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[freetype2] master cb93704 5/5: Document MVAR handling.
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From: |
Werner LEMBERG |
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Subject: |
[freetype2] master cb93704 5/5: Document MVAR handling. |
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Date: |
Wed, 11 Jan 2017 13:28:11 +0000 (UTC) |
branch: master
commit cb937047965ee38f53c54daaa44b6ad9828cce64
Author: Werner Lemberg <address@hidden>
Commit: Werner Lemberg <address@hidden>
Document MVAR handling.
---
include/freetype/ftgasp.h | 12 ++++++++--
include/freetype/tttables.h | 51 +++++++++++++++++++++++++++++++++----------
2 files changed, 49 insertions(+), 14 deletions(-)
diff --git a/include/freetype/ftgasp.h b/include/freetype/ftgasp.h
index d956bee..1269728 100644
--- a/include/freetype/ftgasp.h
+++ b/include/freetype/ftgasp.h
@@ -102,17 +102,25 @@
* FT_Get_Gasp
*
* @description:
- * Read the `gasp' table from a TrueType or OpenType font file and
- * return the entry corresponding to a given character pixel size.
+ * For a TrueType or OpenType font file, return the rasterizer behaviour
+ * flags from the font's `gasp' table corresponding to a given
+ * character pixel size.
*
* @input:
* face :: The source face handle.
+ *
* ppem :: The vertical character pixel size.
*
* @return:
* Bit flags (see @FT_GASP_XXX), or @FT_GASP_NO_TABLE if there is no
* `gasp' table in the face.
*
+ * @note:
+ * If you want to use the MM functionality of OpenType variation fonts
+ * (i.e., using @FT_Set_Var_Design_Coordinates and friends), call this
+ * function *after* setting an instance since the return values can
+ * change.
+ *
* @since:
* 2.3.0
*/
diff --git a/include/freetype/tttables.h b/include/freetype/tttables.h
index c02157d..7a278e2 100644
--- a/include/freetype/tttables.h
+++ b/include/freetype/tttables.h
@@ -175,6 +175,8 @@ FT_BEGIN_HEADER
/* caret_Slope_Run :: The run coefficient of the cursor's */
/* slope. */
/* */
+ /* caret_Offset :: The cursor's offset for slanted fonts. */
+ /* */
/* Reserved :: 8~reserved bytes. */
/* */
/* metric_Data_Format :: Always~0. */
@@ -188,6 +190,11 @@ FT_BEGIN_HEADER
/* short_metrics :: A pointer into the `hmtx' table. */
/* */
/* <Note> */
+ /* For an OpenType variation font, the values of the following fields */
+ /* can change after a call to @FT_Set_Var_Design_Coordinates (and */
+ /* friends) if the font contains an `MVAR' table: `caret_Slope_Rise', */
+ /* `caret_Slope_Run', and `caret_Offset'. */
+ /* */
/* IMPORTANT: The TT_HoriHeader and TT_VertHeader structures should */
/* be identical except for the names of their fields, */
/* which are different. */
@@ -219,7 +226,7 @@ FT_BEGIN_HEADER
/* The following fields are not defined by the TrueType specification */
/* but they are used to connect the metrics header to the relevant */
- /* `HMTX' table. */
+ /* `hmtx' table. */
void* long_metrics;
void* short_metrics;
@@ -297,8 +304,6 @@ FT_BEGIN_HEADER
/* slope. */
/* */
/* caret_Offset :: The cursor's offset for slanted fonts. */
- /* This value is `reserved' in vmtx */
- /* version 1.0. */
/* */
/* Reserved :: 8~reserved bytes. */
/* */
@@ -309,11 +314,17 @@ FT_BEGIN_HEADER
/* smaller than the total number of glyphs */
/* in the font. */
/* */
- /* long_metrics :: A pointer into the `vmtx' table. */
+ /* long_metrics :: A pointer into the `vmtx' table. */
/* */
- /* short_metrics :: A pointer into the `vmtx' table. */
+ /* short_metrics :: A pointer into the `vmtx' table. */
/* */
/* <Note> */
