Android SurfaceView相对论Yout Won'；t画

我有一个XML布局，希望向其中添加我自己的自定义SurfaceView，并在其画布上绘制。当我调试时，画布运行其onDraw并获得unlockandpost函数，但它始终只是一个黑屏。这是我的密码。我已经花了几个小时试图解决这个问题，并尝试了多种替代方法，例如只将自定义SurfaceView添加到XML中，而不是动态添加，但我得到了相同的结果

任何帮助都将不胜感激

多谢各位

<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@color/white"
>
<ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/guitar_neck">
</ImageView>
<RelativeLayout
        android:id="@+id/letter_bar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
/>

}

---

目前，您的

paint

和

backgroundPaint

都具有alpha

0

试试这个：

paint = new Paint();
paint.setColor(0xFFFFFFFF); // Added alpha bits out front to make it visible white
backgroundPaint = new Paint();
backgroundPaint.setARGB(255, 255, 255, 255); // 255 alpha bit, so it's visible black

 public class LetterBar extends SurfaceView implements SurfaceHolder.Callback {
private int width, height, toneWidth, toneHeight;
private Paint backgroundPaint, paint;

private Resources res;
private Drawable myImage;
private Bitmap neck, b;

private LetterThread _thread;

public LetterBar(Context context) throws IOException {
    super(context);
    // TODO Auto-generated constructor stub

    getHolder().addCallback(this);
    _thread = new LetterThread(getHolder(), this);

    paint = new Paint();
    paint.setColor(0xFFFFFF);
    backgroundPaint = new Paint();
    backgroundPaint.setARGB(0, 255, 255, 255);

    res = context.getResources();

    neck = BitmapFactory.decodeFile("/assets/guitar_neck.gif");

    InputStream bitmap=null;
    b = BitmapFactory.decodeResource(context.getResources(), R.drawable.guitar_neck);
    toneWidth = b.getWidth();
    toneHeight = b.getHeight();
}

@Override
public void onDraw(Canvas canvas){
    canvas.drawText("TEST", 20, 20, paint);
    canvas.drawBitmap(b, 0, 0, paint);
}

@Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
    // TODO Auto-generated method stub

}

@Override
public void surfaceCreated(SurfaceHolder arg0) {
    // TODO Auto-generated method stub
    setWillNotDraw(false);
    _thread.setRunning(true);
    _thread.start();
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
    // simply copied from sample application LunarLander:
    // we have to tell thread to shut down & wait for it to finish, or else
    // it might touch the Surface after we return and explode
    boolean retry = true;
    _thread.setRunning(false);
    while (retry) {
        try {
            _thread.join();
            retry = false;
        } catch (InterruptedException e) {
            // we will try it again and again...
        }
    }
}
 }


 public class LetterThread extends Thread {
private SurfaceHolder _surfaceHolder;
private LetterBar letter_bar;
private boolean _run = false;

public LetterThread(SurfaceHolder surfaceHolder, LetterBar bar) {
    _surfaceHolder = surfaceHolder;
    letter_bar = bar;
}

public void setRunning(boolean run) {
    _run = run;
}

@Override
public void run() {
    Canvas c;
    while (_run) {
        c = null;
        try {
            c = _surfaceHolder.lockCanvas(null);
            synchronized (_surfaceHolder) {
                letter_bar.onDraw(c);
            }
        } 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 (c != null) {
                _surfaceHolder.unlockCanvasAndPost(c);
            }
        }
    }
}
 }

paint = new Paint();
paint.setColor(0xFFFFFFFF); // Added alpha bits out front to make it visible white
backgroundPaint = new Paint();
backgroundPaint.setARGB(255, 255, 255, 255); // 255 alpha bit, so it's visible black