gtk/gdk/gdkcolorstate.c

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/* gdkcolorstate.c
*
* Copyright 2024 Matthias Clasen
*
* 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/>.
*/
#include "config.h"
#include "gdkcolorstateprivate.h"
#include <math.h>
/**
* GdkColorState:
*
* A `GdkColorState` object provides the information to interpret
* colors and pixels in a variety of ways.
*
* They are also known as
* [*color spaces*](https://en.wikipedia.org/wiki/Color_space).
*
* Crucially, GTK knows how to convert colors from one color
* state to another.
*
* `GdkColorState objects are immutable and therefore threadsafe.
*
* Since 4.16
*/
G_DEFINE_BOXED_TYPE (GdkColorState, gdk_color_state,
gdk_color_state_ref, gdk_color_state_unref);
/* {{{ Public API */
/**
* gdk_color_state_ref:
* @self: a `GdkColorState`
*
* Increase the reference count of @self.
*
* Returns: the object that was passed in
*
* Since: 4.16
*/
GdkColorState *
(gdk_color_state_ref) (GdkColorState *self)
{
return _gdk_color_state_ref (self);
}
/**
* gdk_color_state_unref:
* @self:a `GdkColorState`
*
* Decrease the reference count of @self.
*
* Unless @self is static, it will be freed
* when the reference count reaches zero.
*
* Since: 4.16
*/
void
(gdk_color_state_unref) (GdkColorState *self)
{
_gdk_color_state_unref (self);
}
/**
* gdk_color_state_get_srgb:
*
* Returns the color state object representing the sRGB color space.
*
* This color state uses the primaries defined by BT.709-6 and the transfer function
* defined by IEC 61966-2-1.
*
* It is equivalent to H.273 ColourPrimaries 1 with TransferCharacteristics 13 and MatrixCoefficients 0.
*
* See e.g. [the CSS Color Module](https://www.w3.org/TR/css-color-4/#predefined-sRGB)
* for details about this colorstate.
*
* Returns: the color state object for sRGB
*
* Since: 4.16
*/
GdkColorState *
gdk_color_state_get_srgb (void)
{
return GDK_COLOR_STATE_SRGB;
}
/**
* gdk_color_state_get_srgb_linear:
*
* Returns the color state object representing the linearized sRGB color space.
*
* This color state uses the primaries defined by BT.709-6 and a linear transfer function.
*
* It is equivalent to H.273 ColourPrimaries 1 with TransferCharacteristics 8 and MatrixCoefficients 0.
*
* See e.g. [the CSS Color Module](https://www.w3.org/TR/css-color-4/#predefined-sRGB-linear)
* for details about this colorstate.
*
* Returns: the color state object for linearized sRGB
*
* Since: 4.16
*/
GdkColorState *
gdk_color_state_get_srgb_linear (void)
{
return GDK_COLOR_STATE_SRGB_LINEAR;
}
/**
* gdk_color_state_get_rec2100_pq:
*
* Returns the color state object representing the rec2100-pq color space.
*
* This color state uses the primaries defined by BT.2020-2 and BT.2100-0 and the transfer
* function defined by SMPTE ST 2084 and BT.2100-2.
*
* It is equivalent to H.273 ColourPrimaries code point 9 with TransferCharacteristics 16.
*
* See e.g. [the CSS HDR Module](https://drafts.csswg.org/css-color-hdr/#valdef-color-rec2100-pq)
* for details about this colorstate.
*
* Returns: the color state object for rec2100-pq
*
* Since: 4.16
*/
GdkColorState *
gdk_color_state_get_rec2100_pq (void)
{
return GDK_COLOR_STATE_REC2100_PQ;
}
/**
* gdk_color_state_get_rec2100_linear:
*
* Returns the color state object representing the linear rec2100 color space.
*
* This color state uses the primaries defined by BT.2020-2 and BT.2100-0 and a linear
* transfer function.
*
* It is equivalent to H.273 ColourPrimaries code point 9 with TransferCharacteristics 8.
*
* See e.g. [the CSS HDR Module](https://drafts.csswg.org/css-color-hdr/#valdef-color-rec2100-linear)
* for details about this colorstate.
