indexing
	description: "."
	copyright: "[
					Copyright (C) 2006 Paolo Redaelli, GTK+ team
					
					This library is free software; you can redistribute it and/or
					modify it under the terms of the GNU Lesser General Public License
					as published by the Free Software Foundation; either version 2.1 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
					Lesser General Public License for more details.

					You should have received a copy of the GNU Lesser General Public
					License along with this library; if not, write to the Free Software
					Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
					02110-1301 USA
			]"

class DRAWINGAREA

creation make

feature
-- /* Drawing Area
--  *
--  * GtkDrawingArea is a blank area where you can draw custom displays
--  * of various kinds.
--  *
--  * This demo has two drawing areas. The checkerboard area shows
--  * how you can just draw something; all you have to do is write
--  * a signal handler for expose_event, as shown here.
--  *
--  * The "scribble" area is a bit more advanced, and shows how to handle
--  * events such as button presses and mouse motion. Click the mouse
--  * and drag in the scribble area to draw squiggles. Resize the window
--  * to clear the area.
--  */

-- #include <gtk/gtk.h>

-- static GtkWidget *window = NULL;
-- /* Pixmap for scribble area, to store current scribbles */
-- static GdkPixmap *pixmap = NULL;

-- /* Create a new pixmap of the appropriate size to store our scribbles */
-- static gboolean
-- scribble_configure_event (GtkWidget	    *widget,
-- 			  GdkEventConfigure *event,
-- 			  gpointer	     data)
-- {
--   if (pixmap)
--     g_object_unref (pixmap);

--   pixmap = gdk_pixmap_new (widget->window,
-- 			   widget->allocation.width,
-- 			   widget->allocation.height,
-- 			   -1);

--   /* Initialize the pixmap to white */
--   gdk_draw_rectangle (pixmap,
-- 		      widget->style->white_gc,
-- 		      TRUE,
-- 		      0, 0,
-- 		      widget->allocation.width,
-- 		      widget->allocation.height);

--   /* We've handled the configure event, no need for further processing. */
--   return TRUE;
-- }

-- /* Redraw the screen from the pixmap */
-- static gboolean
-- scribble_expose_event (GtkWidget      *widget,
-- 		       GdkEventExpose *event,
-- 		       gpointer	       data)
-- {
--   /* We use the "foreground GC" for the widget since it already exists,
--    * but honestly any GC would work. The only thing to worry about
--    * is whether the GC has an inappropriate clip region set.
--    */
  
--   gdk_draw_drawable (widget->window,
-- 		     widget->style->fg_gc[GTK_WIDGET_STATE (widget)],
-- 		     pixmap,
-- 		     /* Only copy the area that was exposed. */
-- 		     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 - 3;
--   update_rect.y = y - 3;
--   update_rect.width = 6;
--   update_rect.height = 6;

--   /* Paint to the pixmap, where we store our state */
--   gdk_draw_rectangle (pixmap,
-- 		      widget->style->black_gc,
-- 		      TRUE,
-- 		      update_rect.x, update_rect.y,
-- 		      update_rect.width, update_rect.height);

--   /* Now invalidate the affected region of the drawing area. */
--   gdk_window_invalidate_rect (widget->window,
-- 			      &update_rect,
-- 			      FALSE);
-- }

-- static gboolean
-- scribble_button_press_event (GtkWidget	    *widget,
-- 			     GdkEventButton *event,
-- 			     gpointer	     data)
-- {
--   if (pixmap == NULL)
--     return FALSE; /* paranoia check, in case we haven't gotten a configure event */
  
--   if (event->button == 1)
--     draw_brush (widget, event->x, event->y);

--   /* We've handled the event, stop processing */
--   return TRUE;
-- }

-- static gboolean
-- scribble_motion_notify_event (GtkWidget	     *widget,
-- 			      GdkEventMotion *event,
-- 			      gpointer	      data)
-- {
--   int x, y;
--   GdkModifierType state;

--   if (pixmap == NULL)
--     return FALSE; /* paranoia check, in case we haven't gotten a configure event */

--   /* This call is very important; it requests the next motion event.
--    * If you don't call gdk_window_get_pointer() you'll only get
--    * a single motion event. The reason is that we specified
--    * GDK_POINTER_MOTION_HINT_MASK to gtk_widget_set_events().
--    * If we hadn't specified that, we could just use event->x, event->y
--    * as the pointer location. But we'd also get deluged in events.
--    * By requesting the next event as we handle the current one,
--    * we avoid getting a huge number of events faster than we
--    * can cope.
--    */
  
--   gdk_window_get_pointer (event->window, &x, &y, &state);
	
--   if (state & GDK_BUTTON1_MASK)
--     draw_brush (widget, x, y);

--   /* We've handled it, stop processing */
--   return TRUE;
-- }


-- static gboolean
-- checkerboard_expose (GtkWidget	    *da,
-- 		     GdkEventExpose *event,
-- 		     gpointer	     data)
-- {
--   gint i, j, xcount, ycount;
--   GdkGC *gc1, *gc2;
--   GdkColor color;
  
-- #define CHECK_SIZE 10
-- #define SPACING 2
  
--   /* At the start of an expose handler, a clip region of event->area
--    * is set on the window, and event->area has been cleared to the
--    * widget's background color. The docs for
--    * gdk_window_begin_paint_region() give more details on how this
--    * works.
--    */

