changedisplay.c

Linux下gtk图形界面开发的各种gtk控件调用方法示例

/* Change Display
 * 
 * Demonstrates migrating a window between different displays and
 * screens. A display is a mouse and keyboard with some number of
 * associated monitors. A screen is a set of monitors grouped
 * into a single physical work area. The neat thing about having
 * multiple displays is that they can be on a completely separate
 * computers, as long as there is a network connection to the
 * computer where the application is running.
 *
 * Only some of the windowing systems where GTK+ runs have the
 * concept of multiple displays and screens. (The X Window System
 * is the main example.) Other windowing systems can only
 * handle one keyboard and mouse, and combine all monitors into
 * a single screen.
 *
 * This is a moderately complex example, and demonstrates:
 *
 *  - Tracking the currently open displays and screens
 *
 *  - Changing the screen for a window
 *
 *  - Letting the user choose a window by clicking on it
 * 
 *  - Using GtkListStore and GtkTreeView
 *
 *  - Using GtkDialog
 */
#include <string.h>
#include <gtk/gtk.h>
#include "demo-common.h"

/* The ChangeDisplayInfo structure corresponds to a toplevel window and
 * holds pointers to widgets inside the toplevel window along with other
 * information about the contents of the window.
 * This is a common organizational structure in real applications.
 */
typedef struct _ChangeDisplayInfo ChangeDisplayInfo;

struct _ChangeDisplayInfo
{
  GtkWidget *window;
  GtkSizeGroup *size_group;

  GtkTreeModel *display_model;
  GtkTreeModel *screen_model;
  GtkTreeSelection *screen_selection;
  
  GdkDisplay *current_display;
  GdkScreen *current_screen;
};

/* These enumerations provide symbolic names for the columns
 * in the two GtkListStore models.
 */
enum
{
  DISPLAY_COLUMN_NAME,
  DISPLAY_COLUMN_DISPLAY,
  DISPLAY_NUM_COLUMNS
};

enum
{
  SCREEN_COLUMN_NUMBER,
  SCREEN_COLUMN_SCREEN,
  SCREEN_NUM_COLUMNS
};

/* Finds the toplevel window under the mouse pointer, if any.
 */
static GtkWidget *
find_toplevel_at_pointer (GdkDisplay *display)
{
  GdkWindow *pointer_window;
  GtkWidget *widget = NULL;

  pointer_window = gdk_display_get_window_at_pointer (display, NULL, NULL);

  /* The user data field of a GdkWindow is used to store a pointer
   * to the widget that created it.
   */
  if (pointer_window)
    gdk_window_get_user_data (pointer_window, (gpointer*) &widget);

  return widget ? gtk_widget_get_toplevel (widget) : NULL;
}

static gboolean
button_release_event_cb (GtkWidget       *widget,
			 GdkEventButton  *event,
			 gboolean        *clicked)
{
  *clicked = TRUE;
  return TRUE;
}

/* Asks the user to click on a window, then waits for them click
 * the mouse. When the mouse is released, returns the toplevel
 * window under the pointer, or NULL, if there is none.
 */
static GtkWidget *
query_for_toplevel (GdkScreen  *screen,
		    const char *prompt)
{
  GdkDisplay *display = gdk_screen_get_display (screen);
  GtkWidget *popup, *label, *frame;
  GdkCursor *cursor;
  GtkWidget *toplevel = NULL;
  
  popup = gtk_window_new (GTK_WINDOW_POPUP);
  gtk_window_set_screen (GTK_WINDOW (popup), screen);
  gtk_window_set_modal (GTK_WINDOW (popup), TRUE);
  gtk_window_set_position (GTK_WINDOW (popup), GTK_WIN_POS_CENTER);
  
  frame = gtk_frame_new (NULL);
  gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_OUT);
  gtk_container_add (GTK_CONTAINER (popup), frame);
  
  label = gtk_label_new (prompt);
  gtk_misc_set_padding (GTK_MISC (label), 10, 10);
  gtk_container_add (GTK_CONTAINER (frame), label);
  
  gtk_widget_show_all (popup);
  cursor = gdk_cursor_new_for_display (display, GDK_CROSSHAIR);
  
  if (gdk_pointer_grab (popup->window, FALSE,
			GDK_BUTTON_RELEASE_MASK,
			NULL,
			cursor,
			GDK_CURRENT_TIME) == GDK_GRAB_SUCCESS)
    {
      gboolean clicked = FALSE;
      
      g_signal_connect (popup, "button-release-event",
			G_CALLBACK (button_release_event_cb), &clicked);
      
      /* Process events until clicked is set by button_release_event_cb.
       * We pass in may_block=TRUE since we want to wait if there
       * are no events currently.
       */
      while (!clicked)
	g_main_context_iteration (NULL, TRUE);
      
      toplevel = find_toplevel_at_pointer (gdk_screen_get_display (screen));
      if (toplevel == popup)
	toplevel = NULL;
    }
      
  gdk_cursor_unref (cursor);
  gtk_widget_destroy (popup);
  gdk_flush ();			/* Really release the grab */
  
  return toplevel;
}

/* Prompts the user for a toplevel window to move, and then moves
 * that window to the currently selected display
 */
static void
query_change_display (ChangeDisplayInfo *info)
{
  GdkScreen *screen = gtk_widget_get_screen (info->window);
  GtkWidget *toplevel;

  toplevel = query_for_toplevel (screen,
				 "Please select the toplevel\n"
				 "to move to the new screen");

  if (toplevel)
    gtk_window_set_screen (GTK_WINDOW (toplevel), info->current_screen);
  else
    gdk_display_beep (gdk_screen_get_display (screen));
}

