webpmux: add "-set bgcolor A,R,G,B"

Similarly to "-set loop <>", this is useful to set
the parameter at global level and not just while assembling
the frames separately.

Change-Id: I79bcbe37f8ff50b9904e78d14011ccbac72f17a1

README.mux

@@ -43,11 +43,12 @@ GET_OPTIONS:
    frame n   get nth frame
 
 SET_OPTIONS:
- Set color profile/metadata:
+ Set color profile/metadata/parameters:
-   loop LOOP_COUNT   set the loop count
+   loop LOOP_COUNT            set the loop count
-   icc  file.icc     set ICC profile
+   bgcolor BACKGROUND_COLOR   set the animation background color
-   exif file.exif    set EXIF metadata
+   icc  file.icc              set ICC profile
-   xmp  file.xmp     set XMP metadata
+   exif file.exif             set EXIF metadata
+   xmp  file.xmp              set XMP metadata
    where:    'file.icc' contains the ICC profile to be set,
              'file.exif' contains the EXIF metadata to be set
              'file.xmp' contains the XMP metadata to be set

examples/webpmux.c

@@ -99,6 +99,7 @@ typedef enum {
   FEATURE_ANMF,
   FEATURE_DURATION,
   FEATURE_LOOP,
+  FEATURE_BGCOLOR,
   LAST_FEATURE
 } FeatureType;
 
@@ -315,11 +316,12 @@ static void PrintHelp(void) {
 
   printf("\n");
   printf("SET_OPTIONS:\n");
-  printf(" Set color profile/metadata:\n");
+  printf(" Set color profile/metadata/parameters:\n");
-  printf("   loop LOOP_COUNT   set the loop count\n");
+  printf("   loop LOOP_COUNT            set the loop count\n");
-  printf("   icc  file.icc     set ICC profile\n");
+  printf("   bgcolor BACKGROUND_COLOR   set the animation background color\n");
-  printf("   exif file.exif    set EXIF metadata\n");
+  printf("   icc  file.icc              set ICC profile\n");
-  printf("   xmp  file.xmp     set XMP metadata\n");
+  printf("   exif file.exif             set EXIF metadata\n");
+  printf("   xmp  file.xmp              set XMP metadata\n");
   printf("   where:    'file.icc' contains the ICC profile to be set,\n");
   printf("             'file.exif' contains the EXIF metadata to be set\n");
   printf("             'file.xmp' contains the XMP metadata to be set\n");
@@ -778,6 +780,13 @@ static int ParseCommandLine(Config* config, const W_CHAR** const unicode_argv) {
         arg->params_ = argv[i + 1];
         ++feature_arg_index;
         i += 2;
+      } else if (!strcmp(argv[i], "bgcolor") &&
+                 (config->action_type_ == ACTION_SET)) {
+        CHECK_NUM_ARGS_AT_LEAST(2, ErrParse);
+        config->type_ = FEATURE_BGCOLOR;
+        arg->params_ = argv[i + 1];
+        ++feature_arg_index;
+        i += 2;
       } else {  // Assume input file.
         if (config->input_ == NULL) {
           config->input_ = wargv[i];
@@ -1053,6 +1062,30 @@ static int Process(const Config* config) {
           }
           break;
         }
+        case FEATURE_BGCOLOR: {
+          WebPMuxAnimParams params = { 0xFFFFFFFF, 0 };
+          uint32_t bgcolor;
+          ok = ParseBgcolorArgs(config->args_[0].params_, &bgcolor);
+          if (!ok) {
+            ERROR_GOTO1("ERROR: Could not parse the background color.\n",
+                        Err2);
+          }
+          ok = CreateMux(config->input_, &mux);
+          if (!ok) goto Err2;
+          ok = (WebPMuxGetAnimationParams(mux, &params) == WEBP_MUX_OK);
+          if (!ok) {
+            ERROR_GOTO1("ERROR: input file does not seem to be an animation.\n",
+                        Err2);
+          }
+          params.bgcolor = bgcolor;
+          err = WebPMuxSetAnimationParams(mux, &params);
+          ok = (err == WEBP_MUX_OK);
+          if (!ok) {
+            ERROR_GOTO2("ERROR (%s): Could not set animation parameters.\n",
+                        ErrorString(err), Err2);
+          }
+          break;
+        }
         default: {
           ERROR_GOTO1("ERROR: Invalid feature for action 'set'.\n", Err2);
           break;

man/webpmux.1

@@ -1,5 +1,5 @@
 .\"                                      Hey, EMACS: -*- nroff -*-
-.TH WEBPMUX 1 "December 12, 2020"
+.TH WEBPMUX 1 "November 3, 2021"
 .SH NAME
 webpmux \- create animated WebP files from non\-animated WebP images, extract
 frames from animated WebP images, and manage XMP/EXIF metadata and ICC profile.
@@ -82,6 +82,11 @@ Set loop count on an animated file.
 .P
 Where: 'loop_count' must be in range [0, 65535].
 .TP
+.BI bgcolor " A,R,G,B
+Set the background color of the canvas on an animated file.
+.P
+Where: 'loop_count' must be in range [0, 65535].
+.TP
 .BI icc " file.icc
 Set ICC profile.
 .P