[dia] [gradient] svg: stop-(color|opacity) from style and gradientTransform

[Hans Breuer <hans src gnome org>]

commit 24505d75bc63dccec4b23abc54e1bee26cafd98e
Author: Hans Breuer <hans breuer org>
Date:   Thu Dec 26 20:50:41 2013 +0100

    [gradient] svg: stop-(color|opacity) from style and gradientTransform
    
    Now stop-color and stop-opacity are read by dia_svg_parse_style() not only
    for our own SVG round-trip. Also included initial gradientTransform, not
    passed down to DiaPattern yet. Finally some stop-color offset clipping.

 lib/dia_svg.c             |   28 +++++++++++++++-
 lib/dia_svg.h             |    3 ++
 lib/pattern.c             |    5 ++-
 plug-ins/svg/svg-import.c |   78 +++++++++++++++++++++++++-------------------
 4 files changed, 78 insertions(+), 36 deletions(-)
---
diff --git a/lib/dia_svg.c b/lib/dia_svg.c
index e3a5106..6766557 100644
--- a/lib/dia_svg.c
+++ b/lib/dia_svg.c
@@ -74,6 +74,9 @@ dia_svg_style_init(DiaSvgStyle *gs, DiaSvgStyle *parent_style)
   gs->font = (parent_style && parent_style->font) ? dia_font_ref(parent_style->font) : NULL;
   gs->font_height = parent_style ? parent_style->font_height : 0.8;
   gs->alignment = parent_style ? parent_style->alignment : ALIGN_LEFT;
+
+  gs->stop_color = parent_style ? parent_style->stop_color : 0x000000; /* default black */
+  gs->stop_opacity = parent_style ? parent_style->stop_opacity : 1.0;
 }
 
 /*!
@@ -99,6 +102,8 @@ dia_svg_style_copy(DiaSvgStyle *dest, DiaSvgStyle *src)
   dest->font = src->font ? dia_font_ref(src->font) : NULL;
   dest->font_height = src->font_height;
   dest->alignment = src->alignment;
+  dest->stop_color = src->stop_color;
+  dest->stop_opacity = src->stop_opacity;
 }
 
 static const struct _SvgNamedColor {
@@ -634,6 +639,16 @@ dia_svg_parse_style_string (DiaSvgStyle *s, real user_scale, const gchar *str)
     } else if (!strncmp("fill-opacity:", ptr, 13)) {
       ptr += 13;
       s->fill_opacity = g_ascii_strtod(ptr, &ptr);
+    } else if (!strncmp("stop-color:", ptr, 11)) {
+      ptr += 11;
+      while (ptr[0] != '\0' && g_ascii_isspace(ptr[0])) ptr++;
+      if (ptr[0] == '\0') break;
+
+      if (!_parse_color (&s->stop_color, ptr))
+        s->stop_color = DIA_SVG_COLOUR_NONE;
+    } else if (!strncmp("stop-opacity:", ptr, 13)) {
+      ptr += 13;
+      s->stop_opacity = g_ascii_strtod(ptr, &ptr);
     } else if (!strncmp("opacity", ptr, 7)) {
       real opacity;
       ptr += 7;
@@ -757,6 +772,17 @@ dia_svg_parse_style(xmlNodePtr node, DiaSvgStyle *s, real user_scale)
     s->fill_opacity *= opacity;
     xmlFree(str);
   }
+  str = xmlGetProp(node, (const xmlChar *)"stop-color");
+  if (str) {
+    if (!_parse_color (&s->stop_color, (char *) str) && strcmp ((const char *) str, "inherit") != 0)
+      s->stop_color = DIA_SVG_COLOUR_NONE;
+    xmlFree(str);
+  }
+  str = xmlGetProp(node, (const xmlChar *)"stop-opacity");
+  if (str) {
+    s->stop_opacity = g_ascii_strtod((char *) str, NULL);
+    xmlFree(str);
+  }
   str = xmlGetProp(node, (const xmlChar *)"fill");
   if (str) {
     if (!_parse_color (&s->fill, (char *) str) && strcmp ((const char *) str, "inherit") != 0)
@@ -778,7 +804,7 @@ dia_svg_parse_style(xmlNodePtr node, DiaSvgStyle *s, real user_scale)
   if (str) {
     s->stroke_opacity = g_ascii_strtod((char *) str, NULL);
     xmlFree(str);
-  }  
+  }
   str = xmlGetProp(node, (const xmlChar *)"stroke-width");
   if (str) {
     s->line_width = g_ascii_strtod((char *) str, NULL);
diff --git a/lib/dia_svg.h b/lib/dia_svg.h
index be53176..87bbe5c 100644
--- a/lib/dia_svg.h
+++ b/lib/dia_svg.h
@@ -57,6 +57,9 @@ struct _DiaSvgStyle {
   DiaFont *font;
   real font_height;
   Alignment alignment;
+
+  gint32 stop_color;
+  real   stop_opacity;
 };
 
