android 图片处理之制作圆角图片

处理圆角图片关键就在于使用 Paint的setXfermode

相关资料：http://blog.youkuaiyun.com/wm111/article/details/7299294

以下是改进一个前人做的圆角图片的例子，少创建一次bitmap

public static Bitmap roundCorners(final Bitmap source, final float radius) {

        int width = source.getWidth();
        int height = source.getHeight();

        Paint paint = new Paint();
        paint.setAntiAlias(true);
        paint.setColor(android.graphics.Color.WHITE);

        Bitmap clipped = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(clipped);
        canvas.drawRoundRect(new RectF(0, 0, width, height), radius, radius,
                paint);
        
        paint.setXfermode(new PorterDuffXfermode(android.graphics.PorterDuff.Mode.SRC_IN));
        canvas.drawBitmap(source, 0, 0, paint);
        
        source.recycle();

        return clipped;

    }

原例：

 
 

  
      /**
 
 
 
 

  
       * Round the corners of a {@link Bitmap}
 
 
 
 

  
       *
 
 
 
 

  
       * @param source
 
 
 
 

  
       * @param radius
 
 
 
 

  
       * @return rounded corner bitmap
 
 
 
 

  
       */
 
 
 
 

  
      public static Bitmap roundCorners(final Bitmap source, final float radius) {
 
 
 
 

  
          int width = source.getWidth();
 
 
 
 

  
          int height = source.getHeight();
 
 
 
 

  
  

 
 
 
 

  
          Paint paint = new Paint();
 
 
 
 

  
          paint.setAntiAlias(true);
 
 
 
 

  
          paint.setColor(WHITE);
 
 
 
 

  
  

 
 
 
 

  
          Bitmap clipped = Bitmap.createBitmap(width, height, ARGB_8888);
 
 
 
 

  
          Canvas canvas = new Canvas(clipped);
 
 
 
 

  
          canvas.drawRoundRect(new RectF(0, 0, width, height), radius, radius,
 
 
 
 

  
                  paint);
 
 
 
 

  
          paint.setXfermode(new PorterDuffXfermode(DST_IN));
 
 
 
 

  
  

 
 
 
 

  
          Bitmap rounded = Bitmap.createBitmap(width, height, ARGB_8888);
 
 
 
 

  
          canvas = new Canvas(rounded);
 
 
 
 

  
          canvas.drawBitmap(source, 0, 0, null);
 
 
 
 

  
          canvas.drawBitmap(clipped, 0, 0, paint);
 
 
 
 

  
  

 
 
 
 

  
          source.recycle();
 
 
 
 

  
          clipped.recycle();
 
 
 
 

  
  

 
 
 
 

  
          return rounded;
 
 
 
 

  
      }