gtk2/gtk/gtkdragsource.c

/* GTK - The GIMP Toolkit
 * Copyright (C) 1995-1999 Peter Mattis, Spencer Kimball and Josh MacDonald
 *
 * 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 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, see <http://www.gnu.org/licenses/>.
 */

/*
 * Modified by the GTK+ Team and others 1997-2000.  See the AUTHORS
 * file for a list of people on the GTK+ Team.  See the ChangeLog
 * files for a list of changes.  These files are distributed with
 * GTK+ at ftp://ftp.gtk.org/pub/gtk/. 
 */

#include "config.h"

#include "gtkdragsource.h"

#include "gtkdnd.h"
#include "gtkdndprivate.h"
#include "gtkgesturedrag.h"
#include "gtkimagedefinitionprivate.h"
#include "gtkintl.h"


typedef struct _GtkDragSourceSite GtkDragSourceSite;

struct _GtkDragSourceSite 
{
  GdkModifierType    start_button_mask;
  GdkContentFormats *target_list;        /* Targets for drag data */
  GdkDragAction      actions;            /* Possible actions */

  GtkImageDefinition *image_def;
  GtkGesture        *drag_gesture;
};
  
static void
gtk_drag_source_gesture_begin (GtkGesture       *gesture,
                               GdkEventSequence *sequence,
                               gpointer          data)
{
  GtkDragSourceSite *site = data;
  guint button;

  if (gtk_gesture_single_get_current_sequence (GTK_GESTURE_SINGLE (gesture)))
    button = 1;
  else
    button = gtk_gesture_single_get_current_button (GTK_GESTURE_SINGLE (gesture));

  g_assert (button >= 1);

  if (!site->start_button_mask ||
      !(site->start_button_mask & (GDK_BUTTON1_MASK << (button - 1))))
    gtk_gesture_set_state (gesture, GTK_EVENT_SEQUENCE_DENIED);
}

static void
gtk_drag_source_gesture_update (GtkGesture       *gesture,
                                GdkEventSequence *sequence,
                                gpointer          data)
{
  gdouble start_x, start_y, offset_x, offset_y;
  GtkDragSourceSite *site = data;
  GtkWidget *widget;

  widget = gtk_event_controller_get_widget (GTK_EVENT_CONTROLLER (gesture));

  if (gtk_gesture_is_recognized (site->drag_gesture))
    {
      gtk_gesture_drag_get_start_point (GTK_GESTURE_DRAG (site->drag_gesture),
                                        &start_x, &start_y);
      gtk_gesture_drag_get_offset (GTK_GESTURE_DRAG (site->drag_gesture),
                                   &offset_x, &offset_y);

      if (gtk_drag_check_threshold (widget, start_x, start_y,
                                    start_x + offset_x, start_y + offset_y))
        {
          GdkDevice *device = gtk_gesture_get_device (site->drag_gesture);

          gtk_event_controller_reset (GTK_EVENT_CONTROLLER (site->drag_gesture));

          gtk_drag_begin_internal (widget,
                                   device,
                                   site->image_def, site->target_list,
                                   site->actions,
                                   start_x, start_y);
        }
    }
}

static void
gtk_drag_source_site_destroy (gpointer data)
{
  GtkDragSourceSite *site = data;

  if (site->target_list)
    gdk_content_formats_unref (site->target_list);

  gtk_image_definition_unref (site->image_def);
  g_clear_object (&site->drag_gesture);
  g_slice_free (GtkDragSourceSite, site);
}

/**
 * gtk_drag_source_set: (method)
 * @widget: a #GtkWidget
 * @start_button_mask: the bitmask of buttons that can start the drag
 * @targets: (allow-none): the targets that the drag will support,
 *     may be %NULL
 * @actions: the bitmask of possible actions for a drag from this widget
 *
 * Sets up a widget so that GTK+ will start a drag operation when the user
 * clicks and drags on the widget. The widget must have a window.
 */
void
gtk_drag_source_set (GtkWidget         *widget,
                     GdkModifierType    start_button_mask,
                     GdkContentFormats *targets,
                     GdkDragAction      actions)
{
  GtkDragSourceSite *site;

