Android的透明画布（surfaceview）

问题描述

我有一个面板，它通过一个RelativeLayout的放置在另一个视图之上。

我想给这个面板透明背景，但没有发现搜索几个小时后，要做到这一点的正确方法。当我设置阿尔法回到0我结束了一个黑色的背景。

希望这里有人能帮助我。

非常感谢！

面板通过此code得出：

 进口android.content.Context;
    进口android.graphics.Canvas;
    进口android.graphics.Paint;
    进口android.util.AttributeSet;
    进口android.view.SurfaceHolder;
    进口android.view.SurfaceView;

    公共类面板扩展了SurfaceView实现SurfaceHolder.Callback {

    私人ViewThread mThread;

    涂料粉刷=新的油漆（）;

    公共面板（上下文的背景下，AttributeSet中的AttributeSet）{
        超（背景下，AttributeSet中的）;
        。getHolder（）的addCallback（本）;
        mThread =新ViewThread（本）;
    }

    公共无效doDraw（帆布油画）{
        canvas.drawARGB（50，120，120，120）;

        paint.setARGB（255，255，0，0）;
        paint.setStrokeWidth（2）;

        INT CanvasHeight = canvas.getHeight（）;
        INT CanvasWidth = canvas.getWidth（）;

        canvas.drawLine（LeftStartX，LeftStartY，StopX，StopY，油漆）;
    }

    公共无效updateDrawing（浮动LB，RB浮动，浮动BD，飘啊，飘AD）{
        左=磅;
        右= RB;
        距离= BD;
        A高= AH;
        ADistance = AD;
    }

    公共无效surfaceChanged（SurfaceHolder持有人，INT格式，诠释的宽度，高度INT）{}


    公共无效surfaceCreated（SurfaceHolder持有者）{
        如果（！mThread.isAlive（））{
            mThread =新ViewThread（本）;
            mThread.setRunning（真正的）;
            mThread.start（）;
        }
    }


    公共无效surfaceDestroyed（SurfaceHolder持有者）{
        如果（mThread.isAlive（））{
            mThread.setRunning（假）;
        }
    }
}
 

解决方案

与关键字surfaceview代替帆布II搜索后发现，这是不可能的。欲了解更多信息，请参阅：如何使surfaceview透明

由于画布的背景是静态的，我把它完全一样的背景。现在看来，它是透明的：）

 位图BG = BitmapFactory.de codeResource（getResources（），R.drawable.background_panel_800_480）;
    canvas.drawBitmap（BG，0，0，NULL）;
 

I've got a panel which is placed on top of another view via a relativelayout.

I would like to give this panel a transparent background, but didn't find the correct way to do this after searching for some hours. When I set the alpha back to 0 I end up with a black background.

Hopefully someone here can help me with this.

Thanks a lot!

The panel is drawn via this code:

    import android.content.Context;
    import android.graphics.Canvas;
    import android.graphics.Paint;
    import android.util.AttributeSet;
    import android.view.SurfaceHolder;
    import android.view.SurfaceView;

    public class Panel extends SurfaceView implements SurfaceHolder.Callback {

    private ViewThread mThread;

    Paint paint = new Paint();

    public Panel(Context context, AttributeSet attributeSet) {
        super(context, attributeSet);
        getHolder().addCallback(this);
        mThread = new ViewThread(this);
    }

    public void doDraw(Canvas canvas) {
        canvas.drawARGB(50, 120, 120, 120);

        paint.setARGB(255, 255, 0, 0);
        paint.setStrokeWidth(2);

        int CanvasHeight = canvas.getHeight();
        int CanvasWidth  = canvas.getWidth();

        canvas.drawLine(LeftStartX, LeftStartY, StopX, StopY, paint);
    }

    public void updateDrawing(float LB, float RB, float BD, float AH, float AD ){
        Left = LB;
        Right = RB;
        Distance = BD;
        AHeight = AH;
        ADistance = AD;
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}


    public void surfaceCreated(SurfaceHolder holder) {
        if (!mThread.isAlive()) {
            mThread = new ViewThread(this);
            mThread.setRunning(true);
            mThread.start();
        }
    }


    public void surfaceDestroyed(SurfaceHolder holder) {
        if (mThread.isAlive()) {
            mThread.setRunning(false);
        }
    }
}

解决方案

After searching with keyword surfaceview instead of canvas iI found out that it isn't possible. For more information see: how to make surfaceview transparent

Because the background of the canvas is static I've gave it the exact same background. Now it looks like it is transparent :)

    Bitmap bg = BitmapFactory.decodeResource(getResources(), R.drawable.background_panel_800_480);
    canvas.drawBitmap(bg, 0, 0, null);

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