[gtk/ngl-vertex-attributes] gtk-demo: Add a test for scrolling with Emoji

[Matthias Clasen <matthiasc src gnome org>]

commit 325592e217537df2fac37d8de603af1a78ca26f9
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Mar 12 01:44:05 2021 -0500

    gtk-demo: Add a test for scrolling with Emoji
    
    Make a text with lots of Emoji and text. This
    is exercising the GL renderers switching between
    different shaders for color and plain glyphs.

 demos/gtk-demo/iconscroll.c | 48 +++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 44 insertions(+), 4 deletions(-)
---
diff --git a/demos/gtk-demo/iconscroll.c b/demos/gtk-demo/iconscroll.c
index 9e2fe9dc8a..2eb9aa6e92 100644
--- a/demos/gtk-demo/iconscroll.c
+++ b/demos/gtk-demo/iconscroll.c
@@ -13,7 +13,7 @@ static GtkWidget *window = NULL;
 static GtkWidget *scrolledwindow;
 static int selected;
 
-#define N_WIDGET_TYPES 7
+#define N_WIDGET_TYPES 8
 
 
 static int hincrement = 5;
@@ -110,6 +110,41 @@ populate_text (gboolean highlight)
   gtk_scrolled_window_set_child (GTK_SCROLLED_WINDOW (scrolledwindow), textview);
 }
 
+static void
+populate_emoji_text (void)
+{
+  GtkWidget *textview;
+  GtkTextBuffer *buffer;
+  GString *s;
+
+  s = g_string_sized_new (1000 * 30 * 4);
+
+  for (int i = 0; i < 1000; i++)
+    {
+      if (i % 2)
+        g_string_append (s, "x");
+      for (int j = 0; j < 30; j++)
+        g_string_append (s, "💓x");
+      g_string_append (s, "\n");
+    }
+
+  buffer = gtk_text_buffer_new (NULL);
+  gtk_text_buffer_set_text (buffer, s->str, s->len);
+
+  g_string_free (s, TRUE);
+
+  textview = gtk_text_view_new ();
+  gtk_text_view_set_buffer (GTK_TEXT_VIEW (textview), buffer);
+
+  hincrement = 0;
+  vincrement = 5;
+
+  gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (scrolledwindow),
+                                  GTK_POLICY_NEVER,
+                                  GTK_POLICY_AUTOMATIC);
+  gtk_scrolled_window_set_child (GTK_SCROLLED_WINDOW (scrolledwindow), textview);
+}
+
 static void
 populate_image (void)
 {
@@ -224,21 +259,26 @@ set_widget_type (int type)
       break;
 
     case 3:
+      gtk_window_set_title (GTK_WINDOW (window), "Scrolling text with Emoji");
+      populate_emoji_text ();
+      break;
+
+    case 4:
       gtk_window_set_title (GTK_WINDOW (window), "Scrolling a big image");
       populate_image ();
       break;
 
-    case 4:
+    case 5:
       gtk_window_set_title (GTK_WINDOW (window), "Scrolling a list");
       populate_list ();
       break;
 
-    case 5:
+    case 6:
       gtk_window_set_title (GTK_WINDOW (window), "Scrolling a columned list");
       populate_list2 ();
       break;
 
-    case 6:
+    case 7:
       gtk_window_set_title (GTK_WINDOW (window), "Scrolling a grid");
       populate_grid ();
       break;