 void dia_svg_style_init (DiaSvgStyle *gs, DiaSvgStyle *parent_style);
diff --git a/lib/pattern.c b/lib/pattern.c
index a7f93e5..5260254 100644
--- a/lib/pattern.c
+++ b/lib/pattern.c
@@ -194,10 +194,13 @@ void
 dia_pattern_add_color (DiaPattern *self, real pos, const Color *color)
 {
   ColorStop stop;
+  real former = 0.0;
 
   g_return_if_fail (self != NULL && color != NULL);
   stop.color  = *color;
-  stop.offset = pos;
+  if (self->stops->len > 0)
+    former = g_array_index (self->stops, ColorStop, self->stops->len - 1).offset;
+  stop.offset = MAX(pos, former);
   g_array_append_val (self->stops, stop);
 }
 
diff --git a/plug-ins/svg/svg-import.c b/plug-ins/svg/svg-import.c
index 4972008..abd8a1d 100644
--- a/plug-ins/svg/svg-import.c
+++ b/plug-ins/svg/svg-import.c
@@ -1196,18 +1196,18 @@ read_image_svg(xmlNodePtr node, DiaSvgStyle *parent_style,
  *
  * Parse a radial or linear gradient and into a DiaPattern.
  * Missing attribute handling for:
- *  - gradientTransform
- *  - style inheritance (would require to parse stop-color and stop-opacity
- *    outside of this function)
+ *  - gradients via CSS
  */
 static DiaPattern *
-read_gradient (xmlNodePtr node, GHashTable  *pattern_ht, DiaContext *ctx)
+read_gradient (xmlNodePtr node, DiaSvgStyle *parent_gs, GHashTable  *pattern_ht, DiaContext *ctx)
 {
   DiaPattern *pat;
   xmlNode    *child;
   xmlChar    *str;
   guint       flags = 0;
   real        old_scale = user_scale;
+  DiaMatrix  *matrix = NULL;
+  DiaSvgStyle gradient_gs;
 
   str = xmlGetProp (node, (const xmlChar *)"gradientUnits");
   if (str) {
@@ -1228,30 +1228,41 @@ read_gradient (xmlNodePtr node, GHashTable  *pattern_ht, DiaContext *ctx)
   /* this should not be user_scaled */
   if ((flags & DIA_PATTERN_USER_SPACE) == 0)
     user_scale = 1.0;
+  str = xmlGetProp (node, (const xmlChar *)"gradientTransform");
+  if (str) {
+    matrix = dia_svg_parse_transform ((char *)str, user_scale);
+  }
   if (xmlStrcmp(node->name, (const xmlChar *)"linearGradient")==0) {
-    pat = dia_pattern_new (DIA_LINEAR_GRADIENT, flags,
-                          _node_get_real (node, "x1", 0.0), _node_get_real (node, "y1", 0.0));
-    dia_pattern_set_point (pat, _node_get_real (node, "x2", 1.0), _node_get_real (node, "y2", 0.0));
+    Point p1 = {_node_get_real (node, "x1", 0.0), _node_get_real (node, "y1", 0.0)};
+    Point p2 = {_node_get_real (node, "x2", 1.0), _node_get_real (node, "y2", 0.0)};
+    if (matrix) {
+      transform_point (&p1, matrix);
+      transform_point (&p2, matrix);
+    }
+    pat = dia_pattern_new (DIA_LINEAR_GRADIENT, flags, p1.x, p1.y);
+    dia_pattern_set_point (pat, p2.x, p2.y);
   } else {
-    real cx = _node_get_real (node, "cx", 0.5);
-    real cy = _node_get_real (node, "cy", 0.5);
-    pat = dia_pattern_new (DIA_RADIAL_GRADIENT, flags, cx, cy);
-    dia_pattern_set_radius (pat, _node_get_real (node, "r", 0.5));
-    dia_pattern_set_point (pat, _node_get_real (node, "fx", cx), _node_get_real (node, "fy", cy));
+    Point c = {_node_get_real (node, "cx", 0.5), _node_get_real (node, "cy", 0.5)};
+    Point f = {_node_get_real (node, "fx", c.x), _node_get_real (node, "fy", c.y)};
+    real r = _node_get_real (node, "r", 0.5);
+    if (matrix) {
+      transform_point (&c, matrix);
+      transform_point (&f, matrix);
+      transform_length (&r, matrix);
+    }
+    pat = dia_pattern_new (DIA_RADIAL_GRADIENT, flags, c.x, c.y);
+    dia_pattern_set_radius (pat, r);
+    dia_pattern_set_point (pat, f.x, f.y);
   }
   /* restore previous user scale */
   user_scale = old_scale;
 
