用mCamera.startPreview（）;

时，它将尝试重绘正在绘制的内容。

lockCanvas不断抛出异常

2 个答案: