Question

public class BackgammonBoardView extends SurfaceView implements SurfaceHolder.Callback {
    /***
     * @author
     * The threads class definition
     */
    class BBVThread extends Thread 
    {

        //mSurfaceHolder and mHandler are part of the thread.
        //mContext is part of the container SurfaceView
        private SurfaceHolder mSurfaceHolder;
        private Handler mHandler;

        //The threads constructor
        public BBVThread(SurfaceHolder surfaceHolder, Context context,
                Handler handler) {

            Log.d(TAG,"BBVThread. Constructor.");

            mSurfaceHolder = surfaceHolder;
            mHandler = handler;
            mContext = context;

            mDiceCup = context.getResources().getDrawable(
                    R.drawable.dicecup);
        }

        @Override
        public void run() {

            Log.d(TAG,"BBVThread. run.");

            Canvas canvas = null;
            try {
                canvas = mSurfaceHolder.lockCanvas(null);
                synchronized (mSurfaceHolder) {

                    Log.d(TAG,"Draw the dice cup...");

                    mDiceCup.setBounds(0, 0, 120,120);
                    mDiceCup.draw(canvas);

                }
            } finally {
                // do this in a finally so that if an exception is thrown
                // during the above, we don't leave the Surface in an
                // inconsistent state
                if (canvas != null) {
                    mSurfaceHolder.unlockCanvasAndPost(canvas);
                }
            }
        }//end run    
    }
    /****
     * end of the BBVThread class
     */

    /* ########################################
     * # BackgammonBoardView Member Variables #
     * ######################################## */
    private Drawable mDiceCup;
    /*
     * End BackGammonBoardView Member Variables
     */

    public BackgammonBoardView(Context context, AttributeSet attrs) 
    {
        super(context, attrs);

        Log.d(TAG,"SurfaceView Constructor.");

        //register out interest in hearing about changes to our surface
        SurfaceHolder holder = getHolder();
        holder.addCallback(this);

        thread = new BBVThread(holder, context, new Handler(){
            @Override
            public void handleMessage(Message m) {

            }
        });


        setFocusable(true); // make sure we get key events
    }

    @Override
    public void surfaceCreated(SurfaceHolder arg0) 
    {

            //Start the thread. This will initiate run which will do the first draw
            thread.start();

            //Norify that the surface has been created
            Log.d(TAG,"SurfaceView. surfaceCreated.");
    }
}

我遵循了我在LunarLander示例中看到的那种代码。我创建了一个res / drawable文件夹。以前我在res / drawable-hdpi中的图像，但是当我没有看到绘制到画布上的图像时，我创建了res / drawable并将.png复制到该文件夹中。我对R.drawable.dicecup的调用解决了，没有任何语法错误。我的图像编辑器中的图像大小为120 x 120像素。当我打开应用程序并且没有任何地方绘制骰子杯图像时，我感到很惊讶。可能有什么不对？

该线程实际上是在surfaceCreated方法中启动的。我从运行中获取了Log.d，所以我知道运行正在执行。据我所知，没有任何错误，程序没有崩溃或任何事情都没有被绘制。

我已经尝试将绘图移回UI线程，但我仍然没有看到任何内容。

P.S。结果证明这是我的错。 Bitmap从我刚用于背景图像的矩形中删除的线程中得到了很好的结果，我还没有发现它。现在我应该知道如何绘制位图以发现这些类型的问题。为了让事情变得简单，我创建了res / drawables并从那里加载图像。

Answer 1

看起来你试图在UI线程以外的线程上调用draw。如果这就是你正在做的事情，那就是它无法正常工作的原因。根据{{3}}，您无法在非UI线程上执行任何UI工作。

可绘制。 Draw不会将图像绘制到屏幕上

1 个答案: