ftmm.h: Revise documentation.

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Werner Lemberg 2017-01-15 16:17:26 +01:00
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1 changed files with 78 additions and 53 deletions

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@ -43,11 +43,10 @@ FT_BEGIN_HEADER
/* Master fonts, i.e., the selection of specific design instances by */
/* setting design axis coordinates. */
/* */
/* George Williams has extended this interface to make it work with */
/* both Type~1 Multiple Masters fonts and GX distortable (var) */
/* fonts. Some of these routines only work with MM fonts, others */
/* will work with both types. They are similar enough that a */
/* consistent interface makes sense. */
/* Besides Adobe MM fonts, the interface supports Apple's TrueType GX */
/* and OpenType variation fonts. Some of the routines only work with */
/* Adobe MM fonts, others will work with all three types. They are */
/* similar enough that a consistent interface makes sense. */
/* */
/*************************************************************************/
@ -58,10 +57,11 @@ FT_BEGIN_HEADER
/* FT_MM_Axis */
/* */
/* <Description> */
/* A simple structure used to model a given axis in design space for */
/* Multiple Masters fonts. */
/* A structure to model a given axis in design space for Multiple */
/* Masters fonts. */
/* */
/* This structure can't be used for GX var fonts. */
/* This structure can't be used for TrueType GX or OpenType variation */
/* fonts. */
/* */
/* <Fields> */
/* name :: The axis's name. */
@ -85,10 +85,11 @@ FT_BEGIN_HEADER
/* FT_Multi_Master */
/* */
/* <Description> */
/* A structure used to model the axes and space of a Multiple Masters */
/* A structure to model the axes and space of a Multiple Masters */
/* font. */
/* */
/* This structure can't be used for GX var fonts. */
/* This structure can't be used for TrueType GX or OpenType variation */
/* fonts. */
/* */
/* <Fields> */
/* num_axis :: Number of axes. Cannot exceed~4. */
@ -115,27 +116,35 @@ FT_BEGIN_HEADER
/* FT_Var_Axis */
/* */
/* <Description> */
/* A simple structure used to model a given axis in design space for */
/* Multiple Masters and GX var fonts. */
/* A structure to model a given axis in design space for Multiple */
/* Masters, TrueType GX, and OpenType variation fonts. */
/* */
/* <Fields> */
/* name :: The axis's name. */
/* Not always meaningful for GX. */
/* Not always meaningful for TrueType GX or OpenType */
/* variation fonts. */
/* */
/* minimum :: The axis's minimum design coordinate. */
/* */
/* def :: The axis's default design coordinate. */
/* FreeType computes meaningful default values for MM; it */
/* is then an integer value, not in 16.16 format. */
/* FreeType computes meaningful default values for Adobe */
/* MM fonts. */
/* */
/* maximum :: The axis's maximum design coordinate. */
/* */
/* tag :: The axis's tag (the GX equivalent to `name'). */
/* FreeType provides default values for MM if possible. */
/* tag :: The axis's tag (the equivalent to `name' for TrueType */
/* GX and OpenType variation fonts). FreeType provides */
/* default values for Adobe MM fonts if possible. */
/* */
/* strid :: The entry in `name' table (another GX version of */
/* `name'). */
/* Not meaningful for MM. */
/* strid :: The axis name entry in the font's `name' table. This */
/* is another (and often better) version of the `name' */
/* field for TrueType GX or OpenType variation fonts. Not */
/* meaningful for Adobe MM fonts. */
/* */
/* <Note> */
/* The fields `minimum', `def', and `maximum' are 16.16 fractional */
/* values for TrueType GX and OpenType variation fonts. For Adobe MM */
/* fonts, the values are integers. */
/* */
typedef struct FT_Var_Axis_
{
@ -157,9 +166,10 @@ FT_BEGIN_HEADER
/* FT_Var_Named_Style */
/* */
/* <Description> */
/* A simple structure used to model a named style in a GX var font. */
/* A structure to model a named style in a TrueType GX or OpenType */
/* variation font. */
/* */
/* This structure can't be used for MM fonts. */
/* This structure can't be used for Adobe MM fonts. */
/* */
/* <Fields> */
/* coords :: The design coordinates for this style. */
@ -185,17 +195,19 @@ FT_BEGIN_HEADER
/* FT_MM_Var */
/* */
/* <Description> */
/* A structure used to model the axes and space of a Multiple Masters */
/* or GX var distortable font. */
/* A structure to model the axes and space of a Adobe MM, TrueType */
/* GX, or OpenType variation font. */
/* */
/* Some fields are specific to one format and not to the other. */
/* Some fields are specific to one format and not to the others. */
/* */
/* <Fields> */
/* num_axis :: The number of axes. The maximum value is~4 for */
/* MM; no limit in GX. */
/* Adobe MM fonts; no limit in TrueType GX or */
/* OpenType variation fonts. */
/* */
/* num_designs :: The number of designs; should be normally */
/* 2^num_axis for MM fonts. Not meaningful for GX */
/* 2^num_axis for Adobe MM fonts. Not meaningful */
/* for TrueType GX or OpenType variation fonts */
/* (where every glyph could have a different */
