render: font: Allow rendering of substrings.

* chickadee/render/font.scm (draw-text*, draw-text): Add start and end
arguments.
* doc/api.texi (Fonts): Document new arguments.

1 files changed, 4 insertions, 0 deletions

diff --git a/doc/api.texi b/doc/api.texi
index 82cde8f..8295b38 100644
--- a/doc/api.texi
+++ b/doc/api.texi
@@ -892,6 +892,7 @@ Return @code{#t} if @var{font} is an italicized font.
 
 @deffn {Procedure} draw-text @var{font} @var{text} @var{position}
        [#:origin] [#:scale] [#:rotation] [#:blend-mode]
+       [#:start 0] [#:end @code{(string-length text)}]
 
 Draw the string @var{text} with the first character starting at
 @var{position} using @var{font}.
@@ -900,6 +901,9 @@ Draw the string @var{text} with the first character starting at
 (draw-text font "Hello, world!" (vec2 128.0 128.0))
 @end example
 
+To render a substring of @var{text}, use the @var{start} and @var{end}
+arguments.
+
 Refer to @code{draw-sprite} (@pxref{Sprites}) for information about
 the other arguments.
 @end deffn