Adding upstream version 2.10.22.upstream/2.10.22upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 985 insertions, 0 deletions

diff --git a/app/display/gimpdisplay.c b/app/display/gimpdisplay.c
new file mode 100644
index 0000000..bf8a238
--- /dev/null
+++ b/app/display/gimpdisplay.c
@@ -0,0 +1,985 @@
+/* GIMP - The GNU 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 3 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, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gegl.h>
+#include <gtk/gtk.h>
+
+#include "libgimpmath/gimpmath.h"
+
+#include "display-types.h"
+#include "tools/tools-types.h"
+
+#include "config/gimpguiconfig.h"
+
+#include "core/gimp.h"
+#include "core/gimpcontainer.h"
+#include "core/gimpcontext.h"
+#include "core/gimpimage.h"
+#include "core/gimpprogress.h"
+
+#include "widgets/gimpdialogfactory.h"
+
+#include "tools/gimptool.h"
+#include "tools/tool_manager.h"
+
+#include "gimpdisplay.h"
+#include "gimpdisplay-handlers.h"
+#include "gimpdisplayshell.h"
+#include "gimpdisplayshell-expose.h"
+#include "gimpdisplayshell-handlers.h"
+#include "gimpdisplayshell-icon.h"
+#include "gimpdisplayshell-scroll.h"
+#include "gimpdisplayshell-scrollbars.h"
+#include "gimpdisplayshell-title.h"
+#include "gimpdisplayshell-transform.h"
+#include "gimpimagewindow.h"
+
+#include "gimp-intl.h"
+
+
+#define FLUSH_NOW_INTERVAL      (G_TIME_SPAN_SECOND / 60)
+
+#define PAINT_AREA_CHUNK_WIDTH  32
+#define PAINT_AREA_CHUNK_HEIGHT 32
+
+
+enum
+{
+  PROP_0,
+  PROP_ID,
+  PROP_GIMP,
+  PROP_IMAGE,
+  PROP_SHELL
+};
+
+
+typedef struct _GimpDisplayPrivate GimpDisplayPrivate;
+
+struct _GimpDisplayPrivate
+{
+  gint            ID;           /*  unique identifier for this display  */
+
+  GimpImage      *image;        /*  pointer to the associated image     */
+  gint            instance;     /*  the instance # of this display as
+                                 *  taken from the image at creation    */
+
+  GeglRectangle   bounding_box;
+
+  GtkWidget      *shell;
+  cairo_region_t *update_region;
+
+  guint64         last_flush_now;
+};
+
+#define GIMP_DISPLAY_GET_PRIVATE(display) \
+        ((GimpDisplayPrivate *) gimp_display_get_instance_private ((GimpDisplay *) (display)))
+
+
+/*  local function prototypes  */
+
+static void     gimp_display_progress_iface_init  (GimpProgressInterface *iface);
+
+static void     gimp_display_set_property           (GObject             *object,
+                                                     guint                property_id,
+                                                     const GValue        *value,
+                                                     GParamSpec          *pspec);
+static void     gimp_display_get_property           (GObject             *object,
+                                                     guint                property_id,
+                                                     GValue              *value,
+                                                     GParamSpec          *pspec);
+
+static GimpProgress * gimp_display_progress_start   (GimpProgress        *progress,
+                                                     gboolean             cancellable,
+                                                     const gchar         *message);
+static void     gimp_display_progress_end           (GimpProgress        *progress);
+static gboolean gimp_display_progress_is_active     (GimpProgress        *progress);
+static void     gimp_display_progress_set_text      (GimpProgress        *progress,
+                                                     const gchar         *message);
+static void     gimp_display_progress_set_value     (GimpProgress        *progress,
+                                                     gdouble              percentage);
+static gdouble  gimp_display_progress_get_value     (GimpProgress        *progress);
+static void     gimp_display_progress_pulse         (GimpProgress        *progress);
+static guint32  gimp_display_progress_get_window_id (GimpProgress        *progress);
+static gboolean gimp_display_progress_message       (GimpProgress        *progress,
+                                                     Gimp                *gimp,
+                                                     GimpMessageSeverity  severity,
+                                                     const gchar         *domain,
+                                                     const gchar         *message);
