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[sfnt] Support variable 'COLR' v1 color lines. 

* include/freetype/ftcolor.h (FT_ColorStopIterator): Add field
`read_variable` to indicate whether a variation index base should be read.

* src/sfnt/ttcolr.c: (FT_PaintFormat_Internal): New enumerations
`FT_COLR_PAINTFORMAT_INTERNAL_VAR_LINEAR_GRADIENT`
`FT_COLR_PAINTFORMAT_INTERNAL_VAR_RADIAL_GRADIENT`, and
`FT_COLR_PAINTFORMAT_INTERNAL_VAR_SWEEP_GRADIENT`.
(read_color_line): New parameter `read_variable`; update callers.
(read_paint): Handle new enumerations.
This commit is contained in:
Dominik Röttsches 2022-07-04 16:29:31 +03:00 committed by Werner Lemberg
parent 7c151abb69
commit 3414fef74f
2 changed files with 66 additions and 11 deletions
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13
include/freetype/ftcolor.h
View File

@ -521,9 +521,10 @@ FT_BEGIN_HEADER
*
* @description:
* This iterator object is needed for @FT_Get_Colorline_Stops. It keeps
* state while iterating over the stops of an @FT_ColorLine,
* representing the `ColorLine` struct of the v1 extensions to 'COLR',
* see 'https://github.com/googlefonts/colr-gradients-spec'.
* state while iterating over the stops of an @FT_ColorLine, representing
* the `ColorLine` struct of the v1 extensions to 'COLR', see
* 'https://github.com/googlefonts/colr-gradients-spec'. Do not manually
* modify fields of this iterator.
*
* @fields:
* num_color_stops ::
@ -537,6 +538,10 @@ FT_BEGIN_HEADER
* An opaque pointer into 'COLR' table data. Set by @FT_Get_Paint.
* Updated by @FT_Get_Colorline_Stops.
*
* read_variable ::
* A boolean keeping track of whether variable color lines are to be
* read. Set by @FT_Get_Paint.
*
* @since:
* 2.11 -- **currently experimental only!** There might be changes
* without retaining backward compatibility of both the API and ABI.
@ -549,6 +554,8 @@ FT_BEGIN_HEADER
FT_Byte* p;
FT_Bool read_variable;
} FT_ColorStopIterator;

