[gtksourceview] styleschemepreview: generate preview using tags

[Christian Hergert <chergert src gnome org>]

commit 3bcb02fcc5e37ccb36017a830b8bedd6b4d41ebd
Author: Christian Hergert <chergert redhat com>
Date:   Tue Oct 12 14:56:27 2021 -0700

    styleschemepreview: generate preview using tags
    
    Rather than rely on a source language, we can just add the tags to the
    view manually. This allows for more control over glyph height and spacing
    between characters to look more like the designs.

 gtksourceview/gtksourcestyleschemepreview.c | 103 ++++++++++++++++++++++++----
 1 file changed, 89 insertions(+), 14 deletions(-)
---
diff --git a/gtksourceview/gtksourcestyleschemepreview.c b/gtksourceview/gtksourcestyleschemepreview.c
index f0baa69c..a2e94e1a 100644
--- a/gtksourceview/gtksourcestyleschemepreview.c
+++ b/gtksourceview/gtksourcestyleschemepreview.c
@@ -28,8 +28,7 @@
 #endif
 
 #include "gtksourcebuffer.h"
-#include "gtksourcelanguage.h"
-#include "gtksourcelanguagemanager.h"
+#include "gtksourcestyle.h"
 #include "gtksourcestylescheme.h"
 #include "gtksourcestyleschemepreview.h"
 #include "gtksourceview.h"
@@ -153,11 +152,96 @@ on_click_pressed_cb (GtkSourceStyleSchemePreview *self,
        g_signal_emit (self, signals [ACTIVATE], 0);
 }
 
+static void
+add_text (GtkSourceBuffer      *buffer,
+         GtkSourceStyleScheme *scheme)
+{
+       static const struct {
+               const char *text;
+               const char *style;
+       } runs[] = {
+               { "XXXXXXXXXXX", "def:type" },
+               { "   ", NULL },
+               { "XXXXXXXXXXXXXXXXXXXX", "def:function" },
+               { "   ", NULL },
+               { "XXXXXXXXXXXXXXX", "def:comment" },
+               { "\n", NULL },
+               { "    ", NULL },
+               { "XXXXXXXXXXXXXXXXXXXX", "def:preprocessor" },
+               { "    ", NULL },
+               { "XXXXX", "def:comment" },
+               { "    ", NULL },
+               { "XXXXXXXX", "def:string" },
+               { "    ", NULL },
+               { "XXXXXXXXXXXX", "def:decimal" },
+               { "\n", NULL },
+               { "    ", NULL },
+               { "XXXXXXXXXXX", "def:keyword" },
+               { "    ", NULL },
+               { "XXXXXXXXXXXXX", "def:boolean" },
+               { "    ", NULL },
+               { "XXXXXXX", "def:comment" },
+               { "\n", NULL },
+               { "    ", NULL },
+               { "XXXXXXXXX", "def:constant" },
+               { "    ", NULL },
+               { "XXX", "def:special-char" },
+               { "    ", NULL },
+               { "XXXXXXX", NULL },
+               { "    ", NULL },
+               { "XXXXXXXXXXXXXXXXXXX", "def:string" },
+               { "\n", NULL },
+               { "          ", NULL },
+               { "XXXXXXXXXXXXXXXXXXX", NULL },
+               { "\n", NULL },
+               { "XXXXXXXXXXXXXXX", NULL },
+               { "    ", NULL },
+               { "XXXXXX", "def:statement" },
+               { "    ", NULL },
+               { "XXXXXXXX", "def:identifier" },
+       };
+       GHashTable *tags;
+       GtkTextIter iter;
+
+       tags = g_hash_table_new (NULL, NULL);
+
+       gtk_text_buffer_get_start_iter (GTK_TEXT_BUFFER (buffer), &iter);
+
+       for (guint i = 0; i < G_N_ELEMENTS (runs); i++)
+       {
+               gtk_text_buffer_insert (GTK_TEXT_BUFFER (buffer), &iter, runs[i].text, -1);
+
+               if (runs[i].style)
+               {
+                       GtkSourceStyle *style = gtk_source_style_scheme_get_style (scheme, runs[i].style);
+
+                       if (style != NULL)
+                       {
+                               GtkTextTag *tag;
+                               GtkTextIter begin;
+
+                               begin = iter;
+                               gtk_text_iter_backward_chars (&begin, g_utf8_strlen (runs[i].text, -1));
+
+                               if (!(tag = g_hash_table_lookup (tags, runs[i].style)))
+                               {
+                                       tag = gtk_text_buffer_create_tag (GTK_TEXT_BUFFER (buffer), NULL, 
NULL);
+                                       gtk_source_style_apply (style, tag);
+                                       g_hash_table_insert (tags, (gpointer)runs[i].style, tag);
+                               }
+
+                               gtk_text_buffer_apply_tag (GTK_TEXT_BUFFER (buffer), tag, &begin, &iter);
+                       }
+               }
+       }
+
+       g_hash_table_unref (tags);
+}
+
 static void
 gtk_source_style_scheme_preview_constructed (GObject *object)
 {
        GtkSourceStyleSchemePreview *self = (GtkSourceStyleSchemePreview *)object;
-       GtkSourceLanguage *lang;
        GtkSourceBuffer *buffer;
        GtkSourceView *view;
        GtkOverlay *overlay;
@@ -188,7 +272,7 @@ gtk_source_style_scheme_preview_constructed (GObject *object)
                             "can-focus", FALSE,
                             "cursor-visible", FALSE,
                             "editable", FALSE,
-                            "right-margin-position", 40,
+                            "right-margin-position", 48,
                             "show-right-margin", TRUE,
                             "top-margin", 6,
                             "bottom-margin", 6,
@@ -207,19 +291,10 @@ gtk_source_style_scheme_preview_constructed (GObject *object)
                                    "visible", FALSE,
                                    NULL);
 
-       lang = gtk_source_language_manager_get_language (gtk_source_language_manager_get_default (), "c");
        buffer = GTK_SOURCE_BUFFER (gtk_text_view_get_buffer (GTK_TEXT_VIEW (view)));
 
        gtk_source_buffer_set_style_scheme (buffer, self->scheme);
-       gtk_source_buffer_set_language (buffer, lang);
-
-       gtk_text_buffer_set_text (GTK_TEXT_BUFFER (buffer), "\
-#include <glib.h>\n\
-  /* comment */\n\
-static void f () { return; }\n\
-typedef struct {\n\
- int i; double d;\n\
- }; char *s = \"string\";", -1);
+       add_text (buffer, self->scheme);
        load_override_font (view);
 
        gtk_frame_set_child (frame, GTK_WIDGET (overlay));