gtk2/gdk/gdkdrop.c

/*
 * Copyright © 2018 Benjamin Otte
 *
 * 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 2.1 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/>.
 *
 * Authors: Benjamin Otte <otte@gnome.org>
 */

#include "config.h"

#include "gdkdndprivate.h"
#include "gdkdisplay.h"
#include "gdksurface.h"
#include "gdkintl.h"
#include "gdkcontentformats.h"
#include "gdkcontentprovider.h"
#include "gdkcontentserializer.h"
#include "gdkcursor.h"
#include "gdkenumtypes.h"
#include "gdkeventsprivate.h"

typedef struct _GdkDropPrivate GdkDropPrivate;

struct _GdkDropPrivate {
  GdkDevice *device;
  GdkDragContext *drag;
  GdkContentFormats *formats;
  GdkDragAction actions;
};

enum {
  PROP_0,
  PROP_ACTIONS,
  PROP_DEVICE,
  PROP_DISPLAY,
  PROP_DRAG,
  PROP_FORMATS,
  N_PROPERTIES
};

static GParamSpec *properties[N_PROPERTIES] = { NULL, };

G_DEFINE_TYPE_WITH_PRIVATE (GdkDrop, gdk_drop, G_TYPE_OBJECT)

/**
 * GdkDrop:
 *
 * The GdkDrop struct contains only private fields and
 * should not be accessed directly.
 */

static void
gdk_drop_default_status (GdkDrop       *self,
                         GdkDragAction  actions)
{
}

static void
gdk_drop_read_local_async (GdkDrop             *self,
                           GdkContentFormats   *formats,
                           int                  io_priority,
                           GCancellable        *cancellable,
                           GAsyncReadyCallback  callback,
                           gpointer             user_data)
{
  GTask *task;

  task = g_task_new (self, cancellable, callback, user_data);
  g_task_set_priority (task, io_priority);
  g_task_set_source_tag (task, gdk_drop_read_local_async);

  g_task_return_new_error (task, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
                                 _("Reading not implemented."));
  g_object_unref (task);
}

static GInputStream *
gdk_drop_read_local_finish (GdkDrop         *self,
                            const char     **out_mime_type,
                            GAsyncResult    *result,
                            GError         **error)
{
  g_return_val_if_fail (g_task_is_valid (result, self), NULL);
  g_return_val_if_fail (g_task_get_source_tag (G_TASK (result)) == gdk_drop_read_local_async, NULL);

  if (out_mime_type)
    *out_mime_type = g_task_get_task_data (G_TASK (result));

  return g_task_propagate_pointer (G_TASK (result), error);
}

static void
gdk_drop_set_property (GObject      *gobject,
                       guint         prop_id,
                       const GValue *value,
                       GParamSpec   *pspec)
{
  GdkDrop *self = GDK_DROP (gobject);
  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);

  switch (prop_id)
    {
    case PROP_ACTIONS:
      gdk_drop_set_actions (self, g_value_get_flags (value));
      break;

    case PROP_DEVICE:
      priv->device = g_value_dup_object (value);
      g_assert (priv->device != NULL);
      break;

    case PROP_DRAG:
      priv->drag = g_value_dup_object (value);
      break;

    case PROP_FORMATS:
      priv->formats = g_value_dup_boxed (value);
#ifdef DROP_SUBCLASS
      g_assert (priv->formats != NULL);
#endif
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
      break;
    }
}

static void
gdk_drop_get_property (GObject    *gobject,
                       guint       prop_id,
                       GValue     *value,
                       GParamSpec *pspec)
{
  GdkDrop *self = GDK_DROP (gobject);
  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);

  switch (prop_id)
    {
    case PROP_ACTIONS:
      g_value_set_flags (value, priv->actions);
      break;

    case PROP_DEVICE:
      g_value_set_object (value, priv->device);
      break;

    case PROP_DISPLAY:
      g_value_set_object (value, gdk_device_get_display (priv->device));
      break;

    case PROP_DRAG:
      g_value_set_object (value, priv->drag);
      break;

    case PROP_FORMATS:
      g_value_set_boxed (value, priv->formats);
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
      break;
    }
}

static void
gdk_drop_finalize (GObject *object)
{
  GdkDrop *self = GDK_DROP (object);
  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);

  g_clear_object (&priv->device);
  g_clear_object (&priv->drag);

  G_OBJECT_CLASS (gdk_drop_parent_class)->finalize (object);
}

static void
gdk_drop_class_init (GdkDropClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);

  klass->status = gdk_drop_default_status;

  object_class->get_property = gdk_drop_get_property;
  object_class->set_property = gdk_drop_set_property;
  object_class->finalize = gdk_drop_finalize;

