Re: [PATCH v7 0/1] MR3865: gdiplus: implement PixelOffsetMode Half and HighQuality for GdipDrawImagePointsRect

[Esme Povirk (＠madewokherd)]

Esme Povirk (@madewokherd) commented about dlls/gdiplus/graphics.c:
> -
>        if (graphics_bounds.Y + graphics_bounds.Height < dst_area_bottom) dst_area_bottom = graphics_bounds.Y + graphics_bounds.Height;
> -
> -
>        // Based on value of dst_area, the pixel number to draw is calculated.
> -
>        if ((offset_mode == PixelOffsetModeHalf) ||
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>            (offset_mode == PixelOffsetModeHighQuality))
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>        {
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>            // Based on experiments dst_area with value 0.5 should be rounded to 0.0
> -
>            // (rounding half down), that't why we are adding 0.4999 instead of 0.5
> -
>            dst_area.left = (INT)(dst_area_left + 0.4999);
> -
>            dst_area.top = (INT)(dst_area_top + 0.4999);
> -
>            dst_area.right = (INT)(dst_area_right + 0.4999);
> -
>            dst_area.bottom = (INT)(dst_area_bottom + 0.4999);
> -
> -
>            // With PixelOffsetMode Half we are checking color in the middle of destination pixel,
> -
>            // that's why we are adding 0.5 to destination.
> -
>            dst_pixel_offset = 0.5;

This seems complicated for what I'd expect is equivalent to a different set of destination points in device space.