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/****************************************************************************
*
* ftsdfrend.c
*
* Signed Distance Field renderer interface (body).
*
* Copyright (C) 2020-2024 by
* David Turner, Robert Wilhelm, and Werner Lemberg.
*
* Written by Anuj Verma.
*
* 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.
*
*/
#include <freetype/internal/ftdebug.h>
#include <freetype/internal/ftobjs.h>
#include <freetype/internal/services/svprop.h>
#include <freetype/ftoutln.h>
#include <freetype/ftbitmap.h>
#include "ftsdfrend.h"
#include "ftsdf.h"
#include "ftsdferrs.h"
/**************************************************************************
*
* The macro FT_COMPONENT is used in trace mode. It is an implicit
* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log
* messages during execution.
*/
#undef FT_COMPONENT
#define FT_COMPONENT sdf
/**************************************************************************
*
* macros and default property values
*
*/
#define SDF_RENDERER( rend ) ( (SDF_Renderer)rend )
/**************************************************************************
*
* for setting properties
*
*/
/* property setter function */
static FT_Error
sdf_property_set( FT_Module module,
const char* property_name,
const void* value,
FT_Bool value_is_string )
{
FT_Error error = FT_Err_Ok;
SDF_Renderer render = SDF_RENDERER( FT_RENDERER( module ) );
FT_UNUSED( value_is_string );
if ( ft_strcmp( property_name, "spread" ) == 0 )
{
FT_Int val = *(const FT_Int*)value;
if ( val > MAX_SPREAD || val < MIN_SPREAD )
{
FT_TRACE0(( "[sdf] sdf_property_set:"
" the `spread' property can have a value\n" ));
FT_TRACE0(( " "
" within range [%d, %d] (value provided: %d)\n",
MIN_SPREAD, MAX_SPREAD, val ));
error = FT_THROW( Invalid_Argument );
goto Exit;
}
render->spread = (FT_UInt)val;
FT_TRACE7(( "[sdf] sdf_property_set:"
" updated property `spread' to %d\n", val ));
}
else if ( ft_strcmp( property_name, "flip_sign" ) == 0 )
{
FT_Int val = *(const FT_Int*)value;
render->flip_sign = val ? 1 : 0;
FT_TRACE7(( "[sdf] sdf_property_set:"
" updated property `flip_sign' to %d\n", val ));
}
else if ( ft_strcmp( property_name, "flip_y" ) == 0 )
{
FT_Int val = *(const FT_Int*)value;
render->flip_y = val ? 1 : 0;
FT_TRACE7(( "[sdf] sdf_property_set:"
" updated property `flip_y' to %d\n", val ));
}
else if ( ft_strcmp( property_name, "overlaps" ) == 0 )
{
FT_Bool val = *(const FT_Bool*)value;
render->overlaps = val;
FT_TRACE7(( "[sdf] sdf_property_set:"
" updated property `overlaps' to %d\n", val ));
}
else
{
FT_TRACE0(( "[sdf] sdf_property_set:"
" missing property `%s'\n", property_name ));
error = FT_THROW( Missing_Property );
}
Exit:
return error;
}
/* property getter function */
static FT_Error
sdf_property_get( FT_Module module,
const char* property_name,
void* value )
{
FT_Error error = FT_Err_Ok;
SDF_Renderer render = SDF_RENDERER( FT_RENDERER( module ) );
if ( ft_strcmp( property_name, "spread" ) == 0 )
{
FT_UInt* val = (FT_UInt*)value;
*val = render->spread;
}
else if ( ft_strcmp( property_name, "flip_sign" ) == 0 )
{
FT_Int* val = (FT_Int*)value;
*val = render->flip_sign;
}
else if ( ft_strcmp( property_name, "flip_y" ) == 0 )
