[PATCH 0/1] MR3971: gdiplus: Optimize GdipDrawImagePointsRect and GDI32_GdipDrawPath

[PATCH 1/1] gdiplus: Optimize GdipDrawImagePointsRect and GDI32_GdipDrawPath

[Bartosz Kosiorek]

From: Bartosz Kosiorek

---
 dlls/gdiplus/graphics.c | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/dlls/gdiplus/graphics.c b/dlls/gdiplus/graphics.c
index 65b33cdc960..1b319c15d26 100644
--- a/dlls/gdiplus/graphics.c
+++ b/dlls/gdiplus/graphics.c
@@ -270,11 +270,11 @@ static INT prepare_dc(GpGraphics *graphics, GpPen *pen)
     else{
         /* Get an estimate for the amount the pen width is affected by the world
          * transform. (This is similar to what some of the wine drivers do.) */
-        pt[0].X = 0.0;
-        pt[0].Y = 0.0;
-        pt[1].X = 1.0;
-        pt[1].Y = 1.0;
-        GdipTransformMatrixPoints(&graphics->worldtrans, pt, 2);
+        pt[0].X = graphics->worldtrans.matrix[4];
+        pt[0].Y = graphics->worldtrans.matrix[5];
+        pt[1].X = graphics->worldtrans.matrix[4] + graphics->worldtrans.matrix[0] + graphics->worldtrans.matrix[2];
+        pt[1].Y = graphics->worldtrans.matrix[5] + graphics->worldtrans.matrix[1] + graphics->worldtrans.matrix[3];
+
         width = sqrt((pt[1].X - pt[0].X) * (pt[1].X - pt[0].X) +
                      (pt[1].Y - pt[0].Y) * (pt[1].Y - pt[0].Y)) / sqrt(2.0);

@@ -3215,19 +3215,16 @@ GpStatus WINGDIPAPI GdipDrawImagePointsRect(GpGraphics *graphics, GpImage *image
             if (do_resampling)
             {
                 GpMatrix dst_to_src;
-                REAL m11, m12, m21, m22, mdx, mdy;
                 REAL x_dx, x_dy, y_dx, y_dy;
                 ARGB *dst_color;
                 GpPointF src_pointf_row, src_pointf;

-                m11 = (ptf[1].X - ptf[0].X) / srcwidth;
-                m12 = (ptf[1].Y - ptf[0].Y) / srcwidth;
-                m21 = (ptf[2].X - ptf[0].X) / srcheight;
-                m22 = (ptf[2].Y - ptf[0].Y) / srcheight;
-                mdx = ptf[0].X - m11 * srcx - m21 * srcy;
-                mdy = ptf[0].Y - m12 * srcx - m22 * srcy;
-
-                GdipSetMatrixElements(&dst_to_src, m11, m12, m21, m22, mdx, mdy);
+                dst_to_src.matrix[0] = (ptf[1].X - ptf[0].X) / srcwidth;
+                dst_to_src.matrix[1] = (ptf[1].Y - ptf[0].Y) / srcwidth;
+                dst_to_src.matrix[2] = (ptf[2].X - ptf[0].X) / srcheight;
+                dst_to_src.matrix[3] = (ptf[2].Y - ptf[0].Y) / srcheight;
+                dst_to_src.matrix[4] = ptf[0].X - dst_to_src.matrix[0] * srcx - dst_to_src.matrix[2] * srcy;
+                dst_to_src.matrix[5] = ptf[0].Y - dst_to_src.matrix[1] * srcx - dst_to_src.matrix[3] * srcy;

stat = GdipInvertMatrix(&dst_to_src);
                 if (stat != Ok) return stat;

[Jeffrey Smith (＠whydoubt)]

Jeffrey Smith (@whydoubt) commented about dlls/gdiplus/graphics.c:
>  else{
>      /* Get an estimate for the amount the pen width is affected by the world
>       * transform. (This is similar to what some of the wine drivers do.) */
> -
>    pt[0].X = 0.0;
> -
>    pt[0].Y = 0.0;
> -
>    pt[1].X = 1.0;
> -
>    pt[1].Y = 1.0;
> -
>    GdipTransformMatrixPoints(&graphics->worldtrans, pt, 2);
> -
>    pt[0].X = graphics->worldtrans.matrix[4];
> -
>    pt[0].Y = graphics->worldtrans.matrix[5];
> -
>    pt[1].X = graphics->worldtrans.matrix[4] + graphics->worldtrans.matrix[0] + graphics->worldtrans.matrix[2];
> -
>    pt[1].Y = graphics->worldtrans.matrix[5] + graphics->worldtrans.matrix[1] + graphics->worldtrans.matrix[3];
> -
>    width = sqrt((pt[1].X - pt[0].X) * (pt[1].X - pt[0].X) +
>                 (pt[1].Y - pt[0].Y) * (pt[1].Y - pt[0].Y)) / sqrt(2.0);

If going for optimization, might as well go the rest of the way cleaning this up.
```suggestion:-6+0
        pt[1].X = graphics->worldtrans.matrix[0] + graphics->worldtrans.matrix[2];
        pt[1].Y = graphics->worldtrans.matrix[1] + graphics->worldtrans.matrix[3];

width = sqrt(pt[1].X * pt[1].X + pt[1].Y * pt[1].Y) / sqrt(2.0);
```
Note: the compiler converts `sqrt(2.0)` to the actual value, so no need move stuff around
to avoid a `sqrt` here.

[Jeffrey Smith (＠whydoubt)]

Is the commit title accurate?  I don't see changes that directly affect `GdipDrawImagePointsRect`.

[Nikolay Sivov (＠nsivov)]

What does this optimize for? Extra function call made once, outside of the loop?