我有一个简单的程序,可以将Camera
的预览绘制到SurfaceView
中。我正在尝试做的是使用onPreviewFrame
方法,每次在SurfaceView
中绘制新的帧时都会调用该方法,以便执行invalidate
方法,该方法应该调用onDraw
方法。实际上,正在调用onDraw
方法,但没有打印任何内容(我猜相机预览覆盖了我试图绘制的文本)。
这是我的SurfaceView
子类的简化版本:
public class Superficie extends SurfaceView implements SurfaceHolder.Callback {
SurfaceHolder mHolder;
public Camera camera;
Superficie(Context context) {
super(context);
mHolder = getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceCreated(final SurfaceHolder holder) {
camera = Camera.open();
try {
camera.setPreviewDisplay(holder);
camera.setPreviewCallback(new PreviewCallback() {
public void onPreviewFrame(byte[] data, Camera arg1) {
invalidar();
}
});
} catch (IOException e) {}
}
public void invalidar(){
invalidate();
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
Camera.Parameters parameters = camera.getParameters();
parameters.setPreviewSize(w, h);
camera.setParameters(parameters);
camera.startPreview();
}
@Override
public void draw(Canvas canvas) {
super.draw(canvas);
// nothing gets drawn :(
Paint p = new Paint(Color.RED);
canvas.drawText("PREVIEW", canvas.getWidth() / 2,
canvas.getHeight() / 2, p);
}
}
发布于 2013-05-16 23:04:35
尝试从surfaceCreated
调用setWillNotDraw(false)
public void surfaceCreated(SurfaceHolder holder) {
try {
setWillNotDraw(false);
mycam.setPreviewDisplay(holder);
mycam.startPreview();
} catch (Exception e) {
e.printStackTrace();
Log.d(TAG,"Surface not created");
}
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawRect(area, rectanglePaint);
Log.w(this.getClass().getName(), "On Draw Called");
}
并从onTouchEvent
调用invalidate
public boolean onTouch(View v, MotionEvent event) {
invalidate();
return true;
}
发布于 2011-09-20 16:04:47
我认为在使用surfaceView的draw方法执行任何操作之前,应该先调用super.draw()
方法。
https://stackoverflow.com/questions/2933882
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