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Add: vf_drawtext: text offset expressions
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@legraphista
legraphista committed Jan 17, 2018
1 parent c28495c commit fd38d34
Showing 1 changed file with 40 additions and 13 deletions.
53 changes: 40 additions & 13 deletions libavfilter/vf_drawtext.c
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Original file line number Diff line number Diff line change
Expand Up @@ -124,6 +124,8 @@ enum var_name {
VAR_TEXT_W, VAR_TW,
VAR_X,
VAR_Y,
VAR_OFFSETX,
VAR_OFFSETY,
VAR_PICT_TYPE,
VAR_VARS_NB
};
Expand Down Expand Up @@ -156,6 +158,10 @@ typedef struct DrawTextContext {
int max_glyph_h; ///< max glyph height
int shadowx, shadowy;
int borderw; ///< border width

int offsetx; ///< offset x
int offsety; ///< offset y

char *fontsize_expr; ///< expression for fontsize
AVExpr *fontsize_pexpr; ///< parsed expressions for fontsize
unsigned int fontsize; ///< font size to use
Expand Down Expand Up @@ -186,7 +192,10 @@ typedef struct DrawTextContext {
struct AVTreeNode *glyphs; ///< rendered glyphs, stored using the UTF-32 char code
char *x_expr; ///< expression for x position
char *y_expr; ///< expression for y position
char *offsetx_expr; ///< expression for offsetx position
char *offsety_expr; ///< expression for offsety position
AVExpr *x_pexpr, *y_pexpr; ///< parsed expressions for x and y
AVExpr *offsetx_pexpr, *offsety_pexpr; ///< parsed expressions for offset x and y
int64_t basetime; ///< base pts time in the real world for display
double var_values[VAR_VARS_NB];
char *a_expr;
Expand Down Expand Up @@ -224,6 +233,8 @@ static const AVOption drawtext_options[]= {
{"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},
{"offsetx", "set offsetx expression", OFFSET(offsetx_expr), AV_OPT_TYPE_STRING, {.str="0"}, CHAR_MIN, CHAR_MAX, FLAGS},
{"offsety", "set offsety expression", OFFSET(offsety_expr), AV_OPT_TYPE_STRING, {.str="0"}, CHAR_MIN, CHAR_MAX, FLAGS},
{"shadowx", "set shadow x offset", OFFSET(shadowx), AV_OPT_TYPE_INT, {.i64=0}, INT_MIN, INT_MAX , FLAGS},
{"shadowy", "set shadow y offset", OFFSET(shadowy), AV_OPT_TYPE_INT, {.i64=0}, INT_MIN, INT_MAX , FLAGS},
{"borderw", "set border width", OFFSET(borderw), AV_OPT_TYPE_INT, {.i64=0}, INT_MIN, INT_MAX , FLAGS},
Expand Down Expand Up @@ -811,10 +822,12 @@ static av_cold void uninit(AVFilterContext *ctx)

av_expr_free(s->x_pexpr);
av_expr_free(s->y_pexpr);
av_expr_free(s->offsetx_pexpr);
av_expr_free(s->offsety_pexpr);
av_expr_free(s->a_pexpr);
av_expr_free(s->fontsize_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->offsetx_pexpr = s->offsety_pexpr = NULL;

av_freep(&s->positions);
s->nb_positions = 0;
Expand Down Expand Up @@ -843,27 +856,35 @@ static int config_input(AVFilterLink *inlink)
ff_draw_color(&s->dc, &s->bordercolor, s->bordercolor.rgba);
ff_draw_color(&s->dc, &s->boxcolor, s->boxcolor.rgba);