{
FT_Int* val = (FT_Int*)value;
*val = render->flip_y;
}
else if ( ft_strcmp( property_name, "overlaps" ) == 0 )
{
FT_Int* val = (FT_Int*)value;
*val = render->overlaps;
}
else
{
FT_TRACE0(( "[sdf] sdf_property_get:"
" missing property `%s'\n", property_name ));
error = FT_THROW( Missing_Property );
}
return error;
}
FT_DEFINE_SERVICE_PROPERTIESREC(
sdf_service_properties,
(FT_Properties_SetFunc)sdf_property_set, /* set_property */
(FT_Properties_GetFunc)sdf_property_get ) /* get_property */
FT_DEFINE_SERVICEDESCREC1(
sdf_services,
FT_SERVICE_ID_PROPERTIES, &sdf_service_properties )
static FT_Module_Interface
ft_sdf_requester( FT_Module module,
const char* module_interface )
{
FT_UNUSED( module );
return ft_service_list_lookup( sdf_services, module_interface );
}
/*************************************************************************/
/*************************************************************************/
/** **/
/** OUTLINE TO SDF CONVERTER **/
/** **/
/*************************************************************************/
/*************************************************************************/
/**************************************************************************
*
* interface functions
*
*/
static FT_Error
ft_sdf_init( FT_Module module ) /* SDF_Renderer */
{
SDF_Renderer sdf_render = SDF_RENDERER( module );
sdf_render->spread = DEFAULT_SPREAD;
sdf_render->flip_sign = 0;
sdf_render->flip_y = 0;
sdf_render->overlaps = 0;
return FT_Err_Ok;
}
static void
ft_sdf_done( FT_Module module )
{
FT_UNUSED( module );
}
/* generate signed distance field from a glyph's slot image */
static FT_Error
ft_sdf_render( FT_Renderer module,
FT_GlyphSlot slot,
FT_Render_Mode mode,
const FT_Vector* origin )
{
FT_Error error = FT_Err_Ok;
FT_Outline* outline = &slot->outline;
FT_Bitmap* bitmap = &slot->bitmap;
FT_Memory memory = NULL;
FT_Renderer render = NULL;
FT_Pos x_shift = 0;
FT_Pos y_shift = 0;
FT_Pos x_pad = 0;
FT_Pos y_pad = 0;
SDF_Raster_Params params;
SDF_Renderer sdf_module = SDF_RENDERER( module );
render = &sdf_module->root;
memory = render->root.memory;
/* check whether slot format is correct before rendering */
if ( slot->format != render->glyph_format )
{
error = FT_THROW( Invalid_Glyph_Format );
goto Exit;
}
/* check whether render mode is correct */
if ( mode != FT_RENDER_MODE_SDF )
{
error = FT_THROW( Cannot_Render_Glyph );
goto Exit;
}
/* deallocate the previously allocated bitmap */
if ( slot->internal->flags & FT_GLYPH_OWN_BITMAP )
{
FT_FREE( bitmap->buffer );
slot->internal->flags &= ~FT_GLYPH_OWN_BITMAP;
}
/* preset the bitmap using the glyph's outline; */
/* the sdf bitmap is similar to an anti-aliased bitmap */
/* with a slightly bigger size and different pixel mode */
if ( ft_glyphslot_preset_bitmap( slot, FT_RENDER_MODE_NORMAL, origin ) )
{
error = FT_THROW( Raster_Overflow );
goto Exit;
}
/* nothing to render */
if ( !bitmap->rows || !bitmap->pitch )
goto Exit;
/* the padding will simply be equal to the `spread' */
x_pad = sdf_module->spread;
y_pad = sdf_module->spread;
/* apply the padding; will be in all the directions */
bitmap->rows += y_pad * 2;
bitmap->width += x_pad * 2;
/* ignore the pitch, pixel mode and set custom */