*
* Returns: the color state object for linearized rec2100
*
* Since: 4.16
*/
GdkColorState *
gdk_color_state_get_rec2100_linear (void)
{
return GDK_COLOR_STATE_REC2100_LINEAR;
}
/**
* gdk_color_state_equal:
* @self: a `GdkColorState`
* @other: another `GdkColorStatee`
*
* Compares two `GdkColorStates` for equality.
*
* Note that this function is not guaranteed to be perfect and two objects
* describing the same color state may compare not equal. However, different
* color states will never compare equal.
*
* Returns: %TRUE if the two color states compare equal
*
* Since: 4.16
*/
gboolean
(gdk_color_state_equal) (GdkColorState *self,
GdkColorState *other)
{
return _gdk_color_state_equal (self, other);
}
/* }}} */
/* {{{ Default implementation */
/* {{{ Vfuncs */
static gboolean
gdk_default_color_state_equal (GdkColorState *self,
GdkColorState *other)
{
return self == other;
}
static const char *
gdk_default_color_state_get_name (GdkColorState *color_state)
{
GdkDefaultColorState *self = (GdkDefaultColorState *) color_state;
return self->name;
}
static GdkColorState *
gdk_default_color_state_get_no_srgb_tf (GdkColorState *color_state)
{
GdkDefaultColorState *self = (GdkDefaultColorState *) color_state;
return self->no_srgb;
}
static GdkFloatColorConvert
gdk_default_color_state_get_convert_to (GdkColorState *color_state,
GdkColorState *target)
{
GdkDefaultColorState *self = (GdkDefaultColorState *) color_state;
if (!GDK_IS_DEFAULT_COLOR_STATE (target))
return NULL;
return self->convert_to[GDK_DEFAULT_COLOR_STATE_ID (target)];
}
static GdkFloatColorConvert
gdk_default_color_state_get_convert_from (GdkColorState *color_state,
GdkColorState *source)
{
GdkDefaultColorState *self = (GdkDefaultColorState *) source;
if (!GDK_IS_DEFAULT_COLOR_STATE (color_state))
return NULL;
return self->convert_to[GDK_DEFAULT_COLOR_STATE_ID (color_state)];
}
/* }}} */
/* {{{ Conversion functions */
#define TRANSFORM(name, eotf, matrix, oetf) \
static void \
name (GdkColorState *self, \
float (*values)[4], \
gsize n_values) \
{ \
for (gsize i = 0; i < n_values; i++) \
{ \
values[i][0] = eotf (values[i][0]); \
values[i][1] = eotf (values[i][1]); \
values[i][2] = eotf (values[i][2]); \
if ((float **)matrix != IDENTITY) \
{ \
float res[3]; \
res[0] = matrix[0][0] * values[i][0] + matrix[0][1] * values[i][1] + matrix[0][2] * values[i][2]; \
res[1] = matrix[1][0] * values[i][0] + matrix[1][1] * values[i][1] + matrix[1][2] * values[i][2]; \
res[2] = matrix[2][0] * values[i][0] + matrix[2][1] * values[i][1] + matrix[2][2] * values[i][2]; \
values[i][0] = res[0]; \
values[i][1] = res[1]; \
values[i][2] = res[2]; \
} \
values[i][0] = oetf (values[i][0]); \
values[i][1] = oetf (values[i][1]); \
values[i][2] = oetf (values[i][2]); \
} \
}
static inline float
srgb_oetf (float v)
{
if (v > 0.0031308f)
return 1.055f * powf (v, 1.f / 2.4f) - 0.055f;
else
return 12.92f * v;
}
static inline float
