mirror of https://github.com/freetype/freetype
Add `FT_FACE_FLAG_SBIX_OVERLAY` and `FT_HAS_SBIX_OVERLAY`.
* include/freetype/freetype.h (FT_FACE_FLAG_SBIX_OVERLAY, FT_HAS_SBIX_OVERLAY): New macro. * src/sfnt/ttsbit.c (tt_face_load_sbit): Handle `FT_FACE_FLAG_SBIX_OVERLAY`. Remove obsolete tracing message.
This commit is contained in:
Werner Lemberg
parent
1949a7ec3a
commit
a8e4563c34
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@ -155,6 +155,7 @@ FT_BEGIN_HEADER
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* FT_FACE_FLAG_HINTER
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* FT_FACE_FLAG_SVG
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* FT_FACE_FLAG_SBIX
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* FT_FACE_FLAG_SBIX_OVERLAY
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*
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* FT_HAS_HORIZONTAL
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* FT_HAS_VERTICAL
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@ -165,6 +166,7 @@ FT_BEGIN_HEADER
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* FT_HAS_MULTIPLE_MASTERS
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* FT_HAS_SVG
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* FT_HAS_SBIX
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* FT_HAS_SBIX_OVERLAY
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*
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* FT_IS_SFNT
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* FT_IS_SCALABLE
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@ -1244,6 +1246,10 @@ FT_BEGIN_HEADER
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* For such fonts, @FT_FACE_FLAG_SCALABLE is not set by default to
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* retain backward compatibility.
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*
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* FT_FACE_FLAG_SBIX_OVERLAY ::
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* [Since 2.12] The face has an 'sbix' OpenType table where outlines
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* should be drawn on top of bitmap strikes.
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*
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*/
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#define FT_FACE_FLAG_SCALABLE ( 1L << 0 )
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#define FT_FACE_FLAG_FIXED_SIZES ( 1L << 1 )
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@ -1263,6 +1269,7 @@ FT_BEGIN_HEADER
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#define FT_FACE_FLAG_VARIATION ( 1L << 15 )
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#define FT_FACE_FLAG_SVG ( 1L << 16 )
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#define FT_FACE_FLAG_SBIX ( 1L << 17 )
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#define FT_FACE_FLAG_SBIX_OVERLAY ( 1L << 18 )
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/**************************************************************************
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@ -1528,6 +1535,73 @@ FT_BEGIN_HEADER
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* A macro that returns true whenever a face object contains an 'sbix'
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* OpenType table *and* outline glyphs.
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*
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* Currently, FreeType only supports bitmap glyphs in PNG format for this
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* table (i.e., JPEG and TIFF formats are unsupported, as are
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* Apple-specific formats not part of the OpenType specification).
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*
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* @note:
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* For backward compatibility, a font with an 'sbix' table is treated as
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* a bitmap-only face. Using @FT_Open_Face with @FT_PARAM_TAG_NO_SBIX,
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* an application can switch off 'sbix' handling so that the face is
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* treated as an ordinary outline font with scalable outlines.
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*
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* Here is some pseudo code that roughly illustrates how to implement
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* 'sbix' handling according to the OpenType specification.
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*
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* ```
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* if ( FT_HAS_SBIX( face ) )
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* {
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* // open font as a scalable one without sbix handling
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* FT_Face face2;
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* FT_Parameter param = { FT_PARAM_TAG_IGNORE_SBIX, NULL };
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* FT_Open_Args args = { FT_OPEN_PARAMS | ...,
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* ...,
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* 1, ¶m };
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*
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*
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* FT_Open_Face( library, &args, 0, &face2 );
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*
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* <sort `face->available_size` as necessary into
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* `preferred_sizes`[*]>
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*
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* for ( i = 0; i < face->num_fixed_sizes; i++ )
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* {
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* size = preferred_sizes[i].size;
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*
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* error = FT_Set_Pixel_Sizes( face, size, size );
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* <error handling omitted>
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*
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* // check whether we have a glyph in a bitmap strike
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* error = FT_Load_Glyph( face,
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* glyph_index,
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* FT_LOAD_SBITS_ONLY |
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* FT_LOAD_BITMAP_METRICS_ONLY );
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* if ( error == FT_Err_Invalid_Argument )
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* continue;
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* else if ( error )
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* <other error handling omitted>
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* else
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* break;
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* }
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*
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* if ( i != face->num_fixed_sizes )
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* <load embedded bitmap with `FT_Load_Glyph`,
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* scale it, display it, etc.>
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*
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* if ( i == face->num_fixed_sizes ||
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* FT_HAS_SBIX_OVERLAY( face ) )
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* <use `face2` to load outline glyph with `FT_Load_Glyph`,
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* scale it, display it on top of the bitmap, etc.>
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* }
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* ```
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*
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* [*] Assuming a target value of 400dpi and available strike sizes 100,
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* 200, 300, and 400dpi, a possible order might be [400, 200, 300, 100]:
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* scaling 200dpi to 400dpi usually gives better results than scaling
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* 300dpi to 400dpi; it is also much faster. However, scaling 100dpi to
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* 400dpi can yield a too pixelated result, thus the preference might be
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* 300dpi over 100dpi.
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*
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* @since:
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* 2.12
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*/
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@ -1535,6 +1609,24 @@ FT_BEGIN_HEADER
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( !!( (face)->face_flags & FT_FACE_FLAG_SBIX ) )
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/**************************************************************************
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*
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* @macro:
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* FT_HAS_SBIX_OVERLAY
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*
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* @description:
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* A macro that returns true whenever a face object contains an 'sbix'
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* OpenType table with bit~1 in its `flags` field set, instructing the
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* application to overlay the bitmap strike with the corresponding
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* outline glyph. See @FT_HAS_SBIX for pseudo code how to use it.
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*
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* @since:
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* 2.12
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*/
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#define FT_HAS_SBIX_OVERLAY( face ) \
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( !!( (face)->face_flags & FT_FACE_FLAG_SBIX_OVERLAY ) )
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/**************************************************************************
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*
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* @enum:
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@ -172,17 +172,8 @@
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goto Exit;
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}
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#ifdef FT_DEBUG_LEVEL_TRACE
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/* we currently don't support bit 1; however, it is better to */
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/* draw at least something... */
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if ( flags == 3 )
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{
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FT_TRACE1(( "tt_face_load_sbit_strikes:"
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" sbix overlay not supported yet\n" ));
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FT_TRACE1(( " "
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" expect bad rendering results\n" ));
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}
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#endif
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face->root.face_flags |= FT_FACE_FLAG_SBIX_OVERLAY;
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/*
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* Count the number of strikes available in the table. We are a bit
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