cwebp: add metadata framework

unused currently, but the intent is to allow each format to populate
exif/xmp/icc with cwebp then transferring it to the webp file.

Change-Id: I0514f62de52fa7f89c595ee7ef2ad7dced910a41

examples/Makefile.am

@@ -20,7 +20,7 @@ dwebp_CPPFLAGS  = $(AM_CPPFLAGS) $(USE_EXPERIMENTAL_CODE)
 dwebp_CPPFLAGS += $(JPEG_INCLUDES) $(PNG_INCLUDES)
 dwebp_LDADD = libexampleutil.la ../src/libwebp.la $(PNG_LIBS) $(JPEG_LIBS)
 
-cwebp_SOURCES = cwebp.c stopwatch.h
+cwebp_SOURCES = cwebp.c metadata.h stopwatch.h
 cwebp_CPPFLAGS  = $(AM_CPPFLAGS) $(USE_EXPERIMENTAL_CODE)
 cwebp_CPPFLAGS += $(JPEG_INCLUDES) $(PNG_INCLUDES) $(TIFF_INCLUDES)
 cwebp_LDADD = ../src/libwebp.la $(JPEG_LIBS) $(PNG_LIBS) $(TIFF_LIBS)

examples/cwebp.c

@@ -46,6 +46,7 @@
 
 
 #include "webp/encode.h"
+#include "./metadata.h"
 #include "./stopwatch.h"
 #ifndef WEBP_DLL
 #if defined(__cplusplus) || defined(c_plusplus)
@@ -270,8 +271,9 @@ static HRESULT ReadPictureWithWIC(const char* filename,
 }
 
 static int ReadPicture(const char* const filename, WebPPicture* const pic,
-                       int keep_alpha) {
+                       int keep_alpha, Metadata* const metadata) {
   int ok;
+  (void)metadata;  // TODO(jzern): add metadata extraction using WIC
   if (pic->width != 0 && pic->height != 0) {
     // If image size is specified, infer it as YUV format.
     FILE* in_file = fopen(filename, "rb");
@@ -578,9 +580,10 @@ static InputFileFormat GetImageType(FILE* in_file) {
 }
 
 static int ReadPicture(const char* const filename, WebPPicture* const pic,
-                       int keep_alpha) {
+                       int keep_alpha, Metadata* const metadata) {
   int ok = 0;
   FILE* in_file = fopen(filename, "rb");
+  (void)metadata;  // TODO(jzern): add metadata extraction to the formats below.
   if (in_file == NULL) {
     fprintf(stderr, "Error! Cannot open input file '%s'\n", filename);
     return ok;
@@ -934,8 +937,10 @@ int main(int argc, const char *argv[]) {
   WebPPicture original_picture;    // when PSNR or SSIM is requested
   WebPConfig config;
   WebPAuxStats stats;
+  Metadata metadata;
   Stopwatch stop_watch;
 
+  MetadataInit(&metadata);
   if (!WebPPictureInit(&picture) ||
       !WebPPictureInit(&original_picture) ||
       !WebPConfigInit(&config)) {
@@ -1128,7 +1133,7 @@ int main(int argc, const char *argv[]) {
   if (verbose) {
     StopwatchReadAndReset(&stop_watch);
   }
-  if (!ReadPicture(in_file, &picture, keep_alpha)) {
+  if (!ReadPicture(in_file, &picture, keep_alpha, &metadata)) {
     fprintf(stderr, "Error! Cannot read input picture file '%s'\n", in_file);
     goto Error;
   }
@@ -1227,6 +1232,7 @@ int main(int argc, const char *argv[]) {
 
  Error:
   free(picture.extra_info);
+  MetadataFree(&metadata);
   WebPPictureFree(&picture);
   WebPPictureFree(&original_picture);
   if (out != NULL) {

examples/metadata.h

@@ -0,0 +1,53 @@
+// Copyright 2012 Google Inc. All Rights Reserved.
+//
+// This code is licensed under the same terms as WebM:
+//  Software License Agreement:  http://www.webmproject.org/license/software/
+//  Additional IP Rights Grant:  http://www.webmproject.org/license/additional/
+// -----------------------------------------------------------------------------
+//
+//  Metadata types and functions.
+//
+
+#ifndef WEBP_EXAMPLES_METADATA_H_
+#define WEBP_EXAMPLES_METADATA_H_
+
+#include "webp/types.h"
+
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
+#endif
+
+typedef struct MetadataPayload {
+  uint8_t* bytes;
+  size_t size;
+} MetadataPayload;
+
+typedef struct Metadata {
+  MetadataPayload exif;
+  MetadataPayload iccp;
+  MetadataPayload xmp;
+} Metadata;
+
+#define METADATA_OFFSET(x) offsetof(Metadata, x)
+
+static void MetadataInit(Metadata* const m) {
+  memset(m, 0, sizeof(*m));
+}
+
+static void MetadataPayloadDelete(MetadataPayload* const payload) {
+  free(payload->bytes);
+  payload->bytes = NULL;
+  payload->size = 0;
+}
+
+static void MetadataFree(Metadata* const m) {
+  MetadataPayloadDelete(&m->exif);
+  MetadataPayloadDelete(&m->iccp);
+  MetadataPayloadDelete(&m->xmp);
+}
+
+#if defined(__cplusplus) || defined(c_plusplus)
+}    // extern "C"
+#endif
+
+#endif  // WEBP_EXAMPLES_METADATA_H_