+static void     gimp_display_progress_canceled      (GimpProgress        *progress,
+                                                     GimpDisplay         *display);
+
+static void     gimp_display_flush_whenever         (GimpDisplay         *display,
+                                                     gboolean             now);
+static void     gimp_display_paint_area             (GimpDisplay         *display,
+                                                     gint                 x,
+                                                     gint                 y,
+                                                     gint                 w,
+                                                     gint                 h);
+
+
+G_DEFINE_TYPE_WITH_CODE (GimpDisplay, gimp_display, GIMP_TYPE_OBJECT,
+                         G_ADD_PRIVATE (GimpDisplay)
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_PROGRESS,
+                                                gimp_display_progress_iface_init))
+
+#define parent_class gimp_display_parent_class
+
+
+static void
+gimp_display_class_init (GimpDisplayClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->set_property = gimp_display_set_property;
+  object_class->get_property = gimp_display_get_property;
+
+  g_object_class_install_property (object_class, PROP_ID,
+                                   g_param_spec_int ("id",
+                                                     NULL, NULL,
+                                                     0, G_MAXINT, 0,
+                                                     GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_GIMP,
+                                   g_param_spec_object ("gimp",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_GIMP,
+                                                        GIMP_PARAM_READWRITE |
+                                                        G_PARAM_CONSTRUCT_ONLY));
+
+  g_object_class_install_property (object_class, PROP_IMAGE,
+                                   g_param_spec_object ("image",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_IMAGE,
+                                                        GIMP_PARAM_READABLE));
+
+  g_object_class_install_property (object_class, PROP_SHELL,
+                                   g_param_spec_object ("shell",
+                                                        NULL, NULL,
+                                                        GIMP_TYPE_DISPLAY_SHELL,
+                                                        GIMP_PARAM_READABLE));
+}
+
+static void
+gimp_display_init (GimpDisplay *display)
+{
+}
+
+static void
+gimp_display_progress_iface_init (GimpProgressInterface *iface)
+{
+  iface->start         = gimp_display_progress_start;
+  iface->end           = gimp_display_progress_end;
+  iface->is_active     = gimp_display_progress_is_active;
+  iface->set_text      = gimp_display_progress_set_text;
+  iface->set_value     = gimp_display_progress_set_value;
+  iface->get_value     = gimp_display_progress_get_value;
+  iface->pulse         = gimp_display_progress_pulse;
+  iface->get_window_id = gimp_display_progress_get_window_id;
+  iface->message       = gimp_display_progress_message;
+}
+
+static void
+gimp_display_set_property (GObject      *object,
+                           guint         property_id,
+                           const GValue *value,
+                           GParamSpec   *pspec)
+{
+  GimpDisplay        *display = GIMP_DISPLAY (object);
+  GimpDisplayPrivate *private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  switch (property_id)
+    {
+    case PROP_GIMP:
+      {
+        gint ID;
+
+        display->gimp = g_value_get_object (value); /* don't ref the gimp */
+        display->config = GIMP_DISPLAY_CONFIG (display->gimp->config);
+
+        do
+          {
+            ID = display->gimp->next_display_ID++;
+
+            if (display->gimp->next_display_ID == G_MAXINT)
+              display->gimp->next_display_ID = 1;
+          }
+        while (gimp_display_get_by_ID (display->gimp, ID));
+
+        private->ID = ID;
+      }
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_display_get_property (GObject    *object,
+                           guint       property_id,
+                           GValue     *value,
+                           GParamSpec *pspec)
+{
+  GimpDisplay        *display = GIMP_DISPLAY (object);
+  GimpDisplayPrivate *private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  switch (property_id)
