gdiplus: Fix a possible floating point exception in path gradients.

[Vincent Povirk]

I don't know any programs affected by this, just noticed it when I set
my test program to clear fpe flags, to test the fix for bug 43290.

Signed-off-by: Vincent Povirk <vincent at codeweavers.com>
---
 dlls/gdiplus/graphics.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/dlls/gdiplus/graphics.c b/dlls/gdiplus/graphics.c
index 43cd6ac..543593e 100644
--- a/dlls/gdiplus/graphics.c
+++ b/dlls/gdiplus/graphics.c
@@ -1493,8 +1493,17 @@ static GpStatus brush_fill_pixels(GpGraphics *graphics, GpBrush *brush,
                         REAL blend_amount, pdy, pdx;
                         pdy = yf - center_point.Y;
                         pdx = xf - center_point.X;
-                        blend_amount = ( (center_point.Y - start_point.Y) * pdx + (start_point.X - center_point.X) * pdy ) / ( dy * pdx - dx * pdy );
-                        outer_color = blend_colors(start_color, end_color, blend_amount);
+
+                        if (fabs(pdx) <= 0.001 && fabs(pdy) <= 0.001)
+                        {
+                            /* Too close to center point, don't try to calculate outer color */
+                            outer_color = start_color;
+                        }
+                        else
+                        {
+                            blend_amount = ( (center_point.Y - start_point.Y) * pdx + (start_point.X - center_point.X) * pdy ) / ( dy * pdx - dx * pdy );
+                            outer_color = blend_colors(start_color, end_color, blend_amount);
+                        }
                     }
 
                     distance = (end_point.Y - start_point.Y) * (start_point.X - xf) +
-- 
2.7.4