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mutter/clutter/clutter-units.c
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

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/* -*- 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 Bassi <ebassi@openedhand.com>
*
* Copyright (C) 2007 OpenedHand
*
* 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, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/**
* SECTION:clutter-units
* @short_description: A logical distance unit
*
* #ClutterUnits is a structure holding a logical distance value along with
* its type, expressed as a value of the #ClutterUnitType enumeration. It is
* possible to use #ClutterUnits to store a position or a size in units
* different than pixels, and convert them whenever needed (for instance
* inside the #ClutterActor::allocate() virtual function, or inside the
* #ClutterActor::get_preferred_width() and #ClutterActor::get_preferred_height()
* virtual functions.
*
* In order to register a #ClutterUnits property, the #ClutterParamSpecUnits
* #GParamSpec sub-class should be used:
*
* |[
* GParamSpec *pspec;
*
* pspec = clutter_param_spec_units ("active-width",
* "Width",
* "Width of the active area, in millimeters",
* CLUTTER_UNIT_MM,
* 0.0, 12.0,
* 12.0,
* G_PARAM_READWRITE);
* g_object_class_install_property (gobject_class, PROP_WIDTH, pspec);
* ]|
*
* A #GValue holding units can be manipulated using clutter_value_set_units()
* and clutter_value_get_units(). #GValue<!-- -->s containing a #ClutterUnits
* value can also be transformed to #GValue<!-- -->s initialized with
* %G_TYPE_INT, %G_TYPE_FLOAT and %G_TYPE_STRING through implicit conversion
* and using g_value_transform().
*
* #ClutterUnits is available since Clutter 1.0
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <glib-object.h>
#include <gobject/gvaluecollector.h>
#include "clutter-units.h"
#include "clutter-private.h"
#define DPI_FALLBACK (96.0)
#define FLOAT_EPSILON (1e-30)
static gfloat
units_mm_to_pixels (gfloat mm)
{
ClutterBackend *backend;
gdouble dpi;
backend = clutter_get_default_backend ();
dpi = clutter_backend_get_resolution (backend);
if (dpi < 0)
dpi = DPI_FALLBACK;
return mm * dpi / 25.4;
}
static gfloat
units_cm_to_pixels (gfloat cm)
{
return units_mm_to_pixels (cm * 10);
}
static gfloat
units_pt_to_pixels (gfloat pt)
{
ClutterBackend *backend;
gdouble dpi;
backend = clutter_get_default_backend ();
dpi = clutter_backend_get_resolution (backend);
if (dpi < 0)
dpi = DPI_FALLBACK;
return pt * dpi / 72.0;
}
static gfloat
units_em_to_pixels (const gchar *font_name,
gfloat em)
{
ClutterBackend *backend = clutter_get_default_backend ();
if (font_name == NULL || *font_name == '\0')
return em * _clutter_backend_get_units_per_em (backend, NULL);
else
{
PangoFontDescription *font_desc;
gfloat res;
font_desc = pango_font_description_from_string (font_name);
if (font_desc == NULL)
res = -1.0;
else
{
res = em * _clutter_backend_get_units_per_em (backend, font_desc);
pango_font_description_free (font_desc);
}
return res;
}
}
/**
* clutter_units_from_mm:
* @units: a #ClutterUnits
* @mm: millimeters
*
* Stores a value in millimiters inside @units
*
* Since: 1.0
*/
void
clutter_units_from_mm (ClutterUnits *units,
gfloat mm)
{
ClutterBackend *backend;
g_return_if_fail (units != NULL);
backend = clutter_get_default_backend ();
units->unit_type = CLUTTER_UNIT_MM;
units->value = mm;
units->pixels = units_mm_to_pixels (mm);
units->pixels_set = TRUE;
