Adding upstream version 2.10.34.upstream/2.10.34upstream

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

1 files changed, 1465 insertions, 0 deletions

diff --git a/libgimpwidgets/gimpruler.c b/libgimpwidgets/gimpruler.c
new file mode 100644
index 0000000..db9f538
--- /dev/null
+++ b/libgimpwidgets/gimpruler.c
@@ -0,0 +1,1465 @@
+/* LIBGIMP - The GIMP Library
+ * Copyright (C) 1995-1997 Peter Mattis and Spencer Kimball
+ *
+ * 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 3 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
+ * <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include <gtk/gtk.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+
+#include "gimpwidgetstypes.h"
+
+#include "gimpruler.h"
+
+
+/**
+ * SECTION: gimpruler
+ * @title: GimpRuler
+ * @short_description: A ruler widget with configurable unit and orientation.
+ *
+ * A ruler widget with configurable unit and orientation.
+ **/
+
+
+#define DEFAULT_RULER_FONT_SCALE    PANGO_SCALE_SMALL
+#define MINIMUM_INCR                5
+#define IMMEDIATE_REDRAW_THRESHOLD  20
+
+
+enum
+{
+  PROP_0,
+  PROP_ORIENTATION,
+  PROP_UNIT,
+  PROP_LOWER,
+  PROP_UPPER,
+  PROP_POSITION,
+  PROP_MAX_SIZE
+};
+
+
+/* All distances below are in 1/72nd's of an inch. (According to
+ * Adobe that's a point, but points are really 1/72.27 in.)
+ */
+typedef struct
+{
+  GtkOrientation   orientation;
+  GimpUnit         unit;
+  gdouble          lower;
+  gdouble          upper;
+  gdouble          position;
+  gdouble          max_size;
+
+  GdkWindow       *input_window;
+  cairo_surface_t *backing_store;
+  gboolean         backing_store_valid;
+  GdkRectangle     last_pos_rect;
+  guint            pos_redraw_idle_id;
+  PangoLayout     *layout;
+  gdouble          font_scale;
+
+  GList           *track_widgets;
+} GimpRulerPrivate;
+
+#define GIMP_RULER_GET_PRIVATE(ruler) \
+  ((GimpRulerPrivate *) gimp_ruler_get_instance_private ((GimpRuler *) (ruler)))
+
+
+typedef struct
+{
+  const gdouble  ruler_scale[16];
+  const gint     subdivide[5];
+} RulerMetric;
+
+static const RulerMetric ruler_metric_decimal =
+{
+  { 1, 2, 5, 10, 25, 50, 100, 250, 500, 1000, 2500, 5000, 10000, 25000, 50000, 100000 },
+  { 1, 5, 10, 50, 100 }
+};
+
+static const RulerMetric ruler_metric_inches =
+{
+  { 1, 2, 6, 12, 36, 100, 250, 500, 1000, 2500, 5000, 10000, 25000, 50000, 100000 },
+  { 1, 4, 8, 16, 12 * 16 }
+};
+
+static const RulerMetric ruler_metric_feet =
+{
+  { 1, 2, 6, 12, 36, 100, 250, 500, 1000, 2500, 5000, 10000, 25000, 50000, 100000 },
+  { 1, 3, 6, 12, 12 * 8 }
+};
+
+static const RulerMetric ruler_metric_yards =
+{
+  { 1, 2, 6, 12, 36, 100, 250, 500, 1000, 2500, 5000, 10000, 25000, 50000, 100000 },
+  { 1, 3, 6, 12, 12 * 12 }
+};
+
+
+static void          gimp_ruler_dispose               (GObject        *object);
+static void          gimp_ruler_set_property          (GObject        *object,
+                                                       guint           prop_id,
+                                                       const GValue   *value,
+                                                       GParamSpec     *pspec);
+static void          gimp_ruler_get_property          (GObject        *object,
+                                                       guint           prop_id,
+                                                       GValue         *value,
+                                                       GParamSpec     *pspec);
+
+static void          gimp_ruler_realize               (GtkWidget      *widget);
+static void          gimp_ruler_unrealize             (GtkWidget      *widget);
+static void          gimp_ruler_map                   (GtkWidget      *widget);
+static void          gimp_ruler_unmap                 (GtkWidget      *widget);
+static void          gimp_ruler_size_allocate         (GtkWidget      *widget,
+                                                       GtkAllocation  *allocation);
+static void          gimp_ruler_size_request          (GtkWidget      *widget,
+                                                       GtkRequisition *requisition);
+static void          gimp_ruler_style_set             (GtkWidget      *widget,
+                                                       GtkStyle       *prev_style);
+static gboolean      gimp_ruler_motion_notify         (GtkWidget      *widget,
+                                                       GdkEventMotion *event);
+static gboolean      gimp_ruler_expose                (GtkWidget      *widget,
+                                                       GdkEventExpose *event);
+
+static void          gimp_ruler_draw_ticks            (GimpRuler      *ruler);
+static GdkRectangle  gimp_ruler_get_pos_rect          (GimpRuler      *ruler,
+                                                       gdouble         position);
+static gboolean      gimp_ruler_idle_queue_pos_redraw (gpointer        data);
+static void          gimp_ruler_queue_pos_redraw      (GimpRuler      *ruler);
+static void          gimp_ruler_draw_pos              (GimpRuler      *ruler,
+                                                       cairo_t        *cr);
+static void          gimp_ruler_make_pixmap           (GimpRuler      *ruler);
+static PangoLayout * gimp_ruler_get_layout            (GtkWidget      *widget,
+                                                       const gchar    *text);
+static const RulerMetric *
+                     gimp_ruler_get_metric            (GimpUnit        unit);
+
+
+G_DEFINE_TYPE_WITH_PRIVATE (GimpRuler, gimp_ruler, GTK_TYPE_WIDGET)
+
+#define parent_class gimp_ruler_parent_class
+
+
+static void
+gimp_ruler_class_init (GimpRulerClass *klass)
+{
+  GObjectClass   *object_class = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  object_class->dispose             = gimp_ruler_dispose;
+  object_class->set_property        = gimp_ruler_set_property;
+  object_class->get_property        = gimp_ruler_get_property;
+
+  widget_class->realize             = gimp_ruler_realize;
+  widget_class->unrealize           = gimp_ruler_unrealize;
+  widget_class->map                 = gimp_ruler_map;
+  widget_class->unmap               = gimp_ruler_unmap;
+  widget_class->size_allocate       = gimp_ruler_size_allocate;
+  widget_class->size_request        = gimp_ruler_size_request;
+  widget_class->style_set           = gimp_ruler_style_set;
+  widget_class->motion_notify_event = gimp_ruler_motion_notify;
+  widget_class->expose_event        = gimp_ruler_expose;
+
+  g_object_class_install_property (object_class,
+                                   PROP_ORIENTATION,
+                                   g_param_spec_enum ("orientation",
+                                                      "Orientation",
+                                                      "The orientation of the ruler",
+                                                      GTK_TYPE_ORIENTATION,
+                                                      GTK_ORIENTATION_HORIZONTAL,
+                                                      GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class,
