gimp/app/tools/gimprectangleselecttool.c

/* The GIMP -- an image manipulation program
 * Copyright (C) 1995 Spencer Kimball and Peter Mattis
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include "config.h"

#include <gtk/gtk.h>

#include "libgimpwidgets/gimpwidgets.h"

#include "tools-types.h"

#include "base/boundary.h"

#include "core/gimpchannel.h"
#include "core/gimpchannel-select.h"
#include "core/gimplayer-floating-sel.h"
#include "core/gimpimage.h"
#include "core/gimpimage-crop.h"
#include "core/gimpimage-undo.h"
#include "core/gimppickable.h"
#include "core/gimp-utils.h"
#include "core/gimpundo.h"
#include "core/gimpundostack.h"

#include "widgets/gimpdialogfactory.h"
#include "widgets/gimphelp-ids.h"
#include "widgets/gimpviewabledialog.h"
#include "widgets/gimpwidgets-utils.h"

#include "display/gimpcanvas.h"
#include "display/gimpdisplay.h"
#include "display/gimpdisplayshell.h"
#include "display/gimpdisplayshell-transform.h"
#include "display/gimpdisplayshell-appearance.h"

#include "gimpselectiontool.h"
#include "gimpselectionoptions.h"
#include "gimprectangletool.h"
#include "gimprectangleoptions.h"
#include "gimprectangleselecttool.h"
#include "gimprectangleselectoptions.h"
#include "gimptoolcontrol.h"

#include "gimp-intl.h"


static void     gimp_rect_select_tool_rectangle_tool_iface_init (GimpRectangleToolInterface *iface);

static GObject *gimp_rect_select_tool_constructor       (GType              type,
                                                         guint              n_params,
                                                         GObjectConstructParam *params);
static void     gimp_rect_select_tool_dispose           (GObject           *object);
static void     gimp_rect_select_tool_finalize          (GObject           *object);
static void     gimp_rect_select_tool_control           (GimpTool          *tool,
                                                         GimpToolAction     action,
                                                         GimpDisplay       *display);
static void     gimp_rect_select_tool_button_press      (GimpTool          *tool,
                                                         GimpCoords        *coords,
                                                         guint32            time,
                                                         GdkModifierType    state,
                                                         GimpDisplay       *display);
static void     gimp_rect_select_tool_button_release    (GimpTool          *tool,
                                                         GimpCoords        *coords,
                                                         guint32            time,
                                                         GdkModifierType    state,
                                                         GimpDisplay       *display);
static void     gimp_rect_select_tool_modifier_key      (GimpTool          *tool,
                                                         GdkModifierType    key,
                                                         gboolean           press,
                                                         GdkModifierType    state,
                                                         GimpDisplay       *display);
static void     gimp_rect_select_tool_oper_update       (GimpTool          *tool,
                                                         GimpCoords        *coords,
                                                         GdkModifierType    state,
                                                         gboolean           proximity,
                                                         GimpDisplay       *display);
static void     gimp_rect_select_tool_cursor_update     (GimpTool          *tool,
                                                         GimpCoords        *coords,
                                                         GdkModifierType    state,
                                                         GimpDisplay       *display);
static void     gimp_rect_select_tool_select            (GimpRectangleTool *rect_tool,
                                                         gint               x,
                                                         gint               y,
                                                         gint               w,
                                                         gint               h);
static gboolean gimp_rect_select_tool_execute           (GimpRectangleTool *rect_tool,
                                                         gint               x,
                                                         gint               y,
                                                         gint               w,
                                                         gint               h);
static void     gimp_rect_select_tool_cancel            (GimpRectangleTool *rect_tool);
static gboolean gimp_rect_select_tool_rectangle_changed (GimpRectangleTool *rect_tool);
static void     gimp_rect_select_tool_real_select       (GimpRectSelectTool *rect_select,
                                                         SelectOps           operation,
                                                         gint                x,
                                                         gint                y,
                                                         gint                w,
                                                         gint                h);

static void     gimp_rect_select_tool_auto_shrink_notify (GimpRectSelectOptions *options,
                                                          GParamSpec            *pspec,
                                                          GimpRectSelectTool    *rect_select);

static void     gimp_rect_select_tool_auto_shrink       (GimpRectSelectTool *rect_select);

G_DEFINE_TYPE_WITH_CODE (GimpRectSelectTool, gimp_rect_select_tool,
                         GIMP_TYPE_SELECTION_TOOL,
                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_RECTANGLE_TOOL,
                                                gimp_rect_select_tool_rectangle_tool_iface_init))

