avfilter/vf_histogram: make foreground and background opacity configurable

doc/filters.texi

@@ -8555,6 +8555,12 @@ Default is @code{linear}.
 @item components
 Set what color components to display.
 Default is @code{7}.
+
+@item fgopacity
+Set foreground opacity. Default is @code{0.7}.
+
+@item bgopacity
+Set background opacity. Default is @code{0.5}.
 @end table
 
 @subsection Examples

libavfilter/vf_histogram.c

@@ -35,14 +35,16 @@ typedef struct HistogramContext {
     int            histogram_size;
     int            mult;
     int            ncomp;
-    const uint8_t  *bg_color;
-    const uint8_t  *fg_color;
+    uint8_t        bg_color[4];
+    uint8_t        fg_color[4];
     int            level_height;
     int            scale_height;
     int            display_mode;
     int            levels_mode;
     const AVPixFmtDescriptor *desc, *odesc;
     int            components;
+    float          fgopacity;
+    float          bgopacity;
     int            planewidth[4];
     int            planeheight[4];
 } HistogramContext;
@@ -63,6 +65,10 @@ static const AVOption histogram_options[] = {
         { "logarithmic", NULL, 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, FLAGS, "levels_mode" },
     { "components", "set color components to display", OFFSET(components), AV_OPT_TYPE_INT, {.i64=7}, 1, 15, FLAGS},
     { "c",          "set color components to display", OFFSET(components), AV_OPT_TYPE_INT, {.i64=7}, 1, 15, FLAGS},
+    { "fgopacity", "set foreground opacity", OFFSET(fgopacity), AV_OPT_TYPE_FLOAT, {.dbl=0.7}, 0, 1, FLAGS},
+    { "f",         "set foreground opacity", OFFSET(fgopacity), AV_OPT_TYPE_FLOAT, {.dbl=0.7}, 0, 1, FLAGS},
+    { "bgopacity", "set background opacity", OFFSET(bgopacity), AV_OPT_TYPE_FLOAT, {.dbl=0.5}, 0, 1, FLAGS},
+    { "b",         "set background opacity", OFFSET(bgopacity), AV_OPT_TYPE_FLOAT, {.dbl=0.5}, 0, 1, FLAGS},
     { NULL }
 };
 
@@ -197,14 +203,17 @@ static int config_input(AVFilterLink *inlink)
     case AV_PIX_FMT_GBRP9:
     case AV_PIX_FMT_GBRAP:
     case AV_PIX_FMT_GBRP:
-        h->bg_color = black_gbrp_color;
-        h->fg_color = white_gbrp_color;
+        memcpy(h->bg_color, black_gbrp_color, 4);
+        memcpy(h->fg_color, white_gbrp_color, 4);
         break;
     default:
-        h->bg_color = black_yuva_color;
-        h->fg_color = white_yuva_color;
+        memcpy(h->bg_color, black_yuva_color, 4);
+        memcpy(h->fg_color, white_yuva_color, 4);
     }
 
+    h->fg_color[3] = h->fgopacity * 255;
+    h->bg_color[3] = h->bgopacity * 255;
+
     h->planeheight[1] = h->planeheight[2] = AV_CEIL_RSHIFT(inlink->h, h->desc->log2_chroma_h);
     h->planeheight[0] = h->planeheight[3] = inlink->h;
     h->planewidth[1]  = h->planewidth[2]  = AV_CEIL_RSHIFT(inlink->w, h->desc->log2_chroma_w);