[gtk/fontrendering-demo] Add a font rendering demo

From: Matthias Clasen <matthiasc src gnome org>
To: commits-list gnome org
Cc:
Subject: [gtk/fontrendering-demo] Add a font rendering demo
Date: Thu, 25 Jul 2019 20:45:21 +0000 (UTC)
commit dec4db5943c63ec878fde6258ff31649a6b37d23
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Jul 27 18:42:22 2018 -0400

    Add a font rendering demo
    
    This renders a magnified version of the text,
    to make the effect of various font rendering options
    more visible.
    
    It also shows the phases of subpixel rendering,
    if you have a recent pango and cairo.

 demos/gtk-demo/demo.gresource.xml |   4 +
 demos/gtk-demo/fontrendering.c    | 216 ++++++++++++++++++++++++++++++++++++++
 demos/gtk-demo/fontrendering.ui   | 180 +++++++++++++++++++++++++++++++
 demos/gtk-demo/meson.build        |   1 +
 4 files changed, 401 insertions(+)
---
diff --git a/demos/gtk-demo/demo.gresource.xml b/demos/gtk-demo/demo.gresource.xml
index 6b6205b6b7..11ed21f593 100644
--- a/demos/gtk-demo/demo.gresource.xml
+++ b/demos/gtk-demo/demo.gresource.xml
@@ -174,6 +174,7 @@
     <file>foreigndrawing.c</file>
     <file>font_features.c</file>
     <file>fontplane.c</file>
+    <file>fontrendering.c</file>
     <file>gestures.c</file>
     <file>glarea.c</file>
     <file>headerbar.c</file>
@@ -281,6 +282,9 @@
   <gresource prefix="/fixed">
     <file>fixed.css</file>
   </gresource>
+  <gresource prefix="/fontrendering">
+    <file>fontrendering.ui</file>
+  </gresource>
   <gresource prefix="/org/gtk/Demo4">
     <file>icons/16x16/actions/application-exit.png</file>
     <file>icons/16x16/actions/document-new.png</file>
diff --git a/demos/gtk-demo/fontrendering.c b/demos/gtk-demo/fontrendering.c
new file mode 100644
index 0000000000..4778f4aced
--- /dev/null
+++ b/demos/gtk-demo/fontrendering.c
@@ -0,0 +1,216 @@
+/* Pango/Font rendering
+ *
+ * Demonstrates various aspects of font rendering.
+ */
+
+#include <gtk/gtk.h>
+
+static GtkWidget *window = NULL;
+static GtkWidget *font_button = NULL;
+static GtkWidget *entry = NULL;
+static GtkWidget *image = NULL;
+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 = 10;
+
+static void
+on_destroy (gpointer data)
+{
+  window = NULL;
+}
+
+static void
+update_image (void)
+{
+  const char *text;
+  PangoFontDescription *desc;
+  PangoLayout *layout;
+  PangoRectangle ink, logical;
+  cairo_surface_t *surface;
+  cairo_t *cr;
+  GdkPixbuf *pixbuf;
+  GdkPixbuf *pixbuf2;
+  const char *hint;
+  cairo_font_options_t *fopt;
+  cairo_hint_style_t hintstyle;
+  cairo_hint_metrics_t hintmetrics;
+
+  if (!context)
+    context = gtk_widget_create_pango_context (image);
+
+  text = gtk_editable_get_text (GTK_EDITABLE (entry));
+  desc = gtk_font_chooser_get_font_desc (GTK_FONT_CHOOSER (font_button));
+
+  fopt = cairo_font_options_copy (pango_cairo_context_get_font_options (context));
+
+  hint = gtk_combo_box_get_active_id (GTK_COMBO_BOX (hinting));
+  if (strcmp (hint, "none") == 0)
+    hintstyle = CAIRO_HINT_STYLE_NONE;
+  else if (strcmp (hint, "slight") == 0)
+    hintstyle = CAIRO_HINT_STYLE_SLIGHT;
+  else if (strcmp (hint, "medium") == 0)
+    hintstyle = CAIRO_HINT_STYLE_MEDIUM;
+  else if (strcmp (hint, "full") == 0)
+    hintstyle = CAIRO_HINT_STYLE_FULL;
+  else
+    hintstyle = CAIRO_HINT_STYLE_DEFAULT;
+  cairo_font_options_set_hint_style (fopt, hintstyle);
+
+  if (gtk_toggle_button_get_active (GTK_TOGGLE_BUTTON (hint_metrics)))
+    hintmetrics = CAIRO_HINT_METRICS_ON;
+  else
+    hintmetrics = CAIRO_HINT_METRICS_OFF;
+  cairo_font_options_set_hint_metrics (fopt, hintmetrics);
+
+  pango_cairo_context_set_font_options (context, fopt);
+  cairo_font_options_destroy (fopt);
+
+  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);
+
+      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_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, 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);
+
+  gtk_picture_set_pixbuf (GTK_PICTURE (image), pixbuf2);
+
+  g_object_unref (pixbuf);
+  g_object_unref (pixbuf2);
+
+  cairo_surface_destroy (surface);
+  pango_font_description_free (desc);
+}
+
+static void
+update_buttons (void)
+{
+  gtk_widget_set_sensitive (up_button, scale < 32);
+  gtk_widget_set_sensitive (down_button, scale > 1);
+}
+
+static void
+scale_up (void)
+{
+  scale += 1;
+  update_buttons ();
+  update_image ();
+}
+
+static void
+scale_down (void)
+{
+  scale -= 1;
+  update_buttons ();
+  update_image ();
+}
+
+GtkWidget *
+do_fontrendering (GtkWidget *do_widget)
+{
+  if (!window)
+    {
+      GtkBuilder *builder;
+
+      builder = gtk_builder_new_from_resource ("/fontrendering/fontrendering.ui");
+      gtk_builder_connect_signals (builder, NULL);
+      window = GTK_WIDGET (gtk_builder_get_object (builder, "window"));
+      gtk_window_set_display (GTK_WINDOW (window),
+                              gtk_widget_get_display (do_widget));
+      g_signal_connect (window, "destroy",
+                        G_CALLBACK (on_destroy), NULL);
+      g_object_set_data_full (G_OBJECT (window), "builder", builder, g_object_unref);
+      font_button = GTK_WIDGET (gtk_builder_get_object (builder, "font_button"));
+      up_button = GTK_WIDGET (gtk_builder_get_object (builder, "up_button"));
+      down_button = GTK_WIDGET (gtk_builder_get_object (builder, "down_button"));
+      entry = GTK_WIDGET (gtk_builder_get_object (builder, "entry"));
+      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);
+      g_signal_connect (entry, "notify::text", G_CALLBACK (update_image), NULL);
+      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);
+
+      update_image ();
+    }
+
+  if (!gtk_widget_get_visible (window))
+    gtk_widget_show (window);
+  else
+    gtk_widget_destroy (window);
+
+  return window;
+}
diff --git a/demos/gtk-demo/fontrendering.ui b/demos/gtk-demo/fontrendering.ui
