[FFmpeg-devel] [PATCH v2] drawtext: Add basic text shaping using libfribidi - Fixes ticket #3758
Marc Jeffreys
maj160 at live.co.uk
Thu Jul 10 12:47:16 CEST 2014
Changes since last time:
I've made the changes to configure, and squashed the patches together.
Option changed from fribidi=1 (default 0) to text_shaping=1 (default 1).
(Ideas for better names are definitely welcome.)
Hopefully I've made the documentation more understandable.
No longer testing for NULL before av_free.
---
configure | 3 ++
doc/filters.texi | 11 ++++
libavfilter/vf_drawtext.c | 130 +++++++++++++++++++++++++++++++++++++++++++---
3 files changed, 138 insertions(+), 6 deletions(-)
diff --git a/configure b/configure
index 658efb2..6777d91 100755
--- a/configure
+++ b/configure
@@ -209,6 +209,7 @@ External library support:
--enable-libfdk-aac enable AAC de/encoding via libfdk-aac [no]
--enable-libflite enable flite (voice synthesis) support via libflite [no]
--enable-libfreetype enable libfreetype [no]
+ --enable-libfribidi enable libfribidi [no]
--enable-libgme enable Game Music Emu via libgme [no]
--enable-libgsm enable GSM de/encoding via libgsm [no]
--enable-libiec61883 enable iec61883 via libiec61883 [no]
@@ -1332,6 +1333,7 @@ EXTERNAL_LIBRARY_LIST="
libflite
libfontconfig
libfreetype
+ libfribidi
libgme
libgsm
libiec61883
@@ -4724,6 +4726,7 @@ enabled libflite && require2 libflite "flite/flite.h" flite_init $flite
enabled fontconfig && enable libfontconfig
enabled libfontconfig && require_pkg_config fontconfig "fontconfig/fontconfig.h" FcInit
enabled libfreetype && require_libfreetype
+enabled libfribidi && require_pkg_config fribidi fribidi.h fribidi_version_info
enabled libgme && require libgme gme/gme.h gme_new_emu -lgme -lstdc++
enabled libgsm && { for gsm_hdr in "gsm.h" "gsm/gsm.h"; do
check_lib "${gsm_hdr}" gsm_create -lgsm && break;
diff --git a/doc/filters.texi b/doc/filters.texi
index ada33a7..1b6f85e 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
+ at 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.
+ at 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:
+ at url{http://fribidi.org/}.
+
@section edgedetect
Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
diff --git a/libavfilter/vf_drawtext.c b/libavfilter/vf_drawtext.c
index 0d829a6..b29411e 100644
--- a/libavfilter/vf_drawtext.c
+++ b/libavfilter/vf_drawtext.c
@@ -59,6 +59,10 @@
#include "internal.h"
#include "video.h"
+#if CONFIG_LIBFRIBIDI
+#include <fribidi.h>
+#endif
+
#include <ft2build.h>
#include FT_FREETYPE_H
#include FT_GLYPH_H
@@ -182,6 +186,9 @@ typedef struct DrawTextContext {
int tc24hmax; ///< 1 if timecode is wrapped to 24 hours, 0 otherwise
int reload; ///< reload text file for each frame
int start_number; ///< starting frame number for n/frame_num var
+#if CONFIG_LIBFRIBIDI
+ int text_shaping; ///< 1 to shape the text before drawing it
+#endif
AVDictionary *metadata;
} DrawTextContext;
@@ -226,6 +233,10 @@ static const AVOption drawtext_options[]= {
{"fix_bounds", "if true, check and fix text coords to avoid clipping", OFFSET(fix_bounds), AV_OPT_TYPE_INT, {.i64=1}, 0, 1, FLAGS},
{"start_number", "start frame number for n/frame_num variable", OFFSET(start_number), AV_OPT_TYPE_INT, {.i64=0}, 0, INT_MAX, FLAGS},
+#if CONFIG_LIBFRIBIDI
+ {"text_shaping", "attempt to shape text before drawing", OFFSET(text_shaping), AV_OPT_TYPE_INT, {.i64=1}, 0, 1, FLAGS},
+#endif
+
/* FT_LOAD_* flags */
{ "ft_load_flags", "set font loading flags for libfreetype", OFFSET(ft_load_flags), AV_OPT_TYPE_FLAGS, { .i64 = FT_LOAD_DEFAULT }, 0, INT_MAX, FLAGS, "ft_load_flags" },
{ "default", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = FT_LOAD_DEFAULT }, .flags = FLAGS, .unit = "ft_load_flags" },