+                                   PROP_UNIT,
+                                   gimp_param_spec_unit ("unit",
+                                                         "Unit",
+                                                         "Unit of ruler",
+                                                         TRUE, TRUE,
+                                                         GIMP_UNIT_PIXEL,
+                                                         GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class,
+                                   PROP_LOWER,
+                                   g_param_spec_double ("lower",
+                                                        "Lower",
+                                                        "Lower limit of ruler",
+                                                        -G_MAXDOUBLE,
+                                                        G_MAXDOUBLE,
+                                                        0.0,
+                                                        GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class,
+                                   PROP_UPPER,
+                                   g_param_spec_double ("upper",
+                                                        "Upper",
+                                                        "Upper limit of ruler",
+                                                        -G_MAXDOUBLE,
+                                                        G_MAXDOUBLE,
+                                                        0.0,
+                                                        GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class,
+                                   PROP_POSITION,
+                                   g_param_spec_double ("position",
+                                                        "Position",
+                                                        "Position of mark on the ruler",
+                                                        -G_MAXDOUBLE,
+                                                        G_MAXDOUBLE,
+                                                        0.0,
+                                                        GIMP_PARAM_READWRITE));
+
+  g_object_class_install_property (object_class,
+                                   PROP_MAX_SIZE,
+                                   g_param_spec_double ("max-size",
+                                                        "Max Size",
+                                                        "Maximum size of the ruler",
+                                                        -G_MAXDOUBLE,
+                                                        G_MAXDOUBLE,
+                                                        0.0,
+                                                        GIMP_PARAM_READWRITE));
+
+  gtk_widget_class_install_style_property (widget_class,
+                                           g_param_spec_double ("font-scale",
+                                                                "Font Scale",
+                                                                "The size of the used font",
+                                                                0.0,
+                                                                G_MAXDOUBLE,
+                                                                DEFAULT_RULER_FONT_SCALE,
+                                                                GIMP_PARAM_READABLE));
+}
+
+static void
+gimp_ruler_init (GimpRuler *ruler)
+{
+  GimpRulerPrivate *priv = GIMP_RULER_GET_PRIVATE (ruler);
+
+  gtk_widget_set_has_window (GTK_WIDGET (ruler), FALSE);
+
+  priv->orientation         = GTK_ORIENTATION_HORIZONTAL;
+  priv->unit                = GIMP_UNIT_PIXEL;
+  priv->lower               = 0;
+  priv->upper               = 0;
+  priv->position            = 0;
+  priv->max_size            = 0;
+
+  priv->backing_store       = NULL;
+  priv->backing_store_valid = FALSE;
+
+  priv->last_pos_rect.x      = 0;
+  priv->last_pos_rect.y      = 0;
+  priv->last_pos_rect.width  = 0;
+  priv->last_pos_rect.height = 0;
+  priv->pos_redraw_idle_id   = 0;
+
+  priv->font_scale          = DEFAULT_RULER_FONT_SCALE;
+}
+
+static void
+gimp_ruler_dispose (GObject *object)
+{
+  GimpRuler        *ruler = GIMP_RULER (object);
+  GimpRulerPrivate *priv  = GIMP_RULER_GET_PRIVATE (ruler);
+
+  while (priv->track_widgets)
+    gimp_ruler_remove_track_widget (ruler, priv->track_widgets->data);
+
+  if (priv->pos_redraw_idle_id)
+    {
+      g_source_remove (priv->pos_redraw_idle_id);
+      priv->pos_redraw_idle_id = 0;
+    }
+
+  G_OBJECT_CLASS (parent_class)->dispose (object);
+}
+
+static void
+gimp_ruler_set_property (GObject      *object,
+                         guint         prop_id,
+                         const GValue *value,
+                         GParamSpec   *pspec)
+{
+  GimpRuler        *ruler = GIMP_RULER (object);
+  GimpRulerPrivate *priv  = GIMP_RULER_GET_PRIVATE (ruler);
+
+  switch (prop_id)
+    {
+    case PROP_ORIENTATION:
+      priv->orientation = g_value_get_enum (value);
+      gtk_widget_queue_resize (GTK_WIDGET (ruler));
+      break;
+
+    case PROP_UNIT:
+      gimp_ruler_set_unit (ruler, g_value_get_int (value));
+      break;
+
+    case PROP_LOWER:
+      gimp_ruler_set_range (ruler,
+                            g_value_get_double (value),
+                            priv->upper,
+                            priv->max_size);
+      break;
+    case PROP_UPPER:
+      gimp_ruler_set_range (ruler,
+                            priv->lower,
+                            g_value_get_double (value),
+                            priv->max_size);
+      break;
+
+    case PROP_POSITION:
+      gimp_ruler_set_position (ruler, g_value_get_double (value));
+      break;
+
+    case PROP_MAX_SIZE:
+      gimp_ruler_set_range (ruler,
+                            priv->lower,
+                            priv->upper,
+                            g_value_get_double (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gimp_ruler_get_property (GObject    *object,
+                         guint       prop_id,
+                         GValue     *value,
+                         GParamSpec *pspec)
+{
+  GimpRuler        *ruler = GIMP_RULER (object);
+  GimpRulerPrivate *priv  = GIMP_RULER_GET_PRIVATE (ruler);
+
+  switch (prop_id)
+    {
+    case PROP_ORIENTATION:
+      g_value_set_enum (value, priv->orientation);
+      break;
+
+    case PROP_UNIT:
+      g_value_set_int (value, priv->unit);
+      break;
+
+    case PROP_LOWER:
+      g_value_set_double (value, priv->lower);
+      break;
+
+    case PROP_UPPER:
+      g_value_set_double (value, priv->upper);
+      break;
+
+    case PROP_POSITION:
+      g_value_set_double (value, priv->position);
+      break;
+
+    case PROP_MAX_SIZE:
+      g_value_set_double (value, priv->max_size);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+/**
+ * gimp_ruler_new:
+ * @orientation: the ruler's orientation.
