3.1.1.1.2 Glyph and Fragment Caches
Glyph caching supports 10 glyph caches and 1 fragment cache to store bitmaps of font characters in memory. Glyphs are first cached in the glyph caches before being displayed. A fragment is a set of glyphs defined in terms of glyph indices.
The Cache Glyph - Revision 1 (section 2.2.2.2.1.2.5) and Cache Glyph - Revision 2 (section 2.2.2.2.1.2.6) Secondary Drawing Orders are used to update the glyph caches. The GlyphIndex (section 2.2.2.2.1.1.2.13) and FastIndex (section 2.2.2.2.1.1.2.14) Primary Drawing Orders consume glyphs from the glyph caches and also populate the Fragment Cache. The FastGlyph (section 2.2.2.2.1.1.2.15) Primary Drawing Order is used to update the glyph caches with a single glyph and to encode the same glyph at a specified position.
The actual layout of the glyph and fragment caches is specified in the Glyph Cache Capability Set (see [MS-RDPBCGR] section 2.2.7.1.8).
The following table shows the default Glyph Cache layout.
|
Glyph cache ID |
Cache entry size (in bytes) |
Number of cache entries |
|---|---|---|
|
0 |
4 |
254 |
|
1 |
4 |
254 |
|
2 |
8 |
254 |
|
3 |
8 |
254 |
|
4 |
16 |
254 |
|
5 |
32 |
254 |
|
6 |
64 |
254 |
|
7 |
128 |
254 |
|
8 |
256 |
254 |
|
9 |
256 |
64 |
There is only one fragment cache, and by default it has 256 entries with 256 bytes as the entry size.