tests/testwidgetfocus.c - external/github.com/GNOME/gtk - Git at Google

 #include <gtk/gtk.h>

 G_GNUC_BEGIN_IGNORE_DEPRECATIONS

 typedef struct _GtkFocusWidget      GtkFocusWidget;
 typedef struct _GtkFocusWidgetClass GtkFocusWidgetClass;

 #define GTK_TYPE_FOCUS_WIDGET           (gtk_focus_widget_get_type ())
 #define GTK_FOCUS_WIDGET(obj)           (G_TYPE_CHECK_INSTANCE_CAST(obj, GTK_TYPE_FOCUS_WIDGET, GtkFocusWidget))
 #define GTK_FOCUS_WIDGET_CLASS(cls)     (G_TYPE_CHECK_CLASS_CAST(cls, GTK_TYPE_FOCUS_WIDGET, GtkFocusWidgetClass))
 #define GTK_IS_FOCUS_WIDGET(obj)        (G_TYPE_CHECK_INSTANCE_TYPE(obj, GTK_TYPE_FOCUS_WIDGET))
 #define GTK_IS_FOCUS_WIDGET_CLASS(cls)   (G_TYPE_CHECK_CLASS_TYPE(cls, GTK_TYPE_FOCUS_WIDGET))
 #define GTK_FOCUS_WIDGET_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS(obj, GTK_TYPE_FOCUS_WIDGET, GtkFocusWidgetClass))

 const char *css =
 "* {"
 "  transition: none; "
 "}"
 "focuswidget {"
 "  padding: 30px;"
 "  font-size: 70%;"
 "}"
 "focuswidget button:nth-child(1) {"
 "  margin-right: 15px;"
 "  margin-bottom: 15px;"
 "}"
 "focuswidget button:nth-child(2) {"
 "  margin-left: 15px;"
 "  margin-bottom: 15px;"
 "}"
 "focuswidget button:nth-child(3) {"
 "  margin-right: 15px;"
 "  margin-top: 15px;"
 "}"
 "focuswidget button:nth-child(4) {"
 "  margin-left: 15px;"
 "  margin-top: 15px;"
 "}"
 "focuswidget button {"
 "  min-width: 80px;"
 "  min-height: 80px;"
 "  margin: 0px;"
 "  border: 5px solid green;"
 "  border-radius: 0px;"
 "  padding: 10px;"
 "  background-image: none;"
 "  background-color: white;"
 "  box-shadow: none;"
 "}"
 "focuswidget button:focus-visible {"
 "  outline-width: 4px;"
 "  outline-color: yellow;"
 "}"
 "focuswidget button:hover {"
 "  background-color: black;"
 "  color: white;"
 "}"
 "focuswidget button label:hover {"
 "  background-color: green;"
 "}"
 ;

 struct _GtkFocusWidget
 {
   GtkWidget parent_instance;
   double mouse_x;
   double mouse_y;

   union {
     struct {
       GtkWidget *child1;
       GtkWidget *child2;
       GtkWidget *child3;
       GtkWidget *child4;
     };
     GtkWidget* children[4];
   };
 };

 struct _GtkFocusWidgetClass
 {
   GtkWidgetClass parent_class;
 };

 GType gtk_focus_widget_get_type (void) G_GNUC_CONST;


 G_DEFINE_TYPE(GtkFocusWidget, gtk_focus_widget, GTK_TYPE_WIDGET)

 static void
 gtk_focus_widget_size_allocate (GtkWidget *widget,
                                 int        width,
                                 int        height,
                                 int        baseline)
 {
   GtkFocusWidget *self = GTK_FOCUS_WIDGET (widget);
   int child_width  = width  / 2;
   int child_height = height / 2;
   GtkAllocation child_alloc;

   child_alloc.x = 0;
   child_alloc.y = 0;
   child_alloc.width = child_width;
   child_alloc.height = child_height;

   gtk_widget_size_allocate (self->child1, &child_alloc, -1);

   child_alloc.x += child_width;

   gtk_widget_size_allocate (self->child2, &child_alloc, -1);

   child_alloc.y += child_height;

   gtk_widget_size_allocate (self->child4, &child_alloc, -1);

   child_alloc.x -= child_width;

   gtk_widget_size_allocate (self->child3, &child_alloc, -1);
 }

 static void
 gtk_focus_widget_measure (GtkWidget      *widget,
                           GtkOrientation  orientation,
                           int             for_size,
                           int            *minimum,
                           int            *natural,
                           int            *minimum_baseline,
                           int            *natural_baseline)
 {
   GtkFocusWidget *self = GTK_FOCUS_WIDGET (widget);
   int min, nat;
   int i;

