lavfi/drawtext: rename and document variables d_expr and d_pexpr

Use the more expressive names draw_expr and draw_pexpr, also more
consistent.

libavfilter/vf_drawtext.c

@@ -147,8 +147,8 @@ typedef struct {
     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   *d_expr;
-    AVExpr *d_pexpr;
+    char   *draw_expr;              ///< expression for draw
+    AVExpr *draw_pexpr;             ///< parsed expression for draw
     int draw;                       ///< set to zero to prevent drawing
     AVLFG  prng;                    ///< random
     char       *tc_opt_string;      ///< specified timecode option string
@@ -175,7 +175,7 @@ static const AVOption drawtext_options[]= {
 {"shadowy",  "set y",                OFFSET(shadowy),            AV_OPT_TYPE_INT,    {.dbl=0},     INT_MIN,  INT_MAX  },
 {"tabsize",  "set tab size",         OFFSET(tabsize),            AV_OPT_TYPE_INT,    {.dbl=4},     0,        INT_MAX  },
 {"basetime", "set base time",        OFFSET(basetime),           AV_OPT_TYPE_INT64,  {.dbl=AV_NOPTS_VALUE},     INT64_MIN,        INT64_MAX  },
-{"draw",     "if false do not draw", OFFSET(d_expr),             AV_OPT_TYPE_STRING, {.str="1"},   CHAR_MIN, CHAR_MAX },
+{"draw",     "if false do not draw", OFFSET(draw_expr),          AV_OPT_TYPE_STRING, {.str="1"},   CHAR_MIN, CHAR_MAX },
 {"timecode", "set initial timecode", OFFSET(tc_opt_string),      AV_OPT_TYPE_STRING, {.str=NULL},  CHAR_MIN, CHAR_MAX },
 {"tc24hmax", "set 24 hours max (timecode only)", OFFSET(tc24hmax), AV_OPT_TYPE_INT,  {.dbl=0},            0,        1 },
 {"r",        "set rate (timecode only)", OFFSET(tc_rate),        AV_OPT_TYPE_RATIONAL, {.dbl=0},          0,  INT_MAX },
@@ -515,7 +515,7 @@ static av_cold void uninit(AVFilterContext *ctx)
 
     av_expr_free(dtext->x_pexpr); dtext->x_pexpr = NULL;
     av_expr_free(dtext->y_pexpr); dtext->y_pexpr = NULL;
-    av_expr_free(dtext->d_pexpr); dtext->d_pexpr = NULL;
+    av_expr_free(dtext->draw_pexpr); dtext->draw_pexpr = NULL;
 
     av_freep(&dtext->boxcolor_string);
     av_freep(&dtext->expanded_text);
@@ -525,7 +525,7 @@ static av_cold void uninit(AVFilterContext *ctx)
     av_freep(&dtext->text);
     av_freep(&dtext->x_expr);
     av_freep(&dtext->y_expr);
-    av_freep(&dtext->d_expr);
+    av_freep(&dtext->draw_expr);
 
     av_freep(&dtext->positions);
     dtext->nb_positions = 0;
@@ -572,7 +572,7 @@ static int config_input(AVFilterLink *inlink)
                              NULL, NULL, fun2_names, fun2, 0, ctx)) < 0 ||
         (ret = av_expr_parse(&dtext->y_pexpr, dtext->y_expr, var_names,
                              NULL, NULL, fun2_names, fun2, 0, ctx)) < 0 ||
-        (ret = av_expr_parse(&dtext->d_pexpr, dtext->d_expr, var_names,
+        (ret = av_expr_parse(&dtext->draw_pexpr, dtext->draw_expr, var_names,
                              NULL, NULL, fun2_names, fun2, 0, ctx)) < 0)
 
         return AVERROR(EINVAL);
@@ -767,7 +767,7 @@ static int draw_text(AVFilterContext *ctx, AVFilterBufferRef *picref,
     dtext->x = dtext->var_values[VAR_X] = av_expr_eval(dtext->x_pexpr, dtext->var_values, &dtext->prng);
     dtext->y = dtext->var_values[VAR_Y] = av_expr_eval(dtext->y_pexpr, dtext->var_values, &dtext->prng);
     dtext->x = dtext->var_values[VAR_X] = av_expr_eval(dtext->x_pexpr, dtext->var_values, &dtext->prng);
-    dtext->draw = av_expr_eval(dtext->d_pexpr, dtext->var_values, &dtext->prng);
+    dtext->draw = av_expr_eval(dtext->draw_pexpr, dtext->var_values, &dtext->prng);
 
     if(!dtext->draw)
         return 0;