------------------------------------------------------------------------------ -- -- -- Copyright (C) 1998-2000 E. Briot, J. Brobecker and A. Charlet -- -- Copyright (C) 2000-2014, AdaCore -- -- -- -- This library is free software; you can redistribute it and/or modify it -- -- under terms of the GNU General Public License as published by the Free -- -- Software Foundation; either version 3, or (at your option) any later -- -- version. This library is distributed in the hope that it will be useful, -- -- but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHAN- -- -- TABILITY or FITNESS FOR A PARTICULAR PURPOSE. -- -- -- -- As a special exception under Section 7 of GPL version 3, you are granted -- -- additional permissions described in the GCC Runtime Library Exception, -- -- version 3.1, as published by the Free Software Foundation. -- -- -- -- You should have received a copy of the GNU General Public License and -- -- a copy of the GCC Runtime Library Exception along with this program; -- -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- -- <http://www.gnu.org/licenses/>. -- -- -- ------------------------------------------------------------------------------ -- <description> -- The Gtk.Drawing_Area.Gtk_Drawing_Area widget is used for creating custom -- user interface elements. It's essentially a blank widget; you can draw on -- it. After creating a drawing area, the application may want to connect to: -- -- -- -- * -- -- Mouse and button press signals to respond to input from the user. (Use -- Gtk.Widget.Add_Events to enable events you wish to receive.) -- -- * -- -- The Gtk.Widget.Gtk_Widget::realize signal to take any necessary actions -- when the widget is instantiated on a particular display. (Create GDK -- resources in response to this signal.) -- -- * -- -- The Gtk.Widget.Gtk_Widget::configure-event signal to take any necessary -- actions when the widget changes size. -- -- * -- -- The Gtk.Widget.Gtk_Widget::draw signal to handle redrawing the contents of -- the widget. -- -- The following code portion demonstrates using a drawing area to display a -- circle in the normal widget foreground color. -- -- Note that GDK automatically clears the exposed area to the background -- color before sending the expose event, and that drawing is implicitly -- clipped to the exposed area. -- -- == Simple GtkDrawingArea usage == -- -- gboolean -- draw_callback (GtkWidget *widget, cairo_t *cr, gpointer data) -- { -- guint width, height; -- GdkRGBA color; -- width = gtk_widget_get_allocated_width (widget); -- height = gtk_widget_get_allocated_height (widget); -- cairo_arc (cr, -- width / 2.0, height / 2.0, -- MIN (width, height) / 2.0, -- 0, 2 * G_PI); -- gtk_style_context_get_color (gtk_widget_get_style_context (widget), -- 0, -- &color); -- gdk_cairo_set_source_rgba (cr, &color); -- cairo_fill (cr); -- return FALSE; -- } -- [...] -- GtkWidget *drawing_area = gtk_drawing_area_new (<!-- -->); -- gtk_widget_set_size_request (drawing_area, 100, 100); -- g_signal_connect (G_OBJECT (drawing_area), "draw", -- G_CALLBACK (draw_callback), NULL); -- -- Draw signals are normally delivered when a drawing area first comes -- onscreen, or when it's covered by another window and then uncovered. You -- can also force an expose event by adding to the "damage region" of the -- drawing area's window; Gtk.Widget.Queue_Draw_Area and -- Gdk.Window.Invalidate_Rect are equally good ways to do this. You'll then -- get a draw signal for the invalid region. -- -- The available routines for drawing are documented on the <link -- linkend="gdk3-Cairo-Interaction">GDK Drawing Primitives</link> page and the -- cairo documentation. -- -- To receive mouse events on a drawing area, you will need to enable them -- with Gtk.Widget.Add_Events. To receive keyboard events, you will need to -- set the "can-focus" property on the drawing area, and you should probably -- draw some user-visible indication that the drawing area is focused. Use -- Gtk.Widget.Has_Focus in your expose event handler to decide whether to draw -- the focus indicator. See Gtk.Style_Context.Render_Focus for one way to draw -- focus. -- -- </description> -- <description> -- See also the Double_Buffer widget provided in the GtkAda examples for an -- advanced example that demonstrates how to use double buffering, to avoid -- flickering in your drawings. -- -- </description> -- <group>Drawing</group> -- <testgtk>libart_demo.adb</testgtk> pragma Ada_2005; pragma Warnings (Off, "*is already use-visible*");
with Glib; use Glib;
with Glib.Types; use Glib.Types;
with Gtk.Buildable; use Gtk.Buildable;
with Gtk.Widget; use Gtk.Widget;
package Gtk.Drawing_Area is
type Gtk_Drawing_Area_Record is new Gtk_Widget_Record with null record;
type Gtk_Drawing_Area is access all Gtk_Drawing_Area_Record'Class;
------------------ -- Constructors -- ------------------ procedure Gtk_New (Drawing_Area : out Gtk_Drawing_Area);
procedure Initialize
(Drawing_Area : not null access Gtk_Drawing_Area_Record'Class);
-- Creates a new drawing area. function Gtk_Drawing_Area_New return Gtk_Drawing_Area;
-- Creates a new drawing area. function Get_Type return Glib.GType;
pragma Import (C, Get_Type, "gtk_drawing_area_get_type");
---------------- -- Interfaces -- ---------------- -- This class implements several interfaces. See Glib.Types -- -- - "Buildable" package Implements_Gtk_Buildable is new Glib.Types.Implements
(Gtk.Buildable.Gtk_Buildable, Gtk_Drawing_Area_Record, Gtk_Drawing_Area);
function "+"
(Widget : access Gtk_Drawing_Area_Record'Class)
return Gtk.Buildable.Gtk_Buildable
renames Implements_Gtk_Buildable.To_Interface;
function "-"
(Interf : Gtk.Buildable.Gtk_Buildable)
return Gtk_Drawing_Area
renames Implements_Gtk_Buildable.To_Object;
end Gtk.Drawing_Area;