Re: [gtk-list] HUGE drawing areas and scrolled windows (odd/bug report?)

[raster redhat com]

On  6 Apr, Ales Hvezda shouted:
->  
->  Hi All, 
->  
->  Thanks Owen for pointing me at the proper way of setting the values of the 
->  scrollbars in scrolled windows.  
->  
->  	Unfortunately I've come across some odd behavior when you have
->  a scrolled_window widget which contains a HUGE drawing area (44000x34000).
->  Attached is a program which shows this odd behavior.   Basically if 
->  you scroll to the far right (or far bottom) you will notice three things:
->  
->  	1) At some point the x or y coordinates will go negative (around
->  	   32768 :-( (press the mouse button in the canvas to see the coords) 
->  
->  	2) The canvas will go black (I'm not doing *any* drawing in my test
->  	   program) (and this is when the events stop)
->  
->  	3) Events will stop happening (no more expose or button press).
->  
->  
->  Please let me know if I've done something really stupid.  I would debug
->  gtk if I knew where to look.  I'm not sure if this is a problem with
->  the drawing area widget or the scrolled window (or viewport) or the signal
->  handling in gtk? (I'm using gtk+ 0.99.9 under Linux)

its' X's limit on window sizes.. X limits windows to 32768x32768
(sitgned short). a drawing area is a large X window. The only way
aroudn this is to do a "virtual window" onto a "virtucal drawing area"
and do it yourself... :)

->  Thanks for any info!
->  
->  
->  								-Ales
->  
->  
->  Build with: gcc -o testd test.c `gtk-config --cflags` `gtk-config --libs`
->  
->  ----- Cut here for test.c -------
->  
->  #include <stdio.h>
->  
->  #include <gtk/gtk.h>
->  #include <gdk/gdk.h>
->  #include <gdk/gdkx.h>
->  
->  GtkWidget *main_window;
->  
->  GtkWidget *main_box;
->  GtkWidget *scrolled_window;
->  GtkWidget *drawing_area;
->  
->  int count=0;
->  
->  gint
->  x_event_expose(GtkWidget *widget, GdkEventExpose *event, char *none)
->  {                 
->  	printf("expose %d\n", count++);
->  }
->  
->  gint
->  x_event_button_pressed(GtkWidget *widget, GdkEventButton *event, char *none) 
->  {
->  	printf("pressed\n");
->  	printf("coords: %f %f\n", event->x, event->y);
->  }
->  
->  int main(int argc, char *argv[])
->  {
->  	GtkWidget *drawbox2; 
->  	GtkWidget *drawbox; 
->  
->  	/* allocate a HUGE canvas */
->  	int max_width = 2200*20;
->          int max_height = 1700*20;
->  
->          gtk_init(&argc, &argv);
->  
->          main_window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
->  
->    	gtk_widget_set_uposition (main_window, 0, 0);
->  
->  	gtk_signal_connect (GTK_OBJECT (main_window), "destroy",
->                        GTK_SIGNAL_FUNC(gtk_main_quit),
->                        NULL);
->  
->  	/* Containers first */        
->          main_box = gtk_vbox_new(FALSE, 1);
->          gtk_container_border_width(GTK_CONTAINER(main_box), 0);
->          gtk_container_add(GTK_CONTAINER(main_window), main_box);
->          gtk_widget_show(main_box);
->  
->          drawbox = gtk_hbox_new(FALSE, 0);
->          gtk_container_border_width(GTK_CONTAINER(drawbox), 0);
->          gtk_container_add(GTK_CONTAINER(main_box), drawbox);
->          gtk_widget_show(drawbox);
->  
->  	scrolled_window = gtk_scrolled_window_new (NULL, NULL);
->  	gtk_container_border_width (GTK_CONTAINER (scrolled_window), 0);
->  	gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (scrolled_window),
->                                        GTK_POLICY_ALWAYS,
->                                        GTK_POLICY_ALWAYS);
->          gtk_widget_set_usize(GTK_WIDGET(scrolled_window), 580, 480);
->          gtk_box_pack_start (GTK_BOX (drawbox), scrolled_window, TRUE, TRUE, 0);
->        	gtk_widget_show (scrolled_window);
->  
->          drawbox2 = gtk_hbox_new(FALSE, 0);
->          gtk_container_border_width(GTK_CONTAINER(drawbox2), 0);
->          gtk_container_add(GTK_CONTAINER(scrolled_window), drawbox2);
->          gtk_widget_show(drawbox2);
->   
->  	drawing_area = gtk_drawing_area_new (); 
->   	gtk_drawing_area_size (GTK_DRAWING_AREA (drawing_area), 
->  		max_width, max_height);
->  
->          gtk_box_pack_start (GTK_BOX (drawbox2), drawing_area, TRUE, TRUE, 0);
->          gtk_widget_show (drawing_area); 
->  
->  	gtk_widget_set_events (drawing_area, GDK_EXPOSURE_MASK | 
->                                               GDK_BUTTON_PRESS_MASK ) ;
->                                               
->  	gtk_signal_connect (GTK_OBJECT (drawing_area), "expose_event",
->                            GTK_SIGNAL_FUNC (x_event_expose), 0);    
->  	gtk_signal_connect (GTK_OBJECT (drawing_area), "button_press_event",
->                             (GtkSignalFunc) x_event_button_pressed, NULL);
->  
->          gtk_widget_show(main_window);
->  
->  	gtk_main();
->  }
->  

-- 
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