Merged trunk

(bzr r14954.1.30)

1 files changed, 1425 insertions, 0 deletions

diff --git a/src/widgets/gimp/ruler.cpp b/src/widgets/gimp/ruler.cpp
new file mode 100644
index 000000000..bfb9c9071
--- /dev/null
+++ b/src/widgets/gimp/ruler.cpp
@@ -0,0 +1,1425 @@
+/*
+ * Customized ruler class for inkscape.  Note that this is a fork of
+ * the GimpRuler widget from GIMP: libgimpwidgets/gimpruler.c.
+ * The GIMP code is released under the GPL 3.  The GIMP code itself
+ * is a fork of the now-obsolete GtkRuler widget from GTK+ 2.
+ *
+ * Major differences between implementations in Inkscape and GIMP are
+ * as follows:
+ *  - We use a 1,2,4,8... scale for inches and 1,2,5,10... for everything
+ *    else.  GIMP uses 1,2,5,10... for everything.
+ *
+ *  - We use a default font size of PANGO_SCALE_X_SMALL for labels,
+ *    GIMP uses PANGO_SCALE_SMALL (i.e., a bit larger than ours).
+ *
+ *  - We abbreviate large numbers in tick-labels (e.g., 10000 -> 10k) 
+ *
+ * Authors:
+ *   Lauris Kaplinski <lauris@kaplinski.com>
+ *   Frank Felfe <innerspace@iname.com>
+ *   bulia byak <buliabyak@users.sf.net>
+ *   Diederik van Lierop <mail@diedenrezi.nl>
+ *   Jon A. Cruz <jon@joncruz.org>
+ *   Alex Valavanis <valavanisalex@gmail.com>
+ *
+ * Copyright (C) 1999-2011 authors
+ *
+ * Released under GNU GPL, read the file 'COPYING' for more information
+ */
+
+#include <cstring>
+#include <cmath>
+#include <cstdio>
+
+#include "ruler.h"
+#include "round.h"
+#include <glibmm/i18n.h>
+#include "util/units.h"
+
+#define ROUND(x) ((int) ((x) + 0.5))
+
+#define GTK_PARAM_READWRITE G_PARAM_READWRITE|G_PARAM_STATIC_NAME|G_PARAM_STATIC_NICK|G_PARAM_STATIC_BLURB
+
+#define DEFAULT_RULER_FONT_SCALE    PANGO_SCALE_X_SMALL
+#define MINIMUM_INCR                5
+#define IMMEDIATE_REDRAW_THRESHOLD  20
+
+using Inkscape::Util::unit_table;
+
+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;
+  Inkscape::Util::Unit const *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;
+} SPRulerPrivate;
+
+#define SP_RULER_GET_PRIVATE(ruler) \
+  G_TYPE_INSTANCE_GET_PRIVATE (ruler, SP_TYPE_RULER, SPRulerPrivate)
+
+
+struct SPRulerMetric
+{
+  gdouble ruler_scale[16];
+  gint    subdivide[5];
+};
+
+// Ruler metric for general use.
+static SPRulerMetric const ruler_metric_general = {
+  { 1, 2, 5, 10, 25, 50, 100, 250, 500, 1000, 2500, 5000, 10000, 25000, 50000, 100000 },
+  { 1, 5, 10, 50, 100 }
+};
+
+// Ruler metric for inch scales.
