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List:       gtk-app-devel
Subject:    Re: gtk drawing demo on win32
From:       Pieter Engelen <engelen.pieter () gmail ! com>
Date:       2004-09-29 10:45:22
Message-ID: 29be34604092903451c00bcbc () mail ! gmail ! com
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Hi,

I have tried to run the demo again, but I didn't succeed. Where do I
have to put this main?  I have tried serveral options, but I get a lot
of error messages. I think I put it on the wrong place.

greetz 
Pieter


On Wed, 22 Sep 2004 14:15:02 -0400, Todd Fisher <toddf@simosoftware.com> wrote:
> 
> 
> Pieter Engelen wrote:
> 
> >hi,
> >I 'm trying to run the following demo on msvc :
> >
> >
> >* 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 <win32config.h>
> >#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;
> >
> >}
> >
> >
> >And I the next error message as I compile
> >
> >\Compiling...
> >jaja.c
> >c:\documents and settings\beq04030\desktop\console\jaja.c(79) :
> >warning C4244: '=' : conversion from 'double ' to 'int ', possible
> >loss of data
> >c:\documents and settings\beq04030\desktop\console\jaja.c(80) :
> >warning C4244: '=' : conversion from 'double ' to 'int ', possible
> >loss of data
> >Linking...
> >LIBCD.lib(crt0.obj) : error LNK2001: unresolved external symbol _main
> >Debug/console.exe : fatal error LNK1120: 1 unresolved externals
> >Error executing link.exe.
> >
> >console.exe - 2 error(s), 2 warning(s)
> >
> >I dont get any error,s when I compile,
> >
> >I can't the problem, I think ist something whit headerfiles. But I'm not sure.
> >
> >could some one help me pleas?
> >
> >Thanks
> >_______________________________________________
> >gtk-app-devel-list mailing list
> >gtk-app-devel-list@gnome.org
> >http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
> >
> >
> >
> You have not defined a main entry point. C/C++ requires
> that an entry point be defined. The msvc compilier can
> typically have one of two entry points, either WinMain
> (if compiled with /subsystem:windows) or main
> (if compilied with /subsystem:console). So, the error
> message you get is a linker error because main is
> undefined. So, you will need to define one, e.g.
> 
> int main( int argc, char **argv ){
> gtk_init(&argc, &argv );
> //...
> gtk_main();
> return 0;
> }
> 
> -todd
> 
>
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