Re: [PATCH 0/1] MR3546: gdiplus: move pointer calculation outside inner loop for alpha_blend_bmp_pixels

[Bartosz Kosiorek (＠gang65)]

On Thu Aug 10 22:58:33 2023 +0000, Nikolay Sivov wrote:
> What difference does this make?
> In previous implementation we calculated `src_color` position every time:
        for (x=0; x<src_width; x++)
        {
            ARGB dst_color, src_color;
            src_color = ((ARGB*)(src + src_stride * y))[x];

With new implementation we are calculating `src_color` position only once (before `x` loop), and we just iterating the `src_color++`:
```
        ARGB *src_color = ((ARGB*)(src + src_stride * y));
        for (x=0; x<src_width; x++)
        {
...

            src_color++;
        }
```
It is much faster (avoiding not needed multiplications), especially for wide images.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/3546#note_41984