#define parent_class gimp_rect_select_tool_parent_class


void
gimp_rect_select_tool_register (GimpToolRegisterCallback  callback,
                                gpointer                  data)
{
  (* callback) (GIMP_TYPE_RECT_SELECT_TOOL,
                GIMP_TYPE_RECT_SELECT_OPTIONS,
                gimp_rect_select_options_gui,
                0,
                "gimp-rect-select-tool",
                _("Rect Select"),
                _("Select a Rectangular part of an image"),
                N_("_Rect Select"), "R",
                NULL, GIMP_HELP_TOOL_RECT_SELECT,
                GIMP_STOCK_TOOL_RECT_SELECT,
                data);
}

static void
gimp_rect_select_tool_class_init (GimpRectSelectToolClass *klass)
{
  GObjectClass      *object_class    = G_OBJECT_CLASS (klass);
  GimpToolClass     *tool_class      = GIMP_TOOL_CLASS (klass);
  GimpDrawToolClass *draw_tool_class = GIMP_DRAW_TOOL_CLASS (klass);

  object_class->constructor  = gimp_rect_select_tool_constructor;
  object_class->dispose      = gimp_rect_select_tool_dispose;
  object_class->finalize     = gimp_rect_select_tool_finalize;
  object_class->set_property = gimp_rectangle_tool_set_property;
  object_class->get_property = gimp_rectangle_tool_get_property;

  gimp_rectangle_tool_install_properties (object_class);

  tool_class->initialize     = gimp_rectangle_tool_initialize;
  tool_class->control        = gimp_rect_select_tool_control;
  tool_class->button_press   = gimp_rect_select_tool_button_press;
  tool_class->button_release = gimp_rect_select_tool_button_release;
  tool_class->motion         = gimp_rectangle_tool_motion;
  tool_class->key_press      = gimp_rectangle_tool_key_press;
  tool_class->modifier_key   = gimp_rect_select_tool_modifier_key;
  tool_class->oper_update    = gimp_rect_select_tool_oper_update;
  tool_class->cursor_update  = gimp_rect_select_tool_cursor_update;

  draw_tool_class->draw      = gimp_rectangle_tool_draw;

  klass->select         = gimp_rect_select_tool_real_select;
}

static void
gimp_rect_select_tool_init (GimpRectSelectTool *rect_select)
{
  GimpTool          *tool      = GIMP_TOOL (rect_select);

  gimp_tool_control_set_tool_cursor (tool->control, GIMP_TOOL_CURSOR_RECT_SELECT);
  gimp_tool_control_set_dirty_mask  (tool->control,
                                     GIMP_DIRTY_IMAGE_SIZE |
                                     GIMP_DIRTY_SELECTION);

  rect_select->undo = NULL;
  rect_select->redo = NULL;
}

static void
gimp_rect_select_tool_rectangle_tool_iface_init (GimpRectangleToolInterface *iface)
{
  iface->execute           = gimp_rect_select_tool_execute;
  iface->cancel            = gimp_rect_select_tool_cancel;
  iface->rectangle_changed = gimp_rect_select_tool_rectangle_changed;
}

static GObject *
gimp_rect_select_tool_constructor (GType                  type,
                                   guint                  n_params,
                                   GObjectConstructParam *params)
{
  GObject  *object;
  GObject  *options;
  GimpTool *tool;

  object = G_OBJECT_CLASS (parent_class)->constructor (type, n_params, params);

  gimp_rectangle_tool_constructor (object);

  tool    = GIMP_TOOL (object);
  options = G_OBJECT (gimp_tool_get_options (tool));

  g_signal_connect_object (options, "notify::auto-shrink",
                           G_CALLBACK (gimp_rect_select_tool_auto_shrink_notify),
                           GIMP_RECTANGLE_TOOL (tool), 0);

  return object;
}

static void
gimp_rect_select_tool_dispose (GObject *object)
{
  GimpTool          *tool      = GIMP_TOOL (object);
  GimpRectangleTool *rectangle = GIMP_RECTANGLE_TOOL (object);
  GObject           *options   = G_OBJECT (gimp_tool_get_options (tool));

  gimp_rectangle_tool_dispose (object);

  g_signal_handlers_disconnect_by_func (options,
                                        G_CALLBACK (gimp_rect_select_tool_auto_shrink_notify),
                                        rectangle);
}

static void
gimp_rect_select_tool_finalize (GObject *object)
{
  G_OBJECT_CLASS (parent_class)->finalize (object);
}

static void
gimp_rect_select_tool_control (GimpTool       *tool,
                               GimpToolAction  action,
                               GimpDisplay    *display)
{
  gimp_rectangle_tool_control (tool, action, display);

