[FFmpeg-devel] [PATCH] libavfilter/vf_drawtext:support to set glyph spacing while drawing text.

[efren yang]

It is applied to every glyph. There is no space between all words in some languages, for example Chinese, Japanese and so on. So a sentence will look very compactly. I think if we could set glyph spacing, it will adapt to more different scenarios. Maybe it is simple but useful.

ffmpeg -i input -vf    drawtext="glyph_spacing=10:text="PROGRAMMING":fontfile=demo.ttf" -f flv 1.flv could set glyph spacing 10 pixel.

Signed-off-by: efren yang <efren_yang at 163.com>
---
 doc/filters.texi          | 4 ++++
 libavfilter/vf_drawtext.c | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/doc/filters.texi b/doc/filters.texi
index 119d1be69d..0f336f8826 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -7077,6 +7077,10 @@ The default value of @var{boxcolor} is "white".
 Set the line spacing in pixels of the border to be drawn around the box using @var{box}.
 The default value of @var{line_spacing} is 0.
 
+ at item glyph_spacing
+Set the glyph spacing in pixels for drawing text.
+The default value of @var{glyph_spacing} is 0.
+
 @item borderw
 Set the width of the border to be drawn around the text using @var{bordercolor}.
 The default value of @var{borderw} is 0.
diff --git a/libavfilter/vf_drawtext.c b/libavfilter/vf_drawtext.c
index f6151443bb..152d8f35d5 100644
--- a/libavfilter/vf_drawtext.c
+++ b/libavfilter/vf_drawtext.c
@@ -162,6 +162,7 @@ typedef struct DrawTextContext {
     unsigned int default_fontsize;  ///< default font size to use
 
     int line_spacing;               ///< lines spacing in pixels
+    int glyph_spacing;              ///< glyph spacing in pixels
     short int draw_box;             ///< draw box around text - true or false
     int boxborderw;                 ///< box border width
     int use_kerning;                ///< font kerning is used - true/false
@@ -214,6 +215,7 @@ static const AVOption drawtext_options[]= {
     {"box",         "set box",              OFFSET(draw_box),           AV_OPT_TYPE_BOOL,   {.i64=0},     0,        1       , FLAGS},
     {"boxborderw",  "set box border width", OFFSET(boxborderw),         AV_OPT_TYPE_INT,    {.i64=0},     INT_MIN,  INT_MAX , FLAGS},
     {"line_spacing",  "set line spacing in pixels", OFFSET(line_spacing),   AV_OPT_TYPE_INT,    {.i64=0},     INT_MIN,  INT_MAX,FLAGS},
+    {"glyph_spacing",  "set glyph spacing in pixels", OFFSET(glyph_spacing),   AV_OPT_TYPE_INT,    {.i64 = 0},     0,  INT_MAX,FLAGS },
     {"fontsize",    "set font size",        OFFSET(fontsize_expr),      AV_OPT_TYPE_STRING, {.str=NULL},  CHAR_MIN, CHAR_MAX , FLAGS},
     {"x",           "set x expression",     OFFSET(x_expr),             AV_OPT_TYPE_STRING, {.str="0"},   CHAR_MIN, CHAR_MAX, FLAGS},
     {"y",           "set y expression",     OFFSET(y_expr),             AV_OPT_TYPE_STRING, {.str="0"},   CHAR_MIN, CHAR_MAX, FLAGS},
@@ -1374,6 +1376,7 @@ static int draw_text(AVFilterContext *ctx, AVFrame *frame,
         s->positions[i].y = y - glyph->bitmap_top + y_max;
         if (code == '\t') x  = (x / s->tabsize + 1)*s->tabsize;
         else              x += glyph->advance;
+        x += s->glyph_spacing;
     }
 
     max_text_line_w = FFMAX(x, max_text_line_w);
-- 
2.13.0.windows.1