units->serial = _clutter_backend_get_units_serial (backend);
}
/**
* clutter_units_from_cm:
* @units: a #ClutterUnits
* @cm: centimeters
*
* Stores a value in centimeters inside @units
*
* Since: 1.2
*/
void
clutter_units_from_cm (ClutterUnits *units,
gfloat cm)
{
ClutterBackend *backend;
g_return_if_fail (units != NULL);
backend = clutter_get_default_backend ();
units->unit_type = CLUTTER_UNIT_CM;
units->value = cm;
units->pixels = units_cm_to_pixels (cm);
units->pixels_set = TRUE;
units->serial = _clutter_backend_get_units_serial (backend);
}
/**
* clutter_units_from_pt:
* @units: a #ClutterUnits
* @pt: typographic points
*
* Stores a value in typographic points inside @units
*
* Since: 1.0
*/
void
clutter_units_from_pt (ClutterUnits *units,
gfloat pt)
{
ClutterBackend *backend;
g_return_if_fail (units != NULL);
backend = clutter_get_default_backend ();
units->unit_type = CLUTTER_UNIT_POINT;
units->value = pt;
units->pixels = units_pt_to_pixels (pt);
units->pixels_set = TRUE;
units->serial = _clutter_backend_get_units_serial (backend);
}
/**
* clutter_units_from_em:
* @units: a #ClutterUnits
* @em: em
*
* Stores a value in em inside @units, using the default font
* name as returned by clutter_backend_get_font_name()
*
* Since: 1.0
*/
void
clutter_units_from_em (ClutterUnits *units,
gfloat em)
{
ClutterBackend *backend;
g_return_if_fail (units != NULL);
backend = clutter_get_default_backend ();
units->unit_type = CLUTTER_UNIT_EM;
units->value = em;
units->pixels = units_em_to_pixels (NULL, em);
units->pixels_set = TRUE;
units->serial = _clutter_backend_get_units_serial (backend);
}
/**
* clutter_units_from_em_for_font:
* @units: a #ClutterUnits
* @font_name: the font name and size
* @em: em
*
* Stores a value in em inside @units using @font_name
*
* Since: 1.0
*/
void
clutter_units_from_em_for_font (ClutterUnits *units,
const gchar *font_name,
gfloat em)
{
ClutterBackend *backend;
g_return_if_fail (units != NULL);
backend = clutter_get_default_backend ();
units->unit_type = CLUTTER_UNIT_EM;
units->value = em;
units->pixels = units_em_to_pixels (font_name, em);
units->pixels_set = TRUE;
units->serial = _clutter_backend_get_units_serial (backend);
}
/**
* clutter_units_from_pixels:
* @units: a #ClutterUnits
* @px: pixels
*
* Stores a value in pixels inside @units
*
* Since: 1.0
*/
void
clutter_units_from_pixels (ClutterUnits *units,
gint px)
{
ClutterBackend *backend;
g_return_if_fail (units != NULL);
backend = clutter_get_default_backend ();
units->unit_type = CLUTTER_UNIT_PIXEL;
units->value = px;
units->pixels = px;
units->pixels_set = TRUE;
units->serial = _clutter_backend_get_units_serial (backend);
}
/**
* clutter_units_get_unit_type:
* @units: a #ClutterUnits
*
* Retrieves the unit type of the value stored inside @units
*
* Return value: a unit type
*
* Since: 1.0
*/
ClutterUnitType
clutter_units_get_unit_type (const ClutterUnits *units)
{
g_return_val_if_fail (units != NULL, CLUTTER_UNIT_PIXEL);
return units->unit_type;
}
/**
* clutter_units_get_unit_value:
* @units: a #ClutterUnits
*
* Retrieves the value stored inside @units
*
* Return value: the value stored inside a #ClutterUnits
*
* Since: 1.0
*/
gfloat
clutter_units_get_unit_value (const ClutterUnits *units)
{
g_return_val_if_fail (units != NULL, 0.0);
return units->value;
}
/**
* clutter_units_copy:
* @units: the #ClutterUnits to copy
*
* Copies @units
*
* Return value: the newly created copy of a #ClutterUnits structure.
