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/****************************************************************************
*
* ttvarc.h
*
* TrueType and OpenType VARC (Variable Composites) support
* (specification).
*
* Copyright (C) 2025-2026 by
* Behdad Esfahbod, David Turner, Robert Wilhelm, and Werner Lemberg.
*
* This file is part of the FreeType project, and may only be used,
* modified, and distributed under the terms of the FreeType project
* license, LICENSE.TXT. By continuing to use, modify, or distribute
* this file you indicate that you have read the license and
* understand and accept it fully.
*
*/
#ifndef TTVARC_H_
#define TTVARC_H_
#include "ttobjs.h"
#ifdef TT_CONFIG_OPTION_GX_VAR_SUPPORT
#include <freetype/internal/ftmmtypes.h>
#endif
FT_BEGIN_HEADER
#ifdef TT_CONFIG_OPTION_VARC
FT_LOCAL( FT_Error )
tt_face_init_varc_axes( FT_Face face,
FT_UInt axis_count );
/**************************************************************************
*
* VARC component flags from the specification.
*
*/
/* Variable Component Flags - from VARC spec. */
#define VARC_RESET_UNSPECIFIED_AXES 0x00000001U /* Bit 0 */
#define VARC_HAVE_AXES 0x00000002U /* Bit 1 */
#define VARC_AXES_HAVE_VARIATION 0x00000004U /* Bit 2 */
#define VARC_TRANSFORM_HAS_VARIATION 0x00000008U /* Bit 3 */
#define VARC_HAVE_TRANSLATE_X 0x00000010U /* Bit 4 */
#define VARC_HAVE_TRANSLATE_Y 0x00000020U /* Bit 5 */
#define VARC_HAVE_ROTATION 0x00000040U /* Bit 6 */
#define VARC_HAVE_CONDITION 0x00000080U /* Bit 7 */
#define VARC_HAVE_SCALE_X 0x00000100U /* Bit 8 */
#define VARC_HAVE_SCALE_Y 0x00000200U /* Bit 9 */
#define VARC_HAVE_TCENTER_X 0x00000400U /* Bit 10 */
#define VARC_HAVE_TCENTER_Y 0x00000800U /* Bit 11 */
#define VARC_GID_IS_24BIT 0x00001000U /* Bit 12 */
#define VARC_HAVE_SKEW_X 0x00002000U /* Bit 13 */
#define VARC_HAVE_SKEW_Y 0x00004000U /* Bit 14 */
/* Reserved flags - bits 15-31 must be zero. */
#define VARC_RESERVED_MASK 0xFFFF8000U
/**************************************************************************
*
* @Struct:
* TT_VarcComponentRec
*
* @Description:
* Represents a single component within a VARC glyph.
*
* @Fields:
* flags ::
* Component flags indicating which optional fields are present.
*
* gid ::
* The glyph ID of the component to be included.
*
* condition_index ::
* Index into the condition list (if `VARC_HAVE_CONDITION` is set).
* Component is only rendered if condition evaluates to true.
*
* axis_indices_index ::
* Index into the axis indices list (if `VARC_HAVE_AXES` is set).
*
* num_axis_values ::
* Number of axis values in the `axis_values` array.
*
* axis_values ::
* Array of normalized axis coordinates (-1.0 to +1.0 in F2DOT14).
* These override the current design space location for this component.
*
* axis_values_var_index ::
* Variation store index for axis values (if `VARC_AXES_HAVE_VARIATION`
* is set).
*
* transform_var_index ::
* Variation store index for transform values (if
* `VARC_TRANSFORM_HAS_VARIATION` is set).
*
* translate_x ::
* translate_y ::
* Translation amounts in font units (26.6 fixed-point).
*
* rotation ::
* Rotation angle in radians, multiplied by pi (16.16 fixed-point).
* So 0x10000 represents pi radians (180 degrees).
*
* scale_x ::
* scale_y ::
* Scale factors (16.16 fixed-point, 1.0 = 0x10000).
*
* skew_x ::
* skew_y ::
* Skew angles in radians, multiplied by pi (16.16 fixed-point).
*
* tcenter_x ::
* tcenter_y ::
* Transformation center point in font units (26.6 fixed-point).
* Transformations are applied relative to this point.
*/
typedef struct TT_VarcComponentRec_
{
FT_UInt32 flags;
FT_UInt gid;
/* conditional rendering */
FT_UInt32 condition_index;
/* axis value overrides */
FT_UInt32 axis_indices_index;
FT_UInt num_axis_values;
FT_Fixed* axis_values; /* normalized coordinates (F2DOT14) */
FT_Bool axis_values_on_heap; /* TRUE if axis_values needs `FT_FREE` */
FT_UInt32 axis_values_var_index;
/* transform variation */
FT_UInt32 transform_var_index;
/* transform components (all 26.6 or 16.16 fixed-point) */
FT_Pos translate_x;
FT_Pos translate_y;
FT_Fixed rotation; /* radians * pi, 16.16 format */
FT_Fixed scale_x;
FT_Fixed scale_y;
FT_Fixed skew_x;
FT_Fixed skew_y;
FT_Pos tcenter_x;
FT_Pos tcenter_y;
} TT_VarcComponentRec, *TT_VarcComponent;
/**************************************************************************
*
* @Struct:
* TT_VarcRec
*
* @Description:
* The 'VARC' table structure, loaded from the font file.
*
* @Fields:
* version_major ::
* Major version of the 'VARC' table (currently 1).
*
* version_minor ::
* Minor version of the 'VARC' table (currently 0).
*
* coverage_offset ::
* Offset to the coverage table from start of 'VARC' table.
