[PATCH 2/5] gdi32: Implement EMFDRV_AlphaBlend().

[Huw Davies]

On Wed, Apr 14, 2021 at 03:27:57PM +0800, Zhiyi Zhang wrote:
> Fix a bug that Tally produces a blank print preview when images have to be scaled.
> 
> Signed-off-by: Zhiyi Zhang <zzhang at codeweavers.com>
> ---
>  dlls/gdi32/enhmfdrv/bitblt.c         | 85 ++++++++++++++++++++++++++++
>  dlls/gdi32/enhmfdrv/enhmetafiledrv.h |  2 +
>  dlls/gdi32/enhmfdrv/init.c           |  2 +-
>  dlls/gdi32/tests/metafile.c          |  4 +-
>  4 files changed, 89 insertions(+), 4 deletions(-)
> 
> diff --git a/dlls/gdi32/enhmfdrv/bitblt.c b/dlls/gdi32/enhmfdrv/bitblt.c
> index 1fc5c0b1040..f0be2b52fc0 100644
> --- a/dlls/gdi32/enhmfdrv/bitblt.c
> +++ b/dlls/gdi32/enhmfdrv/bitblt.c
> @@ -27,6 +27,91 @@
>  #include "enhmetafiledrv.h"
>  #include "wine/debug.h"
>  
> +BOOL CDECL EMFDRV_AlphaBlend( PHYSDEV dev_dst, struct bitblt_coords *dst, PHYSDEV dev_src,
> +                              struct bitblt_coords *src, BLENDFUNCTION func )
> +{
> +    UINT bits_size, bmi_size, emr_size, size, bpp;
> +    BITMAPINFOHEADER *bmih;
> +    EMRALPHABLEND *emr;
> +    HBITMAP hbitmap;
> +    BITMAP bitmap;
> +    BOOL ret;
> +
> +    /* can't use a metafile DC as source */
> +    if (dev_src->funcs == dev_dst->funcs)
> +        return FALSE;
> +
> +    hbitmap = GetCurrentObject(dev_src->hdc, OBJ_BITMAP);
> +    if (GetObjectW(hbitmap, sizeof(BITMAP), &bitmap) != sizeof(BITMAP))
> +        return FALSE;

This would likely be cleaner using the BlendImage entry point
(likewise I suspect StretchBlt would benefit from using PutImage).

Huw.