+static SPRulerMetric const ruler_metric_inches = {
+  { 1, 2, 4,  8, 16, 32,  64, 128, 256,  512, 1024, 2048, 4096, 8192, 16384, 32768 },
+  { 1, 2,  4,  8,  16 }
+};
+
+static void          sp_ruler_dispose              (GObject        *object);
+static void          sp_ruler_set_property         (GObject        *object,
+                                                    guint           prop_id,
+                                                    const GValue   *value,
+                                                    GParamSpec     *pspec);
+static void          sp_ruler_get_property         (GObject        *object,
+                                                    guint           prop_id,
+                                                    GValue         *value,
+                                                    GParamSpec     *pspec);
+
+static void          sp_ruler_realize              (GtkWidget      *widget);
+static void          sp_ruler_unrealize            (GtkWidget      *widget);
+static void          sp_ruler_map                  (GtkWidget      *widget);
+static void          sp_ruler_unmap                (GtkWidget      *widget);
+static void          sp_ruler_size_allocate        (GtkWidget      *widget,
+                                                    GtkAllocation  *allocation);
+
+static void          sp_ruler_get_preferred_width  (GtkWidget      *widget, 
+                                                    gint           *minimum_width,
+                                                    gint           *natural_width);
+
+static void          sp_ruler_get_preferred_height (GtkWidget      *widget, 
+                                                    gint           *minimum_height,
+                                                    gint           *natural_height);
+static void          sp_ruler_style_updated        (GtkWidget      *widget);
+
+static gboolean      sp_ruler_motion_notify        (GtkWidget      *widget,
+                                                    GdkEventMotion *event);
+static gboolean      sp_ruler_draw                 (GtkWidget      *widget,
+                                                    cairo_t        *cr);
+static void          sp_ruler_draw_ticks           (SPRuler        *ruler);
+static GdkRectangle  sp_ruler_get_pos_rect         (SPRuler        *ruler,
+                                                    gdouble         position);
+static gboolean      sp_ruler_idle_queue_pos_redraw(gpointer        data);
+static void          sp_ruler_queue_pos_redraw     (SPRuler        *ruler);
+static void          sp_ruler_draw_pos             (SPRuler        *ruler,
+                                                    cairo_t        *cr);
+static void          sp_ruler_make_pixmap          (SPRuler        *ruler);
+
+static PangoLayout * sp_ruler_get_layout           (GtkWidget      *widget,
+                                                    const gchar    *text);
+
+
+G_DEFINE_TYPE (SPRuler, sp_ruler, GTK_TYPE_WIDGET)
+
+#define parent_class sp_ruler_parent_class
+
+
+static void
+sp_ruler_class_init (SPRulerClass *klass)
+{
+  GObjectClass   *object_class  = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class  = GTK_WIDGET_CLASS (klass);
+
+#if GTK_CHECK_VERSION(3,20,0)
+  gtk_widget_class_set_css_name (widget_class, "ruler-widget");
+#endif
+
+  object_class->dispose              = sp_ruler_dispose;
+  object_class->set_property         = sp_ruler_set_property;
+  object_class->get_property         = sp_ruler_get_property;
+
+  widget_class->realize              = sp_ruler_realize;
+  widget_class->unrealize            = sp_ruler_unrealize;
+  widget_class->map                  = sp_ruler_map;
+  widget_class->unmap                = sp_ruler_unmap;
+  widget_class->size_allocate        = sp_ruler_size_allocate;
+  widget_class->get_preferred_width  = sp_ruler_get_preferred_width;
+  widget_class->get_preferred_height = sp_ruler_get_preferred_height;
+  widget_class->style_updated        = sp_ruler_style_updated;
+  widget_class->draw                 = sp_ruler_draw;
+  widget_class->motion_notify_event = sp_ruler_motion_notify;
+
+  g_type_class_add_private (object_class, sizeof (SPRulerPrivate));
+
+  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,
+						      static_cast<GParamFlags>(GTK_PARAM_READWRITE)));
+
+  /* FIXME: Should probably use g_param_spec_enum */
+  g_object_class_install_property (object_class,
+                                   PROP_UNIT,
+                                   g_param_spec_string ("unit",
+						      _("Unit"),
+						      _("Unit of the ruler"),
+						      "px",
+						      static_cast<GParamFlags>(GTK_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,
+							static_cast<GParamFlags>(GTK_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,
+							static_cast<GParamFlags>(GTK_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,
+							static_cast<GParamFlags>(GTK_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,
+							static_cast<GParamFlags>(GTK_PARAM_READWRITE)));  
+
+  gtk_widget_class_install_style_property (widget_class,
+		                           g_param_spec_double ("font-scale",
+						                NULL, NULL,
+								0.0,
+								G_MAXDOUBLE,
+								DEFAULT_RULER_FONT_SCALE,
+								G_PARAM_READABLE));
+}
+
+static void
+sp_ruler_init (SPRuler *ruler)
+{
+  SPRulerPrivate *priv = SP_RULER_GET_PRIVATE (ruler);
+
+  gtk_widget_set_has_window (GTK_WIDGET (ruler), FALSE);
+
+  priv->orientation          = GTK_ORIENTATION_HORIZONTAL;
+  priv->unit                 = unit_table.getUnit("px");
+  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
+sp_ruler_dispose (GObject *object)
+{
+  SPRuler        *ruler = SP_RULER (object);
+  SPRulerPrivate *priv  = SP_RULER_GET_PRIVATE (ruler);
+
+  while (priv->track_widgets)
+    sp_ruler_remove_track_widget (ruler, GTK_WIDGET(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);
+}
+
+
+/**
+ * sp_ruler_set_range:
+ * @ruler: the SPRuler
+ * @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. 
