[FFmpeg-devel] [PATCH] libavfilter/vf_drawtext: add letter_spacing as an evaluated parameter
Mark Ren
mark.ren77 at gmail.com
Mon Jun 19 20:56:50 EEST 2023
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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