bitmap->pixel_mode = FT_PIXEL_MODE_GRAY;
bitmap->pitch = (int)( bitmap->width );
bitmap->num_grays = 255;
/* allocate new buffer */
if ( FT_ALLOC_MULT( bitmap->buffer, bitmap->rows, bitmap->pitch ) )
goto Exit;
slot->internal->flags |= FT_GLYPH_OWN_BITMAP;
slot->bitmap_top += y_pad;
slot->bitmap_left -= x_pad;
x_shift = 64 * -slot->bitmap_left;
y_shift = 64 * -slot->bitmap_top;
y_shift += 64 * (FT_Int)bitmap->rows;
if ( origin )
{
x_shift += origin->x;
y_shift += origin->y;
}
/* translate outline to render it into the bitmap */
if ( x_shift || y_shift )
FT_Outline_Translate( outline, x_shift, y_shift );
/* set up parameters */
params.root.target = bitmap;
params.root.source = outline;
params.root.flags = FT_RASTER_FLAG_SDF;
params.spread = sdf_module->spread;
params.flip_sign = sdf_module->flip_sign;
params.flip_y = sdf_module->flip_y;
params.overlaps = sdf_module->overlaps;
/* render the outline */
error = render->raster_render( render->raster,
(const FT_Raster_Params*)¶ms );
/* transform the outline back to the original state */
if ( x_shift || y_shift )
FT_Outline_Translate( outline, -x_shift, -y_shift );
Exit:
if ( !error )
{
/* the glyph is successfully rendered to a bitmap */
slot->format = FT_GLYPH_FORMAT_BITMAP;
}
else if ( slot->internal->flags & FT_GLYPH_OWN_BITMAP )
{
FT_FREE( bitmap->buffer );
slot->internal->flags &= ~FT_GLYPH_OWN_BITMAP;
}
return error;
}
/* transform the glyph using matrix and/or delta */
static FT_Error
ft_sdf_transform( FT_Renderer render,
FT_GlyphSlot slot,
const FT_Matrix* matrix,
const FT_Vector* delta )
{
FT_Error error = FT_Err_Ok;
if ( slot->format != render->glyph_format )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
if ( matrix )
FT_Outline_Transform( &slot->outline, matrix );
if ( delta )
FT_Outline_Translate( &slot->outline, delta->x, delta->y );
Exit:
return error;
}
/* return the control box of a glyph's outline */
static void
ft_sdf_get_cbox( FT_Renderer render,
FT_GlyphSlot slot,
FT_BBox* cbox )
{
FT_ZERO( cbox );
if ( slot->format == render->glyph_format )
FT_Outline_Get_CBox( &slot->outline, cbox );
}
/* set render specific modes or attributes */
static FT_Error
ft_sdf_set_mode( FT_Renderer render,
FT_ULong mode_tag,
FT_Pointer data )
{
/* pass it to the rasterizer */
return render->clazz->raster_class->raster_set_mode( render->raster,
mode_tag,
data );
}
FT_DEFINE_RENDERER(
ft_sdf_renderer_class,
FT_MODULE_RENDERER,
sizeof ( SDF_Renderer_Module ),
"sdf",
0x10000L,
0x20000L,
NULL,
(FT_Module_Constructor)ft_sdf_init,
(FT_Module_Destructor) ft_sdf_done,
(FT_Module_Requester) ft_sdf_requester,
FT_GLYPH_FORMAT_OUTLINE,
(FT_Renderer_RenderFunc) ft_sdf_render, /* render_glyph */
(FT_Renderer_TransformFunc)ft_sdf_transform, /* transform_glyph */
(FT_Renderer_GetCBoxFunc) ft_sdf_get_cbox, /* get_glyph_cbox */
(FT_Renderer_SetModeFunc) ft_sdf_set_mode, /* set_mode */
(FT_Raster_Funcs*)&ft_sdf_raster /* raster_class */
)
/*************************************************************************/
/*************************************************************************/
/** **/
/** BITMAP TO SDF CONVERTER **/
/** **/
/*************************************************************************/
