Newbie question

[Aitor Garcia <carrierphasejitter yahoo com>]

I've got a problem with GdkRectangle.

 

Why is that if I do not define update_rect and update_rect1

GdkRectangle variables in the code below  I can not see the points drawn

with gdk_draw_point ?

 

What is the difference between gtk_box_pack_start

and gtk_container_add functions ?.

 

How can I redraw the drawing area to be able to display another set of points.

 

I have tried it by adding a for loop of Nops below the gdk_draw_point

for loop and use another for loop of gdk_draw_point  but I haven't been able to do it.

I would like to make the effect of motion by writting different set of points in a fix rate

time intervals.

 

 

Thanks for your help.

 

Aitor

 

 

#include <gtk/gtk.h>
#include <math.h>

#define IMAGE_WIDTH 256
#define IMAGE_HEIGHT 256 
#define OFFSET (IMAGE_HEIGHT/2)
#define N_POINTS_IN_SINE 120
#define N_POINTS_IN_WINDOW  256
#define PERIOD 100

#ifndef PI
#define PI 3.14159265358979323846
#endif

gboolean on_darea_expose (GtkWidget *widget,
     GdkEventExpose *event,
     gpointer user_data);

static gboolean delete_event( GtkWidget *widget,
                              GdkEvent  *event,
                              gpointer   data )
{
    g_print ("delete event occurred\n");
    return FALSE;
}

static void destroy( GtkWidget *widget,
                     gpointer   data )
{
    gtk_main_quit ();
}

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

  gtk_init (&argc, &argv);

  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);

  g_signal_connect (G_OBJECT (window), "delete_event",
                      G_CALLBACK (delete_event), NULL);
  g_signal_connect (G_OBJECT (window), "destroy",
                      G_CALLBACK (destroy), NULL);

  darea = gtk_drawing_area_new ();
  gtk_widget_set_size_request (darea, IMAGE_WIDTH, IMAGE_HEIGHT);
  gtk_container_add (GTK_CONTAINER (window), darea);
  gtk_signal_connect (GTK_OBJECT (darea), "expose-event",
                      GTK_SIGNAL_FUNC (on_darea_expose), NULL);
  gtk_window_set_title (GTK_WINDOW (window), "test");

  gtk_widget_show_all (window);
 

  gtk_main ();
  return 0;
}

gboolean
on_darea_expose (GtkWidget *widget,
   GdkEventExpose *event,
   gpointer user_data)
{
  int i;
  GdkRectangle update_rect;
  GdkRectangle update_rect1;
  GdkPoint point;

  gdk_draw_line(widget->window,
                widget->style->black_gc,
                0,IMAGE_HEIGHT/2,IMAGE_WIDTH,IMAGE_HEIGHT/2);

  for(i=0;i<=N_POINTS_IN_WINDOW;i++){
    point.x = point.x + 1;
    point.y = OFFSET - cos(2*PI/(N_POINTS_IN_SINE)*i)*OFFSET;
    gdk_draw_point(widget->window, widget->style->black_gc,
                   point.x, point.y);
  }

   
  return TRUE;
}

 

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