Re: rubber-band with overlay

[JParker coinstar com]

G'Day !

I have asked the question over the forum, but have not gotten any responses  :-)

I have an example program I wrote using scribble from the tutorial. Play with it
and maybe you can tell me what I'm doing wrong ...

It currently uses an expanding rectangle, but I have used lines (works great),
and circles (ellipses).



/* 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>
#include <stdlib.h>

typedef struct {
  int x1;
  int y1;
  int x2;
  int y2;
} typPoints;

typPoints cursor;

/* GtkWidget *drawing_area; */
int prevx;
int prevy;

/* 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 to use as paint brush
 *
 *
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);
}
*****/

/*
 * Draw a expanding rectangle on the screen to use as a cursor
 *
 */
static void draw_cursor ( GtkWidget *widget,
                          int    x1,
                          int    y1,
                          int    x2,
                          int    y2)
{
  GdkRectangle update_rect;
  int width, height;

  update_rect.x = 0;
  update_rect.y = 0;
  update_rect.width = widget->allocation.width;
  update_rect.height = widget->allocation.height;

  width = abs(cursor.x2 - cursor.x1);
  height = abs(cursor.y2 - cursor.y1);

  gdk_draw_rectangle (pixmap,
                widget->style->black_gc,
                FALSE,
          cursor.x1, cursor.y1,
                width, height);

  gtk_widget_draw (widget, &update_rect);
}


static gint button_press_event( GtkWidget      *widget,
                                GdkEventButton *event )
{
  if (event->button == 1 && pixmap != NULL)
  {
    cursor.x1 = event->x;
    cursor.y1 = event->y;

    /* draw_brush (widget, event->x, event->y); */
    /* draw_cursor (widget, cursor.x1, cursor.y1, cursor.x2, cursor.y2); */
  }
  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); */
    draw_cursor (widget, cursor.x1, cursor.y1, cursor.x2, cursor.y2);
    Repaint (widget);
  }

  cursor.x2 = x;
  cursor.y2 = y;

  return TRUE;
}

void Repaint (GtkWidget *widget )
{
   GdkRectangle  update_rect;

   /* Init3d (); */

   /* --- clear pixmap --- */
   gdk_draw_rectangle (pixmap,
                       widget->style->white_gc,
                 TRUE,
                 0, 0,
                 widget->allocation.width,
                 widget->allocation.height);

   /* --- Draw molecule in the background --- */
   /* paint (g); */

    /* --- The whole screen --- */
    update_rect.x = 0;
    update_rect.y = 0;
    update_rect.width = widget->allocation.width;
    update_rect.height = widget->allocation.height;

    /* --- Call the expose event - which copies the background
     *     into the widget
     */
    gtk_widget_draw (widget, &update_rect);
}

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 */

cheers,
Jim Parker

Sailboat racing is not a matter of life and death ....  It is far more important
than that !!!


                                                                                                              
                     
                    Bernard Doucet                                                                            
                     
                    <bdoucet progigraph com>        To:     gtk-app-devel-list gnome org                      
                     
                    Sent by:                        cc:                                                       
                     
                    gtk-app-devel-list-admin        Subject:     rubber-band with overlay                     
                     
                    @gnome.org                                                                                
                     
                                                                                                              
                     
                                                                                                              
                     
                    10/04/00 04:35 AM                                                                         
                     
                                                                                                              
                     
                                                                                                              
                     



I want to have a rubber-band using the overlay with gtkglarea widget, I
found some discussion about overlay in the forum, I need some code example
to start, does anybody can help me ?

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