Question

我正在尝试绘制从表面持有者的。lockCanvas()函数返回的画布，但渲染的画布只是白色。

我的MySurface extends SurfaceView和implements SurfaceHolder 构造函数：

MySurface(Context context){
            super(context);
            surfaceHolder = getHolder();
            surfaceHolder.addCallback(this);
            displayThread = new MyDisplayThread(surfaceHolder);
        }

我的surfaceCreated()覆盖

public void surfaceCreated(SurfaceHolder sH){
            displayThread.start();
        }

我的surfaceDestroyed()覆盖

public void surfaceDestroyed(SurfaceHolder sH){
            boolean reset = true;
            while(reset){
                try{
                    displayThread.join();
                    reset = false;
                }catch (InterruptedException e){}
            }
        }

我用于绘图的线程：类变量是：

SurfaceHolder surfaceHolder,
Paint paint,
boolean isRunning,
Canvas canvas = null


 class MyDisplayThread extends Thread {

        MyDisplayThread(SurfaceHolder sH){
            surfaceHolder = sH;
            isRunning = true;
            paint = new Paint();
        }

        @Override
        public void run(){
            while(isRunning){
                canvas = surfaceHolder.lockCanvas();
                try{
                    myDraw();
                }finally {
                    if(canvas != null) surfaceHolder.unlockCanvasAndPost(canvas);
                }
            }
        }

        public void myDraw(){
            paint.setARGB(255,152,54,12);
            canvas.drawText("RSFDS",100,100,paint);
            canvas.drawRect(120,150,300,300,paint);
            paint.setARGB(255,255,255,255);
        }
    }

Answer 1

尝试以下（过去这些对我有用）：

将setWillNotDraw(false);放入surfaceCreated

在绘制每个帧之前，在SurfaceHolder对象上调用postInvalidate();。

Answer 2

您需要在调用getHolder()后再次致电surfaceCreated()。这应该可以解决你的问题。

@Override
public void surfaceCreated(SurfaceHolder holder) {
    surfaceHolder = getHolder();
}

SurfaceHolder在Canvas上没有显示任何内容。 lockCanvas（）[Android]

2 个答案: