mutter/clutter/clutter-units.h
Emmanuele Bassi 83b4ec7a12 units: Cache the pixels value inside Units
When computing the pixels value of a ClutterUnits value we should
be caching the value to avoid recomputing for every call of
clutter_units_to_pixels(). We already have a flag telling us to
return the cached value, but we miss the mechanism to evict the
cache whenever the Backend settings affecting the conversion, that
is default font and resolution, change.

In order to implement the eviction we can use a "serial"; the
Backend will have an internal serial field which we retrieve and
put inside the ClutterUnits structure (we split one of the two
64 bit padding fields into two 32 bit fields to maintain ABI); every
time we call clutter_units_to_pixels() we compare the units serial
with that of the Backend; if they match and pixels_set is set to
TRUE then we just return the stored pixels value. If the serials
do not match then we unset the pixels_set flag and recompute the
pixels value.

We can verify this by adding a simple test unit checking that
by changing the resolution of ClutterBackend we get different
pixel values for 1 em.

http://bugzilla.openedhand.com/show_bug.cgi?id=1843
2009-10-16 15:25:37 +01:00

189 lines
6.4 KiB
C

/* -*- mode:C; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
* Clutter.
*
* An OpenGL based 'interactive canvas' library.
*
* Authored By: Tomas Frydrych <tf@openedhand.com>
* Emmanuele Bassu <ebassi@linux.intel.com>
*
* Copyright (C) 2007, 2008 OpenedHand
* Copyright (C) 2009 Intel Corp.
*
* 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 2 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 <http://www.gnu.org/licenses/>.
*/
#if !defined(__CLUTTER_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
#error "Only <clutter/clutter.h> can be included directly."
#endif
#ifndef __CLUTTER_UNITS_H__
#define __CLUTTER_UNITS_H__
#include <glib-object.h>
#include <cogl/cogl.h>
G_BEGIN_DECLS
/**
* ClutterUnitType:
* @CLUTTER_UNIT_PIXEL: Unit expressed in pixels (with subpixel precision)
* @CLUTTER_UNIT_EM: Unit expressed in em
* @CLUTTER_UNIT_MM: Unit expressed in millimeters
* @CLUTTER_UNIT_POINT: Unit expressed in points
* @CLUTTER_UNIT_CM: Unit expressed in centimeters
*
* The type of unit in which a value is expressed
*
* This enumeration might be expanded at later date
*
* Since: 1.0
*/
typedef enum {
CLUTTER_UNIT_PIXEL,
CLUTTER_UNIT_EM,
CLUTTER_UNIT_MM,
CLUTTER_UNIT_POINT,
CLUTTER_UNIT_CM
} ClutterUnitType;
/**
* ClutterUnits:
*
* An opaque structure, to be used to store sizing and positioning
* values along with their unit.
*
* Since: 1.0
*/
typedef struct _ClutterUnits ClutterUnits;
struct _ClutterUnits
{
/*< private >*/
ClutterUnitType unit_type;
gfloat value;
/* pre-filled by the provided constructors */
/* cached pixel value */
gfloat pixels;
/* whether the :pixels field is set */
guint pixels_set;
/* the serial coming from the backend, used to evict the cache */
gint32 serial;
/* padding for eventual expansion */
gint32 __padding_1;
gint64 __padding_2;
};
GType clutter_units_get_type (void) G_GNUC_CONST;
ClutterUnitType clutter_units_get_unit_type (const ClutterUnits *units);
gfloat clutter_units_get_unit_value (const ClutterUnits *units);
ClutterUnits * clutter_units_copy (const ClutterUnits *units);
void clutter_units_free (ClutterUnits *units);
void clutter_units_from_pixels (ClutterUnits *units,
gint px);
void clutter_units_from_em (ClutterUnits *units,
gfloat em);
void clutter_units_from_em_for_font (ClutterUnits *units,
const gchar *font_name,
gfloat em);
void clutter_units_from_mm (ClutterUnits *units,
gfloat mm);
void clutter_units_from_cm (ClutterUnits *units,
gfloat cm);
void clutter_units_from_pt (ClutterUnits *units,
gfloat pt);
gfloat clutter_units_to_pixels (ClutterUnits *units);
gboolean clutter_units_from_string (ClutterUnits *units,
const gchar *str);
gchar * clutter_units_to_string (const ClutterUnits *units);
/* shorthands for the constructors */
#define clutter_units_pixels clutter_units_from_pixels
#define clutter_units_em clutter_units_from_em
#define clutter_units_em_for_font clutter_units_from_em_for_font
#define clutter_units_mm clutter_units_from_mm
#define clutter_units_cm clutter_units_from_cm
#define clutter_units_pt clutter_units_from_pt
#define CLUTTER_TYPE_UNITS (clutter_units_get_type ())
#define CLUTTER_TYPE_PARAM_UNITS (clutter_param_units_get_type ())
#define CLUTTER_PARAM_SPEC_UNITS(pspec) (G_TYPE_CHECK_INSTANCE_CAST ((pspec), CLUTTER_TYPE_PARAM_UNITS, ClutterParamSpecUnits))
#define CLUTTER_IS_PARAM_SPEC_UNITS(pspec) (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), CLUTTER_TYPE_PARAM_UNITS))
/**
* CLUTTER_VALUE_HOLDS_UNITS:
* @x: a #GValue
*
* Evaluates to %TRUE if @x holds a #ClutterUnits value
*
* Since: 0.8
*/
#define CLUTTER_VALUE_HOLDS_UNITS(x) (G_VALUE_HOLDS ((x), CLUTTER_TYPE_UNITS))
typedef struct _ClutterParamSpecUnits ClutterParamSpecUnits;
/**
* ClutterParamSpecUnits:
* @default_type: default type
* @default_value: default value
* @minimum: lower boundary
* @maximum: higher boundary
*
* #GParamSpec subclass for unit based properties.
*
* Since: 1.0
*/
struct _ClutterParamSpecUnits
{
/*< private >*/
GParamSpec parent_instance;
/*< public >*/
ClutterUnitType default_type;
gfloat default_value;
gfloat minimum;
gfloat maximum;
};
GType clutter_param_units_get_type (void) G_GNUC_CONST;
GParamSpec * clutter_param_spec_units (const gchar *name,
const gchar *nick,
const gchar *blurb,
ClutterUnitType default_type,
gfloat minimum,
gfloat maximum,
gfloat default_value,
GParamFlags flags);
void clutter_value_set_units (GValue *value,
const ClutterUnits *units);
G_CONST_RETURN ClutterUnits *clutter_value_get_units (const GValue *value);
G_END_DECLS
#endif /* __CLUTTER_UNITS_H__ */