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ee883f30d4
An em is a unit of measurement in typography, equal to the point size of the current font. It should be possible to convert a value expressed in em to ClutterUnits by using the current font and the current DPI as stored by the default backend.
464 lines
12 KiB
C
464 lines
12 KiB
C
/* -*- mode:C; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
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/*
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* Clutter.
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*
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* An OpenGL based 'interactive canvas' library.
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*
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* Authored By: Tomas Frydrych <tf@openedhand.com>
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* Emmanuele Bassi <ebassi@openedhand.com>
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*
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* Copyright (C) 2007 OpenedHand
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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/**
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* SECTION:clutter-units
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* @short_description: A logical distance unit.
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*
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* Clutter units are logical units with granularity greater than that of the
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* device units; they are used by #ClutterActorBox and the units-based family
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* of #ClutterActor functions. To convert between Clutter units and device
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* units, use %CLUTTER_UNITS_FROM_DEVICE and %CLUTTER_UNITS_TO_DEVICE macros.
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*
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* #ClutterUnit<!-- -->s can be converted from other units like millimeters,
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* typographic points (at the current resolution) and percentages. It is
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* also possible to convert fixed point values to and from #ClutterUnit
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* values.
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*
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* In order to register a #ClutterUnit property, the #ClutterParamSpecUnit
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* #GParamSpec sub-class should be used:
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*
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* |[
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* GParamSpec *pspec;
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*
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* pspec = clutter_param_spec_unit ("width",
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* "Width",
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* "Width of the actor, in units",
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* 0, CLUTTER_MAXUNIT,
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* 0,
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* G_PARAM_READWRITE);
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* g_object_class_install_property (gobject_class, PROP_WIDTH, pspec);
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* ]|
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*
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* A #GValue holding units can be manipulated using clutter_value_set_unit()
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* and clutter_value_get_unit(). #GValue<!-- -->s containing a #ClutterUnit
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* value can also be transformed to #GValue<!-- -->s containing integer
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* values - with a loss of precision:
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*
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* |[
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* static gboolean
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* units_to_int (const GValue *src,
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* GValue *dest)
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* {
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* g_return_val_if_fail (CLUTTER_VALUE_HOLDS_UNIT (src), FALSE);
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*
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* g_value_init (dest, G_TYPE_INT);
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* return g_value_transform (src, &dest);
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* }
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* ]|
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*
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* The code above is equivalent to:
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*
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* |[
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* static gboolean
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* units_to_int (const GValue *src,
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* GValue *dest)
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* {
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* g_return_val_if_fail (CLUTTER_VALUE_HOLDS_UNIT (src), FALSE);
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*
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* g_value_init (dest, G_TYPE_INT);
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* g_value_set_int (dest,
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* CLUTTER_UNITS_TO_INT (clutter_value_get_unit (src)));
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*
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* return TRUE;
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* }
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* ]|
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*
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* #ClutterUnit is available since Clutter 0.4
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <glib-object.h>
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#include <gobject/gvaluecollector.h>
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#include "clutter-units.h"
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#include "clutter-private.h"
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#define DPI_FALLBACK 96.0
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/**
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* clutter_units_mm:
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* @mm: millimeters to convert
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*
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* Converts a value in millimeters to #ClutterUnit<!-- -->s at
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* the current DPI.
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*
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* Return value: the value in units
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*
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* Since: 1.0
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*/
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ClutterUnit
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clutter_units_mm (gdouble mm)
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{
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ClutterBackend *backend;
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gdouble dpi;
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backend = clutter_get_default_backend ();
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dpi = clutter_backend_get_resolution (backend);
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if (dpi < 0)
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dpi = DPI_FALLBACK;
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return mm * dpi / 25.4;
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}
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/**
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* clutter_units_pt:
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* @pt: typographic points to convert
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*
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* Converts a value in typographic points to #ClutterUnit<!-- -->s
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* at the current DPI.
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*
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* Return value: the value in units
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*
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* Since: 1.0
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*/
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ClutterUnit
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clutter_units_pt (gdouble pt)
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{
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ClutterBackend *backend;
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gdouble dpi;
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backend = clutter_get_default_backend ();
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dpi = clutter_backend_get_resolution (backend);
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if (dpi < 0)
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dpi = DPI_FALLBACK;
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return pt * dpi / 72.0;
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}
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/**
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* clutter_units_em:
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* @em: em to convert
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*
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* Converts a value in em to #ClutterUnit<!-- -->s at the
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* current DPI.