+ */
+void
+sp_ruler_set_range (SPRuler *ruler,
+		    gdouble   lower,
+		    gdouble   upper,
+		    gdouble   max_size)
+{
+  SPRulerPrivate *priv;
+  
+  g_return_if_fail (SP_IS_RULER (ruler));
+
+  priv = SP_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));
+}
+
+/**
+ * sp_ruler_get_range:
+ * @ruler: a #SPRuler
+ * @lower: (allow-none): location to store lower limit of the ruler, or %NULL
+ * @upper: (allow-none): 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 #SPRuler.
+ * See sp_ruler_set_range().
+ **/
+void
+sp_ruler_get_range (SPRuler *ruler,
+		     gdouble  *lower,
+		     gdouble  *upper,
+		     gdouble  *max_size)
+{
+  SPRulerPrivate *priv;
+
+  g_return_if_fail (SP_IS_RULER (ruler));
+  
+  priv = SP_RULER_GET_PRIVATE (ruler);
+
+  if (lower)
+    *lower = priv->lower;
+  if (upper)
+    *upper = priv->upper;
+  if (max_size)
+    *max_size = priv->max_size;
+}
+
+static void
+sp_ruler_set_property (GObject      *object,
+ 			guint         prop_id,
+			const GValue *value,
+			GParamSpec   *pspec)
+{
+  SPRuler *ruler = SP_RULER (object);
+  SPRulerPrivate *priv = SP_RULER_GET_PRIVATE (ruler);
+
+  switch (prop_id)
+    {
+    case PROP_ORIENTATION:
+      priv->orientation = static_cast<GtkOrientation>(g_value_get_enum (value));
+      gtk_widget_queue_resize (GTK_WIDGET (ruler));
+      break;
+    
+    case PROP_UNIT:
+      sp_ruler_set_unit (ruler, unit_table.getUnit(g_value_get_string (value)));
+      break;
+
+    case PROP_LOWER:
+      sp_ruler_set_range (ruler,
+                          g_value_get_double (value),
+                          priv->upper,
+			  priv->max_size);
+      break;
+    case PROP_UPPER:
+      sp_ruler_set_range (ruler,
+                          priv->lower,
+                          g_value_get_double (value),
+			  priv->max_size);
+      break;
+
+    case PROP_POSITION:
+      sp_ruler_set_position (ruler, g_value_get_double (value));
+      break;
+
+    case PROP_MAX_SIZE:
+      sp_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
+sp_ruler_get_property (GObject      *object,
+			guint         prop_id,
+			GValue       *value,
+			GParamSpec   *pspec)
+{
+  SPRuler *ruler = SP_RULER (object);
+  SPRulerPrivate *priv = SP_RULER_GET_PRIVATE (ruler);
+
+  switch (prop_id)
+    {
+    case PROP_ORIENTATION:
+      g_value_set_enum (value, priv->orientation);
+      break;
+    
+    case PROP_UNIT:
+      g_value_set_string (value, priv->unit->abbr.c_str());
+      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;
+    }
+}
+
+static void
+sp_ruler_realize (GtkWidget *widget)
+{
+  SPRuler        *ruler = SP_RULER (widget);
+  SPRulerPrivate *priv  = SP_RULER_GET_PRIVATE (ruler);
+  GtkAllocation   allocation;
+  GdkWindowAttr   attributes;
+  gint            attributes_mask;
+
+  GTK_WIDGET_CLASS (sp_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         |
+			   GDK_POINTER_MOTION_HINT_MASK);
+
+  attributes_mask = GDK_WA_X | GDK_WA_Y;
+
+  priv->input_window = gdk_window_new (gtk_widget_get_parent_window (widget), 
+                                       &attributes, attributes_mask);
+  gdk_window_set_user_data (priv->input_window, ruler);
+
+  sp_ruler_make_pixmap (ruler);
+}
+
+static void
+sp_ruler_unrealize(GtkWidget *widget)
+{
+  SPRuler        *ruler = SP_RULER (widget);
+  SPRulerPrivate *priv  = SP_RULER_GET_PRIVATE (ruler);
+
+  if (priv->backing_store)
+    {
+      cairo_surface_destroy (priv->backing_store);
+      priv->backing_store = NULL;
+    }
+
+  priv->backing_store_valid = FALSE;
+
+  if (priv->layout)
+    {
+      g_object_unref (priv->layout);