+ *
+ * Creates a new ruler.
+ *
+ * Return value: a new #GimpRuler widget.
+ *
+ * Since: 2.8
+ **/
+GtkWidget *
+gimp_ruler_new (GtkOrientation orientation)
+{
+  return g_object_new (GIMP_TYPE_RULER,
+                       "orientation", orientation,
+                       NULL);
+}
+
+static void
+gimp_ruler_update_position (GimpRuler *ruler,
+                            gdouble    x,
+                            gdouble    y)
+{
+  GimpRulerPrivate *priv = GIMP_RULER_GET_PRIVATE (ruler);
+  GtkAllocation     allocation;
+  gdouble           lower;
+  gdouble           upper;
+
+  gtk_widget_get_allocation (GTK_WIDGET (ruler), &allocation);
+  gimp_ruler_get_range (ruler, &lower, &upper, NULL);
+
+  if (priv->orientation == GTK_ORIENTATION_HORIZONTAL)
+    {
+      gimp_ruler_set_position (ruler,
+                               lower +
+                               (upper - lower) * x / allocation.width);
+    }
+  else
+    {
+      gimp_ruler_set_position (ruler,
+                               lower +
+                               (upper - lower) * y / allocation.height);
+    }
+}
+
+/* Returns TRUE if a translation should be done */
+static gboolean
+gtk_widget_get_translation_to_window (GtkWidget *widget,
+                                      GdkWindow *window,
+                                      int       *x,
+                                      int       *y)
+{
+  GdkWindow *w, *widget_window;
+
+  if (! gtk_widget_get_has_window (widget))
+    {
+      GtkAllocation allocation;
+
+      gtk_widget_get_allocation (widget, &allocation);
+
+      *x = -allocation.x;
+      *y = -allocation.y;
+    }
+  else
+    {
+      *x = 0;
+      *y = 0;
+    }
+
+  widget_window = gtk_widget_get_window (widget);
+
+  for (w = window;
+       w && w != widget_window;
+       w = gdk_window_get_effective_parent (w))
+    {
+      gdouble px, py;
+
+      gdk_window_coords_to_parent (w, *x, *y, &px, &py);
+
+      *x += px;
+      *y += py;
+    }
+
+  if (w == NULL)
+    {
+      *x = 0;
+      *y = 0;
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+static void
+gimp_ruler_event_to_widget_coords (GtkWidget *widget,
+                                   GdkWindow *window,
+                                   gdouble    event_x,
+                                   gdouble    event_y,
+                                   gint      *widget_x,
+                                   gint      *widget_y)
+{
+  gint tx, ty;
+
+  if (gtk_widget_get_translation_to_window (widget, window, &tx, &ty))
+    {
+      event_x += tx;
+      event_y += ty;
+    }
+
+  *widget_x = event_x;
+  *widget_y = event_y;
+}
+
+static gboolean
+gimp_ruler_track_widget_motion_notify (GtkWidget      *widget,
+                                       GdkEventMotion *mevent,
+                                       GimpRuler      *ruler)
+{
+  gint widget_x;
+  gint widget_y;
+  gint ruler_x;
+  gint ruler_y;
+
+  widget = gtk_get_event_widget ((GdkEvent *) mevent);
+
+  gimp_ruler_event_to_widget_coords (widget, mevent->window,
+                                     mevent->x, mevent->y,
+                                     &widget_x, &widget_y);
+
+  if (gtk_widget_translate_coordinates (widget, GTK_WIDGET (ruler),
+                                        widget_x, widget_y,
+                                        &ruler_x, &ruler_y))
+    {
+      gimp_ruler_update_position (ruler, ruler_x, ruler_y);
+    }
+
+  return FALSE;
+}
+
+/**
+ * gimp_ruler_add_track_widget:
+ * @ruler: a #GimpRuler
+ * @widget: the track widget to add
+ *
+ * Adds a "track widget" to the ruler. The ruler will connect to
+ * GtkWidget:motion-notify-event: on the track widget and update its
+ * position marker accordingly. The marker is correctly updated also
+ * for the track widget's children, regardless of whether they are
+ * ordinary children of off-screen children.
+ *
+ * Since: 2.8
+ */
+void
+gimp_ruler_add_track_widget (GimpRuler *ruler,
+                             GtkWidget *widget)
+{
+  GimpRulerPrivate *priv;
+
+  g_return_if_fail (GIMP_IS_RULER (ruler));
+  g_return_if_fail (GTK_IS_WIDGET (ruler));
+
+  priv = GIMP_RULER_GET_PRIVATE (ruler);
+
+  g_return_if_fail (g_list_find (priv->track_widgets, widget) == NULL);
+
+  priv->track_widgets = g_list_prepend (priv->track_widgets, widget);
+
+  g_signal_connect (widget, "motion-notify-event",
+                    G_CALLBACK (gimp_ruler_track_widget_motion_notify),
+                    ruler);
+  g_signal_connect_swapped (widget, "destroy",
+                            G_CALLBACK (gimp_ruler_remove_track_widget),
+                            ruler);
+}
+
+/**
+ * gimp_ruler_remove_track_widget:
+ * @ruler: a #GimpRuler
+ * @widget: the track widget to remove
+ *
+ * Removes a previously added track widget from the ruler. See
+ * gimp_ruler_add_track_widget().
