On Sat, 25 Jan 2020 19:55:23 GMT, Nir Lisker <nlis...@openjdk.org> wrote:
>> With regard as to why the tiling version is significantly slower, though, I
>> do have a pretty good idea; as Kevin hinted, the pixel copy into a temporary
>> buffer before copying into the final image is where most the extra time is
>> spent.
>> The reason why it is so much slower is a little bit of a pity, though;
>> profiling a run of the benchmark shows that a lot of time is spent into
>> `IntTo4ByteSameConverter::doConvert`. As it turns out, the reason for this
>> is that, under Windows and the D3D pipeline anyway, the `WriteableImage`
>> used to collate the tiles and the tiles returned from the RTTexture have
>> different pixel formats (IntARGB for the tile and byteBGRA for the
>> `WriteableImage`).
>> So if we could use a `WriteableImage` with an IntARGB pixel format as the
>> recipient for the snapshot (at least as long as no image was provided by the
>> caller), I suspect that the copy would be much faster.
>> Unfortunately it seems the only way to choose the pixel format for a
>> `WritableImage` is to initialize it with a `PixelBuffer`, but then one can
>> no longer use a `PixelWriter` to update it and it desn't seems to me that
>> there is a way to safely access the `PixelBuffer` from an image's reference
>> alone.
>> I'm pretty new to this code base though (which is quite large; I haven't
>> read it all quite yet... ;-), so hopefully there's a way to do that that has
>> simply eluded me so far.
>
>> profiling a run of the benchmark shows that a lot of time is spent into
>> `IntTo4ByteSameConverter::doConvert`
>
> This is a bit naive, but what if you parallelize the code there? I didn't
> test that this produces the correct result, but you can try to replace the
> loops with this:
> IntStream.range(0, h).parallel().forEach(y -> {
> IntStream.range(0, w).parallel().forEach(x -> {
> int pixel = srcarr[srcoff++];
> dstarr[dstoff++] = (byte) (pixel );
> dstarr[dstoff++] = (byte) (pixel >> 8);
> dstarr[dstoff++] = (byte) (pixel >> 16);
> dstarr[dstoff++] = (byte) (pixel >> 24);
> });
> srcoff += srcscanints;
> dstoff += dstscanbytes;
> });
> the `WriteableImage` used to collate the tiles and the tiles returned from
> the `RTTexture` have different pixel formats (`IntARGB` for the tile and
> `byteBGRA` for the `WriteableImage`).
Where did you see these?
> Unfortunately it seems the only way to choose the pixel format for a
> `WritableImage` is to initialize it with a `PixelBuffer`, but then one can no
> longer use a `PixelWriter` to update it...
You can update it with `PixelBuffer#updateBuffer`. I think that you will want
to pass the stitched tile as the dirty region.
-------------
PR: https://git.openjdk.java.net/jfx/pull/68
