Add another offscreen demo

This demo shows rendering multiple times, to achieve a reflection effect.
Inspired by an earlier demo by macslow.

3 files changed, 505 insertions, 2 deletions

diff --git a/demos/gtk-demo/Makefile.am b/demos/gtk-demo/Makefile.am
index f1fc24826a..b2d856856f 100644
--- a/demos/gtk-demo/Makefile.am
+++ b/demos/gtk-demo/Makefile.am
@@ -29,6 +29,7 @@ demos =						\
 	list_store.c				\
 	menus.c					\
 	offscreen_window.c			\
+	offscreen_window2.c			\
 	panes.c					\
 	pickers.c				\
 	pixbufs.c				\
diff --git a/demos/gtk-demo/offscreen_window.c b/demos/gtk-demo/offscreen_window.c
index 15db3d5956..b07db50e91 100644
--- a/demos/gtk-demo/offscreen_window.c
+++ b/demos/gtk-demo/offscreen_window.c
@@ -1,4 +1,4 @@
-/* Offscreen windows
+/* Offscreen windows/Rotated button
  *
  * Offscreen windows can be used to transform parts of a widget
  * hierarchy. Note that the rotated button is fully functional.
@@ -538,7 +538,7 @@ do_offscreen_window (GtkWidget *do_widget)
       window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
       gtk_window_set_screen (GTK_WINDOW (window),
                              gtk_widget_get_screen (do_widget));
-      gtk_window_set_title (GTK_WINDOW (window), "Offscreen windows");
+      gtk_window_set_title (GTK_WINDOW (window), "Rotated widget");
 
       g_signal_connect (window, "destroy",
                         G_CALLBACK (gtk_widget_destroyed), &window);
diff --git a/demos/gtk-demo/offscreen_window2.c b/demos/gtk-demo/offscreen_window2.c
new file mode 100644
index 0000000000..d7e3c9524d
--- /dev/null
+++ b/demos/gtk-demo/offscreen_window2.c
@@ -0,0 +1,502 @@
+/* Offscreen windows/Effects
+ *
+ * Offscreen windows can be used to render elements multiple times to achieve
+ * various effects.
+ */
+#include <gtk/gtk.h>
+
+#define GTK_TYPE_MIRROR_BIN              (gtk_mirror_bin_get_type ())
+#define GTK_MIRROR_BIN(obj)              (G_TYPE_CHECK_INSTANCE_CAST ((obj), GTK_TYPE_MIRROR_BIN, GtkMirrorBin))
+#define GTK_MIRROR_BIN_CLASS(klass)      (G_TYPE_CHECK_CLASS_CAST ((klass), GTK_TYPE_MIRROR_BIN, GtkMirrorBinClass))
+#define GTK_IS_MIRROR_BIN(obj)           (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GTK_TYPE_MIRROR_BIN))
+#define GTK_IS_MIRROR_BIN_CLASS(klass)   (G_TYPE_CHECK_CLASS_TYPE ((klass), GTK_TYPE_MIRROR_BIN))
+#define GTK_MIRROR_BIN_GET_CLASS(obj)    (G_TYPE_INSTANCE_GET_CLASS ((obj), GTK_TYPE_MIRROR_BIN, GtkMirrorBinClass))
+
+typedef struct _GtkMirrorBin   GtkMirrorBin;
+typedef struct _GtkMirrorBinClass  GtkMirrorBinClass;
+
+struct _GtkMirrorBin
+{
+  GtkContainer container;
+
+  GtkWidget *child;
+  GdkWindow *offscreen_window;
+};
+
+struct _GtkMirrorBinClass
+{
+  GtkContainerClass parent_class;
+};
+
+GType      gtk_mirror_bin_get_type  (void) G_GNUC_CONST;
+GtkWidget* gtk_mirror_bin_new       (void);
+
+/*** implementation ***/
+
+static void     gtk_mirror_bin_realize       (GtkWidget       *widget);
+static void     gtk_mirror_bin_unrealize     (GtkWidget       *widget);
+static void     gtk_mirror_bin_size_request  (GtkWidget       *widget,
+                                               GtkRequisition  *requisition);
+static void     gtk_mirror_bin_size_allocate (GtkWidget       *widget,
+                                               GtkAllocation   *allocation);
+static gboolean gtk_mirror_bin_damage        (GtkWidget       *widget,
+                                               GdkEventExpose  *event);
+static gboolean gtk_mirror_bin_expose        (GtkWidget       *widget,
+                                               GdkEventExpose  *offscreen);
+
+static void     gtk_mirror_bin_add           (GtkContainer    *container,
+                                               GtkWidget       *child);
+static void     gtk_mirror_bin_remove        (GtkContainer    *container,