+ *
+ * Since: 2.8
+ */
+void
+gimp_ruler_remove_track_widget (GimpRuler *ruler,
+                                GtkWidget *widget)
+{
+  GimpRulerPrivate *priv;
+
+  g_return_if_fail (GIMP_IS_RULER (ruler));
+  g_return_if_fail (GTK_IS_WIDGET (ruler));
+
+  priv = GIMP_RULER_GET_PRIVATE (ruler);
+
+  g_return_if_fail (g_list_find (priv->track_widgets, widget) != NULL);
+
+  priv->track_widgets = g_list_remove (priv->track_widgets, widget);
+
+  g_signal_handlers_disconnect_by_func (widget,
+                                        gimp_ruler_track_widget_motion_notify,
+                                        ruler);
+  g_signal_handlers_disconnect_by_func (widget,
+                                        gimp_ruler_remove_track_widget,
+                                        ruler);
+}
+
+/**
+ * gimp_ruler_set_unit:
+ * @ruler: a #GimpRuler
+ * @unit:  the #GimpUnit to set the ruler to
+ *
+ * This sets the unit of the ruler.
+ *
+ * Since: 2.8
+ */
+void
+gimp_ruler_set_unit (GimpRuler *ruler,
+                     GimpUnit   unit)
+{
+  GimpRulerPrivate *priv;
+
+  g_return_if_fail (GIMP_IS_RULER (ruler));
+
+  priv = GIMP_RULER_GET_PRIVATE (ruler);
+
+  if (priv->unit != unit)
+    {
+      priv->unit = unit;
+      g_object_notify (G_OBJECT (ruler), "unit");
+
+      priv->backing_store_valid = FALSE;
+      gtk_widget_queue_draw (GTK_WIDGET (ruler));
+    }
+}
+
+/**
+ * gimp_ruler_get_unit:
+ * @ruler: a #GimpRuler
+ *
+ * Return value: the unit currently used in the @ruler widget.
+ *
+ * Since: 2.8
+ **/
+GimpUnit
+gimp_ruler_get_unit (GimpRuler *ruler)
+{
+  g_return_val_if_fail (GIMP_IS_RULER (ruler), 0);
+
+  return GIMP_RULER_GET_PRIVATE (ruler)->unit;
+}
+
+/**
+ * gimp_ruler_set_position:
+ * @ruler: a #GimpRuler
+ * @position: the position to set the ruler to
+ *
+ * This sets the position of the ruler.
+ *
+ * Since: 2.8
+ */
+void
+gimp_ruler_set_position (GimpRuler *ruler,
+                         gdouble    position)
+{
+  GimpRulerPrivate *priv;
+
+  g_return_if_fail (GIMP_IS_RULER (ruler));
+
+  priv = GIMP_RULER_GET_PRIVATE (ruler);
+
+  if (priv->position != position)
+    {
+      GdkRectangle rect;
+      gint xdiff, ydiff;
+
+      priv->position = position;
+      g_object_notify (G_OBJECT (ruler), "position");
+
+      rect = gimp_ruler_get_pos_rect (ruler, priv->position);
+
+      xdiff = rect.x - priv->last_pos_rect.x;
+      ydiff = rect.y - priv->last_pos_rect.y;
+
+      /*
+       * If the position has changed far enough, queue a redraw immediately.
+       * Otherwise, we only queue a redraw in a low priority idle handler, to
+       * allow for other things (like updating the canvas) to run.
+       *
+       * TODO: This might not be necessary any more in GTK3 with the frame
+       *       clock. Investigate this more after the port to GTK3.
+       */
+      if (priv->last_pos_rect.width  != 0 &&
+          priv->last_pos_rect.height != 0 &&
+          (ABS (xdiff) > IMMEDIATE_REDRAW_THRESHOLD ||
+           ABS (ydiff) > IMMEDIATE_REDRAW_THRESHOLD))
+        {
+          if (priv->pos_redraw_idle_id)
+            {
+              g_source_remove (priv->pos_redraw_idle_id);
+              priv->pos_redraw_idle_id = 0;
+            }
+
+          gimp_ruler_queue_pos_redraw (ruler);
+        }
+      else if (! priv->pos_redraw_idle_id)
+        {
+          priv->pos_redraw_idle_id =
+            g_idle_add_full (G_PRIORITY_LOW,
+                             gimp_ruler_idle_queue_pos_redraw,
+                             ruler, NULL);
+        }
+    }
+}
+
+/**
+ * gimp_ruler_get_position:
+ * @ruler: a #GimpRuler
+ *
+ * Return value: the current position of the @ruler widget.
+ *
+ * Since: 2.8
+ **/
+gdouble
+gimp_ruler_get_position (GimpRuler *ruler)
+{
+  g_return_val_if_fail (GIMP_IS_RULER (ruler), 0.0);
+
+  return GIMP_RULER_GET_PRIVATE (ruler)->position;
+}
+
+/**
+ * gimp_ruler_set_range:
+ * @ruler: a #GimpRuler
+ * @lower: the lower limit of the ruler
+ * @upper: the upper limit of the ruler
+ * @max_size: the maximum size of the ruler used when calculating the space to
+ * leave for the text
+ *
+ * This sets the range of the ruler.
+ *
+ * Since: 2.8
+ */
+void
+gimp_ruler_set_range (GimpRuler *ruler,
+                      gdouble    lower,
+                      gdouble    upper,
+                      gdouble    max_size)
+{
+  GimpRulerPrivate *priv;
+
+  g_return_if_fail (GIMP_IS_RULER (ruler));
+
+  priv = GIMP_RULER_GET_PRIVATE (ruler);
+
+  g_object_freeze_notify (G_OBJECT (ruler));
+  if (priv->lower != lower)
+    {
+      priv->lower = lower;
+      g_object_notify (G_OBJECT (ruler), "lower");
+    }
+  if (priv->upper != upper)
+    {
+      priv->upper = upper;
+      g_object_notify (G_OBJECT (ruler), "upper");
+    }
+  if (priv->max_size != max_size)
+    {
+      priv->max_size = max_size;
+      g_object_notify (G_OBJECT (ruler), "max-size");
+    }
+  g_object_thaw_notify (G_OBJECT (ruler));
+
+  priv->backing_store_valid = FALSE;
+  gtk_widget_queue_draw (GTK_WIDGET (ruler));
+}
+
+/**
+ * gimp_ruler_get_range:
+ * @ruler: a #GimpRuler
+ * @lower: location to store lower limit of the ruler, or %NULL
+ * @upper: location to store upper limit of the ruler, or %NULL
+ * @max_size: location to store the maximum size of the ruler used when
+ *            calculating the space to leave for the text, or %NULL.