* Use clutter_units_free() to free the allocated resources
*
* Since: 1.0
*/
ClutterUnits *
clutter_units_copy (const ClutterUnits *units)
{
if (units != NULL)
return g_slice_dup (ClutterUnits, units);
return NULL;
}
/**
* clutter_units_free:
* @units: the #ClutterUnits to free
*
* Frees the resources allocated by @units
*
* You should only call this function on a #ClutterUnits
* created using clutter_units_copy()
*
* Since: 1.0
*/
void
clutter_units_free (ClutterUnits *units)
{
if (units != NULL)
g_slice_free (ClutterUnits, units);
}
/**
* clutter_units_to_pixels:
* @units: units to convert
*
* Converts a value in #ClutterUnits to pixels
*
* Return value: the value in pixels
*
* Since: 1.0
*/
gfloat
clutter_units_to_pixels (ClutterUnits *units)
{
ClutterBackend *backend;
g_return_val_if_fail (units != NULL, 0.0);
/* if the backend settings changed we evict the cached value */
backend = clutter_get_default_backend ();
if (units->serial != _clutter_backend_get_units_serial (backend))
units->pixels_set = FALSE;
if (units->pixels_set)
return units->pixels;
switch (units->unit_type)
{
case CLUTTER_UNIT_MM:
units->pixels = units_mm_to_pixels (units->value);
break;
case CLUTTER_UNIT_CM:
units->pixels = units_cm_to_pixels (units->value);
break;
case CLUTTER_UNIT_POINT:
units->pixels = units_pt_to_pixels (units->value);
break;
case CLUTTER_UNIT_EM:
units->pixels = units_em_to_pixels (NULL, units->value);
break;
case CLUTTER_UNIT_PIXEL:
units->pixels = units->value;
break;
}
units->pixels_set = TRUE;
units->serial = _clutter_backend_get_units_serial (backend);
return units->pixels;
}
/**
* clutter_units_from_string:
* @units: a #ClutterUnits
* @str: the string to convert
*
* Parses a value and updates @units with it
*
* A #ClutterUnits expressed in string should match:
*
* |[
* units: wsp* unit-value wsp* unit-name? wsp*
* unit-value: number
* unit-name: 'px' | 'pt' | 'mm' | 'em' | 'cm'
* number: digit+
* | digit* sep digit+
* sep: '.' | ','
* digit: '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9'
* wsp: (#0x20 | #0x9 | #0xA | #0xB | #0xC | #0xD)+
* ]|
*
* For instance, these are valid strings:
*
* |[
* 10 px
* 5.1 em
* 24 pt
* 12.6 mm
* .3 cm
* ]|
*
* While these are not:
*
* |[
* 42 cats
* omg!1!ponies
* ]|
*
* <note>If no unit is specified, pixels are assumed.</note>
*
* Return value: %TRUE if the string was successfully parsed,
* and %FALSE otherwise
*
* Since: 1.0
*/
gboolean
clutter_units_from_string (ClutterUnits *units,
const gchar *str)
{
ClutterBackend *backend;
ClutterUnitType unit_type;
gfloat value;
g_return_val_if_fail (units != NULL, FALSE);
g_return_val_if_fail (str != NULL, FALSE);
/* strip leading space */
while (g_ascii_isspace (*str))
str++;
if (*str == '\0')
return FALSE;
/* integer part */
value = (gfloat) strtoul (str, (char **) &str, 10);
if (*str == '.' || *str == ',')
{
gfloat divisor = 0.1;
/* 5.cm is not a valid number */
if (!g_ascii_isdigit (*++str))
return FALSE;
while (g_ascii_isdigit (*str))
{
value += (*str - '0') * divisor;
divisor *= 0.1;
str++;
}
}
while (g_ascii_isspace (*str))
str++;
/* assume pixels by default, if no unit is specified */
if (*str == '\0')
unit_type = CLUTTER_UNIT_PIXEL;
else if (strncmp (str, "em", 2) == 0)
{
unit_type = CLUTTER_UNIT_EM;
str += 2;
}
else if (strncmp (str, "mm", 2) == 0)
{
unit_type = CLUTTER_UNIT_MM;
str += 2;
}
else if (strncmp (str, "cm", 2) == 0)
{
unit_type = CLUTTER_UNIT_CM;
str += 2;
}
else if (strncmp (str, "pt", 2) == 0)
{
unit_type = CLUTTER_UNIT_POINT;
str += 2;
}
else if (strncmp (str, "px", 2) == 0)
{
unit_type = CLUTTER_UNIT_PIXEL;
str += 2;
}
else
return FALSE;
/* ensure the unit is only followed by white space */
while (g_ascii_isspace (*str))
str++;
if (*str != '\0')
return FALSE;
backend = clutter_get_default_backend ();
units->unit_type = unit_type;
units->value = value;
units->pixels_set = FALSE;
units->serial = _clutter_backend_get_units_serial (backend);
return TRUE;
}
static const gchar *
clutter_unit_type_name (ClutterUnitType unit_type)
{
switch (unit_type)
{
case CLUTTER_UNIT_MM:
return "mm";
case CLUTTER_UNIT_CM:
return "cm";
case CLUTTER_UNIT_POINT:
return "pt";
case CLUTTER_UNIT_EM:
return "em";
case CLUTTER_UNIT_PIXEL:
