avfilter/drawtext: Add basic text shaping using libfribidi

Fixes ticket #3758

Reviewed-by: Andrey Utkin <andrey.krieger.utkin@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 11 insertions, 0 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index 65106a5c63..0f73314a12 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -3653,6 +3653,8 @@ To enable compilation of this filter, you need to configure FFmpeg with
 @code{--enable-libfreetype}.
 To enable default font fallback and the @var{font} option you need to
 configure FFmpeg with @code{--enable-libfontconfig}.
+To enable the @var{text_shaping} option, you need to configure FFmpeg with
+@code{--enable-libfribidi}.
 
 @subsection Syntax
 
@@ -3707,6 +3709,12 @@ This parameter is mandatory if the fontconfig support is disabled.
 The font size to be used for drawing text.
 The default value of @var{fontsize} is 16.
 
+@item text_shaping
+If set to 1, attempt to shape the text (for example, reverse the order of
+right-to-left text and join Arabic characters) before drawing it.
+Otherwise, just draw the text exactly as given.
+By default 1 (if supported).
+
 @item ft_load_flags
 The flags to be used for loading the fonts.
 
@@ -4010,6 +4018,9 @@ For more information about libfreetype, check:
 For more information about fontconfig, check:
 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
 
+For more information about libfribidi, check:
+@url{http://fribidi.org/}.
+
 @section edgedetect
 
 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.