diff --git a/include/freetype/freetype.h b/include/freetype/freetype.h index 821ace966..a6b4e3af5 100644 --- a/include/freetype/freetype.h +++ b/include/freetype/freetype.h @@ -155,6 +155,7 @@ FT_BEGIN_HEADER * FT_FACE_FLAG_HINTER * FT_FACE_FLAG_SVG * FT_FACE_FLAG_SBIX + * FT_FACE_FLAG_SBIX_OVERLAY * * FT_HAS_HORIZONTAL * FT_HAS_VERTICAL @@ -165,6 +166,7 @@ FT_BEGIN_HEADER * FT_HAS_MULTIPLE_MASTERS * FT_HAS_SVG * FT_HAS_SBIX + * FT_HAS_SBIX_OVERLAY * * FT_IS_SFNT * FT_IS_SCALABLE @@ -1244,6 +1246,10 @@ FT_BEGIN_HEADER * For such fonts, @FT_FACE_FLAG_SCALABLE is not set by default to * retain backward compatibility. * + * FT_FACE_FLAG_SBIX_OVERLAY :: + * [Since 2.12] The face has an 'sbix' OpenType table where outlines + * should be drawn on top of bitmap strikes. + * */ #define FT_FACE_FLAG_SCALABLE ( 1L << 0 ) #define FT_FACE_FLAG_FIXED_SIZES ( 1L << 1 ) @@ -1263,6 +1269,7 @@ FT_BEGIN_HEADER #define FT_FACE_FLAG_VARIATION ( 1L << 15 ) #define FT_FACE_FLAG_SVG ( 1L << 16 ) #define FT_FACE_FLAG_SBIX ( 1L << 17 ) +#define FT_FACE_FLAG_SBIX_OVERLAY ( 1L << 18 ) /************************************************************************** @@ -1528,6 +1535,73 @@ FT_BEGIN_HEADER * A macro that returns true whenever a face object contains an 'sbix' * OpenType table *and* outline glyphs. * + * Currently, FreeType only supports bitmap glyphs in PNG format for this + * table (i.e., JPEG and TIFF formats are unsupported, as are + * Apple-specific formats not part of the OpenType specification). + * + * @note: + * For backward compatibility, a font with an 'sbix' table is treated as + * a bitmap-only face. Using @FT_Open_Face with @FT_PARAM_TAG_NO_SBIX, + * an application can switch off 'sbix' handling so that the face is + * treated as an ordinary outline font with scalable outlines. + * + * Here is some pseudo code that roughly illustrates how to implement + * 'sbix' handling according to the OpenType specification. + * + * ``` + * if ( FT_HAS_SBIX( face ) ) + * { + * // open font as a scalable one without sbix handling + * FT_Face face2; + * FT_Parameter param = { FT_PARAM_TAG_IGNORE_SBIX, NULL }; + * FT_Open_Args args = { FT_OPEN_PARAMS | ..., + * ..., + * 1, ¶m }; + * + * + * FT_Open_Face( library, &args, 0, &face2 ); + * + * available_size` as necessary into + * `preferred_sizes`[*]> + * + * for ( i = 0; i < face->num_fixed_sizes; i++ ) + * { + * size = preferred_sizes[i].size; + * + * error = FT_Set_Pixel_Sizes( face, size, size ); + * + * + * // check whether we have a glyph in a bitmap strike + * error = FT_Load_Glyph( face, + * glyph_index, + * FT_LOAD_SBITS_ONLY | + * FT_LOAD_BITMAP_METRICS_ONLY ); + * if ( error == FT_Err_Invalid_Argument ) + * continue; + * else if ( error ) + * + * else + * break; + * } + * + * if ( i != face->num_fixed_sizes ) + * + * + * if ( i == face->num_fixed_sizes || + * FT_HAS_SBIX_OVERLAY( face ) ) + * + * } + * ``` + * + * [*] Assuming a target value of 400dpi and available strike sizes 100, + * 200, 300, and 400dpi, a possible order might be [400, 200, 300, 100]: + * scaling 200dpi to 400dpi usually gives better results than scaling + * 300dpi to 400dpi; it is also much faster. However, scaling 100dpi to + * 400dpi can yield a too pixelated result, thus the preference might be + * 300dpi over 100dpi. + * * @since: * 2.12 */ @@ -1535,6 +1609,24 @@ FT_BEGIN_HEADER ( !!( (face)->face_flags & FT_FACE_FLAG_SBIX ) ) + /************************************************************************** + * + * @macro: + * FT_HAS_SBIX_OVERLAY + * + * @description: + * A macro that returns true whenever a face object contains an 'sbix' + * OpenType table with bit~1 in its `flags` field set, instructing the + * application to overlay the bitmap strike with the corresponding + * outline glyph. See @FT_HAS_SBIX for pseudo code how to use it. + * + * @since: + * 2.12 + */ +#define FT_HAS_SBIX_OVERLAY( face ) \ + ( !!( (face)->face_flags & FT_FACE_FLAG_SBIX_OVERLAY ) ) + + /************************************************************************** * * @enum: diff --git a/src/sfnt/ttsbit.c b/src/sfnt/ttsbit.c index 0ab602632..bf73d04e5 100644 --- a/src/sfnt/ttsbit.c +++ b/src/sfnt/ttsbit.c @@ -172,17 +172,8 @@ goto Exit; } -#ifdef FT_DEBUG_LEVEL_TRACE - /* we currently don't support bit 1; however, it is better to */ - /* draw at least something... */ if ( flags == 3 ) - { - FT_TRACE1(( "tt_face_load_sbit_strikes:" - " sbix overlay not supported yet\n" )); - FT_TRACE1(( " " - " expect bad rendering results\n" )); - } -#endif + face->root.face_flags |= FT_FACE_FLAG_SBIX_OVERLAY; /* * Count the number of strikes available in the table. We are a bit