+ *
+ * Retrieves values indicating the range and current position of a #GimpRuler.
+ * See gimp_ruler_set_range().
+ *
+ * Since: 2.8
+ **/
+void
+gimp_ruler_get_range (GimpRuler *ruler,
+                      gdouble   *lower,
+                      gdouble   *upper,
+                      gdouble   *max_size)
+{
+  GimpRulerPrivate *priv;
+
+  g_return_if_fail (GIMP_IS_RULER (ruler));
+
+  priv = GIMP_RULER_GET_PRIVATE (ruler);
+
+  if (lower)
+    *lower = priv->lower;
+  if (upper)
+    *upper = priv->upper;
+  if (max_size)
+    *max_size = priv->max_size;
+}
+
+static void
+gimp_ruler_realize (GtkWidget *widget)
+{
+  GimpRuler        *ruler = GIMP_RULER (widget);
+  GimpRulerPrivate *priv  = GIMP_RULER_GET_PRIVATE (ruler);
+  GtkAllocation     allocation;
+  GdkWindowAttr     attributes;
+  gint              attributes_mask;
+
+  GTK_WIDGET_CLASS (gimp_ruler_parent_class)->realize (widget);
+
+  gtk_widget_get_allocation (widget, &allocation);
+
+  attributes.window_type = GDK_WINDOW_CHILD;
+  attributes.x           = allocation.x;
+  attributes.y           = allocation.y;
+  attributes.width       = allocation.width;
+  attributes.height      = allocation.height;
+  attributes.wclass      = GDK_INPUT_ONLY;
+  attributes.event_mask  = (gtk_widget_get_events (widget) |
+                            GDK_EXPOSURE_MASK              |
+                            GDK_POINTER_MOTION_MASK);
+
+  attributes_mask = GDK_WA_X | GDK_WA_Y;
+
+  priv->input_window = gdk_window_new (gtk_widget_get_window (widget),
+                                       &attributes, attributes_mask);
+  gdk_window_set_user_data (priv->input_window, ruler);
+
+  gimp_ruler_make_pixmap (ruler);
+}
+
+static void
+gimp_ruler_unrealize (GtkWidget *widget)
+{
+  GimpRuler        *ruler = GIMP_RULER (widget);
+  GimpRulerPrivate *priv  = GIMP_RULER_GET_PRIVATE (ruler);
+
+  g_clear_pointer (&priv->backing_store, cairo_surface_destroy);
+  priv->backing_store_valid = FALSE;
+
+  g_clear_object (&priv->layout);
+
+  g_clear_pointer (&priv->input_window, gdk_window_destroy);
+
+  GTK_WIDGET_CLASS (gimp_ruler_parent_class)->unrealize (widget);
+}
+
+static void
+gimp_ruler_map (GtkWidget *widget)
+{
+  GimpRulerPrivate *priv = GIMP_RULER_GET_PRIVATE (widget);
+
+  GTK_WIDGET_CLASS (parent_class)->map (widget);
+
+  if (priv->input_window)
+    gdk_window_show (priv->input_window);
+}
+
+static void
+gimp_ruler_unmap (GtkWidget *widget)
+{
+  GimpRulerPrivate *priv = GIMP_RULER_GET_PRIVATE (widget);
+
+  if (priv->input_window)
+    gdk_window_hide (priv->input_window);
+
+  GTK_WIDGET_CLASS (parent_class)->unmap (widget);
+}
+
+static void
+gimp_ruler_size_allocate (GtkWidget     *widget,
+                          GtkAllocation *allocation)
+{
+  GimpRuler        *ruler = GIMP_RULER (widget);
+  GimpRulerPrivate *priv  = GIMP_RULER_GET_PRIVATE (ruler);
+  GtkAllocation     widget_allocation;
+  gboolean          resized;
+
+  gtk_widget_get_allocation (widget, &widget_allocation);
+
+  resized = (widget_allocation.width  != allocation->width ||
+             widget_allocation.height != allocation->height);
+
+  GTK_WIDGET_CLASS (parent_class)->size_allocate (widget, allocation);
+
+  if (gtk_widget_get_realized (widget))
+    {
+      gdk_window_move_resize (priv->input_window,
+                              allocation->x, allocation->y,
+                              allocation->width, allocation->height);
+
+      if (resized)
+        gimp_ruler_make_pixmap (ruler);
+    }
+}
+
+static void
+gimp_ruler_size_request (GtkWidget      *widget,
+                         GtkRequisition *requisition)
+{
+  GimpRulerPrivate *priv  = GIMP_RULER_GET_PRIVATE (widget);
+  GtkStyle         *style = gtk_widget_get_style (widget);
+  PangoLayout      *layout;
+  PangoRectangle    ink_rect;
+  gint              size;
+
+  layout = gimp_ruler_get_layout (widget, "0123456789");
+  pango_layout_get_pixel_extents (layout, &ink_rect, NULL);
+
+  size = 2 + ink_rect.height * 1.7;
+
+  if (priv->orientation == GTK_ORIENTATION_HORIZONTAL)
+    {
+      requisition->width  = style->xthickness * 2 + 1;
+      requisition->height = style->ythickness * 2 + size;
+    }
+  else
+    {
+      requisition->width  = style->xthickness * 2 + size;
+      requisition->height = style->ythickness * 2 + 1;
+    }
+}
+
+static void
+gimp_ruler_style_set (GtkWidget *widget,
+                      GtkStyle  *prev_style)
+{
+  GimpRulerPrivate *priv = GIMP_RULER_GET_PRIVATE (widget);
+
+  GTK_WIDGET_CLASS (gimp_ruler_parent_class)->style_set (widget, prev_style);
+
+  gtk_widget_style_get (widget,
+                        "font-scale", &priv->font_scale,