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*
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* Return value: the value in units
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*
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* Since: 1.0
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*/
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ClutterUnit
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clutter_units_em (gdouble em)
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{
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ClutterBackend *backend;
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const gchar *font_name;
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gdouble dpi;
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ClutterUnit retval = 0;
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backend = clutter_get_default_backend ();
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dpi = clutter_backend_get_resolution (backend);
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font_name = clutter_backend_get_font_name (backend);
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if (G_LIKELY ((font_name && *font_name != '\0')))
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{
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PangoFontDescription *font_desc;
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gdouble font_size = 0;
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font_desc = pango_font_description_from_string (font_name);
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if (G_LIKELY (font_desc != NULL))
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{
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gint pango_size;
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gboolean is_absolute;
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pango_size = pango_font_description_get_size (font_desc);
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is_absolute =
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pango_font_description_get_size_is_absolute (font_desc);
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if (!is_absolute)
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font_size = ((gdouble) font_size) / PANGO_SCALE;
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pango_font_description_free (font_desc);
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}
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/* 10 points at 96 DPI is 12 pixels */
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retval = 1.2 * font_size * dpi / 96.0;
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}
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return retval;
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}
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static GTypeInfo _info = {
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0,
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NULL,
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NULL,
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NULL,
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NULL,
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NULL,
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0,
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0,
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NULL,
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NULL,
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};
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static GTypeFundamentalInfo _finfo = { 0, };
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static void
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clutter_value_init_unit (GValue *value)
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{
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value->data[0].v_int = 0;
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}
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static void
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clutter_value_copy_unit (const GValue *src,
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GValue *dest)
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{
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dest->data[0].v_int = src->data[0].v_int;
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}
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static gchar *
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clutter_value_collect_unit (GValue *value,
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guint n_collect_values,
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GTypeCValue *collect_values,
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guint collect_flags)
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{
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value->data[0].v_int = collect_values[0].v_int;
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return NULL;
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}
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static gchar *
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clutter_value_lcopy_unit (const GValue *value,
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guint n_collect_values,
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GTypeCValue *collect_values,
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guint collect_flags)
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{
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gint32 *units_p = collect_values[0].v_pointer;
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if (!units_p)
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return g_strdup_printf ("value location for `%s' passed as NULL",
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G_VALUE_TYPE_NAME (value));
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*units_p = value->data[0].v_int;
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return NULL;
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}
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static void
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clutter_value_transform_unit_int (const GValue *src,
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GValue *dest)
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{
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dest->data[0].v_int = CLUTTER_UNITS_TO_INT (src->data[0].v_int);
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}
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static void
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clutter_value_transform_int_unit (const GValue *src,
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GValue *dest)
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{
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dest->data[0].v_int = CLUTTER_UNITS_FROM_INT (src->data[0].v_int);
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}
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static const GTypeValueTable _clutter_unit_value_table = {
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clutter_value_init_unit,
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NULL,
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clutter_value_copy_unit,
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NULL,
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"i",
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clutter_value_collect_unit,
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"p",
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clutter_value_lcopy_unit
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};
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GType
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clutter_unit_get_type (void)
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{
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static GType _clutter_unit_type = 0;
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if (G_UNLIKELY (_clutter_unit_type == 0))
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{
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_info.value_table = & _clutter_unit_value_table;
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_clutter_unit_type =
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g_type_register_fundamental (g_type_fundamental_next (),
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I_("ClutterUnit"),
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&_info, &_finfo, 0);
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g_value_register_transform_func (_clutter_unit_type, G_TYPE_INT,
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clutter_value_transform_unit_int);
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g_value_register_transform_func (G_TYPE_INT, _clutter_unit_type,
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clutter_value_transform_int_unit);
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}
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return _clutter_unit_type;
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}
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/**
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* clutter_value_set_unit:
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* @value: a #GValue initialized to #CLUTTER_TYPE_UNIT
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* @units: the units to set
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*
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* Sets @value to @units
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*
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* Since: 0.8
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*/
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void
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clutter_value_set_unit (GValue *value,
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ClutterUnit units)
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{
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g_return_if_fail (CLUTTER_VALUE_HOLDS_UNIT (value));
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value->data[0].v_int = units;
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}
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/**
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* clutter_value_get_unit:
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* @value: a #GValue initialized to #CLUTTER_TYPE_UNIT
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*
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* Gets the #ClutterUnit<!-- -->s contained in @value.
