[gtk/font-rendering-demo-3] Add a grid example

[Matthias Clasen <matthiasc src gnome org>]

commit 3759fda75faa5bb80db6ef590b72638012447393
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Jul 27 23:03:50 2018 -0400

    Add a grid example
    
    This shows (theoretically) all 16 phases of the letter a,
    if we had subpixel positioning already.

 demos/gtk-demo/fontrendering.c  | 84 ++++++++++++++++++++++++++++++++---------
 demos/gtk-demo/fontrendering.ui | 32 +++++++++++++++-
 2 files changed, 98 insertions(+), 18 deletions(-)
---
diff --git a/demos/gtk-demo/fontrendering.c b/demos/gtk-demo/fontrendering.c
index 146bcf1c45..e54f2cb163 100644
--- a/demos/gtk-demo/fontrendering.c
+++ b/demos/gtk-demo/fontrendering.c
@@ -13,10 +13,11 @@ static GtkWidget *hinting = NULL;
 static GtkWidget *hint_metrics = NULL;
 static GtkWidget *up_button = NULL;
 static GtkWidget *down_button = NULL;
+static GtkWidget *text_radio = NULL;
 
 static PangoContext *context;
 
-static int scale = 1;
+static int scale = 10;
 
 static GdkPixbuf *pb;
 
@@ -72,25 +73,74 @@ update_image (void)
   pango_cairo_context_set_font_options (context, fopt);
   cairo_font_options_destroy (fopt);
 
-  layout = pango_layout_new (context);
-  pango_layout_set_text (layout, text, -1);
-  pango_layout_set_font_description (layout, desc);
-  pango_layout_get_extents (layout, &ink, &logical);
+  if (gtk_toggle_button_get_active (GTK_TOGGLE_BUTTON (text_radio)))
+    {
+      layout = pango_layout_new (context);
+      pango_layout_set_font_description (layout, desc);
+      pango_layout_set_text (layout, text, -1);
+      pango_layout_get_extents (layout, &ink, &logical);
 
-  pango_extents_to_pixels (&logical, NULL);
+      pango_extents_to_pixels (&logical, NULL);
 
-  surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, logical.width, logical.height);
-  cr = cairo_create (surface);
-  cairo_set_source_rgb (cr, 1, 1, 1);
-  cairo_paint (cr);
+      surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, logical.width, logical.height);
+      cr = cairo_create (surface);
+      cairo_set_source_rgb (cr, 1, 1, 1);
+      cairo_paint (cr);
 
-  cairo_set_source_rgb (cr, 0, 0, 0);
-  pango_cairo_show_layout (cr, layout);
+      cairo_set_source_rgb (cr, 0, 0, 0);
+      pango_cairo_show_layout (cr, layout);
 
-  cairo_destroy (cr);
+      cairo_destroy (cr);
+      g_object_unref (layout);
+    }
+  else
+    {
+      PangoLayoutIter *iter;
+      PangoGlyphItem *run;
+      PangoGlyphInfo *g;
+      int i, j;
+
+      layout = pango_layout_new (context);
+      pango_layout_set_font_description (layout, desc);
+      pango_layout_set_text (layout, "aaaa", -1);
+      pango_layout_get_extents (layout, &ink, &logical);
+      pango_extents_to_pixels (&logical, NULL);
+
+      iter = pango_layout_get_iter (layout);
+      run = pango_layout_iter_get_run (iter);
+
+      surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, logical.width * 3 / 2, 4*logical.height);
+      cr = cairo_create (surface);
+      cairo_set_source_rgb (cr, 1, 1, 1);
+      cairo_paint (cr);
+
+      cairo_set_source_rgb (cr, 0, 0, 0);
+      for (i = 0; i < 4; i++)
+        {
+          g = &(run->glyphs->glyphs[i]);
+          g->geometry.width = PANGO_UNITS_ROUND (g->geometry.width * 3 / 2);
+        }
+ 
+      for (j = 0; j < 4; j++)
+        {
+          for (i = 0; i < 4; i++)
+            {
+              g = &(run->glyphs->glyphs[i]);
+              g->geometry.x_offset = i * (PANGO_SCALE / 4);
+              g->geometry.y_offset = j * (PANGO_SCALE / 4);
+            }
+
+          cairo_move_to (cr, 0, j * logical.height);
+          pango_cairo_show_layout (cr, layout);
+        }
+
+      cairo_destroy (cr);
+      pango_layout_iter_free (iter);
+      g_object_unref (layout);
+    }
 