+      priv->layout = NULL;
+    }
+
+  if (priv->input_window)
+    {
+      gdk_window_destroy (priv->input_window);
+      priv->input_window = NULL;
+    }
+
+  GTK_WIDGET_CLASS (sp_ruler_parent_class)->unrealize (widget);
+}
+
+static void
+sp_ruler_map (GtkWidget *widget)
+{
+  SPRulerPrivate *priv = SP_RULER_GET_PRIVATE (widget);
+
+  GTK_WIDGET_CLASS (sp_ruler_parent_class)->map (widget);
+
+  if (priv->input_window)
+    gdk_window_show (priv->input_window);
+}
+
+static void
+sp_ruler_unmap (GtkWidget *widget)
+{
+  SPRulerPrivate *priv = SP_RULER_GET_PRIVATE (widget);
+
+  if (priv->input_window)
+    gdk_window_hide (priv->input_window);
+  
+  GTK_WIDGET_CLASS (sp_ruler_parent_class)->unmap (widget);
+}
+
+static void
+sp_ruler_size_allocate (GtkWidget     *widget,
+                        GtkAllocation *allocation)
+{
+  SPRuler        *ruler = SP_RULER(widget);
+  SPRulerPrivate *priv  = SP_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_set_allocation(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)
+        sp_ruler_make_pixmap (ruler);
+    }
+}
+
+static void
+sp_ruler_size_request (GtkWidget      *widget, 
+                       GtkRequisition *requisition)
+{
+  SPRulerPrivate  *priv    = SP_RULER_GET_PRIVATE (widget);
+  PangoLayout     *layout;
+  PangoRectangle   ink_rect;
+  gint             size;
+
+  layout = sp_ruler_get_layout (widget, "0123456789");
+  pango_layout_get_pixel_extents (layout, &ink_rect, NULL);
+
+  size = 2 + ink_rect.height * 1.7;
+
+  GtkStyleContext *context = gtk_widget_get_style_context (widget);
+  GtkBorder        border;
+
+  gtk_style_context_get_border (context, static_cast<GtkStateFlags>(0), &border);
+  
+  requisition->width  = border.left + border.right;
+  requisition->height = border.top  + border.bottom;
+
+  if (priv->orientation == GTK_ORIENTATION_HORIZONTAL)
+    {
+      requisition->width  += 1;
+      requisition->height += size;
+    }
+  else
+    {
+      requisition->width  += size;
+      requisition->height += 1;
+    }
+}
+
+static void
+sp_ruler_style_updated (GtkWidget *widget)
+{
+  SPRulerPrivate *priv = SP_RULER_GET_PRIVATE (widget);
+
+  GTK_WIDGET_CLASS (sp_ruler_parent_class)->style_updated (widget);
+
+  gtk_widget_style_get (widget,
+		        "font-scale", &priv->font_scale,
+			NULL);
+
+  if (priv->layout)
+    {
+     g_object_unref (priv->layout);
+     priv->layout = NULL;
+    }
+}
+
+static void
+sp_ruler_get_preferred_width (GtkWidget *widget,
+                              gint      *minimum_width,
+                              gint      *natural_width)
+{
+  GtkRequisition requisition;
+
+  sp_ruler_size_request (widget, &requisition);
+
+  *minimum_width = *natural_width = requisition.width;
+}
+
+static void
+sp_ruler_get_preferred_height (GtkWidget *widget,
+                               gint      *minimum_height,
+                               gint      *natural_height)
+{
+  GtkRequisition requisition;
+  
+  sp_ruler_size_request(widget, &requisition);
+  
+  *minimum_height = *natural_height = requisition.height;
+}
+
+static gboolean
+sp_ruler_draw (GtkWidget *widget,
+	       cairo_t *cr)
+{
+  SPRuler         *ruler   = SP_RULER (widget);
+  SPRulerPrivate  *priv    = SP_RULER_GET_PRIVATE (ruler);
+  GtkStyleContext *context = gtk_widget_get_style_context (widget);
+  GtkAllocation    allocation;
+
+  gtk_widget_get_allocation (widget, &allocation);
+  gtk_render_background (context, cr, 0, 0, allocation.width, allocation.height);
+  gtk_render_frame (context, cr, 0, 0, allocation.width, allocation.height);
+
+  sp_ruler_draw_ticks (ruler);
+
