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| author | Behdad Esfahbod <behdad@gnome.org> | 2007-05-24 20:17:05 +0000 |
|---|---|---|
| committer | Behdad Esfahbod <behdad@src.gnome.org> | 2007-05-24 20:17:05 +0000 |
| commit | 4bf96efe5913ead12b9a782d8eecbfcfde26e1b1 (patch) | |
| tree | 6d770a00171232e09ced03118672948620a936eb | |
| parent | 48c98597fb8bc2b779500670d20486855681b202 (diff) | |
| download | pango-4bf96efe5913ead12b9a782d8eecbfcfde26e1b1.tar.gz | |
Document how Pango's vertical text support works.
2007-05-24 Behdad Esfahbod <behdad@gnome.org>
* docs/tmpl/vertical.sgml: Document how Pango's vertical text support
works.
svn path=/trunk/; revision=2318
| -rw-r--r-- | ChangeLog | 5 | ||||
| -rw-r--r-- | docs/tmpl/vertical.sgml | 15 |
2 files changed, 20 insertions, 0 deletions
@@ -1,3 +1,8 @@ +2007-05-24 Behdad Esfahbod <behdad@gnome.org> + + * docs/tmpl/vertical.sgml: Document how Pango's vertical text support + works. + 2007-05-23 Behdad Esfahbod <behdad@gnome.org> Part of Bug 440603 – Minor ABI change diff --git a/docs/tmpl/vertical.sgml b/docs/tmpl/vertical.sgml index ccbea1ea..de80afd3 100644 --- a/docs/tmpl/vertical.sgml +++ b/docs/tmpl/vertical.sgml @@ -9,6 +9,21 @@ Laying text out in vertical directions Since 1.16, Pango is able to correctly lay vertical text out. In fact, it can set layouts of mixed vertical and non-vertical text. This section describes the types used for setting vertical text parameters. + +The way this is implemented is through the concept of +<firstterm>gravity</firstterm>. Gravity of normal Latin text is south. A +gravity value of east means that glyphs will be rotated ninety degrees +counterclockwise. So, to render vertical text one needs to set the gravity +and rotate the layout using the matrix machinery already in place. This has +the huge advantage that most algorithms working on a #PangoLayout do not need +any change as the assumption that lines run in the X direction and stack in +the Y direction holds even for vertical text layouts. + +Applications should only need to set base gravity on #PangoContext in use, and +let Pango decide the gravity assigned to each run of text. This automatically +handles text with mixed scripts. A very common use is to set the context base +gravity to auto and rotate the layout normally. Pango will make sure that +Asian languages take the right form, while other scripts are rotated normally. </para> <!-- ##### SECTION See_Also ##### --> |