Add foreigndrawing example to gtk3-demo

This makes it easier accessible and nicer to refer to
from the documentation.

3 files changed, 339 insertions, 0 deletions

diff --git a/demos/gtk-demo/Makefile.am b/demos/gtk-demo/Makefile.am
index e93a45091d..bbe91eae41 100644
--- a/demos/gtk-demo/Makefile.am
+++ b/demos/gtk-demo/Makefile.am
@@ -27,6 +27,7 @@ demos_base =					\
 	expander.c  				\
         filtermodel.c				\
 	font_features.c				\
+	foreigndrawing.c			\
 	gestures.c				\
 	glarea.c				\
 	headerbar.c				\
diff --git a/demos/gtk-demo/demo.gresource.xml b/demos/gtk-demo/demo.gresource.xml
index d0e80f2b34..7301b40932 100644
--- a/demos/gtk-demo/demo.gresource.xml
+++ b/demos/gtk-demo/demo.gresource.xml
@@ -140,6 +140,7 @@
     <file>expander.c</file>
     <file>filtermodel.c</file>
     <file>flowbox.c</file>
+    <file>foreigndrawing.c</file>
     <file>font_features.c</file>
     <file>gestures.c</file>
     <file>glarea.c</file>
diff --git a/demos/gtk-demo/foreigndrawing.c b/demos/gtk-demo/foreigndrawing.c
new file mode 100644
index 0000000000..5a7a3f32d1
--- /dev/null
+++ b/demos/gtk-demo/foreigndrawing.c
@@ -0,0 +1,337 @@
+/* Foreign drawing
+ *
+ * Many applications can't use GTK+ widgets, for a variety of reasons,
+ * but still want their user interface to appear integrated with the
+ * rest of the desktop, and follow GTK+ themes.
+ *
+ * This demo shows how to use GtkStyleContext and the gtk_render_ APIs
+ * to achieve this. Note that this is a very simple, non-interactive
+ * example.
+ */
+
+#include <gtk/gtk.h>
+#include <string.h>
+
+static void
+append_element (GtkWidgetPath *path,
+                const char    *selector)
+{
+  static const struct {
+    const char    *name;
+    GtkStateFlags  state_flag;
+  } pseudo_classes[] = {
+    { "active",        GTK_STATE_FLAG_ACTIVE },
+    { "hover",         GTK_STATE_FLAG_PRELIGHT },
+    { "selected",      GTK_STATE_FLAG_SELECTED },
+    { "disabled",      GTK_STATE_FLAG_INSENSITIVE },
+    { "indeterminate", GTK_STATE_FLAG_INCONSISTENT },
+    { "focus",         GTK_STATE_FLAG_FOCUSED },
+    { "backdrop",      GTK_STATE_FLAG_BACKDROP },
+    { "dir(ltr)",      GTK_STATE_FLAG_DIR_LTR },
+    { "dir(rtl)",      GTK_STATE_FLAG_DIR_RTL },
+    { "link",          GTK_STATE_FLAG_LINK },
+    { "visited",       GTK_STATE_FLAG_VISITED },
+    { "checked",       GTK_STATE_FLAG_CHECKED },
+    { "drop(active)",  GTK_STATE_FLAG_DROP_ACTIVE }
+  };
+  const char *next;
+  char *name;
+  char type;
+  guint i;
+
+  next = strpbrk (selector, "#.:");
+  if (next == NULL)
+    next = selector + strlen (selector);
+
+  name = g_strndup (selector, next - selector);
+  if (g_ascii_isupper (selector[0]))
+    {
+      GType gtype;
+      gtype = g_type_from_name (name);
+      if (gtype == G_TYPE_INVALID)
+        {
+          g_critical ("Unknown type name `%s'", name);
+          g_free (name);
+          return;
+        }
+      gtk_widget_path_append_type (path, gtype);
+    }
+  else
+    {
+      /* Omit type, we're using name */
+      gtk_widget_path_append_type (path, G_TYPE_NONE);
+      gtk_widget_path_iter_set_object_name (path, -1, name);
+    }
+  g_free (name);
+
+  while (*next != '\0')
+    {
+      type = *next;
+      selector = next + 1;
+      next = strpbrk (selector, "#.:");
+      if (next == NULL)
+        next = selector + strlen (selector);
+      name = g_strndup (selector, next - selector);
+
+      switch (type)
+        {
+        case '#':
+          gtk_widget_path_iter_set_name (path, -1, name);
+          break;
+
+        case '.':
+          gtk_widget_path_iter_add_class (path, -1, name);
+          break;
+
+        case ':':
+          for (i = 0; i < G_N_ELEMENTS (pseudo_classes); i++)
+            {
+              if (g_str_equal (pseudo_classes[i].name, name))
