[cairo-commit] cairo/src cairo_pattern.c, 1.21, 1.22 cairoint.h, 1.97, 1.98

[Carl Worth]

Committed by: cworth

Update of /cvs/cairo/cairo/src
In directory gabe:/tmp/cvs-serv6785/src

Modified Files:
	cairo_pattern.c cairoint.h 
Log Message:

        * src/cairo_pattern.c (_cairo_pattern_shader_init): Don't put an
        off-by-one n_stops into cairo_shader_op_t.
        (_cairo_shader_op_find_color_stops): Put search for two color
        stops containing a given offset into its own function. Handle the
        case of before first and after last stop by returning the nearest
        stop twice.
        (_cairo_pattern_calc_color_at_pixel): Handle case of no color
        stops by returning a transparent pixel.


Index: cairo_pattern.c
===================================================================
RCS file: /cvs/cairo/cairo/src/cairo_pattern.c,v
retrieving revision 1.21
retrieving revision 1.22
diff -u -d -r1.21 -r1.22
--- cairo_pattern.c	24 Feb 2005 22:06:03 -0000	1.21
+++ cairo_pattern.c	25 Feb 2005 20:52:47 -0000	1.22
@@ -428,9 +428,7 @@
 			    cairo_shader_op_t *op)
 {
     op->stops = pattern->stops;
-    op->n_stops = pattern->n_stops - 1;
-    op->min_offset = pattern->stops[0].offset;
-    op->max_offset = pattern->stops[op->n_stops].offset;
+    op->n_stops = pattern->n_stops;
     op->extend = pattern->extend;
     
     switch (pattern->filter) {
@@ -449,12 +447,52 @@
     }
 }
 
+/* Find two color stops bounding the given offset. If the given offset
+ * is before the first or after the last stop offset, the nearest
+ * offset is returned twice.
+ */
+static void
+_cairo_shader_op_find_color_stops (cairo_shader_op_t *op,
+				   cairo_fixed_t offset,
+				   cairo_color_stop_t *stops[2])
+{
+    int i;
+
+    /* Before first stop. */
+    if (offset <= op->stops[0].offset) {
+	stops[0] = &op->stops[0];
+	stops[1] = &op->stops[0];
+	return;
+    }
+
+    /* Between two stops. */
+    for (i = 0; i < op->n_stops - 1; i++) {
+	if (offset <= op->stops[i + 1].offset) {
+	    stops[0] = &op->stops[i];
+	    stops[1] = &op->stops[i + 1];
+	    return;
+	}
+    }
+
+    /* After last stop. */
+    stops[0] = &op->stops[op->n_stops - 1];
+    stops[1] = &op->stops[op->n_stops - 1];
+}
+
 void
 _cairo_pattern_calc_color_at_pixel (cairo_shader_op_t *op,
 				    cairo_fixed_t factor,
 				    int *pixel)
 {
-    int i;
+    cairo_color_stop_t *stops[2];
+
+   /* A gradient with no color stops is just transparent. (It'd be
+       smart to catch this no-op much higher in the stack too.)
+     */
+    if (op->n_stops == 0) {
+	*pixel = 0;
+	return;
+    }
     
     switch (op->extend) {
     case CAIRO_EXTEND_REPEAT:
@@ -472,35 +510,26 @@
 	break;
     }
 
-    if (factor < op->min_offset)
-	factor = op->min_offset;
-    else if (factor > op->max_offset)
-	factor = op->max_offset;
-    
-    for (i = 0; i < op->n_stops; i++) {
-	if (factor <= op->stops[i + 1].offset) {
-	    
-	    /* take offset as new 0 of coordinate system */
-	    factor -= op->stops[i].offset;
-	    
-	    /* difference between two offsets == 0, abrubt change */
-	    if (op->stops[i + 1].scale)
-		factor = ((cairo_fixed_48_16_t) factor << 16) /
-		    op->stops[i + 1].scale;
+    _cairo_shader_op_find_color_stops (op, factor, stops);
+
+    /* take offset as new 0 of coordinate system */
+    factor -= stops[0]->offset;
 	    
-	    op->shader_function (op->stops[i].color_char,
-				 op->stops[i + 1].color_char,
-				 factor, pixel);
+    /* difference between two offsets == 0, abrubt change */
+    if (stops[1]->scale)
+	factor = ((cairo_fixed_48_16_t) factor << 16) /
+	    stops[1]->scale;
+
+    op->shader_function (stops[0]->color_char,
+			 stops[1]->color_char,
+			 factor, pixel);
 	    
-	    /* multiply alpha */
-	    if (((unsigned char) (*pixel >> 24)) != 0xff) {
-		*pixel = (*pixel & 0xff000000) |
-		    (MULTIPLY_COLORCOMP (*pixel >> 16, *pixel >> 24) << 16) |
-		    (MULTIPLY_COLORCOMP (*pixel >> 8, *pixel >> 24) << 8) |
-		    (MULTIPLY_COLORCOMP (*pixel >> 0, *pixel >> 24) << 0);
-	    }
-	    break;
-	}
+    /* multiply alpha */
+    if (((unsigned char) (*pixel >> 24)) != 0xff) {
+	*pixel = (*pixel & 0xff000000) |
+	    (MULTIPLY_COLORCOMP (*pixel >> 16, *pixel >> 24) << 16) |
+	    (MULTIPLY_COLORCOMP (*pixel >> 8, *pixel >> 24) << 8) |
+	    (MULTIPLY_COLORCOMP (*pixel >> 0, *pixel >> 24) << 0);
     }
 }
 

Index: cairoint.h
===================================================================
RCS file: /cvs/cairo/cairo/src/cairoint.h,v
retrieving revision 1.97
retrieving revision 1.98
diff -u -d -r1.97 -r1.98
--- cairoint.h	24 Feb 2005 20:28:51 -0000	1.97
+++ cairoint.h	25 Feb 2005 20:52:47 -0000	1.98
@@ -743,8 +743,6 @@
 typedef struct _cairo_shader_op {
     cairo_color_stop_t *stops;
     int n_stops;
-    cairo_fixed_t min_offset;
-    cairo_fixed_t max_offset;
     cairo_extend_t extend;
     cairo_shader_function_t shader_function;
 } cairo_shader_op_t;