Re: 1 expose/configure event function for ALL pixmaps or for EACH??

[Chris Seberino <seberino spawar navy mil>]

Paul,

Hello again.

> you can't draw from a configure event. Only from an expose event.

But configure_event in scribble.c (GTK+ tutorial)
 *does* have drawing code?!?!
I modified it by adding *more* drawing code and it still
worked?!?

What do you put in configure_event to redraw pixmap then?
Where do you put the drawing code then?

Thanks again,

Chris


/* example-start scribble-simple scribble-simple.c */

                    /* GTK - The GIMP Toolkit
                     * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
                     *
                     * This library is free software; you can redistribute it and/or
                     * modify it under the terms of the GNU Library General Public
                     * License as published by the Free Software Foundation; either
                     * version 2 of the License, 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
                     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
                     * Library General Public License for more details.
                     *
                     * You should have received a copy of the GNU Library General Public
                     * License along with this library; if not, write to the
                     * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
                     * Boston, MA 02111-1307, USA.
                     */

                    #include <gtk/gtk.h>

                    /* Backing pixmap for drawing area */
                    static GdkPixmap *pixmap = NULL;

                    /* 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);

                      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;
                    }

                    /* Draw a rectangle on the screen */
                    static void draw_brush( GtkWidget *widget,
                                            gdouble    x,
                                            gdouble    y)
                    {
                      GdkRectangle update_rect;

                      update_rect.x = x - 5;
                      update_rect.y = y - 5;
                      update_rect.width = 10;
                      update_rect.height = 10;
                      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);
                    }

                    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;
                    }

                    void quit ()
                    {
                      gtk_exit (0);
                    }

                    int main( int   argc, 
                              char *argv[] )
                    {
                      GtkWidget *window;
                      GtkWidget *drawing_area;
                      GtkWidget *vbox;

                      GtkWidget *button;

                      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);

                      gtk_signal_connect (GTK_OBJECT (window), "destroy",
                                          GTK_SIGNAL_FUNC (quit), NULL);

                      /* Create the 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);

                      /* Signals used to handle backing 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);

                      /* .. And a quit button */
                      button = gtk_button_new_with_label ("Quit");
                      gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);

                      gtk_signal_connect_object (GTK_OBJECT (button), "clicked",
                                                 GTK_SIGNAL_FUNC (gtk_widget_destroy),
                                                 GTK_OBJECT (window));
                      gtk_widget_show (button);

                      gtk_widget_show (window);

                      gtk_main ();

                      return 0;
                    }
                    /* example-end */