  g_return_if_fail (GTK_IS_WIDGET (widget));

  site = g_object_get_data (G_OBJECT (widget), "gtk-site-data");

  if (site)
    {
      if (site->target_list)
        gdk_content_formats_unref (site->target_list);
    }
  else
    {
      site = g_slice_new0 (GtkDragSourceSite);
      site->image_def = gtk_image_definition_new_empty ();
      site->drag_gesture = gtk_gesture_drag_new (widget);
      gtk_event_controller_set_propagation_phase (GTK_EVENT_CONTROLLER (site->drag_gesture),
                                                  GTK_PHASE_BUBBLE);
      gtk_gesture_single_set_button (GTK_GESTURE_SINGLE (site->drag_gesture), 0);
      g_signal_connect (site->drag_gesture, "begin",
                        G_CALLBACK (gtk_drag_source_gesture_begin),
                        site);
      g_signal_connect (site->drag_gesture, "update",
                        G_CALLBACK (gtk_drag_source_gesture_update),
                        site);

      g_object_set_data_full (G_OBJECT (widget),
                              I_("gtk-site-data"), 
                              site, gtk_drag_source_site_destroy);
    }

  site->start_button_mask = start_button_mask;

  if (targets)
    site->target_list = gdk_content_formats_ref (targets);
  else
    site->target_list = NULL;

  site->actions = actions;
}

/**
 * gtk_drag_source_unset: (method)
 * @widget: a #GtkWidget
 *
 * Undoes the effects of gtk_drag_source_set().
 */
void 
gtk_drag_source_unset (GtkWidget *widget)
{
  g_return_if_fail (GTK_IS_WIDGET (widget));

  g_object_set_data (G_OBJECT (widget), I_("gtk-site-data"), NULL);
}

/**
 * gtk_drag_source_get_target_list: (method)
 * @widget: a #GtkWidget
 *
 * Gets the list of targets this widget can provide for
 * drag-and-drop.
 *
 * Returns: (nullable) (transfer none): the #GdkContentFormats, or %NULL if none
 */
GdkContentFormats *
gtk_drag_source_get_target_list (GtkWidget *widget)
{
  GtkDragSourceSite *site;

  g_return_val_if_fail (GTK_IS_WIDGET (widget), NULL);

  site = g_object_get_data (G_OBJECT (widget), "gtk-site-data");

  return site ? site->target_list : NULL;
}

/**
 * gtk_drag_source_set_target_list: (method)
 * @widget: a #GtkWidget that’s a drag source
 * @target_list: (allow-none): list of draggable targets, or %NULL for none
 *
 * Changes the target types that this widget offers for drag-and-drop.
 * The widget must first be made into a drag source with
 * gtk_drag_source_set().
 */
void
gtk_drag_source_set_target_list (GtkWidget         *widget,
                                 GdkContentFormats *target_list)
{
  GtkDragSourceSite *site;

  g_return_if_fail (GTK_IS_WIDGET (widget));

  site = g_object_get_data (G_OBJECT (widget), "gtk-site-data");
  if (site == NULL)
    {
      g_warning ("gtk_drag_source_set_target_list() requires the widget "
                 "to already be a drag source.");
      return;
    }

  if (target_list)
    gdk_content_formats_ref (target_list);

  if (site->target_list)
    gdk_content_formats_unref (site->target_list);

  site->target_list = target_list;
}

/**
 * gtk_drag_source_add_text_targets: (method)
 * @widget: a #GtkWidget that’s is a drag source
 *
 * Add the text targets supported by #GtkSelectionData to
 * the target list of the drag source.  The targets
 * are added with @info = 0. If you need another value, 
 * use gtk_content_formats_add_text_targets() and
 * gtk_drag_source_set_target_list().
 */
void
gtk_drag_source_add_text_targets (GtkWidget *widget)
{
  GdkContentFormats *target_list;

  target_list = gtk_drag_source_get_target_list (widget);
  if (target_list)
    gdk_content_formats_ref (target_list);
  else
    target_list = gdk_content_formats_new (NULL, 0);
  target_list = gtk_content_formats_add_text_targets (target_list);
  gtk_drag_source_set_target_list (widget, target_list);
  gdk_content_formats_unref (target_list);
}