  GIMP_TOOL_CLASS (parent_class)->control (tool, action, display);
}

static void
gimp_rect_select_tool_button_press (GimpTool        *tool,
                                        GimpCoords      *coords,
                                        guint32          time,
                                        GdkModifierType  state,
                                        GimpDisplay     *display)
{
  GimpRectSelectTool   *rect_select = GIMP_RECT_SELECT_TOOL (tool);
  guint                 function;

  if (tool->display && display != tool->display)
    gimp_rectangle_tool_cancel (GIMP_RECTANGLE_TOOL (tool));

  g_object_get (tool, "function", &function, NULL);

  rect_select->saved_show_selection
    = gimp_display_shell_get_show_selection (GIMP_DISPLAY_SHELL (display->shell));

  if (function == RECT_INACTIVE)
    {
      GimpDisplay *old_display;
      gboolean     edit_started;

      old_display = tool->display;
      tool->display = display;
      gimp_tool_control_activate (tool->control);

      edit_started = gimp_selection_tool_start_edit (GIMP_SELECTION_TOOL (tool),
                                                     coords);

      if (gimp_tool_control_is_active (tool->control))
        gimp_tool_control_halt (tool->control);
      tool->display = old_display;

      if (edit_started)
        return;
    }

  /* if the shift or ctrl keys are down, we don't want to adjust, we
   * want to create a new rectangle, regardless of pointer loc */
  if (state & (GDK_SHIFT_MASK | GDK_CONTROL_MASK))
    g_object_set (tool, "function", RECT_CREATING, NULL);

  gimp_rectangle_tool_button_press (tool, coords, time, state, display);

  /* if we have an existing rectangle in the current display, then
   * we have already "executed", and need to undo at this point,
   * unless the user has done something in the meantime
   */
  g_object_get (tool, "function", &function, NULL);

  if (function == RECT_CREATING)
    {
      rect_select->use_saved_op = FALSE;
    }
  else
    {
      GimpSelectionOptions *options = GIMP_SELECTION_TOOL_GET_OPTIONS (tool);
      GimpImage            *image   = tool->display->image;
      GimpUndo             *undo;
      SelectOps             operation;

      if (rect_select->use_saved_op)
        operation = rect_select->operation;
      else
        g_object_get (options,
                      "operation", &operation,
                      NULL);

      undo = gimp_undo_stack_peek (image->undo_stack);

      if (undo && rect_select->undo == undo)
        {
          /* prevent this change from halting the tool */
          gimp_tool_control_set_preserve (tool->control, TRUE);

          gimp_image_undo (image);

          gimp_tool_control_set_preserve (tool->control, FALSE);

          /* we will need to redo if the user cancels or executes */
          rect_select->redo = gimp_undo_stack_peek (image->redo_stack);
        }

      /* if the operation is "Replace", turn off the marching ants,
         because they are confusing */
      if (operation == SELECTION_REPLACE)
        gimp_display_shell_set_show_selection (GIMP_DISPLAY_SHELL (display->shell),
                                               FALSE);
    }

  rect_select->undo = NULL;
}

static void
gimp_rect_select_tool_button_release (GimpTool        *tool,
                                      GimpCoords      *coords,
                                      guint32          time,
                                      GdkModifierType  state,
                                      GimpDisplay     *display)
{
  GimpRectSelectTool   *rect_select = GIMP_RECT_SELECT_TOOL (tool);
  GimpRectangleTool    *rectangle   = GIMP_RECTANGLE_TOOL (tool);
  GimpSelectionOptions *options     = GIMP_SELECTION_TOOL_GET_OPTIONS (tool);
  gboolean              auto_shrink;

  gimp_tool_pop_status (tool, display);
  gimp_display_shell_set_show_selection (GIMP_DISPLAY_SHELL (display->shell),
                                         rect_select->saved_show_selection);

  /*
   * if the user has not moved the mouse, we need to redo the operation
   * that was undone on button press.
   */
  if (gimp_rectangle_tool_no_movement (rectangle))
    {
      GimpImage             *image       = tool->display->image;
      GimpUndo              *redo;

      redo = gimp_undo_stack_peek (image->redo_stack);

      if (redo && rect_select->redo == redo)
        {
          /* prevent this from halting the tool */
          gimp_tool_control_set_preserve (tool->control, TRUE);

          gimp_image_redo (image);
          rect_select->redo = NULL;

          gimp_tool_control_set_preserve (tool->control, FALSE);
        }
    }

  g_object_get (options,
                "auto-shrink", &auto_shrink,
                NULL);

  if (auto_shrink)
    gimp_rect_select_tool_auto_shrink (rect_select);

  gimp_rectangle_tool_button_release (tool, coords, time, state, display);

  if ((state & GDK_BUTTON3_MASK))
    {
      if (rect_select->redo)
        {
          /* prevent this from halting the tool */
          gimp_tool_control_set_preserve (tool->control, TRUE);

          gimp_image_redo (tool->display->image);

          gimp_tool_control_set_preserve (tool->control, FALSE);
        }

      rect_select->use_saved_op = TRUE;  /* is this correct? */
    }

  rect_select->redo = NULL;
}

static void
gimp_rect_select_tool_modifier_key (GimpTool        *tool,
                                    GdkModifierType  key,
                                    gboolean         press,
                                    GdkModifierType  state,
                                    GimpDisplay     *display)
{
  GIMP_TOOL_CLASS (parent_class)->modifier_key (tool, key, press, state,
                                                display);

  gimp_rectangle_tool_modifier_key (tool, key, press, state, display);
}

static void
gimp_rect_select_tool_oper_update (GimpTool        *tool,
                                   GimpCoords      *coords,
                                   GdkModifierType  state,
                                   gboolean         proximity,
                                   GimpDisplay     *display)
{
  guint function;

  gimp_rectangle_tool_oper_update (tool, coords, state, proximity, display);

  g_object_get (tool, "function", &function, NULL);

  if (function == RECT_INACTIVE)
    GIMP_SELECTION_TOOL (tool)->allow_move = TRUE;
  else
    GIMP_SELECTION_TOOL (tool)->allow_move = FALSE;

  GIMP_TOOL_CLASS (parent_class)->oper_update (tool, coords, state, proximity,
                                               display);
}

static void
gimp_rect_select_tool_cursor_update (GimpTool        *tool,
                                     GimpCoords      *coords,
                                     GdkModifierType  state,
                                     GimpDisplay     *display)
{
  gimp_rectangle_tool_cursor_update (tool, coords, state, display);

  /* override the previous if shift or ctrl are down */
  if (state & (GDK_SHIFT_MASK | GDK_CONTROL_MASK))
    gimp_tool_control_set_cursor (tool->control, GIMP_CURSOR_CROSSHAIR_SMALL);

  GIMP_TOOL_CLASS (parent_class)->cursor_update (tool, coords, state, display);
}


static void
gimp_rect_select_tool_select (GimpRectangleTool *rectangle,
                              gint               x,
                              gint               y,
                              gint               w,
                              gint               h)
{
  GimpTool             *tool        = GIMP_TOOL (rectangle);
  GimpRectSelectTool   *rect_select = GIMP_RECT_SELECT_TOOL (rectangle);
  GimpSelectionOptions *options     = GIMP_SELECTION_TOOL_GET_OPTIONS (tool);
  GimpImage            *image;
  gboolean              rectangle_exists;
  SelectOps             operation;

  gimp_tool_pop_status (tool, tool->display);

  image = tool->display->image;

  rectangle_exists = (x <= image->width && y <= image->height &&
                      x + w >= 0 && y + h >= 0 &&
                      w > 0 && h > 0);

  if (rect_select->use_saved_op)
    operation = rect_select->operation;
  else
    g_object_get (options,
                  "operation", &operation,
                  NULL);

  /* if rectangle exists, turn it into a selection */
  if (rectangle_exists)
    GIMP_RECT_SELECT_TOOL_GET_CLASS (rect_select)->select (rect_select,
                                                               operation,
                                                               x, y, w, h);
}

static void
gimp_rect_select_tool_real_select (GimpRectSelectTool *rect_select,
                                   SelectOps           operation,
                                   gint                x,
                                   gint                y,
                                   gint                w,
                                   gint                h)
{
  GimpTool             *tool    = GIMP_TOOL (rect_select);
  GimpSelectionOptions *options = GIMP_SELECTION_TOOL_GET_OPTIONS (tool);

  gimp_channel_select_rectangle (gimp_image_get_mask (tool->display->image),
                                 x, y, w, h,
                                 operation,
                                 options->feather,
                                 options->feather_radius,
                                 options->feather_radius,
                                 TRUE);
}