+                        NULL);
+
+  priv->backing_store_valid = FALSE;
+
+  g_clear_object (&priv->layout);
+}
+
+static gboolean
+gimp_ruler_motion_notify (GtkWidget      *widget,
+                          GdkEventMotion *event)
+{
+  GimpRuler *ruler = GIMP_RULER (widget);
+
+  gimp_ruler_update_position (ruler, event->x, event->y);
+
+  return FALSE;
+}
+
+static gboolean
+gimp_ruler_expose (GtkWidget      *widget,
+                   GdkEventExpose *event)
+{
+  if (gtk_widget_is_drawable (widget))
+    {
+      GimpRuler        *ruler = GIMP_RULER (widget);
+      GimpRulerPrivate *priv  = GIMP_RULER_GET_PRIVATE (ruler);
+      GtkAllocation     allocation;
+      cairo_t          *cr;
+
+      if (! priv->backing_store_valid)
+        gimp_ruler_draw_ticks (ruler);
+
+      cr = gdk_cairo_create (gtk_widget_get_window (widget));
+      gdk_cairo_region (cr, event->region);
+      cairo_clip (cr);
+
+      gtk_widget_get_allocation (widget, &allocation);
+      cairo_set_source_surface (cr, priv->backing_store,
+                                allocation.x, allocation.y);
+      cairo_paint (cr);
+
+      gimp_ruler_draw_pos (ruler, cr);
+
+      cairo_destroy (cr);
+    }
+
+  return FALSE;
+}
+
+static void
+gimp_ruler_draw_ticks (GimpRuler *ruler)
+{
+  GtkWidget        *widget = GTK_WIDGET (ruler);
+  GtkStyle         *style  = gtk_widget_get_style (widget);
+  GimpRulerPrivate  *priv   = GIMP_RULER_GET_PRIVATE (ruler);
+  GtkStateType       state  = gtk_widget_get_state (widget);
+  GtkAllocation      allocation;
+  cairo_t           *cr;
+  gint               i;
+  gint               width, height;
+  gint               xthickness;
+  gint               ythickness;
+  gint               length, ideal_length;
+  gdouble            lower, upper;  /* Upper and lower limits, in ruler units */
+  gdouble            increment;     /* Number of pixels per unit */
+  gint               scale;         /* Number of units per major unit */
+  gdouble            start, end, cur;
+  gchar              unit_str[32];
+  gint               digit_height;
+  gint               digit_offset;
+  gint               text_size;
+  gint               pos;
+  gdouble            max_size;
+  GimpUnit           unit;
+  PangoLayout       *layout;
+  PangoRectangle     logical_rect, ink_rect;
+  const RulerMetric *ruler_metric;
+
+  if (! gtk_widget_is_drawable (widget))
+    return;
+
+  gtk_widget_get_allocation (widget, &allocation);
+
+  xthickness = style->xthickness;
+  ythickness = style->ythickness;
+
+  layout = gimp_ruler_get_layout (widget, "0123456789");
+  pango_layout_get_extents (layout, &ink_rect, &logical_rect);
+
+  digit_height = PANGO_PIXELS (ink_rect.height) + 2;
+  digit_offset = ink_rect.y;
+
+  if (priv->orientation == GTK_ORIENTATION_HORIZONTAL)
+    {
+      width  = allocation.width;
+      height = allocation.height - ythickness * 2;
+    }
+  else
+    {
+      width  = allocation.height;
+      height = allocation.width - ythickness * 2;
+    }
+
+  cr = cairo_create (priv->backing_store);
+  gdk_cairo_set_source_color (cr, &style->bg[state]);
+
+#if 0
+  gtk_paint_box (style, priv->backing_store,
+                 GTK_STATE_NORMAL, GTK_SHADOW_OUT,
+                 NULL, widget,
+                 priv->orientation == GTK_ORIENTATION_HORIZONTAL ?
+                 "hruler" : "vruler",
+                 0, 0,
+                 allocation.width, allocation.height);
+#else
+  cairo_paint (cr);
+#endif
+
+  gdk_cairo_set_source_color (cr, &style->fg[state]);
+
+  if (priv->orientation == GTK_ORIENTATION_HORIZONTAL)
+    {
+      cairo_rectangle (cr,
+                       xthickness,
+                       height + ythickness,
+                       allocation.width - 2 * xthickness,
+                       1);
+    }
+  else
+    {
+      cairo_rectangle (cr,
+                       height + xthickness,
+                       ythickness,
+                       1,
+                       allocation.height - 2 * ythickness);
+    }
+
+  gimp_ruler_get_range (ruler, &lower, &upper, &max_size);
+
+  if ((upper - lower) == 0)
+    goto out;
+
+  increment = (gdouble) width / (upper - lower);
+
+  /* determine the scale
+   *   use the maximum extents of the ruler to determine the largest
+   *   possible number to be displayed.  Calculate the height in pixels
+   *   of this displayed text. Use this height to find a scale which
+   *   leaves sufficient room for drawing the ruler.
+   *
+   *   We calculate the text size as for the vruler instead of
+   *   actually measuring the text width, so that the result for the
+   *   scale looks consistent with an accompanying vruler.
