[PATCH 0/1] MR8294: gdiplus: Changed comparison from floating-point (ptf) to integer (pti) coordinates for accuracy

[Wei Xie (＠wayne)]

Fixed potential image resampling conditions by using exact pixel coordinates

[PATCH 1/1] gdiplus: Changed comparison from floating-point (ptf) to integer (pti) coordinates for accuracy

[Wei Xie]

From: Wei Xie

Fixed potential image resampling conditions by using exact pixel coordinates
---
 dlls/gdiplus/graphics.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/dlls/gdiplus/graphics.c b/dlls/gdiplus/graphics.c
index 8fa0d689cbe..6dd5a83092f 100644
--- a/dlls/gdiplus/graphics.c
+++ b/dlls/gdiplus/graphics.c
@@ -3260,8 +3260,8 @@ GpStatus WINGDIPAPI GdipDrawImagePointsRect(GpGraphics *graphics, GpImage *image
             graphics->scale, image->xres, image->yres, bitmap->format,
             imageAttributes ? imageAttributes->outside_color : 0);

-        if (ptf[1].Y != ptf[0].Y || ptf[2].X != ptf[0].X ||
-            ptf[1].X - ptf[0].X != srcwidth || ptf[2].Y - ptf[0].Y != srcheight ||
+        if (pti[1].y != pti[0].y || pti[2].x != pti[0].x||
+            pti[1].x - pti[0].x != gdip_round(srcwidth) || pti[2].y - pti[0].y != gdip_round(srcheight) ||
             srcx < 0 || srcy < 0 ||
             srcx + srcwidth > bitmap->width || srcy + srcheight > bitmap->height)
             do_resampling = TRUE;

[Esme Povirk (＠madewokherd)]

I'm not sure about this. We may still want to rescale the image even if the coordinates are within 1 pixel. Maybe we could use a smaller delta?

[Wei Xie (＠wayne)]

[test_draw_image_resampling.cpp](/uploads/283a7f5a477eb2ea2496c371639e32a1/test_draw_image_resampling.cpp)

Using this program to compare the execution results of wine and Windows, it can be seen that the difference below Windows is 0.1 should not be resampled.

![image](/uploads/cbed196176a37c61a495fc50fd49d74b/image.png){width=408 height=104}

![image](/uploads/11190fbfef66ca124778c811fee94ac2/image.png){width=413 height=92}