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*
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* Return value: the units inside the passed #GValue
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*
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* Since: 0.8
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*/
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ClutterUnit
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clutter_value_get_unit (const GValue *value)
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{
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g_return_val_if_fail (CLUTTER_VALUE_HOLDS_UNIT (value), 0);
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return value->data[0].v_int;
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}
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static void
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param_unit_init (GParamSpec *pspec)
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{
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ClutterParamSpecUnit *uspec = CLUTTER_PARAM_SPEC_UNIT (pspec);
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uspec->minimum = CLUTTER_MINUNIT;
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uspec->maximum = CLUTTER_MAXUNIT;
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uspec->default_value = 0;
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}
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static void
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param_unit_set_default (GParamSpec *pspec,
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GValue *value)
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{
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value->data[0].v_int = CLUTTER_PARAM_SPEC_UNIT (pspec)->default_value;
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}
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static gboolean
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param_unit_validate (GParamSpec *pspec,
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GValue *value)
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{
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ClutterParamSpecUnit *uspec = CLUTTER_PARAM_SPEC_UNIT (pspec);
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gint oval = CLUTTER_UNITS_TO_INT (value->data[0].v_int);
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gint min, max, val;
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g_assert (CLUTTER_IS_PARAM_SPEC_UNIT (pspec));
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/* we compare the integer part of the value because the minimum
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* and maximum values cover just that part of the representation
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*/
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min = uspec->minimum;
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max = uspec->maximum;
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val = CLUTTER_UNITS_TO_INT (value->data[0].v_int);
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val = CLAMP (val, min, max);
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if (val != oval)
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{
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value->data[0].v_int = val;
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return TRUE;
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}
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return FALSE;
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}
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static gint
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param_unit_values_cmp (GParamSpec *pspec,
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const GValue *value1,
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const GValue *value2)
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{
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if (value1->data[0].v_int < value2->data[0].v_int)
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return -1;
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else
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return value1->data[0].v_int > value2->data[0].v_int;
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}
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GType
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clutter_param_unit_get_type (void)
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{
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static GType pspec_type = 0;
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if (G_UNLIKELY (pspec_type == 0))
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{
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const GParamSpecTypeInfo pspec_info = {
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sizeof (ClutterParamSpecUnit),
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16,
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param_unit_init,
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CLUTTER_TYPE_UNIT,
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NULL,
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param_unit_set_default,
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param_unit_validate,
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param_unit_values_cmp,
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};
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pspec_type = g_param_type_register_static (I_("ClutterParamSpecUnit"),
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&pspec_info);
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}
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return pspec_type;
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}
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/**
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* clutter_param_spec_unit:
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* @name: name of the property
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* @nick: short name
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* @blurb: description (can be translatable)
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* @minimum: lower boundary
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* @maximum: higher boundary
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* @default_value: default value
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* @flags: flags for the param spec
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*
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* Creates a #GParamSpec for properties using #ClutterUnit<!-- -->s.
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*
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* Return value: the newly created #GParamSpec
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*
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* Since: 0.8
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*/
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GParamSpec *
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clutter_param_spec_unit (const gchar *name,
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const gchar *nick,
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const gchar *blurb,
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ClutterUnit minimum,
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ClutterUnit maximum,
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ClutterUnit default_value,
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GParamFlags flags)
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{
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ClutterParamSpecUnit *uspec;
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g_return_val_if_fail (default_value >= minimum && default_value <= maximum,
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NULL);
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uspec = g_param_spec_internal (CLUTTER_TYPE_PARAM_UNIT,
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name, nick, blurb,
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flags);
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uspec->minimum = minimum;
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uspec->maximum = maximum;
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uspec->default_value = default_value;
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return G_PARAM_SPEC (uspec);
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}
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