   *minimum = 0;
   *natural = 0;

   for (i = 0; i < 4; i ++)
     {
       gtk_widget_measure (self->children[i], orientation, for_size,
                           &min, &nat, NULL, NULL);

       *minimum = MAX (*minimum, min);
       *natural = MAX (*natural, nat);
     }

   *minimum *= 2;
   *natural *= 2;
 }

 static void
 gtk_focus_widget_snapshot (GtkWidget *widget, GtkSnapshot *snapshot)
 {
   GtkFocusWidget *self = GTK_FOCUS_WIDGET (widget);

   gtk_widget_snapshot_child (widget, self->child1, snapshot);
   gtk_widget_snapshot_child (widget, self->child2, snapshot);
   gtk_widget_snapshot_child (widget, self->child3, snapshot);
   gtk_widget_snapshot_child (widget, self->child4, snapshot);

   if (self->mouse_x != G_MININT && self->mouse_y != G_MININT)
     {
       PangoLayout *layout;
       char *text;
       GtkAllocation alloc;
       graphene_rect_t bounds;
       GdkRGBA black = {0, 0, 0, 1};

       gtk_widget_get_allocation (widget, &alloc);

       /* Since event coordinates and drawing is supposed to happen in the
        * same coordinates space, this should all work out just fine. */
       bounds.origin.x = self->mouse_x;
       bounds.origin.y = -30;
       bounds.size.width = 1;
       bounds.size.height = alloc.height;
       gtk_snapshot_append_color (snapshot,
                                  &black,
                                  &bounds);

       bounds.origin.x = -30;
       bounds.origin.y = self->mouse_y;
       bounds.size.width = alloc.width;
       bounds.size.height = 1;
       gtk_snapshot_append_color (snapshot,
                                  &black,
                                  &bounds);

       layout = gtk_widget_create_pango_layout (widget, NULL);
       text = g_strdup_printf ("%.2f×%.2f", self->mouse_x, self->mouse_y);
       pango_layout_set_text (layout, text, -1);

       gtk_snapshot_render_layout (snapshot,
                                   gtk_widget_get_style_context (widget),
                                   self->mouse_x + 2,
                                   self->mouse_y - 15, /* *shrug* */
                                   layout);

       g_free (text);
       g_object_unref (layout);
     }
 }

 static void
 motion_cb (GtkEventControllerMotion *controller,
            double                    x,
            double                    y,
            GtkWidget                *widget)
 {
   GtkFocusWidget *self = GTK_FOCUS_WIDGET (widget);

   self->mouse_x = x;
   self->mouse_y = y;

   gtk_widget_queue_draw (widget);
 }

 static void
 gtk_focus_widget_finalize (GObject *object)
 {
   GtkFocusWidget *self = GTK_FOCUS_WIDGET (object);

   gtk_widget_unparent (self->child1);
   gtk_widget_unparent (self->child2);
   gtk_widget_unparent (self->child3);
   gtk_widget_unparent (self->child4);