+                                               GtkWidget       *widget);
+static void     gtk_mirror_bin_forall        (GtkContainer    *container,
+                                               gboolean         include_internals,
+                                               GtkCallback      callback,
+                                               gpointer         callback_data);
+static GType    gtk_mirror_bin_child_type    (GtkContainer    *container);
+
+G_DEFINE_TYPE (GtkMirrorBin, gtk_mirror_bin, GTK_TYPE_CONTAINER);
+
+static void
+to_child (GtkMirrorBin *bin,
+          double         widget_x,
+          double         widget_y,
+          double        *x_out,
+          double        *y_out)
+{
+  *x_out = widget_x;
+  *y_out = widget_y;
+}
+
+static void
+to_parent (GtkMirrorBin *bin,
+           double         offscreen_x,
+           double         offscreen_y,
+           double        *x_out,
+           double        *y_out)
+{
+  *x_out = offscreen_x;
+  *y_out = offscreen_y;
+}
+
+static void
+gtk_mirror_bin_class_init (GtkMirrorBinClass *klass)
+{
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+  GtkContainerClass *container_class = GTK_CONTAINER_CLASS (klass);
+
+  widget_class->realize = gtk_mirror_bin_realize;
+  widget_class->unrealize = gtk_mirror_bin_unrealize;
+  widget_class->size_request = gtk_mirror_bin_size_request;
+  widget_class->size_allocate = gtk_mirror_bin_size_allocate;
+  widget_class->expose_event = gtk_mirror_bin_expose;
+
+  g_signal_override_class_closure (g_signal_lookup ("damage-event", GTK_TYPE_WIDGET),
+                                   GTK_TYPE_MIRROR_BIN,
+                                   g_cclosure_new (G_CALLBACK (gtk_mirror_bin_damage),
+                                                   NULL, NULL));
+
+  container_class->add = gtk_mirror_bin_add;
+  container_class->remove = gtk_mirror_bin_remove;
+  container_class->forall = gtk_mirror_bin_forall;
+  container_class->child_type = gtk_mirror_bin_child_type;
+}
+
+static void
+gtk_mirror_bin_init (GtkMirrorBin *bin)
+{
+  GTK_WIDGET_UNSET_FLAGS (bin, GTK_NO_WINDOW);
+}
+
+GtkWidget *
+gtk_mirror_bin_new (void)
+{
+  return g_object_new (GTK_TYPE_MIRROR_BIN, NULL);
+}
+
+static GdkWindow *
+pick_offscreen_child (GdkWindow     *offscreen_window,
+                      double         widget_x,
+                      double         widget_y,
+                      GtkMirrorBin *bin)
+{
+ GtkAllocation child_area;
+ double x, y;
+
+ if (bin->child && GTK_WIDGET_VISIBLE (bin->child))
+    {
+      to_child (bin, widget_x, widget_y, &x, &y);
+
+      child_area = bin->child->allocation;
+
+      if (x >= 0 && x < child_area.width &&
+          y >= 0 && y < child_area.height)
+        return bin->offscreen_window;
+    }
+
+  return NULL;
+}
+
+static void
+offscreen_window_to_parent (GdkWindow     *offscreen_window,
+                            double         offscreen_x,
+                            double         offscreen_y,
+                            double        *parent_x,
+                            double        *parent_y,
+                            GtkMirrorBin *bin)
+{
+  to_parent (bin, offscreen_x, offscreen_y, parent_x, parent_y);
+}
+
+static void
+offscreen_window_from_parent (GdkWindow     *window,
+                              double         parent_x,
+                              double         parent_y,
+                              double        *offscreen_x,
+                              double        *offscreen_y,
+                              GtkMirrorBin *bin)
+{
+  to_child (bin, parent_x, parent_y, offscreen_x, offscreen_y);
+}
+
+static void
+gtk_mirror_bin_realize (GtkWidget *widget)
+{
+  GtkMirrorBin *bin = GTK_MIRROR_BIN (widget);
+  GdkWindowAttr attributes;
+  gint attributes_mask;