/*************************************************************************/
/* generate signed distance field from glyph's bitmap */
static FT_Error
ft_bsdf_render( FT_Renderer module,
FT_GlyphSlot slot,
FT_Render_Mode mode,
const FT_Vector* origin )
{
FT_Error error = FT_Err_Ok;
FT_Memory memory = NULL;
FT_Bitmap* bitmap = &slot->bitmap;
FT_Renderer render = NULL;
FT_Bitmap target;
FT_Pos x_pad = 0;
FT_Pos y_pad = 0;
SDF_Raster_Params params;
SDF_Renderer sdf_module = SDF_RENDERER( module );
/* initialize the bitmap in case any error occurs */
FT_Bitmap_Init( &target );
render = &sdf_module->root;
memory = render->root.memory;
/* check whether slot format is correct before rendering */
if ( slot->format != render->glyph_format )
{
error = FT_THROW( Invalid_Glyph_Format );
goto Exit;
}
/* check whether render mode is correct */
if ( mode != FT_RENDER_MODE_SDF )
{
error = FT_THROW( Cannot_Render_Glyph );
goto Exit;
}
if ( origin )
{
FT_ERROR(( "ft_bsdf_render: can't translate the bitmap\n" ));
error = FT_THROW( Unimplemented_Feature );
goto Exit;
}
/* nothing to render */
if ( !bitmap->rows || !bitmap->pitch )
goto Exit;
/* Do not generate SDF if the bitmap is not owned by the */
/* glyph: it might be that the source buffer is already freed. */
if ( !( slot->internal->flags & FT_GLYPH_OWN_BITMAP ) )
{
FT_ERROR(( "ft_bsdf_render: can't generate SDF from"
" unowned source bitmap\n" ));
error = FT_THROW( Invalid_Argument );
goto Exit;
}
FT_Bitmap_New( &target );
/* padding will simply be equal to `spread` */
x_pad = sdf_module->spread;
y_pad = sdf_module->spread;
/* apply padding, which extends to all directions */
target.rows = bitmap->rows + y_pad * 2;
target.width = bitmap->width + x_pad * 2;
/* set up the target bitmap */
target.pixel_mode = FT_PIXEL_MODE_GRAY;
target.pitch = (int)( target.width );
target.num_grays = 255;
if ( FT_ALLOC_MULT( target.buffer, target.rows, target.pitch ) )
goto Exit;
/* set up parameters */
params.root.target = ⌖
params.root.source = bitmap;
params.root.flags = FT_RASTER_FLAG_SDF;
params.spread = sdf_module->spread;
params.flip_sign = sdf_module->flip_sign;
params.flip_y = sdf_module->flip_y;
error = render->raster_render( render->raster,
(const FT_Raster_Params*)¶ms );
Exit:
if ( !error )
{
/* the glyph is successfully converted to a SDF */
if ( slot->internal->flags & FT_GLYPH_OWN_BITMAP )
FT_FREE( bitmap->buffer );
slot->bitmap = target;
slot->bitmap_top += y_pad;
slot->bitmap_left -= x_pad;
if ( target.buffer )
slot->internal->flags |= FT_GLYPH_OWN_BITMAP;
}
else if ( target.buffer )
FT_FREE( target.buffer );
return error;
}
FT_DEFINE_RENDERER(
ft_bitmap_sdf_renderer_class,
FT_MODULE_RENDERER,
sizeof ( SDF_Renderer_Module ),
"bsdf",
0x10000L,
0x20000L,
NULL,
(FT_Module_Constructor)ft_sdf_init,
(FT_Module_Destructor) ft_sdf_done,
(FT_Module_Requester) ft_sdf_requester,
FT_GLYPH_FORMAT_BITMAP,
(FT_Renderer_RenderFunc) ft_bsdf_render, /* render_glyph */
(FT_Renderer_TransformFunc)ft_sdf_transform, /* transform_glyph */
(FT_Renderer_GetCBoxFunc) ft_sdf_get_cbox, /* get_glyph_cbox */
(FT_Renderer_SetModeFunc) ft_sdf_set_mode, /* set_mode */
(FT_Raster_Funcs*)&ft_bitmap_sdf_raster /* raster_class */
)
/* END */