+    {
+    case PROP_ID:
+      g_value_set_int (value, private->ID);
+      break;
+
+    case PROP_GIMP:
+      g_value_set_object (value, display->gimp);
+      break;
+
+    case PROP_IMAGE:
+      g_value_set_object (value, private->image);
+      break;
+
+    case PROP_SHELL:
+      g_value_set_object (value, private->shell);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static GimpProgress *
+gimp_display_progress_start (GimpProgress *progress,
+                             gboolean      cancellable,
+                             const gchar  *message)
+{
+  GimpDisplay        *display = GIMP_DISPLAY (progress);
+  GimpDisplayPrivate *private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  if (private->shell)
+    return gimp_progress_start (GIMP_PROGRESS (private->shell), cancellable,
+                                "%s", message);
+
+  return NULL;
+}
+
+static void
+gimp_display_progress_end (GimpProgress *progress)
+{
+  GimpDisplay        *display = GIMP_DISPLAY (progress);
+  GimpDisplayPrivate *private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  if (private->shell)
+    gimp_progress_end (GIMP_PROGRESS (private->shell));
+}
+
+static gboolean
+gimp_display_progress_is_active (GimpProgress *progress)
+{
+  GimpDisplay        *display = GIMP_DISPLAY (progress);
+  GimpDisplayPrivate *private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  if (private->shell)
+    return gimp_progress_is_active (GIMP_PROGRESS (private->shell));
+
+  return FALSE;
+}
+
+static void
+gimp_display_progress_set_text (GimpProgress *progress,
+                                const gchar  *message)
+{
+  GimpDisplay        *display = GIMP_DISPLAY (progress);
+  GimpDisplayPrivate *private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  if (private->shell)
+    gimp_progress_set_text_literal (GIMP_PROGRESS (private->shell), message);
+}
+
+static void
+gimp_display_progress_set_value (GimpProgress *progress,
+                                 gdouble       percentage)
+{
+  GimpDisplay        *display = GIMP_DISPLAY (progress);
+  GimpDisplayPrivate *private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  if (private->shell)
+    gimp_progress_set_value (GIMP_PROGRESS (private->shell), percentage);
+}
+
+static gdouble
+gimp_display_progress_get_value (GimpProgress *progress)
+{
+  GimpDisplay        *display = GIMP_DISPLAY (progress);
+  GimpDisplayPrivate *private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  if (private->shell)
+    return gimp_progress_get_value (GIMP_PROGRESS (private->shell));
+
+  return 0.0;
+}
+
+static void
+gimp_display_progress_pulse (GimpProgress *progress)
+{
+  GimpDisplay        *display = GIMP_DISPLAY (progress);
+  GimpDisplayPrivate *private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  if (private->shell)
+    gimp_progress_pulse (GIMP_PROGRESS (private->shell));
+}
+
+static guint32
+gimp_display_progress_get_window_id (GimpProgress *progress)
+{
+  GimpDisplay        *display = GIMP_DISPLAY (progress);
+  GimpDisplayPrivate *private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  if (private->shell)
+    return gimp_progress_get_window_id (GIMP_PROGRESS (private->shell));
+
+  return 0;
+}
+
+static gboolean
+gimp_display_progress_message (GimpProgress        *progress,
+                               Gimp                *gimp,
+                               GimpMessageSeverity  severity,
+                               const gchar         *domain,
+                               const gchar         *message)
+{
+  GimpDisplay        *display = GIMP_DISPLAY (progress);
+  GimpDisplayPrivate *private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  if (private->shell)
+    return gimp_progress_message (GIMP_PROGRESS (private->shell), gimp,
+                                  severity, domain, message);
+
+  return FALSE;
+}
+
+static void
+gimp_display_progress_canceled (GimpProgress *progress,
+                                GimpDisplay  *display)
+{
+  gimp_progress_cancel (GIMP_PROGRESS (display));
+}
+
+
+/*  public functions  */
+
+GimpDisplay *
+gimp_display_new (Gimp              *gimp,
+                  GimpImage         *image,
+                  GimpUnit           unit,
+                  gdouble            scale,
+                  GimpUIManager     *popup_manager,
+                  GimpDialogFactory *dialog_factory,
+                  GdkScreen         *screen,
