Vincent Povirk : gdiplus: Implement GdipSetLineSigmaBlend.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 1860b3261813166452efe5cdd4773c9804ad1704
URL:    http://source.winehq.org/git/wine.git/?a=commit;h=1860b3261813166452efe5cdd4...

Author: Vincent Povirk 
Date:   Mon May  4 17:53:48 2009 -0500

gdiplus: Implement GdipSetLineSigmaBlend.

---

dlls/gdiplus/brush.c |   50 ++++++++++++++++++++++++++++++++++++++++++++++----
 1 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/dlls/gdiplus/brush.c b/dlls/gdiplus/brush.c
index 74e7764..60d5970 100644
--- a/dlls/gdiplus/brush.c
+++ b/dlls/gdiplus/brush.c
@@ -1193,15 +1193,57 @@ GpStatus WINGDIPAPI GdipSetLineGammaCorrection(GpLineGradient *line,
 GpStatus WINGDIPAPI GdipSetLineSigmaBlend(GpLineGradient *line, REAL focus,
     REAL scale)
 {
-    static int calls;
+    REAL factors[33];
+    REAL positions[33];
+    int num_points = 0;
+    int i;
+    const int precision = 16;
+    REAL erf_range; /* we use values erf(-erf_range) through erf(+erf_range) */
+    REAL min_erf;
+    REAL scale_erf;
+
+    TRACE("(%p, %0.2f, %0.2f)\n", line, focus, scale);

if(!line || focus < 0.0 || focus > 1.0 || scale < 0.0 || scale > 1.0)
         return InvalidParameter;

-    if(!(calls++))
-        FIXME("not implemented\n");
+    /* we want 2 standard deviations */
+    erf_range = 2.0 / sqrt(2);

-    return NotImplemented;
+    /* calculate the constants we need to normalize the error function to be
+        between 0.0 and scale over the range we need */
+    min_erf = erf(-erf_range);
+    scale_erf = scale / (-2.0 * min_erf);
+
+    if (focus != 0.0)
+    {
+        positions[0] = 0.0;
+        factors[0] = 0.0;
+        for (i=1; i<precision; i++)
+        {
+            positions[i] = focus * i / precision;
+            factors[i] = scale_erf * (erf(2 * erf_range * i / precision - erf_range) - min_erf);
+        }
+        num_points += precision;
+    }
+
+    positions[num_points] = focus;
+    factors[num_points] = scale;
+    num_points += 1;
+
+    if (focus != 1.0)
+    {
+        for (i=1; i<precision; i++)
+        {
+            positions[i+num_points-1] = (focus + ((1.0-focus) * i / precision));
+            factors[i+num_points-1] = scale_erf * (erf(erf_range - 2 * erf_range * i / precision) - min_erf);
+        }
+        num_points += precision;
+        positions[num_points-1] = 1.0;
+        factors[num_points-1] = 0.0;
+    }
+
+    return GdipSetLineBlend(line, factors, positions, num_points);
 }

GpStatus WINGDIPAPI GdipSetLineWrapMode(GpLineGradient *line,