dwebp: move webp decoding to example_util

this will allow reuse by cwebp

Change-Id: I667252fdacfc5436112d21b040ca299273ec1515

examples/Makefile.am

@@ -14,7 +14,7 @@ endif
 
 noinst_LTLIBRARIES = libexampleutil.la
 
-libexampleutil_la_SOURCES = example_util.c example_util.h
+libexampleutil_la_SOURCES = example_util.c example_util.h stopwatch.h
 
 dwebp_SOURCES = dwebp.c stopwatch.h
 dwebp_CPPFLAGS  = $(AM_CPPFLAGS) $(USE_EXPERIMENTAL_CODE)

examples/dwebp.c

@@ -571,11 +571,6 @@ static void Help(void) {
         );
 }
 
-static const char* const kStatusMessages[] = {
-  "OK", "OUT_OF_MEMORY", "INVALID_PARAM", "BITSTREAM_ERROR",
-  "UNSUPPORTED_FEATURE", "SUSPENDED", "USER_ABORT", "NOT_ENOUGH_DATA"
-};
-
 static const char* const kFormatType[] = {
   "unspecified", "lossy", "lossless"
 };
@@ -671,27 +666,11 @@ int main(int argc, const char *argv[]) {
   }
 
   {
-    Stopwatch stop_watch;
     VP8StatusCode status = VP8_STATUS_OK;
     size_t data_size = 0;
     const uint8_t* data = NULL;
-
-    if (!ExUtilReadFile(in_file, &data, &data_size)) return -1;
-
-    if (verbose) {
-      StopwatchReset(&stop_watch);
-    }
-
-    status = WebPGetFeatures(data, data_size, bitstream);
-    if (status != VP8_STATUS_OK) {
-      goto end;
-    }
-
-    if (bitstream->has_animation) {
-      fprintf(stderr,
-              "Error! Decoding of an animated WebP file is not supported.\n"
-              "       Use webpmux to extract the individual frames or\n"
-              "       vwebp to view this image.\n");
+    if (!ExUtilLoadWebP(in_file, &data, &data_size, bitstream)) {
+      goto End;
     }
 
     switch (format) {
@@ -727,31 +706,12 @@ int main(int argc, const char *argv[]) {
         return -1;
     }
 
-    // Decoding call.
-    if (!incremental) {
-      status = WebPDecode(data, data_size, &config);
-    } else {
-      WebPIDecoder* const idec = WebPIDecode(data, data_size, &config);
-      if (idec == NULL) {
-        fprintf(stderr, "Failed during WebPINewDecoder().\n");
-        status = VP8_STATUS_OUT_OF_MEMORY;
-        goto end;
-      } else {
-        status = WebPIUpdate(idec, data, data_size);
-        WebPIDelete(idec);
-      }
-    }
-
-    if (verbose) {
-      const double decode_time = StopwatchReadAndReset(&stop_watch);
-      fprintf(stderr, "Time to decode picture: %.3fs\n", decode_time);
-    }
- end:
+    status = ExUtilDecodeWebP(data, data_size, incremental, verbose, &config);
+ End:
     free((void*)data);
     ok = (status == VP8_STATUS_OK);
     if (!ok) {
-      fprintf(stderr, "Decoding of %s failed.\n", in_file);
-      fprintf(stderr, "Status: %d (%s)\n", status, kStatusMessages[status]);
+      ExUtilPrintWebPError(in_file, status);
       goto Exit;
     }
   }

examples/example_util.c

@@ -15,6 +15,9 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include "webp/decode.h"
+#include "./stopwatch.h"
+
 // -----------------------------------------------------------------------------
 // File I/O
 
@@ -107,3 +110,77 @@ int ExUtilWriteFile(const char* const file_name,
   return ok;
 }
 
+//------------------------------------------------------------------------------
+// WebP decoding
+
+static const char* const kStatusMessages[] = {
+  "OK", "OUT_OF_MEMORY", "INVALID_PARAM", "BITSTREAM_ERROR",
+  "UNSUPPORTED_FEATURE", "SUSPENDED", "USER_ABORT", "NOT_ENOUGH_DATA"
+};
+
+void ExUtilPrintWebPError(const char* const in_file, int status) {
+  fprintf(stderr, "Decoding of %s failed.\n", in_file);
+  fprintf(stderr, "Status: %d", status);
+  if (status >= VP8_STATUS_OK && status <= VP8_STATUS_NOT_ENOUGH_DATA) {
+    fprintf(stderr, "(%s)", kStatusMessages[status]);
+  }
+  fprintf(stderr, "\n");
+}
+
+int ExUtilLoadWebP(const char* const in_file,
+                   const uint8_t** data, size_t* data_size,
+                   WebPBitstreamFeatures* bitstream) {
+  VP8StatusCode status;
+  if (!ExUtilReadFile(in_file, data, data_size)) return 0;
+
+  status = WebPGetFeatures(*data, *data_size, bitstream);
+  if (status != VP8_STATUS_OK) {
+    free((void*)*data);
+    *data = NULL;
+    *data_size = 0;
+    ExUtilPrintWebPError(in_file, status);
+    return 0;
+  }
+  return 1;
+}
+
+VP8StatusCode ExUtilDecodeWebP(const uint8_t* const data, size_t data_size,
+                               int incremental, int verbose,
+                               WebPDecoderConfig* const config) {
+  Stopwatch stop_watch;
+  VP8StatusCode status = VP8_STATUS_OK;
+  if (config == NULL) return 0;
+
+  if (verbose) {
+    StopwatchReset(&stop_watch);
+  }
+
+  if (config->input.has_animation) {
+    fprintf(stderr,
+            "Error! Decoding of an animated WebP file is not supported.\n"
+            "       Use webpmux to extract the individual frames or\n"
+            "       vwebp to view this image.\n");
+  }
+
+  // Decoding call.
+  if (!incremental) {
+    status = WebPDecode(data, data_size, config);
+  } else {
+    WebPIDecoder* const idec = WebPIDecode(data, data_size, config);
+    if (idec == NULL) {
+      fprintf(stderr, "Failed during WebPINewDecoder().\n");
+      return VP8_STATUS_OUT_OF_MEMORY;
+    } else {
+      status = WebPIUpdate(idec, data, data_size);
+      WebPIDelete(idec);
+    }
+  }
+
+  if (verbose) {
+    const double decode_time = StopwatchReadAndReset(&stop_watch);
+    fprintf(stderr, "Time to decode picture: %.3fs\n", decode_time);
+  }
+  return status;
+}
+
+// -----------------------------------------------------------------------------

examples/example_util.h

@@ -19,6 +19,9 @@
 extern "C" {
 #endif
 
+struct WebPDecoderConfig;
+struct WebPBitstreamFeatures;
+
 // Allocates storage for entire file 'file_name' and returns contents and size
 // in 'data' and 'data_size'. Returns 1 on success, 0 otherwise. '*data' should
 // be deleted using free().
@@ -35,6 +38,32 @@ int ExUtilReadFromStdin(const uint8_t** data, size_t* data_size);
 int ExUtilWriteFile(const char* const file_name,
                     const uint8_t* data, size_t data_size);
 
+//------------------------------------------------------------------------------
+// WebP decoding
+
+// Prints an informative error message regarding decode failure of 'in_file'.
+// 'status' is treated as a VP8StatusCode and if valid will be printed as a
+// text string.
+void ExUtilPrintWebPError(const char* const in_file, int status);
+
+// Reads a WebP from 'in_file', returning the contents and size in 'data' and
+// 'data_size'. 'bitstream' is populated using WebPGetFeatures().
+// Returns true on success.
+int ExUtilLoadWebP(const char* const in_file,
+                   const uint8_t** data, size_t* data_size,
+                   struct WebPBitstreamFeatures* bitstream);
+
+// Decodes the WebP contained in 'data'. 'config' is a structure previously
+// initialized by WebPInitDecoderConfig(). 'config->output' should have the
+// desired colorspace selected. If 'incremental' is set to true the WebP
+// incremental decoder will be used. 'verbose' will cause decode timing to be
+// reported.
+// Returns the decoder status. On success 'config->output' will contain the
+// decoded picture.
+enum VP8StatusCode ExUtilDecodeWebP(const uint8_t* const data, size_t data_size,
+                                    int incremental, int verbose,
+                                    struct WebPDecoderConfig* const config);
+
 #ifdef __cplusplus
 }    // extern "C"
 #endif