高斯模糊

RenderScript是Android在API 11之后加入的，用于高效的图片处理，包括模糊、混合、矩阵卷积计算等，代码示例如下:

public Bitmap blurBitmap(Bitmap bitmap){  
          
        //Let's create an empty bitmap with the same size of the bitmap we want to blur  
        Bitmap outBitmap = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Config.ARGB_8888);  
          
        //Instantiate a new Renderscript  
        RenderScript rs = RenderScript.create(getApplicationContext());  
          
        //Create an Intrinsic Blur Script using the Renderscript  
        ScriptIntrinsicBlur blurScript = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));  
          
        //Create the Allocations (in/out) with the Renderscript and the in/out bitmaps  
        Allocation allIn = Allocation.createFromBitmap(rs, bitmap);  
        Allocation allOut = Allocation.createFromBitmap(rs, outBitmap);  
          
        //Set the radius of the blur  
        blurScript.setRadius(25.f);  
          
        //Perform the Renderscript  
        blurScript.setInput(allIn);  
        blurScript.forEach(allOut);  
          
        //Copy the final bitmap created by the out Allocation to the outBitmap  
        allOut.copyTo(outBitmap);  
          
        //recycle the original bitmap  
        bitmap.recycle();  
          
        //After finishing everything, we destroy the Renderscript.  
        rs.destroy();  
          
        return outBitmap;     
    }  
blurScript.setRadius(25.f); 
 设置模糊程度，参数越大，越模糊，参数范围为0-25，否则会报错：
android.renderscript.RSIllegalArgumentException: Radius out of range (0 < r <= 25).