+                  gint               monitor)
+{
+  GimpDisplay        *display;
+  GimpDisplayPrivate *private;
+  GimpImageWindow    *window = NULL;
+  GimpDisplayShell   *shell;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+  g_return_val_if_fail (image == NULL || GIMP_IS_IMAGE (image), NULL);
+  g_return_val_if_fail (GDK_IS_SCREEN (screen), NULL);
+
+  /*  If there isn't an interface, never create a display  */
+  if (gimp->no_interface)
+    return NULL;
+
+  display = g_object_new (GIMP_TYPE_DISPLAY,
+                          "gimp", gimp,
+                          NULL);
+
+  private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  /*  refs the image  */
+  if (image)
+    gimp_display_set_image (display, image);
+
+  /*  get an image window  */
+  if (GIMP_GUI_CONFIG (display->config)->single_window_mode)
+    {
+      GimpDisplay *active_display;
+
+      active_display = gimp_context_get_display (gimp_get_user_context (gimp));
+
+      if (! active_display)
+        {
+          active_display =
+            GIMP_DISPLAY (gimp_container_get_first_child (gimp->displays));
+        }
+
+      if (active_display)
+        {
+          GimpDisplayShell *shell = gimp_display_get_shell (active_display);
+
+          window = gimp_display_shell_get_window (shell);
+        }
+    }
+
+  if (! window)
+    {
+      window = gimp_image_window_new (gimp,
+                                      private->image,
+                                      dialog_factory,
+                                      screen,
+                                      monitor);
+    }
+
+  /*  create the shell for the image  */
+  private->shell = gimp_display_shell_new (display, unit, scale,
+                                           popup_manager,
+                                           screen,
+                                           monitor);
+
+  shell = gimp_display_get_shell (display);
+
+  gimp_display_update_bounding_box (display);
+
+  gimp_image_window_add_shell (window, shell);
+  gimp_display_shell_present (shell);
+
+  /* make sure the docks are visible, in case all other image windows
+   * are iconified, see bug #686544.
+   */
+  gimp_dialog_factory_show_with_display (dialog_factory);
+
+  g_signal_connect (gimp_display_shell_get_statusbar (shell), "cancel",
+                    G_CALLBACK (gimp_display_progress_canceled),
+                    display);
+
+  /* add the display to the list */
+  gimp_container_add (gimp->displays, GIMP_OBJECT (display));
+
+  return display;
+}
+
+/**
+ * gimp_display_delete:
+ * @display:
+ *
+ * Closes the display and removes it from the display list. You should
+ * not call this function directly, use gimp_display_close() instead.
+ */
+void
+gimp_display_delete (GimpDisplay *display)
+{
+  GimpDisplayPrivate *private;
+  GimpTool           *active_tool;
+
+  g_return_if_fail (GIMP_IS_DISPLAY (display));
+
+  private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  /* remove the display from the list */
+  gimp_container_remove (display->gimp->displays, GIMP_OBJECT (display));
+
+  /*  unrefs the image  */
+  gimp_display_set_image (display, NULL);
+
+  active_tool = tool_manager_get_active (display->gimp);
+
+  if (active_tool && active_tool->focus_display == display)
+    tool_manager_focus_display_active (display->gimp, NULL);
+
+  if (private->shell)
+    {
+      GimpDisplayShell *shell  = gimp_display_get_shell (display);
+      GimpImageWindow  *window = gimp_display_shell_get_window (shell);
+
+      /*  set private->shell to NULL *before* destroying the shell.
+       *  all callbacks in gimpdisplayshell-callbacks.c will check
+       *  this pointer and do nothing if the shell is in destruction.
+       */
+      private->shell = NULL;
+
+      if (window)
+        {
+          if (gimp_image_window_get_n_shells (window) > 1)
+            {
+              g_object_ref (shell);
+
+              gimp_image_window_remove_shell (window, shell);
+              gtk_widget_destroy (GTK_WIDGET (shell));
+
+              g_object_unref (shell);
+            }
+          else
+            {
+              gimp_image_window_destroy (window);
+            }
+        }
+      else
+        {
+          g_object_unref (shell);
+        }
+    }
+
+  g_object_unref (display);
+}
+
+/**
+ * gimp_display_close:
+ * @display:
+ *
+ * Closes the display. If this is the last display, it will remain
+ * open, but without an image.