-  pixbuf = gdk_pixbuf_get_from_surface (surface, 0, 0, logical.width, logical.height);
-  pixbuf2 = gdk_pixbuf_scale_simple (pixbuf, logical.width * scale, logical.height * scale, 
GDK_INTERP_NEAREST);
+  pixbuf = gdk_pixbuf_get_from_surface (surface, 0, 0, cairo_image_surface_get_width (surface), 
cairo_image_surface_get_height (surface));
+  pixbuf2 = gdk_pixbuf_scale_simple (pixbuf, gdk_pixbuf_get_width (pixbuf) * scale, gdk_pixbuf_get_height 
(pixbuf) * scale, GDK_INTERP_NEAREST);
 
   g_set_object (&pb, pixbuf2);
 
@@ -101,8 +151,6 @@ update_image (void)
 
   cairo_surface_destroy (surface);
   pango_font_description_free (desc);
-
-  
 }
 
 static void
@@ -172,6 +220,7 @@ do_fontrendering (GtkWidget *do_widget)
       image = GTK_WIDGET (gtk_builder_get_object (builder, "image"));
       hinting = GTK_WIDGET (gtk_builder_get_object (builder, "hinting"));
       hint_metrics = GTK_WIDGET (gtk_builder_get_object (builder, "hint_metrics"));
+      text_radio = GTK_WIDGET (gtk_builder_get_object (builder, "text_radio")); 
 
       g_signal_connect (up_button, "clicked", G_CALLBACK (scale_up), NULL);
       g_signal_connect (down_button, "clicked", G_CALLBACK (scale_down), NULL);
@@ -179,6 +228,7 @@ do_fontrendering (GtkWidget *do_widget)
       g_signal_connect (font_button, "notify::font-desc", G_CALLBACK (update_image), NULL);
       g_signal_connect (hinting, "notify::active", G_CALLBACK (update_image), NULL);
       g_signal_connect (hint_metrics, "notify::active", G_CALLBACK (update_image), NULL);
+      g_signal_connect (text_radio, "notify::active", G_CALLBACK (update_image), NULL);
 
       g_signal_connect (image, "draw", G_CALLBACK (draw), NULL);
 
diff --git a/demos/gtk-demo/fontrendering.ui b/demos/gtk-demo/fontrendering.ui
index 205b2ff01a..e5092ea1d7 100644
--- a/demos/gtk-demo/fontrendering.ui
+++ b/demos/gtk-demo/fontrendering.ui
@@ -152,12 +152,42 @@
             <property name="top-attach">0</property>
           </packing>
         </child>
+        <child>
+          <object class="GtkBox">
+            <property name="visible">1</property>
+            <property name="orientation">horizontal</property>
+            <property name="halign">center</property>
+            <property name="valign">center</property>
+            <style><class name="linked"/></style>
+            <child>
+              <object class="GtkRadioButton" id="text_radio">
+                <property name="visible">1</property>
+                <property name="draw-indicator">0</property>
+                <property name="label">Text</property>
+              </object>
+            </child>
+            <child>
+              <object class="GtkRadioButton" id="grid_radio">
+                <property name="visible">1</property>
+                <property name="draw-indicator">0</property>
+                <property name="label">Grid</property>
+                <property name="group">text_radio</property>
+              </object>
+            </child>
+          </object>
+          <packing>
+            <property name="left-attach">0</property>
+            <property name="top-attach">3</property>
+            <property name="width">7</property>
+          </packing>
+        </child>
         <child>
           <object class="GtkScrolledWindow">
             <property name="visible">1</property>
             <property name="hscrollbar-policy">automatic</property>
             <property name="vscrollbar-policy">automatic</property>
             <property name="propagate-natural-height">1</property>
+            <property name="shadow-type">in</property>
             <property name="hexpand">1</property>
             <property name="vexpand">1</property>
             <child>
@@ -170,7 +200,7 @@
           </object>
           <packing>
             <property name="left-attach">0</property>
-            <property name="top-attach">3</property>
+            <property name="top-attach">4</property>
             <property name="width">7</property>
           </packing>
         </child>