+  cairo_set_source_surface(cr, priv->backing_store, 0, 0);
+  cairo_paint(cr);
+
+  sp_ruler_draw_pos (ruler, cr);
+
+  return FALSE;
+}
+
+static void
+sp_ruler_make_pixmap (SPRuler *ruler)
+{
+  GtkWidget      *widget = GTK_WIDGET (ruler);
+  SPRulerPrivate *priv   = SP_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_ALPHA,
+                                       allocation.width,
+                                       allocation.height);
+
+  priv->backing_store_valid = FALSE;
+}
+
+static void
+sp_ruler_draw_pos (SPRuler *ruler,
+                   cairo_t *cr)
+{
+  GtkWidget       *widget  = GTK_WIDGET (ruler);
+
+  GtkStyleContext *context = gtk_widget_get_style_context (widget);
+  GdkRGBA          color;
+  
+  SPRulerPrivate  *priv    = SP_RULER_GET_PRIVATE (ruler);
+  GdkRectangle      pos_rect;
+
+  if (! gtk_widget_is_drawable (widget))
+      return;
+
+  pos_rect = sp_ruler_get_pos_rect (ruler, sp_ruler_get_position (ruler));
+
+  if ((pos_rect.width > 0) && (pos_rect.height > 0))
+    {
+      gtk_style_context_get_color (context, gtk_widget_get_state_flags (widget),
+                                   &color);
+      gdk_cairo_set_source_rgba (cr, &color);
+
+      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);
+    }
+
+  priv->last_pos_rect = pos_rect;
+}
+
+/**
+ * sp_ruler_new:
+ * @orientation: the ruler's orientation
+ *
+ * Creates a new ruler.
+ *
+ * Return value: a new #SPRuler widget.
+ */
+GtkWidget *
+sp_ruler_new (GtkOrientation orientation)
+{
+  return GTK_WIDGET (g_object_new (SP_TYPE_RULER, 
+		                   "orientation", orientation,
+                                   NULL));
+}
+
+static void
+sp_ruler_update_position (SPRuler *ruler,
+                          gdouble  x,
+                          gdouble  y)
+{
+  SPRulerPrivate *priv = SP_RULER_GET_PRIVATE (ruler);
+  GtkAllocation   allocation;
+  gdouble         lower;
+  gdouble         upper;
+
+  gtk_widget_get_allocation (GTK_WIDGET (ruler), &allocation);
+  sp_ruler_get_range (ruler, &lower, &upper, NULL);
+
+  if (priv->orientation == GTK_ORIENTATION_HORIZONTAL)
+    {
+     sp_ruler_set_position (ruler,
+                            lower +
+                            (upper - lower) * x / allocation.width);
+    }
+  else
+    {
+     sp_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 += px;
+    }
+
+  if (w == NULL)
+    {
+      *x = 0;
+      *y = 0;
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+static void
+sp_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
+sp_ruler_track_widget_motion_notify (GtkWidget      *widget,
+		                     GdkEventMotion *mevent,
+				     SPRuler        *ruler)
+{
+  gint widget_x;
+  gint widget_y;
+  gint ruler_x;
+  gint ruler_y;
+
+  widget = gtk_get_event_widget (reinterpret_cast<GdkEvent *>(mevent));
+
+  sp_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))
+    {
+      sp_ruler_update_position (ruler, ruler_x, ruler_y);
+    }
+
+  return FALSE;  
+}
+
+void
+sp_ruler_add_track_widget (SPRuler   *ruler,
+		           GtkWidget *widget)
+{
+  SPRulerPrivate *priv;
+
+  g_return_if_fail (SP_IS_RULER   (ruler));
+  g_return_if_fail (GTK_IS_WIDGET (ruler));
+
+  priv = SP_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 (sp_ruler_track_widget_motion_notify),
+		    ruler);
+  g_signal_connect (widget, "destroy",
+		    G_CALLBACK (sp_ruler_remove_track_widget),
+		    ruler);
+}
+
+/**
+ * sp_ruler_remove_track_widget:
+ * @ruler: an #SPRuler
+ * @widget: the track widget to remove
+ *
+ * Removes a previously added track widget from the ruler. See
+ * sp_ruler_add_track_widget().