+   */
+  scale = ceil (max_size);
+  g_snprintf (unit_str, sizeof (unit_str), "%d", scale);
+  text_size = strlen (unit_str) * digit_height + 1;
+
+  unit = gimp_ruler_get_unit (ruler);
+
+  ruler_metric = gimp_ruler_get_metric (unit);
+
+  for (scale = 0; scale < G_N_ELEMENTS (ruler_metric->ruler_scale); scale++)
+    if (ruler_metric->ruler_scale[scale] * fabs (increment) > 2 * text_size)
+      break;
+
+  if (scale == G_N_ELEMENTS (ruler_metric->ruler_scale))
+    scale = G_N_ELEMENTS (ruler_metric->ruler_scale) - 1;
+
+  /* drawing starts here */
+  length = 0;
+  for (i = G_N_ELEMENTS (ruler_metric->subdivide) - 1; i >= 0; i--)
+    {
+      gdouble subd_incr;
+
+      /* hack to get proper subdivisions at full pixels */
+      if (unit == GIMP_UNIT_PIXEL && scale == 1 && i == 1)
+        subd_incr = 1.0;
+      else
+        subd_incr = ((gdouble) ruler_metric->ruler_scale[scale] /
+                     (gdouble) ruler_metric->subdivide[i]);
+
+      if (subd_incr * fabs (increment) <= MINIMUM_INCR)
+        continue;
+
+      /* don't subdivide pixels */
+      if (unit == GIMP_UNIT_PIXEL && subd_incr < 1.0)
+        continue;
+
+      /* Calculate the length of the tickmarks. Make sure that
+       * this length increases for each set of ticks
+       */
+      ideal_length = height / (i + 1) - 1;
+      if (ideal_length > ++length)
+        length = ideal_length;
+
+      if (lower < upper)
+        {
+          start = floor (lower / subd_incr) * subd_incr;
+          end   = ceil  (upper / subd_incr) * subd_incr;
+        }
+      else
+        {
+          start = floor (upper / subd_incr) * subd_incr;
+          end   = ceil  (lower / subd_incr) * subd_incr;
+        }
+
+      for (cur = start; cur <= end; cur += subd_incr)
+        {
+          pos = ROUND ((cur - lower) * increment);
+
+          if (priv->orientation == GTK_ORIENTATION_HORIZONTAL)
+            {
+              cairo_rectangle (cr,
+                               pos, height + ythickness - length,
+                               1,   length);
+            }
+          else
+            {
+              cairo_rectangle (cr,
+                               height + xthickness - length, pos,
+                               length,                       1);
+            }
+
+          /* draw label */
+          if (i == 0)
+            {
+              g_snprintf (unit_str, sizeof (unit_str), "%d", (int) cur);
+
+              if (priv->orientation == GTK_ORIENTATION_HORIZONTAL)
+                {
+                  pango_layout_set_text (layout, unit_str, -1);
+                  pango_layout_get_extents (layout, &logical_rect, NULL);
+
+#if 0
+                  gtk_paint_layout (style,
+                                    priv->backing_store,
+                                    state,
+                                    FALSE,
+                                    NULL,
+                                    widget,
+                                    "hruler",
+                                    pos + 2,
+                                    ythickness + PANGO_PIXELS (logical_rect.y - digit_offset),
+                                    layout);
+#else
+                  cairo_move_to (cr,
+                                 pos + 2,
+                                 ythickness + PANGO_PIXELS (logical_rect.y - digit_offset));
+                  pango_cairo_show_layout (cr, layout);
+#endif
+                }
+              else
+                {
+                  gint j;
+
+                  for (j = 0; j < (int) strlen (unit_str); j++)
+                    {
+                      pango_layout_set_text (layout, unit_str + j, 1);
+                      pango_layout_get_extents (layout, NULL, &logical_rect);
+
+#if 0
+                      gtk_paint_layout (style,
+                                        priv->backing_store,
+                                        state,
+                                        FALSE,
+                                        NULL,
+                                        widget,
+                                        "vruler",
+                                        xthickness + 1,
+                                        pos + digit_height * j + 2 + PANGO_PIXELS (logical_rect.y - digit_offset),
+                                        layout);
+#else
+                      cairo_move_to (cr,
+                                     xthickness + 1,
+                                     pos + digit_height * j + 2 + PANGO_PIXELS (logical_rect.y - digit_offset));
+                      pango_cairo_show_layout (cr, layout);
+#endif
+
+                    }
+                }
+            }
+        }
+    }
+
+  cairo_fill (cr);
+
+  priv->backing_store_valid = TRUE;
+
+out:
+  cairo_destroy (cr);
+}
+
+static GdkRectangle
+gimp_ruler_get_pos_rect (GimpRuler *ruler,
+                         gdouble    position)
+{
+  GtkWidget        *widget = GTK_WIDGET (ruler);
+  GtkStyle         *style  = gtk_widget_get_style (widget);
+  GimpRulerPrivate *priv   = GIMP_RULER_GET_PRIVATE (ruler);
+  GtkAllocation     allocation;
+  gint              width, height;
+  gint              xthickness;
+  gint              ythickness;
+  gdouble           upper, lower;
+  gdouble           increment;
+  GdkRectangle      rect = { 0, };
+
+  if (! gtk_widget_is_drawable (widget))
+    return rect;
+
+  gtk_widget_get_allocation (widget, &allocation);
+
+  xthickness = style->xthickness;
+  ythickness = style->ythickness;
+
+  if (priv->orientation == GTK_ORIENTATION_HORIZONTAL)
+    {
+      width  = allocation.width;
+      height = allocation.height - ythickness * 2;
+
+      rect.width = height / 2 + 2;
+      rect.width |= 1;  /* make sure it's odd */
+      rect.height = rect.width / 2 + 1;
+    }
+  else
+    {
+      width  = allocation.width - xthickness * 2;