srgb_eotf (float v)
{
if (v >= 0.04045f)
return powf (((v + 0.055f) / (1.f + 0.055f)), 2.4f);
else
return v / 12.92f;
}
static inline float
pq_eotf (float v)
{
float ninv = (1 << 14) / 2610.0;
float minv = (1 << 5) / 2523.0;
float c1 = 3424.0 / (1 << 12);
float c2 = 2413.0 / (1 << 7);
float c3 = 2392.0 / (1 << 7);
float x = powf (MAX ((powf (v, minv) - c1), 0) / (c2 - (c3 * (powf (v, minv)))), ninv);
return x * 10000 / 203.0;
}
static inline float
pq_oetf (float v)
{
float x = v * 203.0 / 10000.0;
float n = 2610.0 / (1 << 14);
float m = 2523.0 / (1 << 5);
float c1 = 3424.0 / (1 << 12);
float c2 = 2413.0 / (1 << 7);
float c3 = 2392.0 / (1 << 7);
return powf (((c1 + (c2 * powf (x, n))) / (1 + (c3 * powf (x, n)))), m);
}
/* These matrices are derived by combining the standard abc_to_xyz onces:
*
* rec2020_to_srgb = srgb_to_xyz¹ * rec2020_to_xyz
* srgb_to_rec2020 = rec2020_to_xyz¹ * srgb_to_xyz
*
* These values were used here:
*
* static const float srgb_to_xyz[3][3] = {
* { 0.4125288, 0.3581642, 0.1774037 },
* { 0.2127102, 0.7163284, 0.0709615 },
* { 0.0193373, 0.1193881, 0.9343260 },
* }
*
* static const float rec2020_to_xyz[3][3] = {
* { 0.6369615, 0.1448079, 0.1663273 },
* { 0.2627016, 0.6788934, 0.0584050 },
* { 0.0000000, 0.0281098, 1.0449416 },
* };
*
* See http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html
* for how to derive the abc_to_xyz matrices from chromaticity coordinates.
*/
static const float rec2020_to_srgb[3][3] = {
{ 1.659944, -0.588220, -0.071724 },
{ -0.124350, 1.132559, -0.008210 },
{ -0.018466, -0.102459, 1.120924 },
};
static const float srgb_to_rec2020[3][3] = {
{ 0.627610, 0.329815, 0.042574 },
{ 0.069029, 0.919817, 0.011154 },
{ 0.016649, 0.089510, 0.893842 },
};
#define IDENTITY ((float**)0)
#define NONE(x) x
TRANSFORM(gdk_default_srgb_to_srgb_linear, srgb_eotf, IDENTITY, NONE);
TRANSFORM(gdk_default_srgb_linear_to_srgb, NONE, IDENTITY, srgb_oetf)
TRANSFORM(gdk_default_rec2100_pq_to_rec2100_linear, pq_eotf, IDENTITY, NONE)
TRANSFORM(gdk_default_rec2100_linear_to_rec2100_pq, NONE, IDENTITY, pq_oetf)
TRANSFORM(gdk_default_srgb_linear_to_rec2100_linear, NONE, srgb_to_rec2020, NONE)
TRANSFORM(gdk_default_rec2100_linear_to_srgb_linear, NONE, rec2020_to_srgb, NONE)
TRANSFORM(gdk_default_srgb_to_rec2100_linear, srgb_eotf, srgb_to_rec2020, NONE)
TRANSFORM(gdk_default_rec2100_pq_to_srgb_linear, pq_eotf, rec2020_to_srgb, NONE)
TRANSFORM(gdk_default_srgb_linear_to_rec2100_pq, NONE, srgb_to_rec2020, pq_oetf)
TRANSFORM(gdk_default_rec2100_linear_to_srgb, NONE, rec2020_to_srgb, srgb_oetf)
TRANSFORM(gdk_default_srgb_to_rec2100_pq, srgb_eotf, srgb_to_rec2020, pq_oetf)
TRANSFORM(gdk_default_rec2100_pq_to_srgb, pq_eotf, rec2020_to_srgb, srgb_oetf)
#undef IDENTITY
#undef NONE
/* }}} */
static const
GdkColorStateClass GDK_DEFAULT_COLOR_STATE_CLASS = {
.free = NULL, /* crash here if this ever happens */
.equal = gdk_default_color_state_equal,