@@ -482,6 +493,106 @@ static int load_textfile(AVFilterContext *ctx)
return 0;
}
+static inline int is_newline(uint32_t c)
+{
+ return c == '\n' || c == '\r' || c == '\f' || c == '\v';
+}
+
+#if CONFIG_LIBFRIBIDI
+static int shape_text(AVFilterContext *ctx)
+{
+ DrawTextContext *s = ctx->priv;
+ uint8_t *tmp;
+ int ret = 0;
+ static FriBidiFlags flags = FRIBIDI_FLAGS_DEFAULT | \
+ FRIBIDI_FLAGS_ARABIC ;
+ FriBidiChar *unicodestr = NULL;
+ FriBidiStrIndex len;
+ FriBidiParType direction = FRIBIDI_PAR_LTR;
+ FriBidiStrIndex line_start = 0;
+ FriBidiStrIndex line_end = 0;
+ FriBidiLevel *embedding_levels = NULL;
+ FriBidiArabicProp *ar_props = NULL;
+ FriBidiCharType *bidi_types = NULL;
+ FriBidiStrIndex i,j;
+
+ len = strlen(s->text);
+ if (!(unicodestr = av_malloc(len * sizeof(*unicodestr)))) {
+ ret = AVERROR(ENOMEM);
+ goto out;
+ }
+ len = fribidi_charset_to_unicode(FRIBIDI_CHAR_SET_UTF8,
+ s->text, len, unicodestr);
+
+ bidi_types = av_malloc(len * sizeof(*bidi_types));
+ if (!bidi_types) {
+ ret = AVERROR(ENOMEM);
+ goto out;
+ }
+
+ fribidi_get_bidi_types(unicodestr, len, bidi_types);
+
+ embedding_levels = av_malloc(len * sizeof(*embedding_levels));
+ if (!embedding_levels) {
+ ret = AVERROR(ENOMEM);
+ goto out;
+ }
+
+ if (!fribidi_get_par_embedding_levels(bidi_types, len, &direction,
+ embedding_levels)) {
+ ret = AVERROR(ENOMEM);
+ goto out;
+ }
+
+ ar_props = av_malloc(len * sizeof(*ar_props));
+ if (!ar_props) {
+ ret = AVERROR(ENOMEM);
+ goto out;
+ }
+
+ fribidi_get_joining_types(unicodestr, len, ar_props);
+ fribidi_join_arabic(bidi_types, len, embedding_levels, ar_props);
+ fribidi_shape(flags, embedding_levels, len, ar_props, unicodestr);
+
+ for (line_end = 0, line_start = 0; line_end < len; line_end++) {
+ if (is_newline(unicodestr[line_end]) || line_end == len - 1) {
+ if (!fribidi_reorder_line(flags, bidi_types,
+ line_end - line_start + 1, line_start,
+ direction, embedding_levels, unicodestr,
+ NULL)) {
+ ret = AVERROR(ENOMEM);
+ goto out;
+ }
+ line_start = line_end + 1;
+ }
+ }
+
+ /* Remove zero-width fill chars put in by libfribidi */
+ for (i = 0, j = 0; i < len; i++)
+ if (unicodestr[i] != FRIBIDI_CHAR_FILL)
+ unicodestr[j++] = unicodestr[i];
+ len = j;
+
+ if (!(tmp = av_realloc(s->text, (len * 4 + 1) * sizeof(*s->text)))) {
+ /* Use len * 4, as one unicode character can be up to 4 bytes in UTF-8 */
+ ret = AVERROR(ENOMEM);
+ goto out;
+ }
+
+ s->text = tmp;
+ len = fribidi_unicode_to_charset(FRIBIDI_CHAR_SET_UTF8,
+ unicodestr, len, s->text);
+ ret = 0;
+
+out:
+ av_free(unicodestr);
+ av_free(embedding_levels);
+ av_free(ar_props);
+ av_free(bidi_types);
+ return ret;
+}
+#endif
+
static av_cold int init(AVFilterContext *ctx)
{
int err;
@@ -509,6 +620,12 @@ static av_cold int init(AVFilterContext *ctx)
return err;
}
+#if CONFIG_LIBFRIBIDI
+ if (s->text_shaping)
+ if ((err = shape_text(ctx)) < 0)
+ return err;
+#endif
+
if (s->reload && !s->textfile)
av_log(ctx, AV_LOG_WARNING, "No file to reload\n");
@@ -617,11 +734,6 @@ static av_cold void uninit(AVFilterContext *ctx)
av_bprint_finalize(&s->expanded_text, NULL);
}
-static inline int is_newline(uint32_t c)
-{
- return c == '\n' || c == '\r' || c == '\f' || c == '\v';
-}
-
static int config_input(AVFilterLink *inlink)
{
AVFilterContext *ctx = inlink->dst;
@@ -1132,9 +1244,15 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
DrawTextContext *s = ctx->priv;
int ret;
- if (s->reload)
+ if (s->reload) {
if ((ret = load_textfile(ctx)) < 0)
return ret;
+#if CONFIG_LIBFRIBIDI
+ if (s->text_shaping)
+ if ((ret = shape_text(ctx)) < 0)
+ return ret;
+#endif
+ }
s->var_values[VAR_N] = inlink->frame_count+s->start_number;
s->var_values[VAR_T] = frame->pts == AV_NOPTS_VALUE ?
--
1.8.3.1
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