+ */
+void
+sp_ruler_remove_track_widget (SPRuler   *ruler,
+		              GtkWidget *widget)
+{
+  SPRulerPrivate *priv;
+
+  g_return_if_fail (SP_IS_RULER   (ruler));
+  g_return_if_fail (GTK_IS_WIDGET (ruler));
+
+  priv = SP_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,
+		                        (gpointer) G_CALLBACK (sp_ruler_track_widget_motion_notify),
+					ruler);
+  g_signal_handlers_disconnect_by_func (widget,
+		                        (gpointer) G_CALLBACK (sp_ruler_remove_track_widget),
+					ruler);
+}
+
+/**
+ * sp_ruler_set_unit:
+ * @ruler: a #SPRuler
+ * @unit: the #SPMetric to set the ruler to
+ *
+ * This sets the unit of the ruler.
+ */
+void
+sp_ruler_set_unit (SPRuler  *ruler,
+                   Inkscape::Util::Unit const *unit)
+{
+  SPRulerPrivate *priv = SP_RULER_GET_PRIVATE (ruler);
+  
+  g_return_if_fail (SP_IS_RULER (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));
+    }
+}
+
+/**
+ * sp_ruler_get_unit:
+ * @ruler: a #SPRuler
+ *
+ * Return value: the unit currently used in the @ruler widget.
+ **/
+Inkscape::Util::Unit const*
+sp_ruler_get_unit (SPRuler *ruler)
+{
+  return SP_RULER_GET_PRIVATE (ruler)->unit;
+}
+
+/**
+ * sp_ruler_set_position:
+ * @ruler: a #SPRuler
+ * @position: the position to set the ruler to
+ *
+ * This sets the position of the ruler.
+ */
+void
+sp_ruler_set_position (SPRuler *ruler,
+                       gdouble  position)
+{
+    SPRulerPrivate *priv;
+
+    g_return_if_fail (SP_IS_RULER (ruler));
+    
+    priv = SP_RULER_GET_PRIVATE (ruler);
+
+    if (priv->position != position)
+    {
+      GdkRectangle rect;
+      gint xdiff, ydiff;
+
+      priv->position = position;
+      g_object_notify (G_OBJECT (ruler), "position");
+
+      rect = sp_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))
+        {
+          sp_ruler_queue_pos_redraw (ruler);
+        }
+      else if (! priv->pos_redraw_idle_id)
+        {
+          priv->pos_redraw_idle_id =
+            g_idle_add_full (G_PRIORITY_LOW,
+                             sp_ruler_idle_queue_pos_redraw,
+                             ruler, NULL);
+        }
+    }
+}
+
+/**
+ * sp_ruler_get_position:
+ * @ruler: a #SPRuler
+ *
+ * Return value: the current position of the @ruler widget.