+ */
+void
+gimp_display_close (GimpDisplay *display)
+{
+  g_return_if_fail (GIMP_IS_DISPLAY (display));
+
+  if (gimp_container_get_n_children (display->gimp->displays) > 1)
+    {
+      gimp_display_delete (display);
+    }
+  else
+    {
+      gimp_display_empty (display);
+    }
+}
+
+gint
+gimp_display_get_ID (GimpDisplay *display)
+{
+  GimpDisplayPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_DISPLAY (display), -1);
+
+  private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  return private->ID;
+}
+
+GimpDisplay *
+gimp_display_get_by_ID (Gimp *gimp,
+                        gint  ID)
+{
+  GList *list;
+
+  g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
+
+  for (list = gimp_get_display_iter (gimp);
+       list;
+       list = g_list_next (list))
+    {
+      GimpDisplay *display = list->data;
+
+      if (gimp_display_get_ID (display) == ID)
+        return display;
+    }
+
+  return NULL;
+}
+
+/**
+ * gimp_display_get_action_name:
+ * @display:
+ *
+ * Returns: The action name for the given display. The action name
+ * depends on the display ID. The result must be freed with g_free().
+ **/
+gchar *
+gimp_display_get_action_name (GimpDisplay *display)
+{
+  g_return_val_if_fail (GIMP_IS_DISPLAY (display), NULL);
+
+  return g_strdup_printf ("windows-display-%04d",
+                          gimp_display_get_ID (display));
+}
+
+Gimp *
+gimp_display_get_gimp (GimpDisplay *display)
+{
+  g_return_val_if_fail (GIMP_IS_DISPLAY (display), NULL);
+
+  return display->gimp;
+}
+
+GimpImage *
+gimp_display_get_image (GimpDisplay *display)
+{
+  g_return_val_if_fail (GIMP_IS_DISPLAY (display), NULL);
+
+  return GIMP_DISPLAY_GET_PRIVATE (display)->image;
+}
+
+void
+gimp_display_set_image (GimpDisplay *display,
+                        GimpImage   *image)
+{
+  GimpDisplayPrivate *private;
+  GimpImage          *old_image = NULL;
+  GimpDisplayShell   *shell;
+
+  g_return_if_fail (GIMP_IS_DISPLAY (display));
+  g_return_if_fail (image == NULL || GIMP_IS_IMAGE (image));
+
+  private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  shell = gimp_display_get_shell (display);
+
+  if (private->image)
+    {
+      /*  stop any active tool  */
+      tool_manager_control_active (display->gimp, GIMP_TOOL_ACTION_HALT,
+                                   display);
+
+      gimp_display_shell_disconnect (shell);
+
+      gimp_display_disconnect (display);
+
+      g_clear_pointer (&private->update_region, cairo_region_destroy);
+
+      gimp_image_dec_display_count (private->image);
+
+      /*  set private->image before unrefing because there may be code
+       *  that listens for image removals and then iterates the
+       *  display list to find a valid display.
+       */
+      old_image = private->image;
+
+#if 0
+      g_print ("%s: image->ref_count before unrefing: %d\n",
+               G_STRFUNC, G_OBJECT (old_image)->ref_count);
+#endif
+    }
+
+  private->image = image;
+
+  if (image)
+    {
+#if 0
+      g_print ("%s: image->ref_count before refing: %d\n",
+               G_STRFUNC, G_OBJECT (image)->ref_count);
+#endif
+
+      g_object_ref (image);
+
+      private->instance = gimp_image_get_instance_count (image);
+      gimp_image_inc_instance_count (image);
+
+      gimp_image_inc_display_count (image);
+
+      gimp_display_connect (display);
+
+      if (shell)
+        gimp_display_shell_connect (shell);
+    }
+
+  if (old_image)
+    g_object_unref (old_image);
+
+  gimp_display_update_bounding_box (display);
+
+  if (shell)
+    {
+      if (image)
+        {
+          gimp_display_shell_reconnect (shell);
+        }
+      else
+        {
+          gimp_display_shell_title_update (shell);
+          gimp_display_shell_icon_update (shell);
+        }
+    }
+
+  if (old_image != image)
+    g_object_notify (G_OBJECT (display), "image");
+}
+
+gint
+gimp_display_get_instance (GimpDisplay *display)
+{