+                {
+                  gtk_widget_path_iter_set_state (path,
+                                                  -1,
+                                                  gtk_widget_path_iter_get_state (path, -1)
+                                                  | pseudo_classes[i].state_flag);
+                  break;
+                }
+            }
+          if (i == G_N_ELEMENTS (pseudo_classes))
+            g_critical ("Unknown pseudo-class :%s", name);
+          break;
+
+        default:
+          g_assert_not_reached ();
+          break;
+        }
+
+      g_free (name);
+    }
+}
+
+static GtkStyleContext *
+get_style (GtkStyleContext *parent,
+           const char      *selector)
+{
+  GtkWidgetPath *path;
+  GtkStyleContext *context;
+
+  if (parent)
+    path = gtk_widget_path_copy (gtk_style_context_get_path (parent));
+  else
+    path = gtk_widget_path_new ();
+
+  append_element (path, selector);
+
+  context = gtk_style_context_new ();
+  gtk_style_context_set_path (context, path);
+  gtk_style_context_set_parent (context, parent);
+  gtk_widget_path_unref (path);
+
+  return context;
+}
+
+static void
+draw_horizontal_scrollbar (GtkWidget     *widget,
+                           cairo_t       *cr,
+                           gint           x,
+                           gint           y,
+                           gint           width,
+                           gint           height,
+                           gint           position,
+                           GtkStateFlags  state)
+{
+  GtkStyleContext *scrollbar_context;
+  GtkStyleContext *trough_context;
+  GtkStyleContext *slider_context;
+
+  /* This information is taken from the GtkScrollbar docs, see "CSS nodes" */
+  const char *path[3] = {
+    "scrollbar.horizontal",
+    "trough",
+    "slider"
+  };
+
+  scrollbar_context = get_style (NULL, path[0]);
+  trough_context = get_style (scrollbar_context, path[1]);
+  slider_context = get_style (trough_context, path[2]);
+
+  gtk_style_context_set_state (scrollbar_context, state);
+  gtk_style_context_set_state (trough_context, state);
+  gtk_style_context_set_state (slider_context, state);
+
+  gtk_render_background (trough_context, cr, x, y, width, height);
+  gtk_render_frame (trough_context, cr, x, y, width, height);
+  gtk_render_slider (slider_context, cr, x + position, y + 1, 30, height - 2, GTK_ORIENTATION_HORIZONTAL);
+
+  g_object_unref (slider_context);
+  g_object_unref (trough_context);
+  g_object_unref (scrollbar_context);
+}
+
+static void
+draw_text (GtkWidget     *widget,
+           cairo_t       *cr,
+           gint           x,
+           gint           y,
+           gint           width,
+           gint           height,
+           const gchar   *text,
+           GtkStateFlags  state)
+{
+  GtkStyleContext *label_context;
+  GtkStyleContext *selection_context;
+  GtkStyleContext *context;
+  PangoLayout *layout;
+
+  /* This information is taken from the GtkLabel docs, see "CSS nodes" */
+  const char *path[2] = {
+    "label.view",
+    "selection"
+  };
+
+  label_context = get_style (NULL, path[0]);
+  selection_context = get_style (label_context, path[1]);
+
+  gtk_style_context_set_state (label_context, state);
+
+  if (state & GTK_STATE_FLAG_SELECTED)
+    context = selection_context;
+  else
+    context = label_context;
+
+  layout = gtk_widget_create_pango_layout (widget, text);
+
+  gtk_render_background (context, cr, x, y, width, height);
+  gtk_render_frame (context, cr, x, y, width, height);
+  gtk_render_layout (context, cr, x, y, layout);
+
+  g_object_unref (layout);
+
+  g_object_unref (selection_context);
+  g_object_unref (label_context);
+}
+
+static void
+draw_check (GtkWidget     *widget,
