如何擦图像？

Question

我想擦擦Image.Actually我有两个图像一个在前景和另一个在背景当我擦地形图像然后背景图像将不得不如何来做？我在这里发现了很多，但不能得到解决方案呢。有人请帮我解决我的问题。 我尝试这样做：

public class MainActivity extends Activity { 

ImageView img; 

public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    // setContentView(R.layout.activity_main); 
    // img = (ImageView) findViewById(R.id.img); 
    // 
    // new Panel(this); 
    setContentView(new Panel(this)); 

} 

class Panel extends View { 

    private Bitmap mBitmap; 
    private Canvas mCanvas; 
    private Path mPath; 
    private Paint mPaint; 
    Bitmap bitmap; 
    Canvas pcanvas; 
    int x = 0; 
    int y = 0; 
    int r = 0; 

    public Panel(Context context) { 
     super(context); 

     Log.v("Panel", ">>>>>>"); 

     setFocusable(true); 
     setBackgroundColor(Color.MAGENTA); 

     // setting paint 
     mPaint = new Paint(); 
     mPaint.setAlpha(1); 
     mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN)); 
     mPaint.setAntiAlias(true); 

     // getting image from resources 
     Resources r = this.getContext().getResources(); 

     Bitmap bm = BitmapFactory.decodeResource(getResources(), 
       R.drawable.verse); 

     // converting image bitmap into mutable bitmap 

     // bitmap = Bitmap.createBitmap(295, 260, Config.ARGB_8888); 
     bitmap = Bitmap.createBitmap(185, 120, Config.ARGB_8888); 
     pcanvas = new Canvas(); 
     pcanvas.setBitmap(bitmap); // drawXY will result on that Bitmap 
     pcanvas.drawBitmap(bm, 0, 0, null); 

    } 

    @Override 
    protected void onDraw(Canvas canvas) { 

     // draw a circle that is erasing bitmap 
     // pcanvas.drawCircle(x, y, r, mPaint); 
     pcanvas.drawColor(color.transparent); 
     canvas.drawBitmap(bitmap, 0, 0, null); 

     super.onDraw(canvas); 

    } 

    @Override 
    public boolean onTouchEvent(MotionEvent event) { 

     // set paramete to draw circle on touch event 
     x = (int) event.getX(); 
     y = (int) event.getY(); 

     r = 20; 
     // Atlast invalidate canvas 
     invalidate(); 
     return true; 
    } 

} 
} 

Answer 1

您可能需要使用Xfermodes/Porterduff尝试，可能这个线程可以帮助你：Android bitmap mask color, remove color

硬集的颜色，你可以使用

int[] pix=new int[bitmap.getWidth()*bitmap.getHeight()]; 
bitmap.getPixels(pix, 0, 0, bitmap.getWidth(), bitmap.getHeight); 

// do some processing here 
// possible set color of some pixels to Color.TRANSPARENT 

bitmap.setPixels(pix, 0, bitmap.getWidth(), 0, 0, bitmap.getWidth(), bitmap.getHeight());