new file mode 100644
index 0000000000..e00cd78a79
--- /dev/null
+++ b/demos/gtk-demo/fontrendering.ui
@@ -0,0 +1,180 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <object class="GtkAdjustment" id="scale_adj">
+    <property name="upper">24</property>
+    <property name="step-increment">1</property>
+    <property name="page-increment">4</property>
+  </object>
+  <object class="GtkWindow" id="window">
+    <property name="default-width">600</property>
+    <property name="default-height">300</property>
+    <property name="title">Font rendering</property>
+    <child>
+      <object class="GtkGrid">
+        <property name="margin-top">10</property>
+        <property name="row-spacing">10</property>
+        <property name="column-spacing">10</property>
+        <child>
+          <object class="GtkLabel">
+            <property name="margin-start">10</property>
+            <property name="label">Text</property>
+            <property name="xalign">1</property>
+            <style>
+              <class name="dim-label"/>
+            </style>
+          </object>
+        </child>
+        <child>
+          <object class="GtkEntry" id="entry">
+            <property name="text">Fonts render</property>
+            <layout>
+              <property name="left-attach">1</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="margin-start">10</property>
+            <property name="label">Font</property>
+            <property name="xalign">1</property>
+            <style>
+              <class name="dim-label"/>
+            </style>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">1</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkFontButton" id="font_button">
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">1</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Hinting</property>
+            <property name="xalign">1</property>
+            <style>
+              <class name="dim-label"/>
+            </style>
+            <layout>
+              <property name="left-attach">2</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkComboBoxText" id="hinting">
+            <property name="active">0</property>
+            <property name="valign">center</property>
+            <items>
+              <item translatable="yes" id="none">None</item>
+              <item translatable="yes" id="slight">Slight</item>
+              <item translatable="yes" id="medium">Medium</item>
+              <item translatable="yes" id="full">Full</item>
+            </items>
+            <layout>
+              <property name="left-attach">3</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkCheckButton" id="hint_metrics">
+            <child>
+              <object class="GtkLabel">
+                <property name="label">Hint Metrics</property>
+                <style>
+                  <class name="dim-label"/>
+                </style>
+              </object>
+            </child>
+            <layout>
+              <property name="left-attach">3</property>
+              <property name="top-attach">1</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkButton" id="up_button">
+            <property name="icon-name">list-add-symbolic</property>
+            <style>
+              <class name="circular"/>
+            </style>
+            <layout>
+              <property name="left-attach">4</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkButton" id="down_button">
+            <property name="icon-name">list-remove-symbolic</property>
+            <style>
+              <class name="circular"/>
+            </style>
+            <layout>
+              <property name="left-attach">4</property>
+              <property name="top-attach">1</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="hexpand">1</property>
+            <layout>
+              <property name="left-attach">6</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkBox">
+            <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="draw-indicator">0</property>
+                <property name="label">Text</property>
+              </object>
+            </child>
+            <child>
+              <object class="GtkRadioButton" id="grid_radio">
+                <property name="draw-indicator">0</property>
+                <property name="label">Grid</property>
+                <property name="group">text_radio</property>
+              </object>
+            </child>
+            <layout>
+             <property name="left-attach">0</property>
+              <property name="top-attach">3</property>
+              <property name="column-span">7</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkScrolledWindow">
+            <property name="propagate-natural-height">1</property>
+            <property name="shadow-type">in</property>
+            <property name="hexpand">1</property>
+            <property name="vexpand">1</property>
+            <child>
+              <object class="GtkPicture" id="image">
+                <property name="halign">center</property>
+                <property name="valign">center</property>
+                <property name="can-shrink">0</property>
+              </object>
+            </child>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">4</property>
+              <property name="column-span">7</property>
+            </layout>
+          </object>
+        </child>
+      </object>
+    </child>
+  </object>
+</interface>
diff --git a/demos/gtk-demo/meson.build b/demos/gtk-demo/meson.build
index b6f52cb25c..711e466b43 100644
--- a/demos/gtk-demo/meson.build
+++ b/demos/gtk-demo/meson.build
@@ -28,6 +28,7 @@ demos = files([
   'filtermodel.c',
   'fishbowl.c',
   'fixed.c',
+  'fontrendering.c',
   'foreigndrawing.c',
   'gestures.c',
   'glarea.c',
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