return "px";
}
g_warning ("Invalid unit type %d", (int) unit_type);
return "<invalid>";
}
/**
* clutter_units_to_string:
* @units: a #ClutterUnits
*
* Converts @units into a string
*
* See clutter_units_from_string() for the units syntax and for
* examples of output
*
* <note>Fractional values are truncated to the second decimal
* position for em, mm and cm, and to the first decimal position for
* typographic points. Pixels are integers.</note>
*
* Return value: a newly allocated string containing the encoded
* #ClutterUnits value. Use g_free() to free the string
*
* Since: 1.0
*/
gchar *
clutter_units_to_string (const ClutterUnits *units)
{
const gchar *unit_name = NULL;
const gchar *fmt = NULL;
gchar buf[G_ASCII_DTOSTR_BUF_SIZE];
g_return_val_if_fail (units != NULL, NULL);
switch (units->unit_type)
{
/* special case: there is no such thing as "half a pixel", so
* we round up to the nearest integer using C default
*/
case CLUTTER_UNIT_PIXEL:
return g_strdup_printf ("%d px", (int) units->value);
case CLUTTER_UNIT_MM:
unit_name = "mm";
fmt = "%.2f";
break;
case CLUTTER_UNIT_CM:
unit_name = "cm";
fmt = "%.2f";
break;
case CLUTTER_UNIT_POINT:
unit_name = "pt";
fmt = "%.1f";
break;
case CLUTTER_UNIT_EM:
unit_name = "em";
fmt = "%.2f";
break;
default:
g_assert_not_reached ();
break;
}
g_ascii_formatd (buf, G_ASCII_DTOSTR_BUF_SIZE, fmt, units->value);
return g_strconcat (buf, " ", unit_name, NULL);
}
/*
* GValue and GParamSpec integration
*/
/* units to integer */
static void
clutter_value_transform_units_int (const GValue *src,
GValue *dest)
{
dest->data[0].v_int = clutter_units_to_pixels (src->data[0].v_pointer);
}
/* integer to units */
static void
clutter_value_transform_int_units (const GValue *src,
GValue *dest)
{
clutter_units_from_pixels (dest->data[0].v_pointer, src->data[0].v_int);
}
/* units to float */
static void
clutter_value_transform_units_float (const GValue *src,
GValue *dest)
{
dest->data[0].v_float = clutter_units_to_pixels (src->data[0].v_pointer);
}
/* float to units */
static void
clutter_value_transform_float_units (const GValue *src,
GValue *dest)
{
clutter_units_from_pixels (dest->data[0].v_pointer, src->data[0].v_float);
}
/* units to string */
static void
clutter_value_transform_units_string (const GValue *src,
GValue *dest)
{
gchar *string = clutter_units_to_string (src->data[0].v_pointer);
g_value_take_string (dest, string);
}
/* string to units */
static void
clutter_value_transform_string_units (const GValue *src,
GValue *dest)
{
ClutterUnits units = { CLUTTER_UNIT_PIXEL, 0.0f };
clutter_units_from_string (&units, g_value_get_string (src));
clutter_value_set_units (dest, &units);
}
GType
clutter_units_get_type (void)
{
static volatile gsize clutter_units_type__volatile = 0;
if (g_once_init_enter (&clutter_units_type__volatile))
{
GType clutter_units_type =
g_boxed_type_register_static (I_("ClutterUnits"),
(GBoxedCopyFunc) clutter_units_copy,
(GBoxedFreeFunc) clutter_units_free);
g_value_register_transform_func (clutter_units_type, G_TYPE_INT,
clutter_value_transform_units_int);
g_value_register_transform_func (G_TYPE_INT, clutter_units_type,
clutter_value_transform_int_units);
g_value_register_transform_func (clutter_units_type, G_TYPE_FLOAT,
clutter_value_transform_units_float);
g_value_register_transform_func (G_TYPE_FLOAT, clutter_units_type,
clutter_value_transform_float_units);
g_value_register_transform_func (clutter_units_type, G_TYPE_STRING,
clutter_value_transform_units_string);
g_value_register_transform_func (G_TYPE_STRING, clutter_units_type,
clutter_value_transform_string_units);
g_once_init_leave (&clutter_units_type__volatile, clutter_units_type);
}
return clutter_units_type__volatile;
}
/**
* clutter_value_set_units:
* @value: a #GValue initialized to #CLUTTER_TYPE_UNIT
* @units: the units to set
*
* Sets @value to @units
*
* Since: 0.8
*/
void
clutter_value_set_units (GValue *value,
const ClutterUnits *units)
{
g_return_if_fail (CLUTTER_VALUE_HOLDS_UNITS (value));
value->data[0].v_pointer = clutter_units_copy (units);
}
/**
* clutter_value_get_units:
* @value: a #GValue initialized to #CLUTTER_TYPE_UNIT
*
* Gets the #ClutterUnit<!-- -->s contained in @value.
