Modification of gradient syntax to support vector style specification

1 files changed, 73 insertions, 20 deletions

diff --git a/generic/Color.c b/generic/Color.c
index d0c3a81..c83631d 100644
--- a/generic/Color.c
+++ b/generic/Color.c
@@ -375,9 +375,30 @@ ZnDeleteGradientName(char	*name)
  *
  *	graddesc := =type args
  *	  where type := axial | radial | path
- *		args := angle if type = axial; angle in (0..360)
- *		args := x y if type = (radial| path); x and
- *		y being real valued.
+ *
+ *	  If type = axial
+ *		args := angle (0..360) | xs ys xe ye (reals)
+ *
+ *        The first form define the axial gradiant by its slope.
+ *        With this syntax the gradient fits the whole shape.
+ *	  This is a backward compatible syntax.
+ *	  The second form specifies a vector which will be used
+ *	  to draw the gradient. The vector defines both the angle
+ *	  and the gradient area. Parts of the shape that lie before
+ *	  the vector origin are filled with the first color and
+ *	  parts that lie after the vector end are filled with the
+ *	  last color.
+ *
+ *	  If type = radial or path
+ *		args := xs ys [xe ye] (reals)
+ *
+ *	  The vector specified by the 4 coordinates defines the
+ *	  gradient area.  Parts of the shape that lie before
+ *	  the vector origin are filled with the first color and
+ *	  parts that lie after the vector end are filled with the
+ *	  last color. The vector end may be omitted, in such case
+ *	  the gradient fits exactly the whole shape to be filled,
+ *	  this is backward compatible with older gradients.
  *	  
  *	color := colorvalue | colorvalue position |
  *		 colorvalue control position
@@ -388,7 +409,7 @@ ZnDeleteGradientName(char	*name)
  *
  * Results:
  *	The return value is a token for a data structure
- *	describing a gradient.  This token may be passed
+ *	describing a gradient. This token may be passed
  *	to the drawing routines.
  *	If an error prevented the gradient from being created
  *	then NULL is returned and an error message will be
@@ -409,6 +430,30 @@ ZnGetGradientByValue(ZnGradient	*grad)
 }
 
 
+static int
+ParseRealList(const char *str,
+	      const char *stop,
+	      ZnReal	 *list,
+	      int	 max)
+{
+  int	 num;
+  char	 *end;
+
+  num = 0;
+  while ((num < max) && (str != stop)) {
+    list[num] = strtod(str, &end);
+    if (end == str) {
+      /* A syntax error occured, return a 0 count
+       * as a hint for the caller.
+       */
+      return 0;
+    }
+    num++;
+    str = end+strspn(end, " \t");
+  }
+  return num;
+}
+
 ZnGradient *
 ZnGetGradient(Tcl_Interp	*interp,
 	      Tk_Window		tkwin,
@@ -418,11 +463,11 @@ ZnGetGradient(Tcl_Interp	*interp,
   Tcl_HashEntry	*hash;
   ZnGradient	*grad;
   unsigned int	i, j, nspace, num_colors;
-  unsigned int	size;
+  unsigned int	size, num_coords;
   char		type;
   char const	*scan_ptr, *next_ptr, *str_ptr;
   int		angle, position, control;
-  double	x=0, y=0;
+  ZnReal	coords[4];
   char		*color_ptr, *end, segment[SEGMENT_SIZE];
   ZnGradientColor *first, *last;
   XColor	color;
@@ -495,14 +540,13 @@ ZnGetGradient(Tcl_Interp	*interp,
       scan_ptr++;
       if ((*scan_ptr == 'a') && (strncmp(scan_ptr, "axial", 5) == 0)) {
 	scan_ptr += 5;
-	angle = strtol(scan_ptr, &end, 10);
-	nspace = strspn(end, " \t");
-	if ((end+nspace) != next_ptr) {
+	if (ParseRealList(scan_ptr, next_ptr, coords, 1) != 1) {
 	grad_err3:
 	  Tcl_AppendResult(interp, "invalid gradient parameter \"",
 			   desc, "\",", NULL);
 	  goto grad_err1;
 	}
+	angle = (int) coords[0];
       }
       else if (((*scan_ptr == 'r') && (strncmp(scan_ptr, "radial", 6) == 0)) ||
 	       ((*scan_ptr == 'p') && (strncmp(scan_ptr, "path", 4) == 0))) {
@@ -514,14 +558,8 @@ ZnGetGradient(Tcl_Interp	*interp,
 	  type = ZN_PATH_GRADIENT;
 	  scan_ptr += 4;
 	}
-	x = strtod(scan_ptr, &end);
-	if (end == scan_ptr) {
-	  goto grad_err3;
-	}
-	scan_ptr = end;
-	y = strtod(scan_ptr, &end);
-	nspace = strspn(end, " \t");	
-	if ((end+nspace) != next_ptr) {
+	num_coords = ParseRealList(scan_ptr, next_ptr, coords, 4);
+	if ((num_coords != 2) && (num_coords != 4)) {
 	  goto grad_err3;
 	}
       }
@@ -539,14 +577,29 @@ ZnGetGradient(Tcl_Interp	*interp,
     grad = (ZnGradient *) ZnMalloc(sizeof(ZnGradient) +
 				   sizeof(ZnGradientColor)*(num_colors-1));
     grad->ref_count = 1;
+    grad->simple = True;
     grad->num_colors = num_colors;
     grad->type = type;
     if (type == ZN_AXIAL_GRADIENT) {
-      grad->g.angle = angle;
+      if (num_coords == 4) {
+	grad->simple = False;
+	grad->g.p.x = coords[0];
+	grad->g.p.y = coords[1];
+	grad->e.x = coords[2];
+	grad->e.y = coords[3];
+      }
+      else {
+	grad->g.angle = angle;
+      }
     }
     else {
-      grad->g.p.x = x;
-      grad->g.p.y = y;
+      grad->g.p.x = coords[0];
+      grad->g.p.y = coords[1];
+      if (num_coords == 4) {
+	grad->simple = False;
+	grad->e.x = coords[2];
+	grad->e.y = coords[3];
+      }
     }
     grad->hash = hash;
     Tcl_SetHashValue(hash, grad);