Restructure graph view and add background color property

app/src/main.c

@@ -32,6 +32,7 @@ int main(int argc, char **argv)
 {
 	GtkWidget *main_window;
 	GtkWidget *graph_view;
+	GdkRGBA color;
 
 	gtk_init(&argc, &argv);
 
@@ -41,8 +42,15 @@ int main(int argc, char **argv)
 
 	graph_view = gtk_graph_view_new();
 	gtk_container_add(GTK_CONTAINER(main_window), graph_view);
-
+	gtk_widget_show(graph_view);
 	gtk_widget_show_all(main_window);
+
+	color.red = 0.6;
+	color.green = 0.4;
+	color.blue = 0.1;
+	color.alpha = 1.0;
+	gtk_graph_view_set_background_color(GTK_GRAPH_VIEW(graph_view), &color);
+
 	gtk_main();
 
 	return 0;

lib/include/gtk-graph-view.h

@@ -34,7 +34,7 @@ G_BEGIN_DECLS
 
 #define GTK_TYPE_GRAPH_VIEW (gtk_graph_view_get_type())
 
-G_DECLARE_FINAL_TYPE(GtkGraphView, gtk_graph_view, GTK, GRAPH_VIEW, GtkGLArea)
+G_DECLARE_FINAL_TYPE(GtkGraphView, gtk_graph_view, GTK, GRAPH_VIEW, GtkBox)
 
 /**
  * @brief Instanciate new GtkGraphView object
@@ -42,6 +42,16 @@ G_DECLARE_FINAL_TYPE(GtkGraphView, gtk_graph_view, GTK, GRAPH_VIEW, GtkGLArea)
  */
 GtkWidget *gtk_graph_view_new();
 
+/**
+ * @brief Set the background color of the graph view
+ *
+ * This is equivalent to setting the "background-color" property
+ *
+ * @param[in] graph_view GtkGraphView object
+ * @param[in] RGBA background color.
+ */
+void gtk_graph_view_set_background_color(GtkGraphView* graph_view, const GdkRGBA *rgba);
+
 G_END_DECLS
 
 #endif /* __GTK_GRAPH_VIEW_H__ */

lib/src/gtk-graph-view.c

@@ -18,14 +18,79 @@
 #include <epoxy/gl.h>
 
 struct _GtkGraphView {
-	GtkGLArea parent;
+	GtkBox super;
 };
 
 typedef struct {
-	int i; /**< @note This is just a dummy. Remove! */
+	/**
+	 * @brief The gl area displaying the graph view.
+	 * @note This variable is not referenced, because the gl_area is tightly bound to the GrapgView widget itself.
+	 */
+	GtkWidget *gl_area;
+	GdkRGBA background_color;
 } GtkGraphViewPrivate;
 