/**
 * gtk_drag_source_add_image_targets: (method)
 * @widget: a #GtkWidget that’s is a drag source
 *
 * Add the writable image targets supported by #GtkSelectionData to
 * the target list of the drag source. The targets
 * are added with @info = 0. If you need another value, 
 * use gtk_target_list_add_image_targets() and
 * gtk_drag_source_set_target_list().
 */
void
gtk_drag_source_add_image_targets (GtkWidget *widget)
{
  GdkContentFormats *target_list;

  target_list = gtk_drag_source_get_target_list (widget);
  if (target_list)
    gdk_content_formats_ref (target_list);
  else
    target_list = gdk_content_formats_new (NULL, 0);
  target_list = gtk_content_formats_add_image_targets (target_list, TRUE);
  gtk_drag_source_set_target_list (widget, target_list);
  gdk_content_formats_unref (target_list);
}

/**
 * gtk_drag_source_add_uri_targets: (method)
 * @widget: a #GtkWidget that’s is a drag source
 *
 * Add the URI targets supported by #GtkSelectionData to
 * the target list of the drag source.  The targets
 * are added with @info = 0. If you need another value, 
 * use gtk_content_formats_add_uri_targets() and
 * gtk_drag_source_set_target_list().
 */
void
gtk_drag_source_add_uri_targets (GtkWidget *widget)
{
  GdkContentFormats *target_list;

  target_list = gtk_drag_source_get_target_list (widget);
  if (target_list)
    gdk_content_formats_ref (target_list);
  else
    target_list = gdk_content_formats_new (NULL, 0);
  target_list = gtk_content_formats_add_uri_targets (target_list);
  gtk_drag_source_set_target_list (widget, target_list);
  gdk_content_formats_unref (target_list);
}

/**
 * gtk_drag_source_set_icon_surface: (method)
 * @widget: a #GtkWidget
 * @surface: the cairo surface for the drag icon
 * 
 * Sets the icon that will be used for drags from a particular widget
 * from a cairo surface. GTK+ retains a reference for @surface and will
 * release it when it is no longer needed.
 */
void
gtk_drag_source_set_icon_surface (GtkWidget       *widget,
                                  cairo_surface_t *surface)
{
  GtkDragSourceSite *site;

  g_return_if_fail (GTK_IS_WIDGET (widget));

  site = g_object_get_data (G_OBJECT (widget), "gtk-site-data");
  g_return_if_fail (site != NULL);

  g_clear_pointer (&site->image_def, gtk_image_definition_unref);
  site->image_def = gtk_image_definition_new_surface (surface);
}

/**
 * gtk_drag_source_set_icon_name: (method)
 * @widget: a #GtkWidget
 * @icon_name: name of icon to use
 *
 * Sets the icon that will be used for drags from a particular source
 * to a themed icon. See the docs for #GtkIconTheme for more details.
 */
void
gtk_drag_source_set_icon_name (GtkWidget   *widget,
                               const gchar *icon_name)
{
  GtkDragSourceSite *site;

  g_return_if_fail (GTK_IS_WIDGET (widget));
  g_return_if_fail (icon_name != NULL);

  site = g_object_get_data (G_OBJECT (widget), "gtk-site-data");
  g_return_if_fail (site != NULL);

  gtk_image_definition_unref (site->image_def);
  site->image_def = gtk_image_definition_new_icon_name (icon_name);
}

/**
 * gtk_drag_source_set_icon_gicon: (method)
 * @widget: a #GtkWidget
 * @icon: A #GIcon
 * 
 * Sets the icon that will be used for drags from a particular source
 * to @icon. See the docs for #GtkIconTheme for more details.
 */
void
gtk_drag_source_set_icon_gicon (GtkWidget *widget,
                                GIcon     *icon)
{
  GtkDragSourceSite *site;

  g_return_if_fail (GTK_IS_WIDGET (widget));
  g_return_if_fail (icon != NULL);
  
  site = g_object_get_data (G_OBJECT (widget), "gtk-site-data");
  g_return_if_fail (site != NULL);

  gtk_image_definition_unref (site->image_def);
  site->image_def = gtk_image_definition_new_gicon (icon);
}