   G_OBJECT_CLASS (gtk_focus_widget_parent_class)->finalize (object);
 }

 static void
 gtk_focus_widget_init (GtkFocusWidget *self)
 {
   GtkEventController *controller;

   self->child1 = gtk_button_new_with_label ("1");
   gtk_widget_set_parent (self->child1, GTK_WIDGET (self));
   self->child2 = gtk_button_new_with_label ("2");
   gtk_widget_set_parent (self->child2, GTK_WIDGET (self));
   self->child3 = gtk_button_new_with_label ("3");
   gtk_widget_set_parent (self->child3, GTK_WIDGET (self));
   self->child4 = gtk_button_new_with_label ("4");
   gtk_widget_set_parent (self->child4, GTK_WIDGET (self));

   self->mouse_x = G_MININT;
   self->mouse_y = G_MININT;

   controller = gtk_event_controller_motion_new ();
   g_signal_connect (controller, "motion",
 		    G_CALLBACK (motion_cb), self);
   gtk_widget_add_controller (GTK_WIDGET (self), controller);
 }

 static void
 gtk_focus_widget_class_init (GtkFocusWidgetClass *klass)
 {
   GObjectClass   *object_class = G_OBJECT_CLASS (klass);
   GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);

   object_class->finalize = gtk_focus_widget_finalize;

   widget_class->snapshot = gtk_focus_widget_snapshot;
   widget_class->measure = gtk_focus_widget_measure;
   widget_class->size_allocate = gtk_focus_widget_size_allocate;

   gtk_widget_class_set_css_name (widget_class, "focuswidget");
 }

 static void
 quit_cb (GtkWidget *widget,
          gpointer   user_data)
 {
   gboolean *is_done = user_data;

   *is_done = TRUE;

   g_main_context_wakeup (NULL);
 }

 int
 main(int argc, char **argv)
 {
   GtkWidget *window;
   GtkWidget *widget;
   GtkCssProvider *provider;
   gboolean done = FALSE;

   gtk_init ();

   provider = gtk_css_provider_new ();
   gtk_css_provider_load_from_data (provider, css, -1);
   gtk_style_context_add_provider_for_display (gdk_display_get_default (),
                                               GTK_STYLE_PROVIDER (provider),
                                               GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);

   window = gtk_window_new ();
   widget = g_object_new (GTK_TYPE_FOCUS_WIDGET, NULL);

   gtk_window_set_decorated (GTK_WINDOW (window), FALSE);

   gtk_window_set_child (GTK_WINDOW (window), widget);
   g_signal_connect (window, "destroy", G_CALLBACK (quit_cb), &done);

   gtk_window_present (GTK_WINDOW (window));

   while (!done)
     g_main_context_iteration (NULL, TRUE);
 }
	#include <gtk/gtk.h>

	G_GNUC_BEGIN_IGNORE_DEPRECATIONS

	typedef struct _GtkFocusWidget GtkFocusWidget;
	typedef struct _GtkFocusWidgetClass GtkFocusWidgetClass;

	#define GTK_TYPE_FOCUS_WIDGET (gtk_focus_widget_get_type ())
	#define GTK_FOCUS_WIDGET(obj) (G_TYPE_CHECK_INSTANCE_CAST(obj, GTK_TYPE_FOCUS_WIDGET, GtkFocusWidget))
	#define GTK_FOCUS_WIDGET_CLASS(cls) (G_TYPE_CHECK_CLASS_CAST(cls, GTK_TYPE_FOCUS_WIDGET, GtkFocusWidgetClass))
	#define GTK_IS_FOCUS_WIDGET(obj) (G_TYPE_CHECK_INSTANCE_TYPE(obj, GTK_TYPE_FOCUS_WIDGET))
	#define GTK_IS_FOCUS_WIDGET_CLASS(cls) (G_TYPE_CHECK_CLASS_TYPE(cls, GTK_TYPE_FOCUS_WIDGET))
	#define GTK_FOCUS_WIDGET_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS(obj, GTK_TYPE_FOCUS_WIDGET, GtkFocusWidgetClass))