.get_name = gdk_default_color_state_get_name,
.get_no_srgb_tf = gdk_default_color_state_get_no_srgb_tf,
.get_convert_to = gdk_default_color_state_get_convert_to,
};
GdkDefaultColorState gdk_default_color_states[] = {
[GDK_COLOR_STATE_ID_SRGB] = {
.parent = {
.klass = &GDK_DEFAULT_COLOR_STATE_CLASS,
.ref_count = 0,
.depth = GDK_MEMORY_U8_SRGB,
.rendering_color_state = GDK_COLOR_STATE_SRGB_LINEAR,
},
.name = "srgb",
.no_srgb = GDK_COLOR_STATE_SRGB_LINEAR,
.convert_to = {
[GDK_COLOR_STATE_ID_SRGB_LINEAR] = gdk_default_srgb_to_srgb_linear,
[GDK_COLOR_STATE_ID_REC2100_PQ] = gdk_default_srgb_to_rec2100_pq,
[GDK_COLOR_STATE_ID_REC2100_LINEAR] = gdk_default_srgb_to_rec2100_linear,
},
},
[GDK_COLOR_STATE_ID_SRGB_LINEAR] = {
.parent = {
.klass = &GDK_DEFAULT_COLOR_STATE_CLASS,
.ref_count = 0,
.depth = GDK_MEMORY_U8,
.rendering_color_state = GDK_COLOR_STATE_SRGB_LINEAR,
},
.name = "srgb-linear",
.no_srgb = NULL,
.convert_to = {
[GDK_COLOR_STATE_ID_SRGB] = gdk_default_srgb_linear_to_srgb,
[GDK_COLOR_STATE_ID_REC2100_PQ] = gdk_default_srgb_linear_to_rec2100_pq,
[GDK_COLOR_STATE_ID_REC2100_LINEAR] = gdk_default_srgb_linear_to_rec2100_linear,
},
},
[GDK_COLOR_STATE_ID_REC2100_PQ] = {
.parent = {
.klass = &GDK_DEFAULT_COLOR_STATE_CLASS,
.ref_count = 0,
.depth = GDK_MEMORY_FLOAT16,
.rendering_color_state = GDK_COLOR_STATE_REC2100_LINEAR,
},
.name = "rec2100-pq",
.no_srgb = NULL,
.convert_to = {
[GDK_COLOR_STATE_ID_SRGB] = gdk_default_rec2100_pq_to_srgb,
[GDK_COLOR_STATE_ID_SRGB_LINEAR] = gdk_default_rec2100_pq_to_srgb_linear,
[GDK_COLOR_STATE_ID_REC2100_LINEAR] = gdk_default_rec2100_pq_to_rec2100_linear,
},
},
[GDK_COLOR_STATE_ID_REC2100_LINEAR] = {
.parent = {
.klass = &GDK_DEFAULT_COLOR_STATE_CLASS,
.ref_count = 0,
.depth = GDK_MEMORY_FLOAT16,
.rendering_color_state = GDK_COLOR_STATE_REC2100_LINEAR,
},
.name = "rec2100-linear",
.no_srgb = NULL,
.convert_to = {
[GDK_COLOR_STATE_ID_SRGB] = gdk_default_rec2100_linear_to_srgb,
[GDK_COLOR_STATE_ID_SRGB_LINEAR] = gdk_default_rec2100_linear_to_srgb_linear,
[GDK_COLOR_STATE_ID_REC2100_PQ] = gdk_default_rec2100_linear_to_rec2100_pq,
},
},
};
/* }}} */
/* {{{ Private API */
const char *
gdk_color_state_get_name (GdkColorState *self)
{
return self->klass->get_name (self);
}
/*<private>
* gdk_color_state_get_no_srgb_tf:
* @self: a colorstate
*
* This function checks if the colorstate uses an sRGB transfer function
* as final operation. In that case, it is suitable for use with GL_SRGB
* (and the Vulkan equivalents).
*
* If it is suitable, the colorstate without the transfer function is
* returned. Otherwise, this function returns NULL.
*
* Returns: (transfer none): the colorstate without sRGB transfer function.
**/
GdkColorState *
gdk_color_state_get_no_srgb_tf (GdkColorState *self)
{
if (!GDK_DEBUG_CHECK (LINEAR))
return FALSE;
return self->klass->get_no_srgb_tf (self);
}
/* }}} */
/* vim:set foldmethod=marker expandtab: */