+      height = allocation.height;
+
+      rect.height = width / 2 + 2;
+      rect.height |= 1;  /* make sure it's odd */
+      rect.width = rect.height / 2 + 1;
+    }
+
+  gimp_ruler_get_range (ruler, &lower, &upper, NULL);
+
+  if (priv->orientation == GTK_ORIENTATION_HORIZONTAL)
+    {
+      increment = (gdouble) width / (upper - lower);
+
+      rect.x = ROUND ((position - lower) * increment) + (xthickness - rect.width) / 2 - 1;
+      rect.y = (height + rect.height) / 2 + ythickness;
+    }
+  else
+    {
+      increment = (gdouble) height / (upper - lower);
+
+      rect.x = (width + rect.width) / 2 + xthickness;
+      rect.y = ROUND ((position - lower) * increment) + (ythickness - rect.height) / 2 - 1;
+    }
+
+  rect.x += allocation.x;
+  rect.y += allocation.y;
+
+  return rect;
+}
+
+static gboolean
+gimp_ruler_idle_queue_pos_redraw (gpointer data)
+{
+  GimpRuler        *ruler = data;
+  GimpRulerPrivate *priv  = GIMP_RULER_GET_PRIVATE (ruler);
+
+  gimp_ruler_queue_pos_redraw (ruler);
+
+  priv->pos_redraw_idle_id = 0;
+
+  return G_SOURCE_REMOVE;
+}
+
+static void
+gimp_ruler_queue_pos_redraw (GimpRuler *ruler)
+{
+  GimpRulerPrivate  *priv = GIMP_RULER_GET_PRIVATE (ruler);
+  const GdkRectangle rect = gimp_ruler_get_pos_rect (ruler, priv->position);
+
+  gtk_widget_queue_draw_area (GTK_WIDGET (ruler),
+                              rect.x,
+                              rect.y,
+                              rect.width,
+                              rect.height);
+
+  if (priv->last_pos_rect.width  != 0 &&
+      priv->last_pos_rect.height != 0)
+    {
+      gtk_widget_queue_draw_area (GTK_WIDGET (ruler),
+                                  priv->last_pos_rect.x,
+                                  priv->last_pos_rect.y,
+                                  priv->last_pos_rect.width,
+                                  priv->last_pos_rect.height);
+
+      priv->last_pos_rect.x      = 0;
+      priv->last_pos_rect.y      = 0;
+      priv->last_pos_rect.width  = 0;
+      priv->last_pos_rect.height = 0;
+    }
+}
+
+static void
+gimp_ruler_draw_pos (GimpRuler *ruler,
+                     cairo_t   *cr)
+{
+  GtkWidget        *widget = GTK_WIDGET (ruler);
+  GtkStyle         *style  = gtk_widget_get_style (widget);
+  GimpRulerPrivate *priv   = GIMP_RULER_GET_PRIVATE (ruler);
+  GtkStateType      state  = gtk_widget_get_state (widget);
+  GdkRectangle      pos_rect;
+
+  if (! gtk_widget_is_drawable (widget))
+    return;
+
+  pos_rect = gimp_ruler_get_pos_rect (ruler, gimp_ruler_get_position (ruler));
+
+  if ((pos_rect.width > 0) && (pos_rect.height > 0))
+    {
+      gdk_cairo_set_source_color (cr, &style->fg[state]);
+
+      cairo_move_to (cr, pos_rect.x, pos_rect.y);
+
+      if (priv->orientation == GTK_ORIENTATION_HORIZONTAL)
+        {
+          cairo_line_to (cr, pos_rect.x + pos_rect.width / 2.0,
+                             pos_rect.y + pos_rect.height);
+          cairo_line_to (cr, pos_rect.x + pos_rect.width,
+                             pos_rect.y);
+        }
+      else
+        {
+          cairo_line_to (cr, pos_rect.x + pos_rect.width,
+                             pos_rect.y + pos_rect.height / 2.0);
+          cairo_line_to (cr, pos_rect.x,
+                             pos_rect.y + pos_rect.height);
+        }
+
+      cairo_fill (cr);
+    }
+
+  if (priv->last_pos_rect.width  != 0 &&
+      priv->last_pos_rect.height != 0)
+    {
+      gdk_rectangle_union (&priv->last_pos_rect,
+                           &pos_rect,
+                           &priv->last_pos_rect);
+    }
+  else
+    {
+      priv->last_pos_rect = pos_rect;
+    }
+}
+
+static void
+gimp_ruler_make_pixmap (GimpRuler *ruler)
+{
+  GtkWidget        *widget = GTK_WIDGET (ruler);
+  GimpRulerPrivate *priv   = GIMP_RULER_GET_PRIVATE (ruler);
+  GtkAllocation     allocation;
+
+  gtk_widget_get_allocation (widget, &allocation);
+
+  if (priv->backing_store)
+    cairo_surface_destroy (priv->backing_store);
+
+  priv->backing_store =
+    gdk_window_create_similar_surface (gtk_widget_get_window (widget),
+                                       CAIRO_CONTENT_COLOR,
+                                       allocation.width,
+                                       allocation.height);
+
+  priv->backing_store_valid = FALSE;
+}
+
+static PangoLayout *
+gimp_ruler_create_layout (GtkWidget   *widget,
+                          const gchar *text)
+{
+  GimpRulerPrivate *priv = GIMP_RULER_GET_PRIVATE (widget);
+  PangoLayout      *layout;
+  PangoAttrList    *attrs;
+  PangoAttribute   *attr;
+
+  layout = gtk_widget_create_pango_layout (widget, text);
+
+  attrs = pango_attr_list_new ();
+
+  attr = pango_attr_scale_new (priv->font_scale);
+  attr->start_index = 0;
+  attr->end_index   = -1;
+  pango_attr_list_insert (attrs, attr);
+
+  pango_layout_set_attributes (layout, attrs);
+  pango_attr_list_unref (attrs);
+
+  return layout;
+}
+
+static PangoLayout *
+gimp_ruler_get_layout (GtkWidget   *widget,
+                       const gchar *text)
+{
+  GimpRulerPrivate *priv = GIMP_RULER_GET_PRIVATE (widget);
+
+  if (priv->layout)
+    {
+      pango_layout_set_text (priv->layout, text, -1);
+      return priv->layout;
+    }
+
+  priv->layout = gimp_ruler_create_layout (widget, text);
+
+  return priv->layout;
+}
+
+#define FACTOR_EPSILON  0.0000001
+#define FACTOR_EQUAL(u, f) (ABS (f - gimp_unit_get_factor (u)) < FACTOR_EPSILON)
+
+static const RulerMetric *
+gimp_ruler_get_metric (GimpUnit unit)
+{
+  /*  not enabled until we double checked the metrics  */
+  return &ruler_metric_decimal;
+
+  if (unit == GIMP_UNIT_INCH)
+    {
+      return  &ruler_metric_inches;
+    }
+  else if (FACTOR_EQUAL (unit, 0.083333))
+    {
+      return  &ruler_metric_feet;
+    }
+  else if (FACTOR_EQUAL (unit, 0.027778))
+    {
+      return  &ruler_metric_yards;
+    }
+
+  return &ruler_metric_decimal;
+}