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program scribble_simple;
{$mode objfpc} {$H+}
uses glib2, gtk2, gdk2;
var
pixmap : PGdkPixmap; (* Backing pixmap for drawing area *)
(* Create a new backing pixmap of the appropriate size *)
function configure_event ( widget : PGtkWidget;
event : PGdkEventConfigure): gboolean; cdecl;
begin
if pixmap <> nil then
g_object_unref (pixmap);
pixmap := gdk_pixmap_new (widget^.window,
widget^.allocation.width,
widget^.allocation.height,
-1);
gdk_draw_rectangle (pixmap,
widget^.style^.white_gc,
gTRUE,
0, 0,
widget^.allocation.width,
widget^.allocation.height);
configure_event := TRUE;
end;
(* Redraw the screen from the backing pixmap *)
function expose_event ( widget : PGtkWidget;
event : PGdkEventExpose) : gboolean; cdecl;
begin
gdk_draw_drawable (widget^.window,
widget^.style^.fg_gc[GTK_WIDGET_STATE (widget)],
pixmap,
event^.area.x, event^.area.y,
event^.area.x, event^.area.y,
event^.area.width, event^.area.height);
expose_event := FALSE;
end;
(* Draw a rectangle on the screen *)
procedure draw_brush (widget : PGtkWidget;
x, y : gdouble); cdecl;
var
update_rect : TGdkRectangle;
begin
update_rect.x := round (x - 5.0);
update_rect.y := round (y - 5.0);
update_rect.width := 10;
update_rect.height := 10;
gdk_draw_rectangle (pixmap,
widget^.style^.black_gc,
gTRUE,
update_rect.x, update_rect.y,
update_rect.width, update_rect.height);
gtk_widget_queue_draw_area (widget,
update_rect.x, update_rect.y,
update_rect.width, update_rect.height);
end;
function button_press_event ( widget : PGtkWidget;
event : PGdkEventbutton): gboolean; cdecl;
begin
if (event^.button = 1) and (pixmap <> NULL) then
draw_brush (widget, event^.x, event^.y);
button_press_event := TRUE;
end;
function motion_notify_event ( widget: PGtkWidget;
event : PGdkEventMotion): gboolean; cdecl;
var
x, y : gint;
state : TGdkModifierType;
begin
if event^.is_hint = gTRUE then
gdk_window_get_pointer (event^.window, @x, @y, @state)
else begin
x := round (event^.x);
y := round (event^.y);
state := event^.state;
end;
if ((state and GDK_BUTTON1_MASK) <> 0) and (pixmap <> NULL) then
draw_brush (widget, x, y);
motion_notify_event := TRUE;
end;
procedure quit;
begin
halt;
end;
var
window,
drawing_area,
vbox : PGtkWidget;
button : PGtkWidget;
begin
gtk_init (@argc, @argv);
window := gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_widget_set_name (window, 'Test Input');
vbox := gtk_vbox_new (FALSE, 0);
gtk_container_add (GTK_CONTAINER (window), vbox);
gtk_widget_show (vbox);
g_signal_connect (G_OBJECT (window), 'destroy',
G_CALLBACK (@quit), NULL);
(* Create the drawing area *)
drawing_area := gtk_drawing_area_new ();
gtk_widget_set_size_request (GTK_WIDGET (drawing_area), 200, 200);
gtk_box_pack_start (GTK_BOX (vbox), drawing_area, TRUE, TRUE, 0);
gtk_widget_show (drawing_area);
(* Signals used to handle backing pixmap *)
g_signal_connect (G_OBJECT (drawing_area), 'expose_event',
G_CALLBACK (@expose_event), NULL);
g_signal_connect (G_OBJECT (drawing_area),'configure_event',
G_CALLBACK (@configure_event), NULL);
(* Event signals *)
g_signal_connect (G_OBJECT (drawing_area), 'motion_notify_event',
G_CALLBACK (@motion_notify_event), NULL);
g_signal_connect (G_OBJECT (drawing_area), 'button_press_event',
G_CALLBACK (@button_press_event), NULL);
gtk_widget_set_events (drawing_area, GDK_EXPOSURE_MASK
or GDK_LEAVE_NOTIFY_MASK
or GDK_BUTTON_PRESS_MASK
or GDK_POINTER_MOTION_MASK
or GDK_POINTER_MOTION_HINT_MASK);
(* .. And a quit button *)
button := gtk_button_new_with_label ('Quit');
gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);
g_signal_connect_swapped (G_OBJECT (button), 'clicked',
G_CALLBACK (@gtk_widget_destroy),
window);
gtk_widget_show (button);
gtk_widget_show (window);
gtk_main ();
end.
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