+ */
+gdouble
+sp_ruler_get_position (SPRuler *ruler)
+{
+    g_return_val_if_fail (SP_IS_RULER (ruler), 0.0);
+
+    return SP_RULER_GET_PRIVATE (ruler)->position;
+}
+
+static gboolean
+sp_ruler_motion_notify (GtkWidget      *widget,
+                        GdkEventMotion *event)
+{
+  SPRuler *ruler = SP_RULER(widget);
+
+  sp_ruler_update_position (ruler, event->x, event->y);
+
+  return FALSE;
+}
+
+static void
+sp_ruler_draw_ticks (SPRuler *ruler)
+{
+    GtkWidget       *widget  = GTK_WIDGET (ruler);
+
+    GtkStyleContext *context = gtk_widget_get_style_context (widget);
+    GtkBorder        border;
+    GdkRGBA          color;
+
+    SPRulerPrivate  *priv    = SP_RULER_GET_PRIVATE (ruler);
+    GtkAllocation    allocation;
+    cairo_t         *cr;
+    gint             i;
+    gint             width, height;
+    gint             length, ideal_length;
+    gdouble          lower, upper; /* Upper and lower limits, in ruler units */
+    gdouble          increment;    /* Number of pixels per unit */
+    guint            scale;        /* Number of units per major unit */
+    gdouble          start, end, cur;
+    gchar            unit_str[32];
+    gint             digit_height;
+    gint             digit_offset;
+    gchar            digit_str[2] = { '\0', '\0' };
+    gint             text_size;
+    gint             pos;
+    gdouble          max_size;
+    Inkscape::Util::Unit const *unit = NULL;
+    SPRulerMetric    ruler_metric = ruler_metric_general; /* The metric to use for this unit system */
+    PangoLayout     *layout;
+    PangoRectangle   logical_rect, ink_rect;
+
+    if (! gtk_widget_is_drawable (widget))
+      return;
+
+    gtk_widget_get_allocation (widget, &allocation);
+
+    gtk_style_context_get_border (context, static_cast<GtkStateFlags>(0), &border);
+
+    layout = sp_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 - (border.top + border.bottom);
+     }
+    else
+     {
+        width = allocation.height;
+        height = allocation.width - (border.top + border.bottom);
+     }
+
+    cr = cairo_create (priv->backing_store);
+    
+    cairo_set_operator (cr, CAIRO_OPERATOR_CLEAR);
+    cairo_paint (cr);
+    cairo_set_operator (cr, CAIRO_OPERATOR_OVER);
+
+    gtk_style_context_get_color (context, gtk_widget_get_state_flags (widget),
+                                 &color);
+    gdk_cairo_set_source_rgba (cr, &color);
+
+    if (priv->orientation == GTK_ORIENTATION_HORIZONTAL)
+      {
+        cairo_rectangle (cr,
+                         border.left,
+                         height + border.top,
+                         allocation.width - (border.left + border.right),
+                         1);      
+      }
+    else
+      {
+        cairo_rectangle (cr,
+                         height + border.left,
+                         border.top,
+                         1,
+                         allocation.height - (border.top + border.bottom));
+      }
+
+    sp_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 (priv->max_size);
+    sprintf (unit_str, "%d", scale);
+    text_size = strlen (unit_str) * digit_height + 1;
+
+    /* Inkscape change to ruler: Use a 1,2,4,8... scale for inches
+     * or a 1,2,5,10... scale for everything else */
+    if (*sp_ruler_get_unit (ruler) == *unit_table.getUnit("in"))
+      ruler_metric = ruler_metric_inches;
+
+    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;
+
+    unit = sp_ruler_get_unit (ruler);
+
+    /* 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 == *unit_table.getUnit("px") && 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;
+
+        /* 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;
+          }
+
+        gint tick_index = 0;
+
+        for (cur = start; cur <= end; cur += subd_incr)
+          {
+            // due to the typical values for cur, lower and increment, pos will often end up to
+            // be e.g. 641.50000000000; rounding behaviour is not defined in such a case (see round.h)
+            // and jitter will be apparent (upon redrawing some of the lines on the ruler might jump a
+            // by a pixel, and jump back on the next redraw). This is suppressed by adding 1e-9 (that's only one nanopixel ;-))
+            pos = gint(Inkscape::round((cur - lower) * increment + 1e-12));
+
+            if (priv->orientation == GTK_ORIENTATION_HORIZONTAL)
+             {
+               cairo_rectangle (cr,
+                                pos, height + border.top - length,
+                                1,   length);
+             }