/* number of designs). */
/* */
@ -205,19 +217,20 @@ FT_BEGIN_HEADER
/* The font can tell the user that, for example, */
/* [Weight=1.5,Width=1.1] is `Bold'. */
/* */
/* For Type 1 Multiple Masters fonts, this value */
/* is always zero because the format does not */
/* support named styles. */
/* For Adobe Multiple Masters fonts, this value is */
/* always zero because the format does not support */
/* named styles. */
/* */
/* axis :: An axis descriptor table. */
/* GX fonts contain slightly more data than MM. */
/* TrueType GX and OpenType variation fonts */
/* contain slightly more data than Adobe MM fonts. */
/* Memory management of this pointer is done */
/* internally by FreeType. */
/* */
/* namedstyle :: A named style table. */
/* Only meaningful with GX. */
/* Memory management of this pointer is done */
/* internally by FreeType. */
/* Only meaningful for TrueType GX and OpenType */
/* variation fonts. Memory management of this */
/* pointer is done internally by FreeType. */
/* */
typedef struct FT_MM_Var_
{
@ -236,9 +249,10 @@ FT_BEGIN_HEADER
/* FT_Get_Multi_Master */
/* */
/* <Description> */
/* Retrieve the Multiple Master descriptor of a given font. */
/* Retrieve a variation descriptor of a given Adobe MM font. */
/* */
/* This function can't be used with GX fonts. */
/* This function can't be used with TrueType GX or OpenType variation */
/* fonts. */
/* */
/* <Input> */
/* face :: A handle to the source face. */
@ -260,13 +274,15 @@ FT_BEGIN_HEADER
/* FT_Get_MM_Var */
/* */
/* <Description> */
/* Retrieve the Multiple Master/GX var descriptor of a given font. */
/* Retrieve a variation descriptor for a given font. */
/* */
/* This function works with all supported variation formats. */
/* */
/* <Input> */
/* face :: A handle to the source face. */
/* */
/* <Output> */
/* amaster :: The Multiple Masters/GX var descriptor. */
/* amaster :: The variation descriptor. */
/* Allocates a data structure, which the user must */
/* deallocate with `free' after use. */
/* */
@ -284,10 +300,11 @@ FT_BEGIN_HEADER
/* FT_Set_MM_Design_Coordinates */
/* */
/* <Description> */
/* For Multiple Masters fonts, choose an interpolated font design */
/* through design coordinates. */
/* For Adobe MM fonts, choose an interpolated font design through */
/* design coordinates. */
/* */
/* This function can't be used with GX fonts. */
/* This function can't be used with TrueType GX or OpenType variation */
/* fonts. */
/* */
/* <InOut> */
/* face :: A handle to the source face. */
@ -315,8 +332,9 @@ FT_BEGIN_HEADER
/* FT_Set_Var_Design_Coordinates */
/* */
/* <Description> */
/* For Multiple Master or GX Var fonts, choose an interpolated font */
/* design through design coordinates. */
/* Choose an interpolated font design through design coordinates. */
/* */
/* This function works with all supported variation formats. */
/* */
/* <InOut> */
/* face :: A handle to the source face. */
@ -344,8 +362,10 @@ FT_BEGIN_HEADER
/* FT_Get_Var_Design_Coordinates */
/* */
/* <Description> */
/* For Multiple Master and GX Var fonts, get the design coordinates */
/* of the currently selected interpolated font. */
/* Get the design coordinates of the currently selected interpolated */
/* font. */
/* */
/* This function works with all supported variation formats. */
/* */
/* <Input> */
/* face :: A handle to the source face. */
@ -372,8 +392,10 @@ FT_BEGIN_HEADER
/* FT_Set_MM_Blend_Coordinates */
/* */
/* <Description> */
/* For Multiple Masters and GX var fonts, choose an interpolated font */
/* design through normalized blend coordinates. */
/* Choose an interpolated font design through normalized blend */
/* coordinates. */
/* */
/* This function works with all supported variation formats. */
/* */
/* <InOut> */
/* face :: A handle to the source face. */
@ -385,8 +407,9 @@ FT_BEGIN_HEADER
/* use default values for the remaining axes. */
/* */
/* coords :: The design coordinates array (each element must be */
/* between 0 and 1.0 for MM fonts, and between -1.0 and */
/* 1.0 for GX var fonts). */
/* between 0 and 1.0 for Adobe MM fonts, and between */
/* -1.0 and 1.0 for TrueType GX and OpenType variation */
/* fonts). */
/* */
/* <Return> */
/* FreeType error code. 0~means success. */
@ -403,16 +426,18 @@ FT_BEGIN_HEADER
/* FT_Get_MM_Blend_Coordinates */
/* */
/* <Description> */
/* For Multiple Masters and GX var fonts, get the normalized blend */
/* coordinates of the currently selected interpolated font. */
/* Get the normalized blend coordinates of the currently selected */
/* interpolated font. */
/* */
/* This function works with all supported variation formats. */
/* */
/* <Input> */
/* face :: A handle to the source face. */
/* */
/* num_coords :: The number of normalized blend coordinates to */
/* retrieve. If it is larger than the number of axes, */
/* set the excess values to~0.5 for MM fonts, and to~0 */
/* for GX var fonts. */
/* set the excess values to~0.5 for Adobe MM fonts, and */
/* to~0 for TrueType GX and OpenType variation fonts. */
/* */
/* <Output> */
/* coords :: The normalized blend coordinates array. */