select region in GTK+

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Может уже кто делал такое. Приложение рисует картинку. Потом необходимо по картинке сделать выделение прямоугольной области с получением координат/размеров этой области. Типа как в графическом редакторе. Я посмотрел как это делают в gnome-paint, но там придется почти весь код редактора в приложение запихивать. Возможно есть какое-то простое решение? Подскажите пожалуйста.

Ссылка

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Да не должно быть сложного решения. Конечно, все зависит от того, какой виджет используется для отрисовки изображения, но в любом случае нужно просто повесит соответствующие обработчики на сигналы button_press_event, button_release_event, motion_notify.

Вот пример для GtkDrawingArea: В качестве pixmap может быть картинка.

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

static GdkPixmap *pixmap = NULL; static GdkPixmap *temp_pixmap = NULL;

static GdkRectangle rect; static GdkPoint point; static gboolean in_draw;

/* Create a new backing pixmap of the appropriate size */ static gint configure_event( GtkWidget *widget, GdkEventConfigure *event ) { if (pixmap) g_object_unref (pixmap); if (temp_pixmap) g_object_unref (temp_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);

temp_pixmap = gdk_pixmap_new (widget->window, widget->allocation.width, widget->allocation.height, -1); return TRUE; }

/* Redraw the screen from the backing pixmap */ static gint expose_event( GtkWidget *widget, GdkEventExpose *event ) { gdk_draw_drawable (temp_pixmap, widget->style->black_gc, pixmap, event->area.x, event->area.y, event->area.x, event->area.y, event->area.width, event->area.height);

if (in_draw) gdk_draw_rectangle (temp_pixmap, widget->style->black_gc, FALSE, rect.x, rect.y, rect.width, rect.height);

gdk_draw_drawable (widget->window, widget->style->fg_gc[GTK_WIDGET_STATE (widget)], temp_pixmap, event->area.x, event->area.y, event->area.x, event->area.y, event->area.width, event->area.height); return FALSE; }

static void update_area (GtkWidget *widget) { gtk_widget_queue_draw_area (widget, rect.x, rect.y, rect.width + 1, rect.height + 1); }

static gint button_press_event( GtkWidget *widget, GdkEventButton *event ) { if (event->button == 1 && pixmap != NULL) { rect.x = event->x; rect.y= event->y; rect.width = 0; rect.height = 0; point.x = rect.x; point.y = rect.y; in_draw = TRUE; update_area (widget); }

return TRUE; }

static gint button_release_event (GtkWidget *widget, GdkEventButton *event ) { if (event->button == 1 && pixmap != NULL) { in_draw = FALSE; update_area (widget); } g_message ("Selected region x=%d y=%d width=%d height=%d", rect.x, rect.y, rect.width, rect.height); return TRUE; }

anonymous
(14.04.04 02:50:03 MSD)

Ссылка

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

static GdkPixmap *pixmap = NULL;
static GdkPixmap *temp_pixmap = NULL;

static GdkRectangle rect;
static GdkPoint point;
static gboolean in_draw;

/* Create a new backing pixmap of the appropriate size */
static gint configure_event( GtkWidget         *widget,
                             GdkEventConfigure *event )
{
  if (pixmap)
    g_object_unref (pixmap);
  if (temp_pixmap)
    g_object_unref (temp_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);

  temp_pixmap = gdk_pixmap_new (widget->window,
			   widget->allocation.width,
			   widget->allocation.height,
			   -1);
  return TRUE;
}

/* Redraw the screen from the backing pixmap */
static gint expose_event( GtkWidget      *widget,
                          GdkEventExpose *event )
{
  gdk_draw_drawable (temp_pixmap,
		     widget->style->black_gc,
		     pixmap,
		     event->area.x, event->area.y,
		     event->area.x, event->area.y,
		     event->area.width, event->area.height);

  if (in_draw)
	gdk_draw_rectangle (temp_pixmap,
    			      widget->style->black_gc,
			      FALSE,
			      rect.x, rect.y,
			      rect.width, rect.height);

  
  gdk_draw_drawable (widget->window,
		     widget->style->fg_gc[GTK_WIDGET_STATE (widget)],
		     temp_pixmap,
		     event->area.x, event->area.y,
		     event->area.x, event->area.y,
		     event->area.width, event->area.height);
		     
  return FALSE;
}

static void update_area (GtkWidget *widget)
{
  gtk_widget_queue_draw_area (widget, 
		      rect.x, rect.y,
		      rect.width + 1, rect.height + 1);
}

static gint button_press_event( GtkWidget      *widget,
                                GdkEventButton *event )
{
  if (event->button == 1 && pixmap != NULL)
    {
      rect.x = event->x; rect.y= event->y;
      rect.width = 0; rect.height = 0;
      point.x = rect.x; point.y = rect.y;
      in_draw = TRUE;
      
      update_area (widget);
    }

  return TRUE;
}

static gint button_release_event (GtkWidget      *widget,
                                GdkEventButton *event )
{
  if (event->button == 1 && pixmap != NULL)
    {
      in_draw = FALSE;
      update_area (widget);
    }
    
  g_message ("Selected region x=%d y=%d width=%d height=%d", rect.x, rect.y, rect.width, rect.height);
  return TRUE;
}

anonymous
(14.04.04 02:51:05 MSD)

Ссылка

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 (in_draw && state & GDK_BUTTON1_MASK && pixmap)
   {
    in_draw = FALSE;
    update_area (widget);
    in_draw = TRUE;
    rect.width = abs (x - point.x);
    rect.height = abs (y - point.y);
    rect.x = MIN (x, point.x);
    rect.y = MIN (y, point.y);
    update_area (widget);    
   }
  
  return TRUE;
}

void quit ()
{
  exit (0);
}

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

  GtkWidget *button;

  gtk_init (&argc, &argv);
  
  in_draw = FALSE;

  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);

  vbox = gtk_vbox_new (FALSE, 0);
  gtk_container_add (GTK_CONTAINER (window), vbox);
  gtk_widget_show (vbox);

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

  /* Create the drawing area */

  drawing_area = gtk_drawing_area_new ();
  gtk_widget_set_size_request (GTK_WIDGET (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 */

  g_signal_connect (G_OBJECT (drawing_area), "expose_event",
		    G_CALLBACK (expose_event), NULL);
  g_signal_connect (G_OBJECT (drawing_area),"configure_event",
		    G_CALLBACK (configure_event), NULL);

  /* Event signals */

  g_signal_connect (G_OBJECT (drawing_area), "motion_notify_event",
		    G_CALLBACK (motion_notify_event), NULL);
  g_signal_connect (G_OBJECT (drawing_area), "button_press_event",
		    G_CALLBACK (button_press_event), NULL);
  g_signal_connect (G_OBJECT (drawing_area), "button_release_event",
		    G_CALLBACK (button_release_event), NULL);

  gtk_widget_set_events (drawing_area, GDK_EXPOSURE_MASK
			 | GDK_LEAVE_NOTIFY_MASK
			 | GDK_BUTTON_PRESS_MASK
			 | GDK_BUTTON_RELEASE_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);

  g_signal_connect_swapped (G_OBJECT (button), "clicked",
			    G_CALLBACK (gtk_widget_destroy),
			    G_OBJECT (window));
  gtk_widget_show (button);

  gtk_widget_show (window);

  gtk_main ();

  return 0;
}

anonymous
(14.04.04 02:52:04 MSD)