+            else 
+             {
+               cairo_rectangle (cr,
+                                height + border.left - length, pos,
+                                length,                        1);
+             }
+
+            /* draw label */
+            double label_spacing_px = fabs(increment*(double)ruler_metric.ruler_scale[scale]/ruler_metric.subdivide[i]);
+            if (i == 0 && 
+                (label_spacing_px > 6*digit_height || tick_index%2 == 0 || cur == 0) && 
+                (label_spacing_px > 3*digit_height || tick_index%4 == 0 || cur == 0))
+              {
+                if (std::abs((int)cur) >= 2000 && (((int) cur)/1000)*1000 == ((int) cur))
+                    sprintf (unit_str, "%dk", ((int) cur)/1000);
+                else
+                    sprintf (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);
+
+                    cairo_move_to (cr,
+                                   pos + 2,
+                                   border.top + PANGO_PIXELS (logical_rect.y - digit_offset));
+
+                    pango_cairo_show_layout(cr, layout);
+                  }
+                else
+                  {
+                    gint j;
+
+                    for (j = 0; j < (int) strlen (unit_str); j++)
+                      {
+                        digit_str[0] = unit_str[j];
+                        pango_layout_set_text (layout, digit_str, 1);
+                        pango_layout_get_extents (layout, NULL, &logical_rect);
+
+                        cairo_move_to (cr,
+                                       border.left + 1,
+                                       pos + digit_height * j + 2 + PANGO_PIXELS (logical_rect.y - digit_offset));
+                        pango_cairo_show_layout (cr, layout);
+                      }
+                  }
+              }
+        
+            ++tick_index;
+          }
+      }
+
+    cairo_fill (cr);
+
+  priv->backing_store_valid = TRUE;
+
+out:
+    cairo_destroy (cr);
+}
+
+static GdkRectangle
+sp_ruler_get_pos_rect (SPRuler *ruler,
+                       gdouble  position)
+{
+  GtkWidget        *widget = GTK_WIDGET (ruler);
+  SPRulerPrivate   *priv   = SP_RULER_GET_PRIVATE (ruler);
+  GtkAllocation     allocation;
+  gint              width, height;
+  gint              xthickness;
+  gint              ythickness;
+  gdouble           upper, lower;
+  gdouble           increment;
+  GdkRectangle      rect = { 0, 0, 0, 0 };
+
+  if (! gtk_widget_is_drawable (widget))
+    return rect;
+
+  gtk_widget_get_allocation (widget, &allocation);
+
+  GtkStyleContext *context = gtk_widget_get_style_context (widget);
+  GtkBorder padding;
+
+  gtk_style_context_get_border(context, static_cast<GtkStateFlags>(0), &padding);
+
+  xthickness = padding.left + padding.right;
+  ythickness = padding.top + padding.bottom;
+
+  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;
+    }
+
+  sp_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;
+    }
+
+  return rect;
+}
+
+static gboolean
+sp_ruler_idle_queue_pos_redraw (gpointer data)
+{
+  SPRuler        *ruler = (SPRuler *)data;
+  SPRulerPrivate *priv  = SP_RULER_GET_PRIVATE (ruler);
+
+  sp_ruler_queue_pos_redraw (ruler);
+
+  gboolean ret = g_source_remove(priv->pos_redraw_idle_id);
+  priv->pos_redraw_idle_id = 0;
+
+  return ret;
+}
+
+static void
+sp_ruler_queue_pos_redraw (SPRuler *ruler)
+{
+  SPRulerPrivate    *priv = SP_RULER_GET_PRIVATE (ruler);
+  const GdkRectangle rect = sp_ruler_get_pos_rect (ruler, priv->position);
+  GtkAllocation      allocation;
+
+  gtk_widget_get_allocation (GTK_WIDGET(ruler), &allocation);
+
+  gtk_widget_queue_draw_area (GTK_WIDGET(ruler),
+                              rect.x + allocation.x,
+                              rect.y + allocation.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 + allocation.x,
+                                  priv->last_pos_rect.y + allocation.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 PangoLayout*
+sp_ruler_create_layout (GtkWidget   *widget,
+                        const gchar *text)
+{
+  SPRulerPrivate *priv = SP_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 *
+sp_ruler_get_layout (GtkWidget   *widget,
+                     const gchar *text)
+{
+  SPRulerPrivate *priv = SP_RULER_GET_PRIVATE (widget);
+
+  if (priv->layout)
+    {
+      pango_layout_set_text (priv->layout, text, -1);
+      return priv->layout;
+    }
+
+  priv->layout = sp_ruler_create_layout (widget, text);
+
+  return priv->layout;
+}
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :