Merge commit '9b2c57be'

* commit '9b2c57be':
  drawtext: Add an alpha option

Conflicts:
	doc/filters.texi
	libavfilter/vf_drawtext.c
Merged-by: Michael Niedermayer <michaelni@gmx.at>

doc/filters.texi

@@ -4057,6 +4057,16 @@ The font family to be used for drawing text. By default Sans.
 The font file to be used for drawing text. The path must be included.
 This parameter is mandatory if the fontconfig support is disabled.
 
+@item draw
+This option does not exist, please see the timeline system
+
+@item alpha
+Draw the text applying alpha blending. The value can
+be either a number between 0.0 and 1.0
+The expression accepts the same variables @var{x, y} do.
+The default value is 1.
+Please see fontcolor_expr
+
 @item fontsize
 The font size to be used for drawing text.
 The default value of @var{fontsize} is 16.

libavfilter/vf_drawtext.c

@@ -179,6 +179,9 @@ typedef struct DrawTextContext {
     AVExpr *x_pexpr, *y_pexpr;      ///< parsed expressions for x and y
     int64_t basetime;               ///< base pts time in the real world for display
     double var_values[VAR_VARS_NB];
+    char   *a_expr;
+    AVExpr *a_pexpr;
+    int alpha;
     AVLFG  prng;                    ///< random
     char       *tc_opt_string;      ///< specified timecode option string
     AVRational  tc_rate;            ///< frame rate for timecode
@@ -229,6 +232,7 @@ static const AVOption drawtext_options[]= {
     {"r",               "set rate (timecode only)",         OFFSET(tc_rate),       AV_OPT_TYPE_RATIONAL, {.dbl=0},           0,  INT_MAX, FLAGS},
     {"rate",            "set rate (timecode only)",         OFFSET(tc_rate),       AV_OPT_TYPE_RATIONAL, {.dbl=0},           0,  INT_MAX, FLAGS},
     {"reload",     "reload text file for each frame",                       OFFSET(reload),     AV_OPT_TYPE_INT, {.i64=0}, 0, 1, FLAGS},
+    { "alpha",       "apply alpha while rendering", OFFSET(a_expr),      AV_OPT_TYPE_STRING, { .str = "1"     },          .flags = FLAGS },
     {"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},
 
@@ -749,6 +753,8 @@ static int config_input(AVFilterLink *inlink)
     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->a_pexpr, s->a_expr, var_names,
                              NULL, NULL, fun2_names, fun2, 0, ctx)) < 0)
 
         return AVERROR(EINVAL);
@@ -1052,7 +1058,8 @@ static int expand_text(AVFilterContext *ctx, char *text, AVBPrint *bp)
 
 static int draw_glyphs(DrawTextContext *s, AVFrame *frame,
                        int width, int height,
-                       FFDrawColor *color, int x, int y, int borderw)
+                       FFDrawColor *color,
+                       int x, int y, int borderw)
 {
     char *text = s->expanded_text.str;
     uint32_t code = 0;
@@ -1092,6 +1099,29 @@ static int draw_glyphs(DrawTextContext *s, AVFrame *frame,
     return 0;
 }
 
+
+static void update_color_with_alpha(DrawTextContext *s, FFDrawColor *color, const FFDrawColor incolor)
+{
+    *color = incolor;
+    color->rgba[3] = (color->rgba[3] * s->alpha) / 255;
+    ff_draw_color(&s->dc, color, color->rgba);
+}
+
+static void update_alpha(DrawTextContext *s)
+{
+    double alpha = av_expr_eval(s->a_pexpr, s->var_values, &s->prng);
+
+    if (isnan(alpha))
+        return;
+
+    if (alpha >= 1.0)
+        s->alpha = 255;
+    else if (alpha <= 0)
+        s->alpha = 0;
+    else
+        s->alpha = 256 * alpha;
+}
+
 static int draw_text(AVFilterContext *ctx, AVFrame *frame,
                      int width, int height)
 {
@@ -1114,6 +1144,11 @@ static int draw_text(AVFilterContext *ctx, AVFrame *frame,
     struct tm ltime;
     AVBPrint *bp = &s->expanded_text;
 
+    FFDrawColor fontcolor;
+    FFDrawColor shadowcolor;
+    FFDrawColor bordercolor;
+    FFDrawColor boxcolor;
+
     av_bprint_clear(bp);
 
     if(s->basetime != AV_NOPTS_VALUE)
@@ -1239,29 +1274,35 @@ static int draw_text(AVFilterContext *ctx, AVFrame *frame,
     s->y = s->var_values[VAR_Y] = av_expr_eval(s->y_pexpr, s->var_values, &s->prng);
     s->x = s->var_values[VAR_X] = av_expr_eval(s->x_pexpr, s->var_values, &s->prng);
 
+    update_alpha(s);
+    update_color_with_alpha(s, &fontcolor  , s->fontcolor  );
+    update_color_with_alpha(s, &shadowcolor, s->shadowcolor);
+    update_color_with_alpha(s, &bordercolor, s->bordercolor);
+    update_color_with_alpha(s, &boxcolor   , s->boxcolor   );
+
     box_w = FFMIN(width - 1 , max_text_line_w);
     box_h = FFMIN(height - 1, y + s->max_glyph_h);
 
     /* draw box */
     if (s->draw_box)
-        ff_blend_rectangle(&s->dc, &s->boxcolor,
+        ff_blend_rectangle(&s->dc, &boxcolor,
                            frame->data, frame->linesize, width, height,
                            s->x - s->boxborderw, s->y - s->boxborderw,
                            box_w + s->boxborderw * 2, box_h + s->boxborderw * 2);
 
     if (s->shadowx || s->shadowy) {
         if ((ret = draw_glyphs(s, frame, width, height,
-                               &s->shadowcolor, s->shadowx, s->shadowy, 0)) < 0)
+                               &shadowcolor, s->shadowx, s->shadowy, 0)) < 0)
             return ret;
     }
 
     if (s->borderw) {
         if ((ret = draw_glyphs(s, frame, width, height,
-                               &s->bordercolor, 0, 0, s->borderw)) < 0)
+                               &bordercolor, 0, 0, s->borderw)) < 0)
             return ret;
     }
     if ((ret = draw_glyphs(s, frame, width, height,
-                           &s->fontcolor, 0, 0, 0)) < 0)
+                           &fontcolor, 0, 0, 0)) < 0)
         return ret;
 
     return 0;