/*
 * This function is called if the user clicks and releases the left
 * button without moving it.  There are the things we might want
 * to do here:
 * 1) If there is an existing rectangle and we are inside it, we
 *    convert it into a selection.
 * 2) If there is an existing rectangle and we are outside it, we
 *    clear it.
 * 3) If there is no rectangle and there is a floating selection,
 *    we anchor it.
 * 4) If there is no rectangle and we are inside the selection, we
 *    create a rectangle from the selection bounds.
 * 5) If there is no rectangle and we are outside the selection,
 *    we clear the selection.
 */
static gboolean
gimp_rect_select_tool_execute (GimpRectangleTool *rectangle,
                               gint               x,
                               gint               y,
                               gint               w,
                               gint               h)
{
  if (w == 0 && h == 0)
    {
      GimpImage   *image     = GIMP_TOOL (rectangle)->display->image;
      GimpChannel *selection = gimp_image_get_mask (image);
      gint         pressx;
      gint         pressy;

      if (gimp_image_floating_sel (image))
        {
          floating_sel_anchor (gimp_image_floating_sel (image));
          return TRUE;
        }

      g_object_get (rectangle,
                    "pressx", &pressx,
                    "pressy", &pressy,
                    NULL);

      /*  if the click was inside the marching ants  */
      if (gimp_pickable_get_opacity_at (GIMP_PICKABLE (selection),
                                        pressx, pressy) > 127)
        {
          const BoundSeg *segs_in;
          const BoundSeg *segs_out;
          gint            n_segs_in;
          gint            n_segs_out;

          if (gimp_channel_boundary (selection,
                                     &segs_in, &segs_out,
                                     &n_segs_in, &n_segs_out,
                                     0, 0, 0, 0))
            {
              gint x1 = 0;
              gint y1 = 0;
              gint x2 = 0;
              gint y2 = 0;

              if (n_segs_in > 0)
                {
                  gint i;

                  x1 = segs_in[0].x1;
                  x2 = segs_in[0].x1;
                  y1 = segs_in[0].y1;
                  y2 = segs_in[0].y1;

                  for (i = 1; i < n_segs_in; i++)
                    {
                      x1 = MIN (x1, segs_in[i].x1);
                      x2 = MAX (x2, segs_in[i].x1);
                      y1 = MIN (y1, segs_in[i].y1);
                      y2 = MAX (y2, segs_in[i].y1);
                    }
                }

              g_object_set (rectangle,
                            "x1", x1,
                            "y1", y1,
                            "x2", x2,
                            "y2", y2,
                            NULL);
            }
          else
            {
              g_object_set (rectangle,
                            "x1", 0,
                            "y1", 0,
                            "x2", image->width,
                            "y2", image->height,
                            NULL);
            }

          g_object_set (rectangle, "function", RECT_MOVING, NULL);

          return FALSE;
        }
      else
        {
          GimpTool *tool = GIMP_TOOL (rectangle);

          /* prevent this change from halting the tool */
          gimp_tool_control_set_preserve (tool->control, TRUE);

          /* otherwise clear the selection */
          gimp_channel_clear (selection, NULL, TRUE);

          gimp_tool_control_set_preserve (tool->control, FALSE);
        }
    }

  return TRUE;
}

static void
gimp_rect_select_tool_cancel (GimpRectangleTool *rectangle)
{
  GimpTool           *tool        = GIMP_TOOL (rectangle);
  GimpRectSelectTool *rect_select = GIMP_RECT_SELECT_TOOL (rectangle);

  if (tool->display)
    {
      GimpImage *image = tool->display->image;
      GimpUndo  *undo;

      /* if we have an existing rectangle in the current display, then
       * we have already "executed", and need to undo at this point,
       * unless the user has done something in the meantime
       */
      undo = gimp_undo_stack_peek (image->undo_stack);

      if (undo && rect_select->undo == undo)
        {
          /* prevent this change from halting the tool */
          gimp_tool_control_set_preserve (tool->control, TRUE);

          gimp_image_undo (image);
          gimp_image_flush (image);

          gimp_tool_control_set_preserve (tool->control, FALSE);
        }
    }

  rect_select->undo = NULL;
  rect_select->redo = NULL;
}

static gboolean
gimp_rect_select_tool_rectangle_changed (GimpRectangleTool  *rectangle)
{
  GimpTool *tool = GIMP_TOOL (rectangle);