+ /* For an OpenType variation font, the values of the following fields */
+ /* can change after a call to @FT_Set_Var_Design_Coordinates (and */
+ /* friends) if the font contains an `MVAR' table: `Ascender', */
+ /* `Descender', `Line_Gap', `caret_Slope_Rise', `caret_Slope_Run', */
+ /* and `caret_Offset'. */
+ /* */
/* IMPORTANT: The TT_HoriHeader and TT_VertHeader structures should */
/* be identical except for the names of their fields, */
/* which are different. */
@@ -344,8 +355,8 @@ FT_BEGIN_HEADER
FT_UShort number_Of_VMetrics;
/* The following fields are not defined by the TrueType specification */
- /* but they're used to connect the metrics header to the relevant */
- /* `HMTX' or `VMTX' table. */
+ /* but they are used to connect the metrics header to the relevant */
+ /* `hmtx' or `vmtx' table. */
void* long_metrics;
void* short_metrics;
@@ -359,12 +370,22 @@ FT_BEGIN_HEADER
/* TT_OS2 */
/* */
/* <Description> */
- /* A structure used to model a TrueType OS/2 table. All fields */
+ /* A structure used to model a TrueType `OS/2' table. All fields */
/* comply to the OpenType specification. */
/* */
/* Note that we now support old Mac fonts that do not include an OS/2 */
/* table. In this case, the `version' field is always set to 0xFFFF. */
/* */
+ /* For an OpenType variation font, the values of the following fields */
+ /* can change after a call to @FT_Set_Var_Design_Coordinates (and */
+ /* friends) if the font contains an `MVAR' table: `sCapHeight', */
+ /* `sTypoAscender', `sTypoDescender', `sTypoLineGap', `sxHeight', */
+ /* `usWinAscent', `usWinDescent', `yStrikeoutPosition', */
+ /* `yStrikeoutSize', `ySubscriptXOffset', `ySubScriptXSize', */
+ /* `ySubscriptYOffset', `ySubscriptYSize', `ySuperscriptXOffset', */
+ /* `ySuperscriptXSize', `ySuperscriptYOffset', and */
+ /* `ySuperscriptYSize'. */
+
typedef struct TT_OS2_
{
FT_UShort version; /* 0x0001 - more or 0xFFFF */
@@ -429,11 +450,17 @@ FT_BEGIN_HEADER
/* TT_Postscript */
/* */
/* <Description> */
- /* A structure used to model a TrueType PostScript table. All fields */
+ /* A structure used to model a TrueType `post' table. All fields */
/* comply to the TrueType specification. This structure does not */
/* reference the PostScript glyph names, which can be nevertheless */
/* accessed with the `ttpost' module. */
/* */
+ /* <Note> */
+ /* For an OpenType variation font, the values of the following fields */
+ /* can change after a call to @FT_Set_Var_Design_Coordinates (and */
+ /* friends) if the font contains an `MVAR' table: `underlinePosition' */
+ /* and `underlineThickness'. */
+ /* */
typedef struct TT_Postscript_
{
FT_Fixed FormatType;
@@ -447,7 +474,7 @@ FT_BEGIN_HEADER
FT_ULong maxMemType1;
/* Glyph names follow in the file, but we don't */
- /* load them by default. See the ttpost.c file. */
+ /* load them by default. See file `ttpost.c'. */
} TT_Postscript;
@@ -458,7 +485,7 @@ FT_BEGIN_HEADER
/* TT_PCLT */
/* */
/* <Description> */
- /* A structure used to model a TrueType PCLT table. All fields */
+ /* A structure used to model a TrueType `PCLT' table. All fields */
/* comply to the TrueType specification. */
/* */
typedef struct TT_PCLT_
@@ -488,7 +515,7 @@ FT_BEGIN_HEADER
/* TT_MaxProfile */
/* */
/* <Description> */
- /* The maximum profile is a table containing many max values, which */
+ /* The maximum profile (`maxp') table contains many max values, which */
/* can be used to pre-allocate arrays. This ensures that no memory */
/* allocation occurs during a glyph load. */
/* */
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