	const char *css =
	"* {"
	" transition: none; "
	"}"
	"focuswidget {"
	" padding: 30px;"
	" font-size: 70%;"
	"}"
	"focuswidget button:nth-child(1) {"
	" margin-right: 15px;"
	" margin-bottom: 15px;"
	"}"
	"focuswidget button:nth-child(2) {"
	" margin-left: 15px;"
	" margin-bottom: 15px;"
	"}"
	"focuswidget button:nth-child(3) {"
	" margin-right: 15px;"
	" margin-top: 15px;"
	"}"
	"focuswidget button:nth-child(4) {"
	" margin-left: 15px;"
	" margin-top: 15px;"
	"}"
	"focuswidget button {"
	" min-width: 80px;"
	" min-height: 80px;"
	" margin: 0px;"
	" border: 5px solid green;"
	" border-radius: 0px;"
	" padding: 10px;"
	" background-image: none;"
	" background-color: white;"
	" box-shadow: none;"
	"}"
	"focuswidget button:focus-visible {"
	" outline-width: 4px;"
	" outline-color: yellow;"
	"}"
	"focuswidget button:hover {"
	" background-color: black;"
	" color: white;"
	"}"
	"focuswidget button label:hover {"
	" background-color: green;"
	"}"
	;

	struct _GtkFocusWidget
	{
	GtkWidget parent_instance;
	double mouse_x;
	double mouse_y;

	union {
	struct {
	GtkWidget *child1;
	GtkWidget *child2;
	GtkWidget *child3;
	GtkWidget *child4;
	};
	GtkWidget* children[4];
	};
	};

	struct _GtkFocusWidgetClass
	{
	GtkWidgetClass parent_class;
	};

	GType gtk_focus_widget_get_type (void) G_GNUC_CONST;


	G_DEFINE_TYPE(GtkFocusWidget, gtk_focus_widget, GTK_TYPE_WIDGET)

	static void
	gtk_focus_widget_size_allocate (GtkWidget *widget,
	int width,
	int height,
	int baseline)
	{
	GtkFocusWidget *self = GTK_FOCUS_WIDGET (widget);
	int child_width = width / 2;
	int child_height = height / 2;
	GtkAllocation child_alloc;

	child_alloc.x = 0;
	child_alloc.y = 0;
	child_alloc.width = child_width;
	child_alloc.height = child_height;

	gtk_widget_size_allocate (self->child1, &child_alloc, -1);

	child_alloc.x += child_width;

	gtk_widget_size_allocate (self->child2, &child_alloc, -1);

	child_alloc.y += child_height;

	gtk_widget_size_allocate (self->child4, &child_alloc, -1);

	child_alloc.x -= child_width;

	gtk_widget_size_allocate (self->child3, &child_alloc, -1);
	}

	static void
	gtk_focus_widget_measure (GtkWidget *widget,
	GtkOrientation orientation,
	int for_size,
	int *minimum,
	int *natural,
	int *minimum_baseline,
	int *natural_baseline)
	{
	GtkFocusWidget *self = GTK_FOCUS_WIDGET (widget);
	int min, nat;
	int i;

	*minimum = 0;
	*natural = 0;

	for (i = 0; i < 4; i ++)
	{
	gtk_widget_measure (self->children[i], orientation, for_size,
	&min, &nat, NULL, NULL);

	minimum = MAX (minimum, min);
	natural = MAX (natural, nat);
	}

	minimum = 2;
	natural = 2;
	}

	static void
	gtk_focus_widget_snapshot (GtkWidget widget, GtkSnapshot snapshot)
	{
	GtkFocusWidget *self = GTK_FOCUS_WIDGET (widget);

	gtk_widget_snapshot_child (widget, self->child1, snapshot);
	gtk_widget_snapshot_child (widget, self->child2, snapshot);
	gtk_widget_snapshot_child (widget, self->child3, snapshot);
	gtk_widget_snapshot_child (widget, self->child4, snapshot);

	if (self->mouse_x != G_MININT && self->mouse_y != G_MININT)
	{
	PangoLayout *layout;
	char *text;
	GtkAllocation alloc;
	graphene_rect_t bounds;
	GdkRGBA black = {0, 0, 0, 1};

	gtk_widget_get_allocation (widget, &alloc);