-G_DEFINE_TYPE_WITH_PRIVATE(GtkGraphView, gtk_graph_view, GTK_TYPE_GL_AREA)
+G_DEFINE_TYPE_WITH_PRIVATE(GtkGraphView, gtk_graph_view, GTK_TYPE_BOX)
+
+enum {
+	PROP_BG_COLOR = 1,
+	N_PROPERTIES
+};
+
+/**
+ * @brief Make the gl area the current context and set the clear color
+ * @param[in] gl_area openGL area
+ * @param[in] rgba Clear color
+ */
+static void gl_area_set_clear_color(GtkGLArea *gl_area, const GdkRGBA *rgba)
+{
+	g_return_if_fail(gl_area);
+	g_return_if_fail(rgba != NULL);
+	gtk_gl_area_make_current(gl_area);
+	glClearColor(rgba->red, rgba->green, rgba->blue, rgba->alpha);
+}
+
+static gboolean gl_render(GtkGLArea *gl_area, GdkGLContext *context, GtkGraphView *view)
+{
+	GtkGraphViewPrivate *priv;
+
+	priv = gtk_graph_view_get_instance_private(view);
+
+	gl_area_set_clear_color(gl_area, &priv->background_color);
+	glClear(GL_COLOR_BUFFER_BIT);
+	glFlush();
+
+	return TRUE;
+}
+
+static void gtk_graph_view_get_property(GObject *obj, guint property_id, GValue *value, GParamSpec *pspec)
+{
+}
+
+static void gtk_graph_view_set_property(GObject *obj, guint property_id, const GValue *value, GParamSpec *pspec)
+{
+	gpointer data_ptr;
+	GtkGraphViewPrivate *priv;
+
+	priv = gtk_graph_view_get_instance_private(GTK_GRAPH_VIEW(obj));
+
+	switch (property_id) {
+	case PROP_BG_COLOR:
+		data_ptr = g_value_get_boxed(value);
+		if (!data_ptr)
+			break;
+		priv->background_color.red = ((GdkRGBA *)data_ptr)->red;
+		priv->background_color.green = ((GdkRGBA *)data_ptr)->green;
+		priv->background_color.blue = ((GdkRGBA *)data_ptr)->blue;
+		priv->background_color.alpha = ((GdkRGBA *)data_ptr)->alpha;
+		break;
+	default:
+		G_OBJECT_WARN_INVALID_PROPERTY_ID(obj, property_id, pspec);
+		break;
+	}
+}
+
+static GParamSpec *gtk_graph_view_properties[N_PROPERTIES] = {NULL};
 
 /**
  * @brief Init class structure of GtkGraphView
@@ -33,9 +98,17 @@ G_DEFINE_TYPE_WITH_PRIVATE(GtkGraphView, gtk_graph_view, GTK_TYPE_GL_AREA)
  */
 static void gtk_graph_view_class_init(GtkGraphViewClass *klass)
 {
-	(void)klass;
+	GObjectClass *oclass;
 
-	return;
+	oclass = G_OBJECT_CLASS(klass);
+	oclass->set_property = gtk_graph_view_set_property;
+	oclass->get_property = gtk_graph_view_get_property;
+
+	gtk_graph_view_properties[PROP_BG_COLOR] =
+			g_param_spec_boxed("background-color", "background color", "Background color of Graph View",
+					   GDK_TYPE_RGBA, G_PARAM_READWRITE);
+
+	g_object_class_install_properties(oclass, N_PROPERTIES, gtk_graph_view_properties);
 }
 
 /**
@@ -47,10 +120,34 @@ static void gtk_graph_view_init(GtkGraphView *obj)
 	GtkGraphViewPrivate *priv;
 
 	priv = gtk_graph_view_get_instance_private(obj);
-	priv->i = 0;
+
+	/* Create new GTK GL_Area as only child of the box */
+	priv->gl_area = gtk_gl_area_new();
+	g_signal_connect(priv->gl_area, "render", G_CALLBACK(gl_render), obj);
+	gtk_container_add(GTK_CONTAINER(obj), priv->gl_area);
+	gtk_box_set_child_packing(GTK_BOX(obj), priv->gl_area, TRUE, TRUE, 0, GTK_PACK_START);
+	gtk_widget_show(priv->gl_area);
+
+	priv->background_color.red = 0.0;
+	priv->background_color.green = 0.0;
+	priv->background_color.blue = 0.0;
+	priv->background_color.alpha = 1.0;
 }
 
 GtkWidget *gtk_graph_view_new()
 {
 	return gtk_widget_new(GTK_TYPE_GRAPH_VIEW, NULL);
 }
+
+void gtk_graph_view_set_background_color(GtkGraphView *graph_view, const GdkRGBA *rgba)
+{
+	GValue color_value = G_VALUE_INIT;
+
+	g_return_if_fail(GTK_IS_GRAPH_VIEW(graph_view));
+	g_return_if_fail(rgba != NULL);
+
+	g_value_init(&color_value, GDK_TYPE_RGBA);
+	g_value_set_boxed(&color_value, rgba);
+	g_object_set_property(G_OBJECT(graph_view), "background-color", &color_value);
+	g_value_unset(&color_value);
+}