/* Fills in the screen list based on the current display
 */
static void
fill_screens (ChangeDisplayInfo *info)
{
  gtk_list_store_clear (GTK_LIST_STORE (info->screen_model));

  if (info->current_display)
    {
      gint n_screens = gdk_display_get_n_screens (info->current_display);
      gint i;
      
      for (i = 0; i < n_screens; i++)
	{
	  GdkScreen *screen = gdk_display_get_screen (info->current_display, i);
	  GtkTreeIter iter;
	  
	  gtk_list_store_append (GTK_LIST_STORE (info->screen_model), &iter);
	  gtk_list_store_set (GTK_LIST_STORE (info->screen_model), &iter,
			      SCREEN_COLUMN_NUMBER, i,
			      SCREEN_COLUMN_SCREEN, screen,
			      -1);

	  if (i == 0)
	    gtk_tree_selection_select_iter (info->screen_selection, &iter);
	}
    }
}

/* Called when the user clicks on a button in our dialog or
 * closes the dialog through the window manager. Unless the
 * "Change" button was clicked, we destroy the dialog.
 */
static void
response_cb (GtkDialog         *dialog,
	     gint               response_id,
	     ChangeDisplayInfo *info)
{
  if (response_id == GTK_RESPONSE_OK)
    query_change_display (info);
  else
    gtk_widget_destroy (GTK_WIDGET (dialog));
}

/* Called when the user clicks on "Open..." in the display
 * frame. Prompts for a new display, and then opens a connection
 * to that display.
 */
static void
open_display_cb (GtkWidget         *button,
		 ChangeDisplayInfo *info)
{
  GtkWidget *dialog;
  GtkWidget *display_entry;
  GtkWidget *dialog_label;
  gchar *new_screen_name = NULL;
  GdkDisplay *result = NULL;
  
  dialog = gtk_dialog_new_with_buttons ("Open Display",
					GTK_WINDOW (info->window),
					GTK_DIALOG_MODAL,
					GTK_STOCK_CANCEL, GTK_RESPONSE_CANCEL,
					GTK_STOCK_OK, GTK_RESPONSE_OK,
					NULL);

  gtk_dialog_set_default_response (GTK_DIALOG (dialog), GTK_RESPONSE_OK);
  display_entry = gtk_entry_new ();
  gtk_entry_set_activates_default (GTK_ENTRY (display_entry), TRUE);
  dialog_label =
    gtk_label_new ("Please enter the name of\nthe new display\n");

  gtk_container_add (GTK_CONTAINER (GTK_DIALOG (dialog)->vbox), dialog_label);
  gtk_container_add (GTK_CONTAINER (GTK_DIALOG (dialog)->vbox), display_entry);

  gtk_widget_grab_focus (display_entry);
  gtk_widget_show_all (GTK_BIN (dialog)->child);
  
  while (!result)
    {
      gint response_id = gtk_dialog_run (GTK_DIALOG (dialog));
      if (response_id != GTK_RESPONSE_OK)
	break;
      
      new_screen_name = gtk_editable_get_chars (GTK_EDITABLE (display_entry),
						0, -1);

      if (strcmp (new_screen_name, "") != 0)
	{
	  result = gdk_display_open (new_screen_name);
	  if (!result)
	    {
	      gchar *error_msg =
		g_strdup_printf  ("Can't open display :\n\t%s\nplease try another one\n",
				  new_screen_name);
	      gtk_label_set_text (GTK_LABEL (dialog_label), error_msg);
	      g_free (error_msg);
	    }

	  g_free (new_screen_name);
	}
    }
  
  gtk_widget_destroy (dialog);
}

/* Called when the user clicks on the "Close" button in the
 * "Display" frame. Closes the selected display.
 */
static void
close_display_cb (GtkWidget         *button,
		  ChangeDisplayInfo *info)
{
  if (info->current_display)
    gdk_display_close (info->current_display);
}

/* Called when the selected row in the display list changes.
 * Updates info->current_display, then refills the list of
 * screens.
 */
static void
display_changed_cb (GtkTreeSelection  *selection,
		    ChangeDisplayInfo *info)
{
  GtkTreeModel *model;
  GtkTreeIter iter;

  if (info->current_display)
    g_object_unref (info->current_display);
  if (gtk_tree_selection_get_selected (selection, &model, &iter))
    gtk_tree_model_get (model, &iter,
			DISPLAY_COLUMN_DISPLAY, &info->current_display,
			-1);
  else
    info->current_display = NULL;

  fill_screens (info);
}

/* Called when the selected row in the sceen list changes.
 * Updates info->current_screen.
 */
static void
screen_changed_cb (GtkTreeSelection  *selection,
		   ChangeDisplayInfo *info)