Gradient fixes

* Port fix for bug 7685 from pixman. Patch by Carl Worth

* Add projective version of radial gradient code.

* Make sure that all Pict*Gradient types have PictGradient as prefix,
  since code in various places relies on that.

render/picture.c

@@ -1051,6 +1051,7 @@ CreateRadialGradientPicture (Picture pid, xPointFixed *inner, xPointFixed *outer
     radial = &pPicture->pSourcePict->radial;
 
     radial->type = SourcePictTypeRadial;
+#if 0
     {
         double x = (double)innerRadius / (double)outerRadius;
         radial->dx = (outer->x - inner->x);
@@ -1066,7 +1067,20 @@ CreateRadialGradientPicture (Picture pid, xPointFixed *inner, xPointFixed *outer
         x = outerRadius/65536.;
         radial->a = x*x - radial->dx*radial->dx - radial->dy*radial->dy;
     }
-
+#endif
+    radial->c1.x = inner->x;
+    radial->c1.y = inner->y;
+    radial->c1.radius = innerRadius;
+    radial->c2.x = outer->x;
+    radial->c2.y = outer->y;
+    radial->c2.radius = outerRadius;
+    radial->cdx = (radial->c2.x - radial->c1.x) / 65536.;
+    radial->cdy = (radial->c2.y - radial->c1.y) / 65536.;
+    radial->dr = (radial->c2.radius - radial->c1.radius) / 65536.;
+    radial->A = (  radial->cdx * radial->cdx
+		   + radial->cdy * radial->cdy
+		   - radial->dr  * radial->dr);
+    
     initGradient(pPicture->pSourcePict, nStops, stops, colors, error);
     if (*error) {
         xfree(pPicture);

render/picturestr.h

@@ -105,17 +105,26 @@ typedef struct _PictLinearGradient {
     xPointFixed p2;
 } PictLinearGradient, *PictLinearGradientPtr;
 
+typedef struct _PictCircle {
+    xFixed x;
+    xFixed y;
+    xFixed radius;
+} PictCircle, *PictCirclePtr;
+
 typedef struct _PictRadialGradient {
     unsigned int type;
+    unsigned int class;
     int nstops;
     PictGradientStopPtr stops;
-    double fx;
-    double fy;
-    double dx;
-    double dy;
-    double a;
-    double m;
-    double b;
+    int stopRange;
+    CARD32 *colorTable;
+    int colorTableSize;
+    PictCircle c1;
+    PictCircle c2;
+    double cdx;
+    double cdy;
+    double dr;
+    double A;
 } PictRadialGradient, *PictRadialGradientPtr;
 
 typedef struct _PictConicalGradient {