  /**
   * GdkDrop:actions:
   *
   * The possible actions for this drop
   */
  properties[PROP_ACTIONS] =
    g_param_spec_flags ("actions",
                        "Actions",
                        "The possible actions for this drop",
                         GDK_TYPE_DRAG_ACTION,
                         GDK_ACTION_ALL,
                         G_PARAM_READWRITE |
                         G_PARAM_CONSTRUCT_ONLY |
                         G_PARAM_STATIC_STRINGS |
                         G_PARAM_EXPLICIT_NOTIFY);

  /**
   * GdkDrop:device:
   *
   * The #GdkDevice performing the drop
   */
  properties[PROP_DEVICE] =
    g_param_spec_object ("device",
                         "Device",
                         "The device performing the drop",
                         GDK_TYPE_DEVICE,
                         G_PARAM_READWRITE |
                         G_PARAM_CONSTRUCT_ONLY |
                         G_PARAM_STATIC_STRINGS |
                         G_PARAM_EXPLICIT_NOTIFY);

  /**
   * GdkDrop:display:
   *
   * The #GdkDisplay that the drop belongs to.
   */
  properties[PROP_DISPLAY] =
    g_param_spec_object ("display",
                         "Display",
                         "Display this drag belongs to",
                         GDK_TYPE_DISPLAY,
                         G_PARAM_READABLE |
                         G_PARAM_STATIC_STRINGS |
                         G_PARAM_EXPLICIT_NOTIFY);

  /**
   * GdkDrop:drag:
   *
   * The #GdkDrag that initiated this drop
   */
  properties[PROP_DRAG] =
    g_param_spec_object ("drag",
                         "Drag",
                         "The drag that initiated this drop",
                         GDK_TYPE_DRAG_CONTEXT,
                         G_PARAM_READWRITE |
                         G_PARAM_CONSTRUCT_ONLY |
                         G_PARAM_STATIC_STRINGS |
                         G_PARAM_EXPLICIT_NOTIFY);

  /**
   * GdkDrop:formats:
   *
   * The possible formats that the drop can provide its data in.
   */
  properties[PROP_FORMATS] =
    g_param_spec_boxed ("formats",
                        "Formats",
                        "The possible formats for data",
                        GDK_TYPE_CONTENT_FORMATS,
                        G_PARAM_READWRITE |
                        G_PARAM_CONSTRUCT_ONLY |
                        G_PARAM_STATIC_STRINGS |
                        G_PARAM_EXPLICIT_NOTIFY);
  g_object_class_install_properties (object_class, N_PROPERTIES, properties);
}

static void
gdk_drop_init (GdkDrop *self)
{
}

/**
 * gdk_drop_get_display:
 * @self: a #GdkDrop
 *
 * Gets the #GdkDisplay that @self was created for.
 *
 * Returns: (transfer none): a #GdkDisplay
 **/
GdkDisplay *
gdk_drop_get_display (GdkDrop *self)
{
  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);

  g_return_val_if_fail (GDK_IS_DROP (self), NULL);

  return gdk_device_get_display (priv->device);
}

/**
 * gdk_drop_get_device:
 * @self: a #GdkDrop
 *
 * Returns the #GdkDevice performing the drop.
 *
 * Returns: (transfer none): The #GdkDevice performing the drop.
 **/
GdkDevice *
gdk_drop_get_device (GdkDrop *self)
{
  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);

  g_return_val_if_fail (GDK_IS_DROP (self), NULL);

  return priv->device;
}

/**
 * gdk_drop_get_formats:
 * @self: a #GdkDrop
 *
 * Returns the #GdkContentFormats that the drop offers the data
 * to be read in.
 *
 * Returns: (transfer none): The possible #GdkContentFormats
 **/
GdkContentFormats *
gdk_drop_get_formats (GdkDrop *self)
{
  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);

  g_return_val_if_fail (GDK_IS_DROP (self), NULL);

  return priv->formats;
}

/**
 * gdk_drop_get_actions:
 * @self: a #GdkDrop
 *
 * Returns the possible actions for this #GdkDrop. If this value
 * contains multiple actions - ie gdk_drag_action_is_unique()
 * returns %FALSE for the result - gdk_drag_finish() must choose
 * the action to use when accepting the drop.
 *
 * This value may change over the lifetime of the #GdkDrop both
 * as a response to source side actions as well as to calls to
 * gdk_drop_status() or gdk_drag_finish(). The source side will
 * not change this value anymore once a drop has started.
 *
 * Returns: The possible #GdkDragActions
 **/
GdkDragAction
gdk_drop_get_actions (GdkDrop *self)
{
  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);

  g_return_val_if_fail (GDK_IS_DROP (self), 0);

  return priv->actions;
}

void
gdk_drop_set_actions (GdkDrop       *self,
                      GdkDragAction  actions)
{
  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);

  g_return_if_fail (GDK_IS_DROP (self));
  g_return_if_fail ((actions & GDK_ACTION_ASK) == 0);

  if (priv->actions == actions)
    return;

  priv->actions = actions;

