[FFmpeg-devel] [PATCH] libavfilter/vf_drawtext: add letter_spacing as an evaluated parameter
Paul B Mahol
onemda at gmail.com
Tue Jun 20 18:57:35 EEST 2023
On Tue, Jun 20, 2023 at 4:27 PM Francesco Carusi <klimklim at tiscali.it>
wrote:
> You can find an overview of the changes here:
>
> https://github.com/yethie/FFmpeg/blob/master/drawtext/CHANGES.md
>
> and the new code here:
>
> https://github.com/yethie/FFmpeg/blob/master/libavfilter/vf_drawtext.c
This have been already merged, with some minor changes.
>
>
>
> On 19/06/2023 19:56, Mark Ren wrote:
> > Ah alright I see. When might that push come through and is there
> somewhere
> > I can look at the kind of changes in the meantime?
> >
> > On Mon, Jun 19, 2023 at 12:39 PM Paul B Mahol <onemda at gmail.com> wrote:
> >
> >>
> >> On Mon, Jun 19, 2023 at 6:34 PM Mark Ren <mark.ren77 at gmail.com> wrote:
> >>
> >>> When enabled it will add pixels (or subtract if given a negative value)
> >>> between each letters,
> >>> set use_kerning to false,
> >>> and add the pixels to text_w.
> >>>
> >> Conflicts with big drawtext filter set that will be pushed soon.
> >>
> >>
> >>> Signed-off-by: Mark Ren <mark.ren77 at gmail.com>
> >>> ---
> >>> libavfilter/vf_drawtext.c | 24 ++++++++++++++++++++----
> >>> 1 file changed, 20 insertions(+), 4 deletions(-)
> >>>
> >>> diff --git a/libavfilter/vf_drawtext.c b/libavfilter/vf_drawtext.c
> >>> index 71ab851462..ec8313820d 100644
> >>> --- a/libavfilter/vf_drawtext.c
> >>> +++ b/libavfilter/vf_drawtext.c
> >>> @@ -183,6 +183,7 @@ typedef struct DrawTextContext {
> >>> unsigned int fontsize; ///< font size to use
> >>> unsigned int default_fontsize; ///< default font size to use
> >>>
> >>> + int letter_spacing; ///< letter spacing in pixels
> >>> int line_spacing; ///< lines spacing in pixels
> >>> short int draw_box; ///< draw box around text - true
> or
> >>> false
> >>> int boxborderw; ///< box border width
> >>> @@ -208,6 +209,8 @@ typedef struct DrawTextContext {
> >>> char *a_expr;
> >>> AVExpr *a_pexpr;
> >>> int alpha;
> >>> + char* letter_spacing_expr; ///< expression for letter spacing
> >>> + AVExpr* letter_spacing_pexpr; ///< parsed expression for letter
> >>> spacing
> >>> AVLFG prng; ///< random
> >>> char *tc_opt_string; ///< specified timecode option
> string
> >>> AVRational tc_rate; ///< frame rate for timecode
> >>> @@ -237,6 +240,7 @@ static const AVOption drawtext_options[]= {
> >>> {"shadowcolor", "set shadow color", OFFSET(shadowcolor.rgba),
> >>> AV_OPT_TYPE_COLOR, {.str="black"}, 0, 0, FLAGS},
> >>> {"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},
> >>> + {"letter_spacing", "set letter spacing in pixels",
> >>> OFFSET(letter_spacing_expr), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0,
> FLAGS},
> >>> {"line_spacing", "set line spacing in pixels",
> >>> OFFSET(line_spacing), AV_OPT_TYPE_INT, {.i64=0}, INT_MIN,
> >>> INT_MAX,FLAGS},
> >>> {"fontsize", "set font size", OFFSET(fontsize_expr),
> >>> AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0 , FLAGS},