s->var_values[VAR_w] = s->var_values[VAR_W] = s->var_values[VAR_MAIN_W] = inlink->w;
s->var_values[VAR_h] = s->var_values[VAR_H] = s->var_values[VAR_MAIN_H] = inlink->h;
s->var_values[VAR_SAR] = inlink->sample_aspect_ratio.num ? av_q2d(inlink->sample_aspect_ratio) : 1;
s->var_values[VAR_DAR] = (double)inlink->w / inlink->h * s->var_values[VAR_SAR];
s->var_values[VAR_HSUB] = 1 << s->dc.hsub_max;
s->var_values[VAR_VSUB] = 1 << s->dc.vsub_max;
s->var_values[VAR_X] = NAN;
s->var_values[VAR_Y] = NAN;
s->var_values[VAR_T] = NAN;
s->var_values[VAR_w] = s->var_values[VAR_W] = s->var_values[VAR_MAIN_W] = inlink->w;
s->var_values[VAR_h] = s->var_values[VAR_H] = s->var_values[VAR_MAIN_H] = inlink->h;
s->var_values[VAR_SAR] = inlink->sample_aspect_ratio.num ? av_q2d(inlink->sample_aspect_ratio) : 1;
s->var_values[VAR_DAR] = (double)inlink->w / inlink->h * s->var_values[VAR_SAR];
s->var_values[VAR_HSUB] = 1 << s->dc.hsub_max;
s->var_values[VAR_VSUB] = 1 << s->dc.vsub_max;
s->var_values[VAR_X] = NAN;
s->var_values[VAR_Y] = NAN;
s->var_values[VAR_OFFSETX] = NAN;
s->var_values[VAR_OFFSETY] = NAN;
s->var_values[VAR_T] = NAN;

av_lfg_init(&s->prng, av_get_random_seed());

av_expr_free(s->x_pexpr);
av_expr_free(s->y_pexpr);
av_expr_free(s->offsetx_pexpr);
av_expr_free(s->offsety_pexpr);
av_expr_free(s->a_pexpr);
s->x_pexpr = s->y_pexpr = s->a_pexpr = NULL;
s->x_pexpr = s->y_pexpr = s->a_pexpr = s->offsetx_pexpr = s->offsety_pexpr = NULL;

if ((ret = av_expr_parse(&s->x_pexpr, s->x_expr, var_names,
NULL, NULL, fun2_names, fun2, 0, ctx)) < 0 ||
(ret = av_expr_parse(&s->y_pexpr, s->y_expr, var_names,
NULL, NULL, fun2_names, fun2, 0, ctx)) < 0 ||
(ret = av_expr_parse(&s->offsetx_pexpr, s->offsetx_expr, var_names,
NULL, NULL, fun2_names, fun2, 0, ctx)) < 0 ||
(ret = av_expr_parse(&s->offsety_pexpr, s->offsety_expr, var_names,
NULL, NULL, fun2_names, fun2, 0, ctx)) < 0 ||
(ret = av_expr_parse(&s->a_pexpr, s->a_expr, var_names,
NULL, NULL, fun2_names, fun2, 0, ctx)) < 0)

Expand Down Expand Up @@ -1392,6 +1413,12 @@ static int draw_text(AVFilterContext *ctx, AVFrame *frame,
struct tm ltime;
AVBPrint *bp = &s->expanded_text;

s->offsetx = s->var_values[VAR_OFFSETX] = av_expr_eval(s->offsetx_pexpr, s->var_values, &s->prng);
s->offsety = s->var_values[VAR_OFFSETY] = av_expr_eval(s->offsety_pexpr, s->var_values, &s->prng);

int offset_x = s->offsetx;
int offset_y = s->offsety;

FFDrawColor fontcolor;
FFDrawColor shadowcolor;
FFDrawColor bordercolor;
Expand Down Expand Up @@ -1507,8 +1534,8 @@ static int draw_text(AVFilterContext *ctx, AVFrame *frame,
}

/* save position */
s->positions[i].x = x + glyph->bitmap_left;
s->positions[i].y = y - glyph->bitmap_top + y_max;
s->positions[i].x = x + glyph->bitmap_left + offset_x;
s->positions[i].y = y - glyph->bitmap_top + y_max + offset_y;

if((code == ' ' || code == '\t') && s->word_spacing > 0)
x += s->word_spacing;
Expand Down

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