64
src/sfnt/ttcolr.c
View File

@ -66,6 +66,9 @@
typedef enum FT_PaintFormat_Internal_
{
FT_COLR_PAINTFORMAT_INTERNAL_VAR_SOLID = 3,
FT_COLR_PAINTFORMAT_INTERNAL_VAR_LINEAR_GRADIENT = 5,
FT_COLR_PAINTFORMAT_INTERNAL_VAR_RADIAL_GRADIENT = 7,
FT_COLR_PAINTFORMAT_INTERNAL_VAR_SWEEP_GRADIENT = 9,
FT_COLR_PAINTFORMAT_INTERNAL_SCALE_CENTER = 18,
FT_COLR_PAINTFORMAT_INTERNAL_SCALE_UNIFORM = 20,
FT_COLR_PAINTFORMAT_INTERNAL_SCALE_UNIFORM_CENTER = 22,
@ -477,8 +480,9 @@
static FT_Bool
read_color_line( FT_Byte* color_line_p,
FT_ColorLine *colorline )
read_color_line( FT_Byte* color_line_p,
FT_ColorLine* colorline,
FT_Bool read_variable )
{
FT_Byte* p = color_line_p;
FT_PaintExtend paint_extend;
@ -493,6 +497,7 @@
colorline->color_stop_iterator.num_color_stops = FT_NEXT_USHORT( p );
colorline->color_stop_iterator.p = p;
colorline->color_stop_iterator.current_color_stop = 0;
colorline->color_stop_iterator.read_variable = read_variable;
return 1;
}
@ -604,6 +609,7 @@
{
FT_Byte* paint_base = p;
FT_Byte* child_table_p = NULL;
FT_Bool do_read_var = FALSE;
FT_ULong var_index_base = 0;
/* Longest varIndexBase offset is 5 in the spec. */
FT_ItemVarDelta item_deltas[6] = { 0, 0, 0, 0, 0, 0 };
@ -691,10 +697,14 @@
if ( !get_child_table_pointer( colr, paint_base, &p, &child_table_p ) )
return 0;
if ( apaint->format == FT_COLR_PAINTFORMAT_LINEAR_GRADIENT )
if ( apaint->format == FT_COLR_PAINTFORMAT_LINEAR_GRADIENT ||
( do_read_var =
( (FT_PaintFormat_Internal)apaint->format ==
FT_COLR_PAINTFORMAT_INTERNAL_VAR_LINEAR_GRADIENT ) ) )
{
if ( !read_color_line( child_table_p,
&apaint->u.linear_gradient.colorline ) )
&apaint->u.linear_gradient.colorline,
do_read_var ) )
return 0;
/*
@ -708,16 +718,22 @@
apaint->u.linear_gradient.p2.x = INT_TO_FIXED( FT_NEXT_SHORT( p ) );
apaint->u.linear_gradient.p2.y = INT_TO_FIXED( FT_NEXT_SHORT( p ) );
apaint->format = FT_COLR_PAINTFORMAT_LINEAR_GRADIENT;
return 1;
}
else if ( apaint->format == FT_COLR_PAINTFORMAT_RADIAL_GRADIENT )
else if ( apaint->format == FT_COLR_PAINTFORMAT_RADIAL_GRADIENT ||
( do_read_var =
( (FT_PaintFormat_Internal)apaint->format ==
FT_COLR_PAINTFORMAT_INTERNAL_VAR_RADIAL_GRADIENT ) ) )
{
FT_Pos tmp;
if ( !read_color_line( child_table_p,
&apaint->u.radial_gradient.colorline ) )
&apaint->u.radial_gradient.colorline,
do_read_var ) )
return 0;
/* In the OpenType specification, `r0` and `r1` are defined as */
@ -737,13 +753,19 @@
tmp = INT_TO_FIXED( FT_NEXT_SHORT( p ) );
apaint->u.radial_gradient.r1 = tmp < 0 ? FT_INT_MAX : tmp;
apaint->format = FT_COLR_PAINTFORMAT_RADIAL_GRADIENT;
return 1;
}
else if ( apaint->format == FT_COLR_PAINTFORMAT_SWEEP_GRADIENT )
else if ( apaint->format == FT_COLR_PAINTFORMAT_SWEEP_GRADIENT ||
( do_read_var =
( (FT_PaintFormat_Internal)apaint->format ==
FT_COLR_PAINTFORMAT_INTERNAL_VAR_SWEEP_GRADIENT ) ) )
{
if ( !read_color_line( child_table_p,
&apaint->u.sweep_gradient.colorline ) )
&apaint->u.sweep_gradient.colorline,
do_read_var) )
return 0;
apaint->u.sweep_gradient.center.x =
@ -756,6 +778,8 @@
apaint->u.sweep_gradient.end_angle =
F2DOT14_TO_FIXED( FT_NEXT_SHORT( p ) );
apaint->format = FT_COLR_PAINTFORMAT_SWEEP_GRADIENT;
return 1;
}
@ -1228,6 +1252,8 @@
Colr* colr = (Colr*)face->colr;
FT_Byte* p;
FT_Long var_index_base;
FT_Int item_deltas[2];
if ( !colr || !colr->table )
@ -1251,6 +1277,28 @@
color_stop->color.alpha = FT_NEXT_SHORT( p );
if ( iterator->read_variable )
{
/* Pointer p needs to be advanced independently of whether we intend */
/* to take variable deltas into account or not. Otherwise iteration */
/* would fail due to wrong offsets. */
var_index_base = FT_NEXT_ULONG( p );
#ifdef TT_CONFIG_OPTION_GX_VAR_SUPPORT
if ( VARIABLE_COLRV1_ENABLED )
{
if ( !get_deltas_for_var_index_base( face, colr,
var_index_base,
2,
item_deltas ) )
return 0;
color_stop->stop_offset += (FT_Fixed)item_deltas[0] << 2;
color_stop->color.alpha += item_deltas[1];
}
#endif
}
iterator->p = p;
iterator->current_color_stop++;