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I´ve been madifyng(sorry about my english) the Scrible example Gtk and I have a question:is there any form to reset(clear) the drawing_area?This is the code that I´ve done(it´s poor):

#include <stdlib.h>
#include <gtk/gtk.h>
/* Backing pixmap for drawing area */
static GdkPixmap *pixmap = NULL;



GtkWidget *drawing_area;
GdkFont *font;

/* Create a new backing pixmap of the appropriate size */
static gint configure_event( GtkWidget *widget,
GdkEventConfigure *event )
{
if (pixmap)
gdk_pixmap_unref(pixmap);

pixmap = gdk_pixmap_new(widget->window,
widget->allocation.width,
widget->allocation.height,
-1);
gdk_draw_rectangle (pixmap,
widget->style->white_gc,
TRUE,
0,0,
widget->allocation.width,
widget->allocation.height);

//pinto escalas
gdk_draw_line(pixmap,drawing_area->style->black_gc,10,190,390,190);
gdk_draw_line(pixmap,drawing_area->style->black_gc,190,10,190,390);

font=gdk_font_load("-adobe-helvetica-medium-r-normal--*-120-*-*-*-*-*-*");

//Se pinta la
gdk_draw_string(pixmap,font,drawing_area->style->black_gc,200,10,"Vdelante");
gdk_draw_string(pixmap,font,drawing_area->style->black_gc,200,390,"Vatras");
//Se pinta la
gdk_draw_string(pixmap,font,drawing_area->style->black_gc,10,200,"Wantihorario");
gdk_draw_string(pixmap,font,drawing_area->style->black_gc,345,200,"Whorario");
return TRUE;
}
/* Redraw the screen from the backing pixmap */
static gint expose_event( GtkWidget *widget,
GdkEventExpose *event )
{
gdk_draw_pixmap(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);

return FALSE;
}
static void draw_brush( GtkWidget *widget,
gdouble x,
gdouble y)
{
GdkRectangle update_rect;

update_rect.x = x - 1.5;
update_rect.y = y - 1.5;
update_rect.width = 3;
update_rect.height = 3;
gdk_draw_rectangle (pixmap,
widget->style->black_gc,
TRUE,
update_rect.x, update_rect.y,
update_rect.width, update_rect.height);
gtk_widget_draw (widget, &update_rect);

gdk_draw_line(pixmap,drawing_area->style->black_gc,10,190,390,190);
gdk_draw_line(pixmap,drawing_area->style->black_gc,190,10,190,390);

font=gdk_font_load("-adobe-helvetica-medium-r-normal--*-120-*-*-*-*-*-*");

//Se pinta la
gdk_draw_string(pixmap,font,widget->style->black_gc,200,10,"Vdelante");
gdk_draw_string(pixmap,font,drawing_area->style->black_gc,200,390,"Vatras");
//Se pinta la
gdk_draw_string(pixmap,font,drawing_area->style->black_gc,10,200,"Wantihorario");
gdk_draw_string(pixmap,font,drawing_area->style->black_gc,345,200,"Whorario");
}
static gint button_press_event( GtkWidget *widget,
GdkEventButton *event )
{
if (event->button == 1 && pixmap != NULL)
draw_brush (widget, event->x, event->y);

return TRUE;
}
static gint motion_notify_event( GtkWidget *widget,
GdkEventMotion *event )
{
int x, y;
GdkModifierType state;

if (event->is_hint)
gdk_window_get_pointer (event->window, &x, &y, &state);
else
{
x = event->x;
y = event->y;
state = event->state;
}

if (state & GDK_BUTTON1_MASK && pixmap != NULL)
//draw_brush (widget, x, y);

return TRUE;
}

/**** salgo de la aplicaion***/
gint delete_event( GtkWidget *widget,
GdkEvent *event,
gpointer data )
{
gtk_main_quit ();
return(FALSE);
}
void quit ()
{
gtk_exit (0);
}
void limpiardraw ( GtkWidget *widget, GdkEventExpose *event )
{
/******** aqui limpio el drawing_area*****************/
gdk_window_clear(drawing_area->window);
/* if (pixmap)
gdk_pixmap_unref(pixmap);*/

/* pixmap = gdk_pixmap_new(widget->window,
widget->allocation.width,
widget->allocation.height,
-1);*/
/*gdk_draw_rectangle (pixmap,
widget->style->white_gc,
TRUE,
0,0,
widget->allocation.width,
widget->allocation.height);*/

