1 files changed, 123 insertions, 0 deletions
diff --git a/demos/gtk-demo/demo4widget.c b/demos/gtk-demo/demo4widget.c
new file mode 100644
index 0000000000..3478272197
--- /dev/null
+++ b/demos/gtk-demo/demo4widget.c
@@ -0,0 +1,123 @@
+#include <math.h>
+#include "demo4widget.h"
+#include "hsla.h"
+
+struct _Demo4Widget
+{
+  GtkWidget parent_instance;
+  PangoLayout *layout;
+  GskColorStop stops[8];
+  gsize n_stops;
+
+  guint tick;
+};
+
+struct _Demo4WidgetClass
+{
+  GtkWidgetClass parent_class;
+};
+
+G_DEFINE_TYPE (Demo4Widget, demo4_widget, GTK_TYPE_WIDGET)
+
+static void
+rotate_color (GdkRGBA *rgba)
+{
+  GdkHSLA hsla;
+
+  _gdk_hsla_init_from_rgba (&hsla, rgba);
+  hsla.hue -= 1;
+  _gdk_rgba_init_from_hsla (rgba, &hsla);
+}
+
+static gboolean
+rotate_colors (GtkWidget     *widget,
+               GdkFrameClock *clock,
+               gpointer       user_data)
+{
+  Demo4Widget *self = DEMO4_WIDGET (widget);
+
+  for (unsigned int i = 0; i < self->n_stops; i++)
+    rotate_color (&self->stops[i].color);
+
+  gtk_widget_queue_draw (widget);
+
+  return G_SOURCE_CONTINUE;
+}
+
+static void
+demo4_widget_init (Demo4Widget *self)
+{
+  PangoFontDescription *desc;
+
+  self->n_stops = 8;
+  self->stops[0].offset = 0;
+  self->stops[0].color = (GdkRGBA) { 1, 0, 0, 1 };
+
+  for (unsigned int i = 1; i < self->n_stops; i++)
+    {
+      GdkHSLA hsla;
+
+      self->stops[i].offset = i / (double)(self->n_stops - 1);
+      _gdk_hsla_init_from_rgba (&hsla, &self->stops[i - 1].color);
+      hsla.hue += 360.0 / (double)(self->n_stops - 1);
+      _gdk_rgba_init_from_hsla (&self->stops[i].color, &hsla);
+    }
+
+  self->layout = gtk_widget_create_pango_layout (GTK_WIDGET (self), "123");
+  desc = pango_font_description_from_string ("Cantarell Bold 210");
+  pango_layout_set_font_description (self->layout, desc);
+  pango_font_description_free (desc);
+
+  self->tick = gtk_widget_add_tick_callback (GTK_WIDGET (self), rotate_colors, NULL, NULL);
+}
+
+static void
+demo4_widget_dispose (GObject *object)
+{
+  Demo4Widget *self = DEMO4_WIDGET (object);
+
+  g_clear_object (&self->layout);
+  gtk_widget_remove_tick_callback (GTK_WIDGET (self), self->tick);
+
+  G_OBJECT_CLASS (demo4_widget_parent_class)->dispose (object);
+}
+
+static void
+demo4_widget_snapshot (GtkWidget   *widget,
+                       GtkSnapshot *snapshot)
+{
+  Demo4Widget *self = DEMO4_WIDGET (widget);
+  int width, height;
+
+  width = gtk_widget_get_width (widget);
+  height = gtk_widget_get_height (widget);
+
+  gtk_snapshot_push_mask (snapshot);
+  gtk_snapshot_append_layout (snapshot, self->layout, &(GdkRGBA) { 0, 0, 0, 1 });
+  gtk_snapshot_pop (snapshot);
+
+  gtk_snapshot_append_linear_gradient (snapshot,
+                                       &GRAPHENE_RECT_INIT (0, 0, width, height),
+                                       &GRAPHENE_POINT_INIT (0, 0),
+                                       &GRAPHENE_POINT_INIT (width, height),
+                                       self->stops,
+                                       self->n_stops);
+  gtk_snapshot_pop (snapshot);
+}
+
+static void
+demo4_widget_class_init (Demo4WidgetClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (class);
+
+  object_class->dispose = demo4_widget_dispose;
+
+  widget_class->snapshot = demo4_widget_snapshot;
+}
+
+GtkWidget *
+demo4_widget_new (void)
+{
+  return g_object_new (DEMO4_TYPE_WIDGET, NULL);
+}