> >>> {"x", "set x expression", OFFSET(x_expr),
> >>> AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS},
> >>> @@ -812,7 +816,7 @@ static av_cold int init(AVFilterContext *ctx)
> >>> FT_STROKER_LINEJOIN_ROUND, 0);
> >>> }
> >>>
> >>> - s->use_kerning = FT_HAS_KERNING(s->face);
> >>> + s->use_kerning = FT_HAS_KERNING(s->face) && !s->letter_spacing;
> >>>
> >>> /* load the fallback glyph with code 0 */
> >>> load_glyph(ctx, NULL, 0);
> >>> @@ -857,8 +861,9 @@ static av_cold void uninit(AVFilterContext *ctx)
> >>> av_expr_free(s->y_pexpr);
> >>> av_expr_free(s->a_pexpr);
> >>> av_expr_free(s->fontsize_pexpr);
> >>> + av_expr_free(s->letter_spacing_pexpr);
> >>>
> >>> - s->x_pexpr = s->y_pexpr = s->a_pexpr = s->fontsize_pexpr = NULL;
> >>> + s->x_pexpr = s->y_pexpr = s->a_pexpr = s->fontsize_pexpr =
> >>> s->letter_spacing_pexpr = NULL;
> >>>
> >>> av_freep(&s->positions);
> >>> s->nb_positions = 0;
> >>> @@ -903,13 +908,16 @@ static int config_input(AVFilterLink *inlink)
> >>> av_expr_free(s->x_pexpr);
> >>> av_expr_free(s->y_pexpr);
> >>> av_expr_free(s->a_pexpr);
> >>> - s->x_pexpr = s->y_pexpr = s->a_pexpr = NULL;
> >>> + av_expr_free(s->letter_spacing_pexpr);
> >>> + s->x_pexpr = s->y_pexpr = s->a_pexpr = s->letter_spacing_pexpr =
> >>> NULL;
> >>>
> >>> if ((ret = av_expr_parse(&s->x_pexpr, expr = s->x_expr,
> var_names,
> >>> NULL, NULL, fun2_names, fun2, 0, ctx))
> < 0
> >>> ||
> >>> (ret = av_expr_parse(&s->y_pexpr, expr = s->y_expr,
> var_names,
> >>> NULL, NULL, fun2_names, fun2, 0, ctx))
> < 0
> >>> ||
> >>> (ret = av_expr_parse(&s->a_pexpr, expr = s->a_expr,
> var_names,
> >>> + NULL, NULL, fun2_names, fun2, 0, ctx)) <
> 0
> >>> ||
> >>> + (ret = av_expr_parse(&s->letter_spacing_pexpr, expr =
> >>> s->letter_spacing_expr, var_names,
> >>> NULL, NULL, fun2_names, fun2, 0, ctx))
> < 0)
> >>> {
> >>> av_log(ctx, AV_LOG_ERROR, "Failed to parse expression: %s
> \n",
> >>> expr);
> >>> return AVERROR(EINVAL);
> >>> @@ -1525,6 +1533,9 @@ continue_on_invalid2:
> >>> dummy.fontsize = s->fontsize;
> >>> glyph = av_tree_find(s->glyphs, &dummy, glyph_cmp, NULL);
> >>>
> >>> + /* letter spacing */
> >>> + x += s->letter_spacing;
> >>> +
> >>> /* kerning */
> >>> if (s->use_kerning && prev_glyph && glyph->code) {
> >>> FT_Get_Kerning(s->face, prev_glyph->code, glyph->code,
> >>> @@ -1539,7 +1550,12 @@ continue_on_invalid2:
> >>> else x += glyph->advance;
> >>> }
> >>>
> >>> - max_text_line_w = FFMAX(x, max_text_line_w);
> >>> + s->letter_spacing = av_expr_eval(s->letter_spacing_pexpr,
> >>> s->var_values, &s->prng);
> >>> + if (s->letter_spacing < 0) {
> >>> + max_text_line_w = x+ s->letter_spacing;
> >>> + } else {
> >>> + max_text_line_w = FFMAX(x, max_text_line_w) +
> s->letter_spacing;
> >>> + }
> >>>
> >>> s->var_values[VAR_TW] = s->var_values[VAR_TEXT_W] =
> max_text_line_w;
> >>> s->var_values[VAR_TH] = s->var_values[VAR_TEXT_H] = y +
> >>> s->max_glyph_h;
> >>> --
> >>> 2.40.1
> >>>
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