+  GimpDisplayPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_DISPLAY (display), 0);
+
+  private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  return private->instance;
+}
+
+GimpDisplayShell *
+gimp_display_get_shell (GimpDisplay *display)
+{
+  GimpDisplayPrivate *private;
+
+  g_return_val_if_fail (GIMP_IS_DISPLAY (display), NULL);
+
+  private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  return GIMP_DISPLAY_SHELL (private->shell);
+}
+
+void
+gimp_display_empty (GimpDisplay *display)
+{
+  GimpDisplayPrivate *private;
+  GList              *iter;
+
+  g_return_if_fail (GIMP_IS_DISPLAY (display));
+
+  private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  g_return_if_fail (GIMP_IS_IMAGE (private->image));
+
+  for (iter = display->gimp->context_list; iter; iter = g_list_next (iter))
+    {
+      GimpContext *context = iter->data;
+
+      if (gimp_context_get_display (context) == display)
+        gimp_context_set_image (context, NULL);
+    }
+
+  gimp_display_set_image (display, NULL);
+
+  gimp_display_shell_empty (gimp_display_get_shell (display));
+}
+
+void
+gimp_display_fill (GimpDisplay *display,
+                   GimpImage   *image,
+                   GimpUnit     unit,
+                   gdouble      scale)
+{
+  GimpDisplayPrivate *private;
+
+  g_return_if_fail (GIMP_IS_DISPLAY (display));
+  g_return_if_fail (GIMP_IS_IMAGE (image));
+
+  private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  g_return_if_fail (private->image == NULL);
+
+  gimp_display_set_image (display, image);
+
+  gimp_display_shell_fill (gimp_display_get_shell (display),
+                           image, unit, scale);
+}
+
+void
+gimp_display_update_bounding_box (GimpDisplay *display)
+{
+  GimpDisplayPrivate *private;
+  GimpDisplayShell   *shell;
+  GeglRectangle       bounding_box = {};
+
+  g_return_if_fail (GIMP_IS_DISPLAY (display));
+
+  private = GIMP_DISPLAY_GET_PRIVATE (display);
+  shell   = gimp_display_get_shell (display);
+
+  if (shell)
+    {
+      bounding_box = gimp_display_shell_get_bounding_box (shell);
+
+      if (! gegl_rectangle_equal (&bounding_box, &private->bounding_box))
+        {
+          GeglRectangle diff_rects[4];
+          gint          n_diff_rects;
+          gint          i;
+
+          n_diff_rects = gegl_rectangle_subtract (diff_rects,
+                                                  &private->bounding_box,
+                                                  &bounding_box);
+
+          for (i = 0; i < n_diff_rects; i++)
+            {
+              gimp_display_paint_area (display,
+                                       diff_rects[i].x,     diff_rects[i].y,
+                                       diff_rects[i].width, diff_rects[i].height);
+            }
+
+          private->bounding_box = bounding_box;
+
+          gimp_display_shell_scroll_clamp_and_update (shell);
+          gimp_display_shell_scrollbars_update (shell);
+        }
+    }
+  else
+    {
+      private->bounding_box = bounding_box;
+    }
+}
+
+void
+gimp_display_update_area (GimpDisplay *display,
+                          gboolean     now,
+                          gint         x,
+                          gint         y,
+                          gint         w,
+                          gint         h)
+{
+  GimpDisplayPrivate *private;
+
+  g_return_if_fail (GIMP_IS_DISPLAY (display));
+
+  private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  if (now)
+    {
+      gimp_display_paint_area (display, x, y, w, h);
+    }
+  else
+    {
+      cairo_rectangle_int_t rect;
+      gint                  image_width;
+      gint                  image_height;
+
+      image_width  = gimp_image_get_width  (private->image);
+      image_height = gimp_image_get_height (private->image);
+
+      rect.x      = CLAMP (x,     0, image_width);
+      rect.y      = CLAMP (y,     0, image_height);
+      rect.width  = CLAMP (x + w, 0, image_width)  - rect.x;