+            cairo_t       *cr,
+            gint           x,
+            gint           y,
+            GtkStateFlags  state)
+{
+  GtkStyleContext *button_context;
+  GtkStyleContext *check_context;
+
+  /* This information is taken from the GtkCheckButton docs, see "CSS nodes" */
+  const char *path[2] = {
+    "checkbutton",
+    "check"
+  };
+
+  button_context = get_style (NULL, path[0]);
+  check_context = get_style (button_context, path[1]);
+
+  gtk_style_context_set_state (check_context, state);
+
+  gtk_render_background (check_context, cr, x, y, 20, 20);
+  gtk_render_frame (check_context, cr, x, y, 20, 20);
+  gtk_render_check (check_context, cr, x, y, 20, 20);
+
+  g_object_unref (check_context);
+  g_object_unref (button_context);
+
+}
+
+static void
+draw_radio (GtkWidget     *widget,
+            cairo_t       *cr,
+            gint           x,
+            gint           y,
+            GtkStateFlags  state)
+{
+  GtkStyleContext *button_context;
+  GtkStyleContext *check_context;
+
+  /* This information is taken from the GtkRadioButton docs, see "CSS nodes" */
+  const char *path[2] = {
+    "radiobutton",
+    "radio"
+  };
+
+  button_context = get_style (NULL, path[0]);
+  check_context = get_style (button_context, path[1]);
+
+  gtk_style_context_set_state (check_context, state);
+
+  gtk_render_background (check_context, cr, x, y, 20, 20);
+  gtk_render_frame (check_context, cr, x, y, 20, 20);
+  gtk_render_option (check_context, cr, x, y, 20, 20);
+
+  g_object_unref (check_context);
+  g_object_unref (button_context);
+
+}
+
+static gboolean
+draw_cb (GtkWidget *widget,
+         cairo_t   *cr)
+{
+  gint width, height;
+
+  width = gtk_widget_get_allocated_width (widget);
+  height = gtk_widget_get_allocated_height (widget);
+
+  cairo_rectangle (cr, 0, 0, width, height);
+  cairo_set_source_rgb (cr, 0, 0, 0);
+  cairo_fill (cr);
+
+  draw_horizontal_scrollbar (widget, cr, 10, 10, width - 20, 10, 30, GTK_STATE_FLAG_NORMAL);
+  draw_horizontal_scrollbar (widget, cr, 10, 30, width - 20, 10, 40, GTK_STATE_FLAG_PRELIGHT);
+  draw_horizontal_scrollbar (widget, cr, 10, 50, width - 20, 10, 50, GTK_STATE_FLAG_ACTIVE|GTK_STATE_FLAG_PRELIGHT);
+
+  draw_text (widget, cr, 10,  70, width - 20, 20, "Not selected", GTK_STATE_FLAG_NORMAL);
+  draw_text (widget, cr, 10, 100, width - 20, 20, "Selected", GTK_STATE_FLAG_SELECTED);
+
+  draw_check (widget, cr,  10, 130, GTK_STATE_FLAG_NORMAL);
+  draw_check (widget, cr,  40, 130, GTK_STATE_FLAG_CHECKED);
+  draw_radio (widget, cr,  70, 130, GTK_STATE_FLAG_NORMAL);
+  draw_radio (widget, cr, 100, 130, GTK_STATE_FLAG_CHECKED);
+
+  return FALSE;
+}
+
+GtkWidget *
+do_foreigndrawing (GtkWidget *do_widget)
+{
+  static GtkWidget *window = NULL;
+
+  if (!window)
+    {
+      GtkWidget *box;
+      GtkWidget *da;
+
+      window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+      gtk_window_set_title (GTK_WINDOW (window), "Foreign drawing");
+      gtk_window_set_screen (GTK_WINDOW (window),
+                             gtk_widget_get_screen (do_widget));
+      g_signal_connect (window, "destroy",
+                        G_CALLBACK (gtk_widget_destroyed), &window);
+
+      box = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 10);
+      gtk_container_add (GTK_CONTAINER (window), box);
+      da = gtk_drawing_area_new ();
+      gtk_widget_set_size_request (da, 200, 200);
+      gtk_widget_set_hexpand (da, TRUE);
+      gtk_widget_set_vexpand (da, TRUE);
+      gtk_widget_set_app_paintable (da, TRUE);
+      gtk_container_add (GTK_CONTAINER (box), da);
+
+      g_signal_connect (da, "draw", G_CALLBACK (draw_cb), NULL);
+    }
+
+  if (!gtk_widget_get_visible (window))
+    gtk_widget_show_all (window);
+  else
+    gtk_widget_destroy (window);
+
+  return window;
+}