Bitmap转成高斯模糊图片

优点：处理速度快

/**
* 转成高斯模糊图片
*
* 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
*/
public static Bitmap blurBitmap(Bitmap bitmap, Context context) {

    //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(), Bitmap.Config.ARGB_8888);

    //Instantiate a new Renderscript
    RenderScript rs = RenderScript.create(context);

    //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;
}