[IconFetcher] Add support for font rendering as icon.

Issue: #1132

doc/rofi.1

@@ -1328,6 +1328,54 @@ modes are shown, even if the rest of the input text would match results from \fB
 If no match, the input is handled by the first combined modes.
 
 .SH FAQ
+.SS What icon formats are supported
+.PP
+Rofi supports 3 ways of specifying an icon:
+
+.RS
+.IP \(bu 2
+Filename
+.IP \(bu 2
+icon-name, this is looked up via the icon-theme.
+.IP \(bu 2
+Markup String. It renders a string as an icon.
+
+.RE
+
+.PP
+For the first two options, GdkPixbuf is used to open and render the icons.
+This in general gives support for most required image formats.
+For the string option it uses Pango to render the string. The string needs to
+start with a \fB\fC<span\fR tag, that allows you to set color and font.
+
+.PP
+Markup string:
+
+.PP
+.RS
+
+.nf
+echo -en "testing\\0icon\\x1f<span color='red'>⏻</span>" | ./rofi -dmenu
+
+.fi
+.RE
+
+.PP
+Getting supported icon formats:
+
+.PP
+.RS
+
+.nf
+G_MESSAGES_DEBUG=Helpers.IconFetcher rofi
+
+.fi
+.RE
+
+.PP
+This uses the debug framework and prints out a list of supported image  file
+extensions.
+
 .SS The text in the window switcher is not nicely aligned.
 .PP
 Try using a mono-space font.

doc/rofi.1.markdown

@@ -857,6 +857,34 @@ If no match, the input is handled by the first combined modes.
 
 ## FAQ
 
+### What icon formats are supported
+
+Rofi supports 3 ways of specifying an icon:
+
+* Filename
+* icon-name, this is looked up via the icon-theme.
+* Markup String. It renders a string as an icon.
+
+
+For the first two options, GdkPixbuf is used to open and render the icons.
+This in general gives support for most required image formats.
+For the string option it uses Pango to render the string. The string needs to
+start with a `<span` tag, that allows you to set color and font.
+
+Markup string:
+
+```bash
+echo -en "testing\0icon\x1f<span color='red'>⏻</span>" | ./rofi -dmenu
+```
+
+Getting supported icon formats:
+
+```bash
+G_MESSAGES_DEBUG=Helpers.IconFetcher rofi
+```
+This uses the debug framework and prints out a list of supported image  file
+extensions.
+
 ### The text in the window switcher is not nicely aligned.
 
 Try using a mono-space font.

source/rofi-icon-fetcher.c

@@ -294,12 +294,12 @@ static void rofi_icon_fetcher_worker(thread_state *sdata,
 
   if (g_path_is_absolute(sentry->entry->name)) {
     icon_path = sentry->entry->name;
-  } else if (g_str_has_prefix(sentry->entry->name, "font:")) {
+  } else if (g_str_has_prefix(sentry->entry->name, "<span")) {
     cairo_surface_t *surface = cairo_image_surface_create(
         CAIRO_FORMAT_ARGB32, sentry->wsize, sentry->hsize);
     cairo_t *cr = cairo_create(surface);
     PangoLayout *layout = pango_cairo_create_layout(cr);
-    pango_layout_set_text(layout, &sentry->entry->name[5], -1);
+    pango_layout_set_markup(layout, sentry->entry->name, -1);
 
     int width, height;
     pango_layout_get_size(layout, &width, &height);