-  /* if there is a single color on the gradient
+  /* if there are single stop value on the gradient
+   *  - use it as default stop-color and stop-opacity
    *  - parse it to initialize currentColor
-   *  - use it as fall-back color for the whole gradient?
    */
-  {
-    DiaSvgStyle gs;
-    dia_svg_style_init (&gs, NULL);
-    dia_svg_parse_style (node, &gs, user_scale);
-    /* not stop-color, but should be better than nothing */
-  }
+  dia_svg_style_init (&gradient_gs, parent_gs);
+  dia_svg_parse_style (node, &gradient_gs, user_scale);
 
   /* stops and focal point can be defined by reference */
   str = xmlGetProp(node, (const xmlChar *)"xlink:href");
@@ -1267,13 +1278,13 @@ read_gradient (xmlNodePtr node, GHashTable  *pattern_ht, DiaContext *ctx)
   child = node->children;
   while (child) {
     if (xmlStrcmp(child->name, (const xmlChar *)"stop")==0) {
-      Color color = color_black;
+      DiaSvgStyle gs;
+      Color color;
       real offset = 0.0;
-      str = xmlGetProp(child, (const xmlChar *)"stop-color");
-      if (str) {
-       dia_svg_parse_color((const gchar*)str, &color);
-       xmlFree(str);
-      }
+
+      dia_svg_style_init (&gs, &gradient_gs);
+      dia_svg_parse_style (child, &gs, user_scale);
+
       str = xmlGetProp(child, (const xmlChar *)"offset");
       if (str) {
        if (strrchr (str, '%'))
@@ -1282,15 +1293,13 @@ read_gradient (xmlNodePtr node, GHashTable  *pattern_ht, DiaContext *ctx)
          offset = g_ascii_strtod ((const char*)str, NULL);
        xmlFree(str);
       }
-      str = xmlGetProp(child, (const xmlChar *)"stop-opacity");
-      if (str) {
-       color.alpha = g_ascii_strtod ((const char*)str, NULL);
-       xmlFree(str);
-      }
+      color = get_colour (gs.stop_color, gs.stop_opacity);
       dia_pattern_add_color (pat, offset, &color);
     }
     child = child->next;
   }
+  if (matrix)
+    g_free (matrix);
 
   return pat;
 }
@@ -1567,8 +1576,9 @@ read_items (xmlNodePtr   startnode,
              !xmlStrcmp(node->name, (const xmlChar *)"radialGradient") ||
              !xmlStrcmp(node->name, (const xmlChar *)"style") ||
              !xmlStrcmp(node->name, (const xmlChar *)"pattern") ||
+             !xmlStrcmp(node->name, (const xmlChar *)"mask") ||
              !xmlStrcmp(node->name, (const xmlChar *)"defs")) {
-      /* read_defs was already handling these */
+      /* read_defs was already handling these, mostly;) */
     } else if(!xmlStrcmp(node->name, (const xmlChar *)"use")) {
       xmlChar *key = xmlGetNsProp (node, (const xmlChar *)"href", (const xmlChar *)"xlink");
       
@@ -1713,7 +1723,7 @@ read_defs (xmlNodePtr   startnode,
        !xmlStrcmp(node->name, (const xmlChar *)"radialGradient")) {
       xmlChar *val = xmlGetProp (node, (const xmlChar *)"id");
       if (val) {
-       DiaPattern *pat = read_gradient (node, pattern_ht, ctx);
+       DiaPattern *pat = read_gradient (node, parent_gs, pattern_ht, ctx);
        if (pat)
          g_hash_table_insert (pattern_ht, g_strdup(val), pat);
        xmlFree (val);
@@ -1726,7 +1736,7 @@ read_defs (xmlNodePtr   startnode,
 
       /* Commonly seen in <defs/> are
        *   clipPath, font, filter, linearGradient, mask, marker, pattern, radialGradient, style
-       * all not supported as of this writing.
+       * mostly not supported as of this writing.
        * Less commonly used are normal objects which could be supported here.
        */
       for (list = defs; list != NULL; list = g_list_next (list)) {