+  gint border_width;
+  GtkRequisition child_requisition;
+
+  GTK_WIDGET_SET_FLAGS (widget, GTK_REALIZED);
+
+  border_width = GTK_CONTAINER (widget)->border_width;
+
+  attributes.x = widget->allocation.x + border_width;
+  attributes.y = widget->allocation.y + border_width;
+  attributes.width = widget->allocation.width - 2 * border_width;
+  attributes.height = widget->allocation.height - 2 * border_width;
+  attributes.window_type = GDK_WINDOW_CHILD;
+  attributes.event_mask = gtk_widget_get_events (widget)
+                        | GDK_EXPOSURE_MASK
+                        | GDK_POINTER_MOTION_MASK
+                        | GDK_BUTTON_PRESS_MASK
+                        | GDK_BUTTON_RELEASE_MASK
+                        | GDK_SCROLL_MASK
+                        | GDK_ENTER_NOTIFY_MASK
+                        | GDK_LEAVE_NOTIFY_MASK;
+
+  attributes.visual = gtk_widget_get_visual (widget);
+  attributes.colormap = gtk_widget_get_colormap (widget);
+  attributes.wclass = GDK_INPUT_OUTPUT;
+
+  attributes_mask = GDK_WA_X | GDK_WA_Y | GDK_WA_VISUAL | GDK_WA_COLORMAP;
+
+  widget->window = gdk_window_new (gtk_widget_get_parent_window (widget),
+                                   &attributes, attributes_mask);
+  gdk_window_set_user_data (widget->window, widget);
+  g_signal_connect (widget->window, "pick-embedded-child",
+                    G_CALLBACK (pick_offscreen_child), bin);
+
+  attributes.window_type = GDK_WINDOW_OFFSCREEN;
+
+  child_requisition.width = child_requisition.height = 0;
+  if (bin->child && GTK_WIDGET_VISIBLE (bin->child))
+    {
+      attributes.width = bin->child->allocation.width;
+      attributes.height = bin->child->allocation.height;
+    }
+  bin->offscreen_window = gdk_window_new (gtk_widget_get_root_window (widget),
+                                          &attributes, attributes_mask);
+  gdk_window_set_user_data (bin->offscreen_window, widget);
+  if (bin->child)
+    gtk_widget_set_parent_window (bin->child, bin->offscreen_window);
+  gdk_offscreen_window_set_embedder (bin->offscreen_window, widget->window);
+  g_signal_connect (bin->offscreen_window, "to-embedder",
+                    G_CALLBACK (offscreen_window_to_parent), bin);
+  g_signal_connect (bin->offscreen_window, "from-embedder",
+                    G_CALLBACK (offscreen_window_from_parent), bin);
+
+  widget->style = gtk_style_attach (widget->style, widget->window);
+
+  gtk_style_set_background (widget->style, widget->window, GTK_STATE_NORMAL);
+  gtk_style_set_background (widget->style, bin->offscreen_window, GTK_STATE_NORMAL);
+  gdk_window_show (bin->offscreen_window);
+}
+
+static void
+gtk_mirror_bin_unrealize (GtkWidget *widget)
+{
+  GtkMirrorBin *bin = GTK_MIRROR_BIN (widget);
+
+  gdk_window_set_user_data (bin->offscreen_window, NULL);
+  gdk_window_destroy (bin->offscreen_window);
+  bin->offscreen_window = NULL;
+
+  GTK_WIDGET_CLASS (gtk_mirror_bin_parent_class)->unrealize (widget);
+}
+
+static GType
+gtk_mirror_bin_child_type (GtkContainer *container)
+{
+  GtkMirrorBin *bin = GTK_MIRROR_BIN (container);
+
+  if (bin->child)
+    return G_TYPE_NONE;
+
+  return GTK_TYPE_WIDGET;
+}
+
+static void
+gtk_mirror_bin_add (GtkContainer *container,
+                     GtkWidget    *widget)
+{
+  GtkMirrorBin *bin = GTK_MIRROR_BIN (container);
+
+  if (!bin->child)
+    {
+      gtk_widget_set_parent_window (widget, bin->offscreen_window);
+      gtk_widget_set_parent (widget, GTK_WIDGET (bin));
+      bin->child = widget;
+    }
+  else
+    g_warning ("GtkMirrorBin cannot have more than one child\n");
+}
+
+static void
+gtk_mirror_bin_remove (GtkContainer *container,
+                        GtkWidget    *widget)
+{
+  GtkMirrorBin *bin = GTK_MIRROR_BIN (container);
+  gboolean was_visible;
+
+  was_visible = GTK_WIDGET_VISIBLE (widget);
+