--   /* It would be a bit more efficient to keep these
--    * GC's around instead of recreating on each expose, but
--    * this is the lazy/slow way.
--    */
--   gc1 = gdk_gc_new (da->window);
--   color.red = 30000;
--   color.green = 0;
--   color.blue = 30000;
--   gdk_gc_set_rgb_fg_color (gc1, &color);

--   gc2 = gdk_gc_new (da->window);
--   color.red = 65535;
--   color.green = 65535;
--   color.blue = 65535;
--   gdk_gc_set_rgb_fg_color (gc2, &color);
  
--   xcount = 0;
--   i = SPACING;
--   while (i < da->allocation.width)
--     {
--       j = SPACING;
--       ycount = xcount % 2; /* start with even/odd depending on row */
--       while (j < da->allocation.height)
-- 	{
-- 	  GdkGC *gc;
	
-- 	  if (ycount % 2)
-- 	    gc = gc1;
-- 	  else
-- 	    gc = gc2;

-- 	  /* If we're outside event->area, this will do nothing.
-- 	   * It might be mildly more efficient if we handled
-- 	   * the clipping ourselves, but again we're feeling lazy.
-- 	   */
-- 	  gdk_draw_rectangle (da->window,
-- 			      gc,
-- 			      TRUE,
-- 			      i, j,
-- 			      CHECK_SIZE,
-- 			      CHECK_SIZE);

-- 	  j += CHECK_SIZE + SPACING;
-- 	  ++ycount;
-- 	}

--       i += CHECK_SIZE + SPACING;
--       ++xcount;
--     }
  
--   g_object_unref (gc1);
--   g_object_unref (gc2);
  
--   /* return TRUE because we've handled this event, so no
--    * further processing is required.
--    */
--   return TRUE;
-- }

-- GtkWidget *
-- do_drawingarea (GtkWidget *do_widget)
-- {
--   GtkWidget *frame;
--   GtkWidget *vbox;
--   GtkWidget *da;
--   GtkWidget *label;
  
--   if (!window)
--     {
--       window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
--       gtk_window_set_screen (GTK_WINDOW (window),
-- 			     gtk_widget_get_screen (do_widget));
--       gtk_window_set_title (GTK_WINDOW (window), "Drawing Area");

--       g_signal_connect (window, "destroy", G_CALLBACK (gtk_widget_destroyed), &window);

--       gtk_container_set_border_width (GTK_CONTAINER (window), 8);

--       vbox = gtk_vbox_new (FALSE, 8);
--       gtk_container_set_border_width (GTK_CONTAINER (vbox), 8);
--       gtk_container_add (GTK_CONTAINER (window), vbox);

--       /*
--        * Create the checkerboard area
--        */
		
--       label = gtk_label_new (NULL);
--       gtk_label_set_markup (GTK_LABEL (label),
-- 			    "<u>Checkerboard pattern</u>");
--       gtk_box_pack_start (GTK_BOX (vbox), label, FALSE, FALSE, 0);
		
--       frame = gtk_frame_new (NULL);
--       gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN);
--       gtk_box_pack_start (GTK_BOX (vbox), frame, TRUE, TRUE, 0);
		
--       da = gtk_drawing_area_new ();
--       /* set a minimum size */
--       gtk_widget_set_size_request (da, 100, 100);

--       gtk_container_add (GTK_CONTAINER (frame), da);

--       g_signal_connect (da, "expose_event",
-- 			G_CALLBACK (checkerboard_expose), NULL);

--       /*
--        * Create the scribble area
--        */
		
--       label = gtk_label_new (NULL);
--       gtk_label_set_markup (GTK_LABEL (label),
-- 			    "<u>Scribble area</u>");
--       gtk_box_pack_start (GTK_BOX (vbox), label, FALSE, FALSE, 0);
		
--       frame = gtk_frame_new (NULL);
--       gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN);
--       gtk_box_pack_start (GTK_BOX (vbox), frame, TRUE, TRUE, 0);
		
--       da = gtk_drawing_area_new ();
--       /* set a minimum size */
--       gtk_widget_set_size_request (da, 100, 100);

--       gtk_container_add (GTK_CONTAINER (frame), da);

--       /* Signals used to handle backing pixmap */
		
--       g_signal_connect (da, "expose_event",
-- 			G_CALLBACK (scribble_expose_event), NULL);
--       g_signal_connect (da,"configure_event",
-- 			G_CALLBACK (scribble_configure_event), NULL);
		
--       /* Event signals */
		
--       g_signal_connect (da, "motion_notify_event",
-- 			G_CALLBACK (scribble_motion_notify_event), NULL);
--       g_signal_connect (da, "button_press_event",
-- 			G_CALLBACK (scribble_button_press_event), NULL);


--       /* Ask to receive events the drawing area doesn't normally
--        * subscribe to
--        */
--       gtk_widget_set_events (da, gtk_widget_get_events (da)
-- 			     | GDK_LEAVE_NOTIFY_MASK
-- 			     | GDK_BUTTON_PRESS_MASK
-- 			     | GDK_POINTER_MOTION_MASK
-- 			     | GDK_POINTER_MOTION_HINT_MASK);

--     }

--   if (!GTK_WIDGET_VISIBLE (window))
--     {
--       gtk_widget_show_all (window);
--     }
--   else
--     {
--       gtk_widget_destroy (window);
--       window = NULL;
--     }

--   return window;
-- }
end