  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_ACTIONS]);
}

/**
 * gdk_drop_get_drag:
 * @self: a #GdkDrop
 *
 * If this is an in-app drag-and-drop operation, returns the #GdkDrag
 * that corresponds to this drop.
 *
 * If it is not, %NULL is returned.
 *
 * Returns: (transfer none) (nullable): the corresponding #GdkDrag
 **/
GdkDragContext *
gdk_drop_get_drag (GdkDrop *self)
{
  GdkDropPrivate *priv = gdk_drop_get_instance_private (self);

  g_return_val_if_fail (GDK_IS_DROP (self), 0);

  return priv->drag;
}

/**
 * gdk_drop_status:
 * @self: a #GdkDrop
 * @actions: Supported actions of the destination, or 0 to indicate
 *    that a drop will not be accepted
 *
 * Selects all actions that are potentially supported by the destination.
 *
 * When calling this function, do not restrict the passed in actions to
 * the ones provided by gdk_drop_get_actions(). Those actions may
 * change in the future, even depending on the actions you provide here.
 *
 * This function should be called by drag destinations in response to
 * %GDK_DRAG_ENTER or %GDK_DRAG_MOTION events. If the destination does
 * not yet know the exact actions it supports, it should set any possible
 * actions first and then later call this function again.
 */
void
gdk_drop_status (GdkDrop       *self,
                 GdkDragAction  actions)
{
  g_return_if_fail (GDK_IS_DROP (self));

  GDK_DROP_GET_CLASS (self)->status (self, actions);
}

/**
 * gdk_drop_finish:
 * @self: a #GdkDrop
 * @action: the action performed by the destination or 0 if the drop
 *     failed
 *
 * Ends the drag operation after a drop.
 * 
 * The @action must be a single action selected from the actions
 * available via gdk_drop_get_actions().
 **/
void
gdk_drop_finish (GdkDrop       *self,
                 GdkDragAction  action)
{
  g_return_if_fail (GDK_IS_DROP (self));
  g_return_if_fail (gdk_drag_action_is_unique (action));

  GDK_DROP_GET_CLASS (self)->finish (self, action);
}

/**
 * gdk_drop_read_async:
 * @self: a #GdkDrop
 * @mime_types: (array zero-terminated=1) (element-type utf8):
 *     pointer to an array of mime types
 * @io_priority: the io priority for the read operation
 * @cancellable: (allow-none): optional #GCancellable object,
 *     %NULL to ignore
 * @callback: (scope async): a #GAsyncReadyCallback to call when
 *     the request is satisfied
 * @user_data: (closure): the data to pass to @callback
 *
 * Asynchronously read the dropped data from a #GdkDrop
 * in a format that complies with one of the mime types.
 */
void
gdk_drop_read_async (GdkDrop             *self,
                     const char         **mime_types,
                     int                  io_priority,
                     GCancellable        *cancellable,
                     GAsyncReadyCallback  callback,
                     gpointer             user_data)
{
  GdkContentFormats *formats;

  g_return_if_fail (GDK_IS_DROP (self));
  g_return_if_fail (mime_types != NULL && mime_types[0] != NULL);
  g_return_if_fail (cancellable == NULL || G_IS_CANCELLABLE (cancellable));
  g_return_if_fail (callback != NULL);

  formats = gdk_content_formats_new (mime_types, g_strv_length ((char **) mime_types));

  GDK_DROP_GET_CLASS (self)->read_async (self,
                                         formats,
                                         io_priority,
                                         cancellable,
                                         callback,
                                         user_data);

  gdk_content_formats_unref (formats);
}

/**
 * gdk_drop_read_finish:
 * @self: a #GdkDrop
 * @out_mime_type: (out) (type utf8): return location for the used mime type
 * @result: a #GAsyncResult
 * @error: (allow-none): location to store error information on failure, or %NULL
 *
 * Finishes an async drop read operation, see gdk_drop_read_async().
 *
 * Returns: (nullable) (transfer full): the #GInputStream, or %NULL
 */
GInputStream *
gdk_drop_read_finish (GdkDrop       *self,
                      const char   **out_mime_type,
                      GAsyncResult  *result,
                      GError       **error)
{
  g_return_val_if_fail (GDK_IS_DROP (self), NULL);
  g_return_val_if_fail (error == NULL || *error == NULL, NULL);

  if (g_async_result_is_tagged (result, gdk_drop_read_local_async))
    {
      return gdk_drop_read_local_finish (self, out_mime_type, result, error);
    }
  else
    {
      return GDK_DROP_GET_CLASS (self)->read_finish (self, out_mime_type, result, error);
    }
}