	/* Since event coordinates and drawing is supposed to happen in the
	* same coordinates space, this should all work out just fine. */
	bounds.origin.x = self->mouse_x;
	bounds.origin.y = -30;
	bounds.size.width = 1;
	bounds.size.height = alloc.height;
	gtk_snapshot_append_color (snapshot,
	&black,
	&bounds);

	bounds.origin.x = -30;
	bounds.origin.y = self->mouse_y;
	bounds.size.width = alloc.width;
	bounds.size.height = 1;
	gtk_snapshot_append_color (snapshot,
	&black,
	&bounds);

	layout = gtk_widget_create_pango_layout (widget, NULL);
	text = g_strdup_printf ("%.2f×%.2f", self->mouse_x, self->mouse_y);
	pango_layout_set_text (layout, text, -1);

	gtk_snapshot_render_layout (snapshot,
	gtk_widget_get_style_context (widget),
	self->mouse_x + 2,
	self->mouse_y - 15, /* shrug */
	layout);

	g_free (text);
	g_object_unref (layout);
	}
	}

	static void
	motion_cb (GtkEventControllerMotion *controller,
	double x,
	double y,
	GtkWidget *widget)
	{
	GtkFocusWidget *self = GTK_FOCUS_WIDGET (widget);

	self->mouse_x = x;
	self->mouse_y = y;

	gtk_widget_queue_draw (widget);
	}

	static void
	gtk_focus_widget_finalize (GObject *object)
	{
	GtkFocusWidget *self = GTK_FOCUS_WIDGET (object);

	gtk_widget_unparent (self->child1);
	gtk_widget_unparent (self->child2);
	gtk_widget_unparent (self->child3);
	gtk_widget_unparent (self->child4);

	G_OBJECT_CLASS (gtk_focus_widget_parent_class)->finalize (object);
	}

	static void
	gtk_focus_widget_init (GtkFocusWidget *self)
	{
	GtkEventController *controller;

	self->child1 = gtk_button_new_with_label ("1");
	gtk_widget_set_parent (self->child1, GTK_WIDGET (self));
	self->child2 = gtk_button_new_with_label ("2");
	gtk_widget_set_parent (self->child2, GTK_WIDGET (self));
	self->child3 = gtk_button_new_with_label ("3");
	gtk_widget_set_parent (self->child3, GTK_WIDGET (self));
	self->child4 = gtk_button_new_with_label ("4");
	gtk_widget_set_parent (self->child4, GTK_WIDGET (self));

	self->mouse_x = G_MININT;
	self->mouse_y = G_MININT;

	controller = gtk_event_controller_motion_new ();
	g_signal_connect (controller, "motion",
	G_CALLBACK (motion_cb), self);
	gtk_widget_add_controller (GTK_WIDGET (self), controller);
	}

	static void
	gtk_focus_widget_class_init (GtkFocusWidgetClass *klass)
	{
	GObjectClass *object_class = G_OBJECT_CLASS (klass);
	GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);

	object_class->finalize = gtk_focus_widget_finalize;

	widget_class->snapshot = gtk_focus_widget_snapshot;
	widget_class->measure = gtk_focus_widget_measure;
	widget_class->size_allocate = gtk_focus_widget_size_allocate;

	gtk_widget_class_set_css_name (widget_class, "focuswidget");
	}

	static void
	quit_cb (GtkWidget *widget,
	gpointer user_data)
	{
	gboolean *is_done = user_data;

	*is_done = TRUE;

	g_main_context_wakeup (NULL);
	}

	int
	main(int argc, char **argv)
	{
	GtkWidget *window;
	GtkWidget *widget;
	GtkCssProvider *provider;
	gboolean done = FALSE;

	gtk_init ();

	provider = gtk_css_provider_new ();
	gtk_css_provider_load_from_data (provider, css, -1);
	gtk_style_context_add_provider_for_display (gdk_display_get_default (),
	GTK_STYLE_PROVIDER (provider),
	GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);

	window = gtk_window_new ();
	widget = g_object_new (GTK_TYPE_FOCUS_WIDGET, NULL);

	gtk_window_set_decorated (GTK_WINDOW (window), FALSE);

	gtk_window_set_child (GTK_WINDOW (window), widget);
	g_signal_connect (window, "destroy", G_CALLBACK (quit_cb), &done);

	gtk_window_present (GTK_WINDOW (window));

	while (!done)
	g_main_context_iteration (NULL, TRUE);
	}