*
* multi_var_store_offset ::
* Offset to the `MultiItemVariationStore`.
*
* condition_list_offset ::
* Offset to the condition list.
*
* axis_indices_list_offset ::
* Offset to the axis indices list.
*
* var_composite_glyphs_offset ::
* Offset to the glyph records (CFF2-style index).
*
* coverage ::
* Pointer to the coverage table data.
*
* condition_list ::
* Pointer to the condition list data, or `NULL` if the table has no
* condition list.
*
* axis_indices_list ::
* Pointer to the CFF2-style index that contains the axis indices for
* component axis-value tuples, or `NULL` if the table has no axis
* indices list.
*
* var_composite_glyphs ::
* Pointer to the CFF2-style index that contains the component records
* for the glyphs referenced by `coverage`.
*
* multi_var_store ::
* The loaded `MultiItemVariationStore` for variation deltas.
*
* multi_var_store_loaded ::
* A boolean that indicates whether `multi_var_store` points to a
* `MultiItemVariationStore` in the table.
*
* table ::
* Pointer to the raw 'VARC' table data.
*
* table_size ::
* Size of the 'VARC' table in bytes.
*/
typedef struct TT_VarcRec_
{
FT_UShort version_major;
FT_UShort version_minor;
/* table offsets */
FT_ULong coverage_offset;
FT_ULong multi_var_store_offset;
FT_ULong condition_list_offset;
FT_ULong axis_indices_list_offset;
FT_ULong var_composite_glyphs_offset;
/* loaded data pointers */
FT_Byte* coverage;
FT_Byte* condition_list;
FT_Byte* axis_indices_list;
FT_Byte* var_composite_glyphs;
#ifdef TT_CONFIG_OPTION_GX_VAR_SUPPORT
/* `MultiItemVariationStore` - stores tuples of deltas, */
/* not single values */
FT_Byte* multi_var_store; /* pointer to MultiItemVariationStore data */
FT_Bool multi_var_store_loaded;
#endif
/* raw table data */
void* table;
FT_ULong table_size;
} TT_VarcRec, *TT_Varc;
/**************************************************************************
*
* Maximum recursion depth for VARC glyph loading.
* This prevents stack overflow and infinite loops from malformed fonts.
*/
#define TT_VARC_MAX_NESTING_LEVEL 16
/**************************************************************************
*
* @Struct:
* TT_VarcContextRec
*
* @Description:
* Context structure for recursive VARC glyph loading.
* Tracks recursion depth and visited glyphs for cycle detection.
*
* @Fields:
* recursion_depth ::
* Current depth in the recursion stack.
*
* visited_glyphs ::
* Array of glyph IDs currently being processed.
* Used for cycle detection to prevent infinite loops.
*
* parent_matrix ::
* The transformation matrix accumulated from parent components.
*
* parent_delta ::
* The translation accumulated from parent components.
*
* has_parent_transform ::
* A boolean that indicates whether `parent_matrix` and `parent_delta`
* contain a transform to apply to child components.
*
* font_coords ::
* The face's normalized variation coordinates before loading the VARC
* glyph. The context owns this array.
*
* num_font_coords ::
* The number of coordinates in `font_coords`.
*
* current_coords ::
* The normalized variation coordinates used to evaluate deltas at the
* current recursion level. This points to `font_coords` at the top
* level or to a component's temporary coordinate array at deeper
* levels; the context does not own the latter.
*
* num_corrent_coords ::
* The number of coordinates in `current_coords`.
*/
typedef struct TT_VarcContextRec_
{
FT_UInt recursion_depth;
FT_UInt visited_glyphs[TT_VARC_MAX_NESTING_LEVEL];
/* Parent transform to compose with child transforms. */
FT_Matrix parent_matrix;
FT_Vector parent_delta;
FT_Bool has_parent_transform;
/* Font's original variation coordinates (before VARC processing). */
/* Used when RESET_UNSPECIFIED_AXES is not set at depth 1. */
FT_Fixed* font_coords;
FT_UInt num_font_coords;
/* Current variation coords for delta evaluation at this recursion level.
* Points to `font_coords` at depth 1, or parent's coords at depth > 1.
* Not owned - do not free. */
FT_Fixed* current_coords;
FT_UInt num_current_coords;
/* Reusable buffers to avoid per-component allocations. */
FT_Fixed* axis_values_buffer;
FT_UInt axis_values_buffer_size;
FT_Fixed* deltas_buffer;
FT_UInt deltas_buffer_size;
FT_Fixed* coords_buffer;
FT_UInt coords_buffer_size;
FT_UInt* indices_buffer;
FT_UInt indices_buffer_size;
} TT_VarcContextRec, *TT_VarcContext;
/**************************************************************************
*
* VARC API functions
*
*/
/* Load the VARC table from the font stream. */
FT_LOCAL( FT_Error )
tt_face_load_varc( FT_Face face,
FT_Stream stream );
/* Free the VARC table resources. */
FT_LOCAL( void )
tt_face_free_varc( FT_Face face );
/* Check whether a glyph has VARC data. */
FT_LOCAL( FT_Bool )
tt_face_has_varc_glyph( FT_Face face,
FT_UInt glyph_index );
/* Load a VARC glyph into the glyph slot. */
FT_LOCAL( FT_Error )
tt_face_load_varc_glyph( FT_Face face,
FT_GlyphSlot glyph_slot,
FT_UInt glyph_index,
FT_Int32 load_flags );
#endif /* TT_CONFIG_OPTION_VARC */
FT_END_HEADER
#endif /* TTVARC_H_ */
/* END */