+      rect.height = CLAMP (y + h, 0, image_height) - rect.y;
+
+      if (private->update_region)
+        cairo_region_union_rectangle (private->update_region, &rect);
+      else
+        private->update_region = cairo_region_create_rectangle (&rect);
+    }
+}
+
+void
+gimp_display_flush (GimpDisplay *display)
+{
+  g_return_if_fail (GIMP_IS_DISPLAY (display));
+
+  /* FIXME: we can end up being called during shell construction if "show all"
+   * is enabled by default, in which case the shell's display pointer is still
+   * NULL
+   */
+  if (gimp_display_get_shell (display))
+    gimp_display_flush_whenever (display, FALSE);
+}
+
+void
+gimp_display_flush_now (GimpDisplay *display)
+{
+  g_return_if_fail (GIMP_IS_DISPLAY (display));
+
+  gimp_display_flush_whenever (display, TRUE);
+}
+
+
+/*  private functions  */
+
+static void
+gimp_display_flush_whenever (GimpDisplay *display,
+                             gboolean     now)
+{
+  GimpDisplayPrivate *private = GIMP_DISPLAY_GET_PRIVATE (display);
+
+  if (private->update_region)
+    {
+      gint n_rects = cairo_region_num_rectangles (private->update_region);
+      gint i;
+
+      for (i = 0; i < n_rects; i++)
+        {
+          cairo_rectangle_int_t rect;
+
+          cairo_region_get_rectangle (private->update_region,
+                                      i, &rect);
+
+          gimp_display_paint_area (display,
+                                   rect.x,
+                                   rect.y,
+                                   rect.width,
+                                   rect.height);
+        }
+
+      g_clear_pointer (&private->update_region, cairo_region_destroy);
+    }
+
+  if (now)
+    {
+      guint64 now = g_get_monotonic_time ();
+
+      if ((now - private->last_flush_now) > FLUSH_NOW_INTERVAL)
+        {
+          gimp_display_shell_flush (gimp_display_get_shell (display), TRUE);
+
+          private->last_flush_now = now;
+        }
+    }
+  else
+    {
+      gimp_display_shell_flush (gimp_display_get_shell (display), now);
+    }
+}
+
+static void
+gimp_display_paint_area (GimpDisplay *display,
+                         gint         x,
+                         gint         y,
+                         gint         w,
+                         gint         h)
+{
+  GimpDisplayPrivate *private = GIMP_DISPLAY_GET_PRIVATE (display);
+  GimpDisplayShell   *shell   = gimp_display_get_shell (display);
+  GeglRectangle       rect;
+  gint                x1, y1, x2, y2;
+  gdouble             x1_f, y1_f, x2_f, y2_f;
+
+  if (! gegl_rectangle_intersect (&rect,
+                                  &private->bounding_box,
+                                  GEGL_RECTANGLE (x, y, w, h)))
+    {
+      return;
+    }
+
+  /*  display the area  */
+  gimp_display_shell_transform_bounds (shell,
+                                       rect.x,
+                                       rect.y,
+                                       rect.x + rect.width,
+                                       rect.y + rect.height,
+                                       &x1_f, &y1_f, &x2_f, &y2_f);
+
+  /*  make sure to expose a superset of the transformed sub-pixel expose
+   *  area, not a subset. bug #126942. --mitch
+   *
+   *  also accommodate for spill introduced by potential box filtering.
+   *  (bug #474509). --simon
+   */
+  x1 = floor (x1_f - 0.5);
+  y1 = floor (y1_f - 0.5);
+  x2 = ceil (x2_f + 0.5);
+  y2 = ceil (y2_f + 0.5);
+
+  /*  align transformed area to a coarse grid, to simplify the
+   *  invalidated area
+   */
+  x1 = floor ((gdouble) x1 / PAINT_AREA_CHUNK_WIDTH)  * PAINT_AREA_CHUNK_WIDTH;
+  y1 = floor ((gdouble) y1 / PAINT_AREA_CHUNK_HEIGHT) * PAINT_AREA_CHUNK_HEIGHT;
+  x2 = ceil  ((gdouble) x2 / PAINT_AREA_CHUNK_WIDTH)  * PAINT_AREA_CHUNK_WIDTH;
+  y2 = ceil  ((gdouble) y2 / PAINT_AREA_CHUNK_HEIGHT) * PAINT_AREA_CHUNK_HEIGHT;
+
+  gimp_display_shell_expose_area (shell, x1, y1, x2 - x1, y2 - y1);
+}