  /* prevent change in selection from halting the tool */
  gimp_tool_control_set_preserve (tool->control, TRUE);

  if (tool->display)
    {
      GimpRectSelectTool   *rect_select = GIMP_RECT_SELECT_TOOL (tool);
      GimpImage            *image       = tool->display->image;
      GimpUndo             *undo;
      gint                  x1, y1, x2, y2;

      /* if we got here via button release, we have already undone the
       * previous operation.  But if we got here by some other means,
       * we need to undo it now.
       */
      undo = gimp_undo_stack_peek (image->undo_stack);

      if (undo && rect_select->undo == undo)
        {
          gimp_image_undo (image);
          rect_select->undo = NULL;
        }

      g_object_get (rectangle,
                    "x1", &x1,
                    "y1", &y1,
                    "x2", &x2,
                    "y2", &y2,
                    NULL);

      gimp_rect_select_tool_select (rectangle, x1, y1, x2 - x1, y2 - y1);

      /* save the undo that we got when executing */
      rect_select->undo = gimp_undo_stack_peek (image->undo_stack);
      rect_select->redo = NULL;

      if (! rect_select->use_saved_op)
        {
          /* remember the operation now in case we modify the rectangle */
          g_object_get (gimp_tool_get_options (tool),
                        "operation", &rect_select->operation,
                        NULL);
          rect_select->use_saved_op = TRUE;
        }

      gimp_image_flush (image);
    }

  gimp_tool_control_set_preserve (tool->control, FALSE);

  return TRUE;
}

static void
gimp_rect_select_tool_auto_shrink_notify (GimpRectSelectOptions *options,
                                          GParamSpec            *pspec,
                                          GimpRectSelectTool    *rect_select)
{
  gboolean auto_shrink;

  g_object_get (GIMP_SELECTION_OPTIONS (options),
                "auto-shrink",   &auto_shrink,
                NULL);

  if (auto_shrink)
    gimp_rect_select_tool_auto_shrink (rect_select);

  g_signal_emit_by_name (GIMP_RECTANGLE_TOOL (rect_select),
                         "rectangle-changed", NULL);
}



static void
gimp_rect_select_tool_auto_shrink (GimpRectSelectTool *rect_select)
{
  GimpRectangleTool    *rectangle = GIMP_RECTANGLE_TOOL (rect_select);
  GimpTool             *tool      = GIMP_TOOL (rect_select);
  GimpDisplay          *display   = GIMP_TOOL (rect_select)->display;
  gint                  width;
  gint                  height;
  gint                  offset_x  = 0;
  gint                  offset_y  = 0;
  gint                  rx1, ry1;
  gint                  rx2, ry2;
  gint                  x1, y1;
  gint                  x2, y2;
  gint                  shrunk_x1;
  gint                  shrunk_y1;
  gint                  shrunk_x2;
  gint                  shrunk_y2;
  gboolean              shrink_merged;

  if (! display)
    return;

  width  = display->image->width;
  height = display->image->height;

  g_object_get (gimp_tool_get_options (tool),
                "shrink-merged", &shrink_merged,
                NULL);

  g_object_get (rectangle,
                "x1", &rx1,
                "y1", &ry1,
                "x2", &rx2,
                "y2", &ry2,
                NULL);

  x1 = rx1 - offset_x  > 0      ? rx1 - offset_x : 0;
  x2 = rx2 - offset_x  < width  ? rx2 - offset_x : width;
  y1 = ry1 - offset_y  > 0      ? ry1 - offset_y : 0;
  y2 = ry2 - offset_y  < height ? ry2 - offset_y : height;

  if (gimp_image_crop_auto_shrink (display->image,
                                   x1, y1, x2, y2,
                                   ! shrink_merged,
                                   &shrunk_x1,
                                   &shrunk_y1,
                                   &shrunk_x2,
                                   &shrunk_y2))
    {
      gimp_draw_tool_pause (GIMP_DRAW_TOOL (rectangle));

      g_object_set (rectangle,
                    "x1", offset_x + shrunk_x1,
                    "y1", offset_y + shrunk_y1,
                    "x2", offset_x + shrunk_x2,
                    "y2", offset_y + shrunk_y2,
                    NULL);

      gimp_rectangle_tool_configure (rectangle);

      gimp_draw_tool_resume (GIMP_DRAW_TOOL (rectangle));
    }
}