//pinto escalas
gdk_draw_line(pixmap,drawing_area->style->black_gc,10,190,390,190);
gdk_draw_line(pixmap,drawing_area->style->black_gc,190,10,190,390);

font=gdk_font_load("-adobe-helvetica-medium-r-normal--*-120-*-*-*-*-*-*");

//Se pinta la
gdk_draw_string(pixmap,font,drawing_area->style->black_gc,200,10,"Vdelante");
gdk_draw_string(pixmap,font,drawing_area->style->black_gc,200,390,"Vatras");
//Se pinta la
gdk_draw_string(pixmap,font,drawing_area->style->black_gc,10,200,"Wantihorario");
gdk_draw_string(pixmap,font,drawing_area->style->black_gc,345,200,"Whorario");
}
int main( int argc,
char *argv[] )
{
GtkWidget *Teleoperacion;
GtkWidget *vbox;
GtkWidget *button;
GtkWidget *limpiar;


/*
GtkWidget *button;
GtkWidget *limpiar;*/

gtk_init (&argc, &argv);

Teleoperacion = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_widget_set_usize(Teleoperacion,410,410);
gtk_widget_set_name (GTK_WIDGET(Teleoperacion), "Teleoperacion");

vbox = gtk_vbox_new (FALSE, 0);
gtk_container_add (GTK_CONTAINER (Teleoperacion), vbox);
gtk_widget_show (vbox);
/* Crear el drawing area */

drawing_area = gtk_drawing_area_new ();
gtk_drawing_area_size (GTK_DRAWING_AREA (drawing_area), 200, 200);
gtk_box_pack_start (GTK_BOX (vbox), drawing_area, TRUE, TRUE, 0);

gtk_widget_show (drawing_area);
/* Señales del pixmap*/

gtk_signal_connect (GTK_OBJECT (drawing_area), "expose_event",
(GtkSignalFunc) expose_event, NULL);
gtk_signal_connect (GTK_OBJECT(drawing_area),"configure_event",
(GtkSignalFunc) configure_event, NULL);
/* Event signals */

gtk_signal_connect (GTK_OBJECT (drawing_area), "motion_notify_event",
(GtkSignalFunc) motion_notify_event, NULL);
gtk_signal_connect (GTK_OBJECT (drawing_area), "button_press_event",
(GtkSignalFunc) button_press_event, NULL);

gtk_widget_set_events (drawing_area, GDK_EXPOSURE_MASK
| GDK_LEAVE_NOTIFY_MASK
| GDK_BUTTON_PRESS_MASK
| GDK_POINTER_MOTION_MASK
| GDK_POINTER_MOTION_HINT_MASK);


/******* conecto las señales ****************/
gtk_signal_connect (GTK_OBJECT (Teleoperacion), "delete_event",
GTK_SIGNAL_FUNC (delete_event), NULL);

/* .. boton de limpiar */
limpiar=gtk_button_new_with_label ("Limpiar");
gtk_box_pack_start (GTK_BOX (vbox), limpiar, FALSE, FALSE, 0);
// le conecto para destruir la aplicacion
gtk_signal_connect_object (GTK_OBJECT (limpiar), "clicked",
GTK_SIGNAL_FUNC (limpiardraw),
NULL);
/* .. boton de salir */
button = gtk_button_new_with_label ("Quit");
gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);
// le conecto para destruir la aplicacion
gtk_signal_connect_object (GTK_OBJECT (button), "clicked",
GTK_SIGNAL_FUNC (quit),
GTK_OBJECT (Teleoperacion));
gtk_widget_show (limpiar);
gtk_widget_show (button);


gtk_widget_show (Teleoperacion);

gtk_main ();

return 0;
}


I want to clear the drawing_area but not clear the lines(the scales)
Thanks
javigis

PD: limpiar=clear

Please, can respond somebody to me?
I only need to reset the drawing_area, but keeping the line scales.
Thanks

[Spanish] Crea una segunda drawing_area en blanco, dibuja en ella las líneas de escala, e intercámbiala por la primera. Así limpias la drawing_area sin que haya parpadeo ni se vea el redibujado.

[English] Create a second drawing_area, draw on it the scale lines and swap it with the first one. That way, you can clean the drawing_area with no flicker nor redraw effects.

_________________
David Vilches

[Spanish]Gracias por responder paisano.Como intercambio esas drawing_area?Las intercambio en expose_event?
[English]Thanks to respond countryman. How interchange those drawing_area? Them interchange in expose_event?

Gracias de uevo por responder