+  if (bin->child == widget)
+    {
+      gtk_widget_unparent (widget);
+
+      bin->child = NULL;
+
+      if (was_visible && GTK_WIDGET_VISIBLE (container))
+        gtk_widget_queue_resize (GTK_WIDGET (container));
+    }
+}
+
+static void
+gtk_mirror_bin_forall (GtkContainer *container,
+                        gboolean      include_internals,
+                        GtkCallback   callback,
+                        gpointer      callback_data)
+{
+  GtkMirrorBin *bin = GTK_MIRROR_BIN (container);
+
+  g_return_if_fail (callback != NULL);
+
+  if (bin->child)
+    (*callback) (bin->child, callback_data);
+}
+
+static void
+gtk_mirror_bin_size_request (GtkWidget      *widget,
+                              GtkRequisition *requisition)
+{
+  GtkMirrorBin *bin = GTK_MIRROR_BIN (widget);
+  GtkRequisition child_requisition;
+
+  child_requisition.width = 0;
+  child_requisition.height = 0;
+
+  if (bin->child && GTK_WIDGET_VISIBLE (bin->child))
+    gtk_widget_size_request (bin->child, &child_requisition);
+
+  requisition->width = GTK_CONTAINER (widget)->border_width * 2 + child_requisition.width + 10;
+  requisition->height = GTK_CONTAINER (widget)->border_width * 2 + child_requisition.height * 2 + 10;
+}
+
+static void
+gtk_mirror_bin_size_allocate (GtkWidget     *widget,
+                               GtkAllocation *allocation)
+{
+  GtkMirrorBin *bin = GTK_MIRROR_BIN (widget);
+  gint border_width;
+  gint w, h;
+  widget->allocation = *allocation;
+
+  border_width = GTK_CONTAINER (widget)->border_width;
+
+  w = allocation->width - border_width * 2;
+  h = allocation->height - border_width * 2;
+
+  if (GTK_WIDGET_REALIZED (widget))
+    gdk_window_move_resize (widget->window,
+                            allocation->x + border_width,
+                            allocation->y + border_width,
+                            w, h);
+
+  if (bin->child && GTK_WIDGET_VISIBLE (bin->child))
+    {
+      GtkRequisition child_requisition;
+      GtkAllocation child_allocation;
+
+      gtk_widget_get_child_requisition (bin->child, &child_requisition);
+      child_allocation.x = 0;
+      child_allocation.y = 0;
+      child_allocation.height = child_requisition.height;
+      child_allocation.width = child_requisition.width;
+
+      if (GTK_WIDGET_REALIZED (widget))
+        gdk_window_move_resize (bin->offscreen_window,
+                                allocation->x + border_width,
+                                allocation->y + border_width,
+                                child_allocation.width, child_allocation.height);
+      gtk_widget_size_allocate (bin->child, &child_allocation);
+    }
+}
+
+static gboolean
+gtk_mirror_bin_damage (GtkWidget      *widget,
+                        GdkEventExpose *event)
+{
+  gdk_window_invalidate_rect (widget->window, NULL, FALSE);
+
+  return TRUE;
+}
+
+static gboolean
+gtk_mirror_bin_expose (GtkWidget      *widget,
+                        GdkEventExpose *event)
+{
+  GtkMirrorBin *bin = GTK_MIRROR_BIN (widget);
+  gint width, height;
+
+  if (GTK_WIDGET_DRAWABLE (widget))
+    {
+      if (event->window == widget->window)
+        {
+          GdkPixmap *pixmap;
+          GtkAllocation child_area;
+          cairo_t *cr;
+          cairo_matrix_t matrix;
+          cairo_pattern_t *mask;
+
+          if (bin->child && GTK_WIDGET_VISIBLE (bin->child))
+            {
+              pixmap = gdk_offscreen_window_get_pixmap (bin->offscreen_window);
+              gdk_drawable_get_size (pixmap, &width, &height);
+              child_area = bin->child->allocation;
+
+              cr = gdk_cairo_create (widget->window);
+
+              cairo_save (cr);
+
+              cairo_rectangle (cr, 0, 0, width, height);
+              cairo_clip (cr);
+
+              /* paint the offscreen child */
