Android模糊与RenderScript

Question

I try to make a gaussian blur on an android Bitmap but I get this error:

rsAssert failed: !mTypes.size() and rsAssert failed: !mElements.size()

Here is my code :

public Bitmap blurBitmap(Bitmap src) {
    Bitmap outBitmap = src.copy(src.getConfig(), true);

    final RenderScript rs = RenderScript.create(this);
    final Allocation input = Allocation.createFromBitmap(rs, src);
    final Allocation output = Allocation.createFromBitmap(rs, outBitmap);

    final ScriptIntrinsicBlur script =
            ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
    script.setRadius(25f);
    script.setInput(input);
    script.forEach(output);
    output.copyTo(outBitmap);

    rs.destroy();

    return outBitmap;
}

Note that I used android.support.v8.renderscript to ensure compatibility with android lower versions.

Someone would have an idea to fix it?

Thanks.

Martin

Answer 1

The Element arguments of ScriptIntrinsicBlur should be the same of Allocation's element, so you should use Allocation.getElement() , rather than direct Element.U8_4(rs) .

final ScriptIntrinsicBlur script =
    ScriptIntrinsicBlur.create(rs, input.getElement());

And you might also want move those final to class private member , since some of them might be different every time your bitmap is different.

And FYI, script.setRadius(25f) is way too high, that will cause slow calculation. If you need such heavy blur, you might consider to scale down the original bitmap at certain level, and blur it, then scale up to your canvas, which will be much faster than heavy blur for a huge image.

One more thing, if you don't care to keep the original bitmap, the allocation of input and output can be the same one, which might save some memory.

Answer 2

While there isn't a good way to increase blur radius, for very large images you can essentially fake it by scaling down (ex .5 original size), blurring, then scaling up to original size. Be careful not to scale too far down as the resulting bitmap will become pixelated.