*
* Return value: the units inside the passed #GValue
*
* Since: 0.8
*/
G_CONST_RETURN ClutterUnits *
clutter_value_get_units (const GValue *value)
{
g_return_val_if_fail (CLUTTER_VALUE_HOLDS_UNITS (value), NULL);
return value->data[0].v_pointer;
}
static void
param_units_init (GParamSpec *pspec)
{
ClutterParamSpecUnits *uspec = CLUTTER_PARAM_SPEC_UNITS (pspec);
uspec->minimum = -G_MAXFLOAT;
uspec->maximum = G_MAXFLOAT;
uspec->default_value = 0.0f;
uspec->default_type = CLUTTER_UNIT_PIXEL;
}
static void
param_units_set_default (GParamSpec *pspec,
GValue *value)
{
ClutterParamSpecUnits *uspec = CLUTTER_PARAM_SPEC_UNITS (pspec);
ClutterUnits units;
units.unit_type = uspec->default_type;
units.value = uspec->default_value;
units.pixels_set = FALSE;
clutter_value_set_units (value, &units);
}
static gboolean
param_units_validate (GParamSpec *pspec,
GValue *value)
{
ClutterParamSpecUnits *uspec = CLUTTER_PARAM_SPEC_UNITS (pspec);
ClutterUnits *units = value->data[0].v_pointer;
ClutterUnitType otype = units->unit_type;
gfloat oval = units->value;
g_assert (CLUTTER_IS_PARAM_SPEC_UNITS (pspec));
if (otype != uspec->default_type)
{
gchar *str = clutter_units_to_string (units);
g_warning ("The units value of '%s' does not have the same unit "
"type as declared by the ClutterParamSpecUnits of '%s'",
str,
clutter_unit_type_name (otype));
g_free (str);
return FALSE;
}
units->value = CLAMP (units->value,
uspec->minimum,
uspec->maximum);
return units->value != oval;
}
static gint
param_units_values_cmp (GParamSpec *pspec,
const GValue *value1,
const GValue *value2)
{
ClutterUnits *units1 = value1->data[0].v_pointer;
ClutterUnits *units2 = value2->data[0].v_pointer;
gfloat v1, v2;
if (units1->unit_type == units2->unit_type)
{
v1 = units1->value;
v2 = units2->value;
}
else
{
v1 = clutter_units_to_pixels (units1);
v2 = clutter_units_to_pixels (units2);
}
if (v1 < v2)
return - (v2 - v1 > FLOAT_EPSILON);
else
return v1 - v2 > FLOAT_EPSILON;
}
GType
clutter_param_units_get_type (void)
{
static GType pspec_type = 0;
if (G_UNLIKELY (pspec_type == 0))
{
const GParamSpecTypeInfo pspec_info = {
sizeof (ClutterParamSpecUnits),
16,
param_units_init,
CLUTTER_TYPE_UNITS,
NULL,
param_units_set_default,
param_units_validate,
param_units_values_cmp,
};
pspec_type = g_param_type_register_static (I_("ClutterParamSpecUnit"),
&pspec_info);
}
return pspec_type;
}
/**
* clutter_param_spec_units:
* @name: name of the property
* @nick: short name
* @blurb: description (can be translatable)
* @default_type: the default type for the #ClutterUnits
* @minimum: lower boundary
* @maximum: higher boundary
* @default_value: default value
* @flags: flags for the param spec
*
* Creates a #GParamSpec for properties using #ClutterUnits.
*
* Return value: the newly created #GParamSpec
*
* Since: 1.0
*/
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)
{
ClutterParamSpecUnits *uspec;
g_return_val_if_fail (default_value >= minimum && default_value <= maximum,
NULL);
uspec = g_param_spec_internal (CLUTTER_TYPE_PARAM_UNITS,
name, nick, blurb,
flags);
uspec->default_type = default_type;
uspec->minimum = minimum;
uspec->maximum = maximum;
uspec->default_value = default_value;
return G_PARAM_SPEC (uspec);
}
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