+              gdk_cairo_set_source_pixmap (cr, pixmap, 0, 0);
+              cairo_paint (cr);
+
+              cairo_restore (cr);
+
+              cairo_matrix_init (&matrix, 1.0, 0.0, 0.3, 1.0, 0.0, 0.0);
+              cairo_matrix_scale (&matrix, 1.0, -1.0);
+              cairo_matrix_translate (&matrix, -10, - 3 * height - 10);
+              cairo_transform (cr, &matrix);
+
+              cairo_rectangle (cr, 0, height, width, height);
+              cairo_clip (cr);
+
+              gdk_cairo_set_source_pixmap (cr, pixmap, 0, height);
+
+              /* create linear gradient as mask-pattern to fade out the source */
+              mask = cairo_pattern_create_linear (0.0, height, 0.0, 2*height);
+              cairo_pattern_add_color_stop_rgba (mask, 0.0,  0.0, 0.0, 0.0, 0.0);
+              cairo_pattern_add_color_stop_rgba (mask, 0.25, 0.0, 0.0, 0.0, 0.01);
+              cairo_pattern_add_color_stop_rgba (mask, 0.5,  0.0, 0.0, 0.0, 0.25);
+              cairo_pattern_add_color_stop_rgba (mask, 0.75, 0.0, 0.0, 0.0, 0.5);
+              cairo_pattern_add_color_stop_rgba (mask, 1.0,  0.0, 0.0, 0.0, 1.0);
+
+              /* paint the reflection */
+              cairo_mask (cr, mask);
+
+              cairo_pattern_destroy (mask);
+              cairo_destroy (cr);
+            }
+        }
+      else if (event->window == bin->offscreen_window)
+        {
+          gtk_paint_flat_box (widget->style, event->window,
+                              GTK_STATE_NORMAL, GTK_SHADOW_NONE,
+                              &event->area, widget, "blah",
+                              0, 0, -1, -1);
+
+          if (bin->child)
+            gtk_container_propagate_expose (GTK_CONTAINER (widget),
+                                            bin->child,
+                                            event);
+        }
+    }
+
+  return FALSE;
+}
+
+/*** ***/
+
+static GtkWidget *window = NULL;
+
+GtkWidget *
+do_offscreen_window2 (GtkWidget *do_widget)
+{
+  if (!window)
+    {
+      GtkWidget *bin, *vbox;
+      GtkWidget *hbox, *entry, *applybutton, *backbutton;
+      GtkSizeGroup *group;
+
+      window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+      gtk_window_set_screen (GTK_WINDOW (window),
+                             gtk_widget_get_screen (do_widget));
+      gtk_window_set_title (GTK_WINDOW (window), "Effects");
+
+      g_signal_connect (window, "destroy",
+                        G_CALLBACK (gtk_widget_destroyed), &window);
+
+      gtk_container_set_border_width (GTK_CONTAINER (window), 10);
+
+      vbox = gtk_vbox_new (0, FALSE);
+
+      bin = gtk_mirror_bin_new ();
+
+      group = gtk_size_group_new (GTK_SIZE_GROUP_VERTICAL);
+
+      hbox = gtk_hbox_new (FALSE, 6);
+      backbutton = gtk_button_new ();
+      gtk_container_add (GTK_CONTAINER (backbutton),
+                         gtk_image_new_from_stock (GTK_STOCK_GO_BACK, 4));
+      gtk_size_group_add_widget (group, backbutton);
+      entry = gtk_entry_new ();
+      gtk_size_group_add_widget (group, entry);
+      applybutton = gtk_button_new ();
+      gtk_size_group_add_widget (group, applybutton);
+      gtk_container_add (GTK_CONTAINER (applybutton),
+                         gtk_image_new_from_stock (GTK_STOCK_APPLY, 4));
+
+      gtk_container_add (GTK_CONTAINER (window), vbox);
+      gtk_box_pack_start (GTK_BOX (vbox), bin, TRUE, TRUE, 0);
+      gtk_container_add (GTK_CONTAINER (bin), hbox);
+      gtk_box_pack_start (GTK_BOX (hbox), backbutton, FALSE, FALSE, 0);
+      gtk_box_pack_start (GTK_BOX (hbox), entry, TRUE, TRUE, 0);
+      gtk_box_pack_start (GTK_BOX (hbox), applybutton, FALSE, FALSE, 0);
+    }
+
+  if (!GTK_WIDGET_VISIBLE (window))
+    gtk_widget_show_all (window);
+  else
+    {
+      gtk_widget_destroy (window);
+      window = NULL;
+    }
+
+  return window;
+}
+