Commit 6432b8c490937508c599f89278305ceb1c00f5c2
2016-08-21T10:50:46
Update documentation of size requests.
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diff --git a/include/freetype/freetype.h b/include/freetype/freetype.h
index 8f104ab..6fe3518 100644
--- a/include/freetype/freetype.h
+++ b/include/freetype/freetype.h
@@ -2345,13 +2345,22 @@ FT_BEGIN_HEADER
/* FT_Size_Request_Type */
/* */
/* <Description> */
- /* An enumeration type that lists the supported size request types. */
+ /* An enumeration type that lists the supported size request types, */
+ /* i.e., what input size (in font units) maps to the requested output */
+ /* size (in pixels, as computed from the arguments of */
+ /* @FT_Size_Request). */
/* */
/* <Values> */
/* FT_SIZE_REQUEST_TYPE_NOMINAL :: */
/* The nominal size. The `units_per_EM' field of @FT_FaceRec is */
/* used to determine both scaling values. */
/* */
+ /* This is the standard scaling found in most applications. In */
+ /* particular, use this size request type for TrueType fonts if */
+ /* they provide optical scaling or something similar. Note, */
+ /* however, that `units_per_EM' is a rather abstract value which */
+ /* bears no relation to the actual size of the glyphs in a font. */
+ /* */
/* FT_SIZE_REQUEST_TYPE_REAL_DIM :: */
/* The real dimension. The sum of the `ascender' and (minus of) */
/* the `descender' fields of @FT_FaceRec are used to determine both */
@@ -2405,22 +2414,28 @@ FT_BEGIN_HEADER
/* <Fields> */
/* type :: See @FT_Size_Request_Type. */
/* */
- /* width :: The desired width. */
+ /* width :: The desired width, given as a 26.6 fractional */
+ /* point value (with 72pt = 1in). */
/* */
- /* height :: The desired height. */
+ /* height :: The desired height, given as a 26.6 fractional */
+ /* point value (with 72pt = 1in). */
/* */
- /* horiResolution :: The horizontal resolution. If set to zero, */
- /* `width' is treated as a 26.6 fractional pixel */
- /* value. */
+ /* horiResolution :: The horizontal resolution (dpi, i.e., pixels per */
+ /* inch). If set to zero, `width' is treated as a */
+ /* 26.6 fractional *pixel* value. */
/* */
- /* vertResolution :: The vertical resolution. If set to zero, */
- /* `height' is treated as a 26.6 fractional pixel */
- /* value. */
+ /* vertResolution :: The vertical resolution (dpi, i.e., pixels per */
+ /* inch). If set to zero, `height' is treated as a */
+ /* 26.6 fractional *pixel* value. */
/* */
/* <Note> */
/* If `width' is zero, then the horizontal scaling value is set equal */
/* to the vertical scaling value, and vice versa. */
/* */
+ /* If `type' is FT_SIZE_REQUEST_TYPE_SCALES, `width' and `height' are */
+ /* interpreted directly as 16.16 fractional scaling values, without */
+ /* any further modification. */
+ /* */
typedef struct FT_Size_RequestRec_
{
FT_Size_Request_Type type;