From 2a0b7589734538cc794896494d4dd77fd7bb5b7b Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Mon, 25 Aug 2014 17:47:53 +0000
Subject: [PATCH] Fix order of radial gradient stops in wxMSW.

Ensure that the order of stops is consistent with the documentation and other
platforms behaviour, i.e. they are counted from inside to outside of the
circle and not vice versa, which happens to be the GDI+ convention.

Closes #16443.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77481 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 src/msw/graphics.cpp | 32 +++++++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 7 deletions(-)

diff --git a/src/msw/graphics.cpp b/src/msw/graphics.cpp
index 35237953b8..0ca6e03f73 100644
--- a/src/msw/graphics.cpp
+++ b/src/msw/graphics.cpp
@@ -281,7 +281,9 @@ protected:
 private:
     // common part of Create{Linear,Radial}GradientBrush()
     template <typename T>
-    void SetGradientStops(T *brush, const wxGraphicsGradientStops& stops);
+    void SetGradientStops(T *brush,
+                          const wxGraphicsGradientStops& stops,
+                          bool reversed = false);
 
     Brush* m_brush;
     Image* m_brushImage;
@@ -852,7 +854,8 @@ void wxGDIPlusBrushData::Init()
 template <typename T>
 void
 wxGDIPlusBrushData::SetGradientStops(T *brush,
-        const wxGraphicsGradientStops& stops)
+        const wxGraphicsGradientStops& stops,
+        bool reversed)
 {
     const unsigned numStops = stops.GetCount();
     if ( numStops <= 2 )
@@ -865,12 +868,25 @@ wxGDIPlusBrushData::SetGradientStops(T *brush,
     wxVector<Color> colors(numStops);
     wxVector<REAL> positions(numStops);
 
-    for ( unsigned i = 0; i < numStops; i++ )
+    if ( reversed )
     {
-        wxGraphicsGradientStop stop = stops.Item(i);
+        for ( unsigned i = 0; i < numStops; i++ )
+        {
+            wxGraphicsGradientStop stop = stops.Item(numStops - i - 1);
 
-        colors[i] = wxColourToColor(stop.GetColour());
-        positions[i] = stop.GetPosition();
+            colors[i] = wxColourToColor(stop.GetColour());
+            positions[i] = 1.0 - stop.GetPosition();
+        }
+    }
+    else
+    {
+        for ( unsigned i = 0; i < numStops; i++ )
+        {
+            wxGraphicsGradientStop stop = stops.Item(i);
+
+            colors[i] = wxColourToColor(stop.GetColour());
+            positions[i] = stop.GetPosition();
+        }
     }
 
     brush->SetInterpolationColors(&colors[0], &positions[0], numStops);
@@ -909,7 +925,9 @@ wxGDIPlusBrushData::CreateRadialGradientBrush(wxDouble xo, wxDouble yo,
     int count = 1;
     brush->SetSurroundColors(&col, &count);
 
-    SetGradientStops(brush, stops);
+    // Because the GDI+ API draws radial gradients from outside towards the
+    // center we have to reverse the order of the gradient stops.
+    SetGradientStops(brush, stops, true);
 }
 
 //-----------------------------------------------------------------------------