add a -quiet option to 'dwebp'

(useful for tests)

Change-Id: Ia07f407bc1e819a1d3cab64a02317d058733261b

README

@@ -279,6 +279,7 @@ Use following options to convert into alternate image formats:
   -incremental . use incremental decoding (useful for tests)
   -h     ....... this help message
   -v     ....... verbose (e.g. print encoding/decoding times)
+  -quiet ....... quiet mode, don't print anything
   -noasm ....... disable all assembly optimizations
 
 Visualization tool:

examples/dwebp.c

@@ -555,6 +555,7 @@ static void Help(void) {
          "  -incremental . use incremental decoding (useful for tests)\n"
          "  -h     ....... this help message\n"
          "  -v     ....... verbose (e.g. print encoding/decoding times)\n"
+         "  -quiet ....... quiet mode, don't print anything\n"
 #ifndef WEBP_DLL
          "  -noasm ....... disable all assembly optimizations\n"
 #endif
@@ -569,6 +570,7 @@ int main(int argc, const char *argv[]) {
   int ok = 0;
   const char *in_file = NULL;
   const char *out_file = NULL;
+  int quiet = 0;
 
   WebPDecoderConfig config;
   WebPDecBuffer* const output_buffer = &config.output;
@@ -603,6 +605,8 @@ int main(int argc, const char *argv[]) {
       format = BMP;
     } else if (!strcmp(argv[c], "-tiff")) {
       format = TIFF;
+    } else if (!strcmp(argv[c], "-quiet")) {
+      quiet = 1;
     } else if (!strcmp(argv[c], "-version")) {
       const int version = WebPGetDecoderVersion();
       printf("%d.%d.%d\n",
@@ -665,6 +669,8 @@ int main(int argc, const char *argv[]) {
     return -1;
   }
 
+  if (quiet) verbose = 0;
+
   {
     VP8StatusCode status = VP8_STATUS_OK;
     size_t data_size = 0;
@@ -721,13 +727,16 @@ int main(int argc, const char *argv[]) {
   }
 
   if (out_file != NULL) {
+    if (!quiet) {
       fprintf(stderr, "Decoded %s. Dimensions: %d x %d %s. Format: %s. "
                       "Now saving...\n",
               in_file, output_buffer->width, output_buffer->height,
               bitstream->has_alpha ? " (with alpha)" : "",
               kFormatType[bitstream->format]);
+    }
     ok = SaveOutput(output_buffer, format, out_file);
   } else {
+    if (!quiet) {
       fprintf(stderr, "File %s can be decoded "
                       "(dimensions: %d x %d %s. Format: %s).\n",
               in_file, output_buffer->width, output_buffer->height,
@@ -736,6 +745,7 @@ int main(int argc, const char *argv[]) {
       fprintf(stderr, "Nothing written; "
                       "use -o flag to save the result as e.g. PNG.\n");
     }
+  }
  Exit:
   WebPFreeDecBuffer(output_buffer);
   return ok ? 0 : -1;

man/dwebp.1

@@ -1,5 +1,5 @@
 .\"                                      Hey, EMACS: -*- nroff -*-
-.TH DWEBP 1 "August 13, 2015"
+.TH DWEBP 1 "August 17, 2015"
 .SH NAME
 dwebp \- decompress a WebP file to an image file
 .SH SYNOPSIS
@@ -98,6 +98,9 @@ is applied \fIafter\fP cropping.
 If either (but not both) of the \fBwidth\fP or \fBheight\fP parameters is 0,
 the value will be calculated preserving the aspect-ratio.
 .TP
+.B \-quiet
+Do not print anything.
+.TP
 .B \-v
 Print extra information (decoding time in particular).
 .TP