[gtk+] Change way alpha is used when recoloring symbolics

[Alexander Larsson <alexl src gnome org>]

commit afeb50009dc6268a94d88f18340bd192897a0fbb
Author: Alexander Larsson <alexl redhat com>
Date:   Tue Aug 12 09:17:59 2014 +0200

    Change way alpha is used when recoloring symbolics
    
    If the foreground color has an alpha != 1 we used to just pass that into
    the svg. This is useful to e.g. render an insensitive icon. However,
    that is not an ideal model for symbolics. For instance, if the icon uses
    overlapping areas when drawing, expecting these to be opaque then the
    transparent color will result in a different alpha value for the overlapping
    area. Also, non-foreground symbolic colors are still rendered opaque, and
    the recoloring of pngs can't handle transparent colors.
    
    So, instead we extract any alpha from the foreground, render using the
    opaque colors and then apply the foreground alpha to the entire result.
    This means we get an even transparency, even for other colors, and we
    can apply alpha for the pngs too.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=734668

 gtk/gtkicontheme.c |   35 ++++++++++++++++++++++++++++-------
 1 files changed, 28 insertions(+), 7 deletions(-)
---
diff --git a/gtk/gtkicontheme.c b/gtk/gtkicontheme.c
index 79ee908..f4fc82f 100644
--- a/gtk/gtkicontheme.c
+++ b/gtk/gtkicontheme.c
@@ -4235,6 +4235,18 @@ symbolic_cache_get_proxy (SymbolicPixbufCache *symbolic_cache,
 
   return symbolic_cache->proxy_pixbuf;
 }
+
+static gchar *
+rgba_to_string_noalpha (const GdkRGBA *rgba)
+{
+  GdkRGBA color;
+
+  color = *rgba;
+  color.alpha = 1.0;
+
+  return gdk_rgba_to_string (&color);
+}
+
 static void
 rgba_to_pixel(const GdkRGBA  *rgba,
              guint8 pixel[4])
@@ -4242,7 +4254,7 @@ rgba_to_pixel(const GdkRGBA  *rgba,
   pixel[0] = rgba->red * 255;
   pixel[1] = rgba->green * 255;
   pixel[2] = rgba->blue * 255;
-  pixel[3] = rgba->alpha * 255;
+  pixel[3] = 255;
 }
 
 static GdkPixbuf *
@@ -4255,9 +4267,12 @@ color_symbolic_pixbuf (GdkPixbuf *symbolic,
   int width, height, x, y, src_stride, dst_stride;
   guchar *src_data, *dst_data;
   guchar *src_row, *dst_row;
+  int alpha;
   GdkPixbuf *colored;
   guint8 fg_pixel[4], success_pixel[4], warning_pixel[4], error_pixel[4];
 
+  alpha = fg_color->alpha * 255;
+
   rgba_to_pixel (fg_color, fg_pixel);
   rgba_to_pixel (success_color, success_pixel);
   rgba_to_pixel (warning_color, warning_pixel);
@@ -4284,7 +4299,7 @@ color_symbolic_pixbuf (GdkPixbuf *symbolic,
           int c1, c2, c3, c4;
 
           a = src_row[3];
-          dst_row[3] = a;
+          dst_row[3] = a * alpha / 255;
 
           if (a == 0)
             {
@@ -4382,23 +4397,27 @@ gtk_icon_info_load_symbolic_svg (GtkIconInfo    *icon_info,
   gchar *size;
   gchar *file_data, *escaped_file_data;
   gsize file_len;
+  double alpha;
+  gchar alphastr[G_ASCII_DTOSTR_BUF_SIZE];
 
-  css_fg = gdk_rgba_to_string (fg);
+  alpha = fg->alpha;
+
+  css_fg = rgba_to_string_noalpha (fg);
 
   css_success = css_warning = css_error = NULL;
 
   if (warning_color)
-    css_warning = gdk_rgba_to_string (warning_color);
+    css_warning = rgba_to_string_noalpha (warning_color);
   else
     css_warning = g_strdup ("rgb(245,121,62)");
 
   if (error_color)
-    css_error = gdk_rgba_to_string (error_color);
+    css_error = rgba_to_string_noalpha (error_color);
   else
     css_error = g_strdup ("rgb(204,0,0)");
 
   if (success_color)
-    css_success = gdk_rgba_to_string (success_color);
+    css_success = rgba_to_string_noalpha (success_color);
   else
     css_success = g_strdup ("rgb(78,154,6)");
 
@@ -4436,6 +4455,8 @@ gtk_icon_info_load_symbolic_svg (GtkIconInfo    *icon_info,
   escaped_file_data = g_markup_escape_text (file_data, file_len);
   g_free (file_data);
 
+  g_ascii_dtostr (alphastr, G_ASCII_DTOSTR_BUF_SIZE, CLAMP (alpha, 0, 1));
+
   data = g_strconcat ("<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\"?>\n"
                       "<svg version=\"1.1\"\n"
                       "     xmlns=\"http://www.w3.org/2000/svg\"\n";
@@ -4456,7 +4477,7 @@ gtk_icon_info_load_symbolic_svg (GtkIconInfo    *icon_info,
                       "      fill: ", css_success, " !important;\n"
                       "    }\n"
                       "  </style>\n"
-                      "  <xi:include href=\"data:text/xml,", escaped_file_data, "\"/>\n"
+                      "  <g opacity=\"", alphastr, "\" ><xi:include href=\"data:text/xml,", 
escaped_file_data, "\"/></g>\n"
                       "</svg>",
                       NULL);
   g_free (escaped_file_data);