WebPMuxAssemble() returns WebPData*.

Also add an API 'WebPDataFree()'

Change-Id: I00dc4c67fd78a541a18aaf0e65b8ef62d9769803

README.mux

@@ -81,10 +81,10 @@ profile & XMP metadata.
   // ... (Prepare XMP metadata).
   WebPMuxSetMetadata(mux, &xmp, copy_data);
   // Get data from mux in WebP RIFF format.
-  WebPMuxAssemble(mux, &output_data, &output_data_size);
+  WebPMuxAssemble(mux, &output_data);
   WebPMuxDelete(mux);
-  // ... (Consume output_data; e.g. write output_data to file).
+  // ... (Consume output_data; e.g. write output_data.bytes_ to file).
-  free(output_data);
+  WebPDataClear(&output_data);
 
 
 Example#2 (pseudo code): Get image & color profile data from a WebP file.

examples/webpmux.c

@@ -135,12 +135,6 @@ static int WebPDataCopy(const WebPData* const src, WebPData* const dst) {
   return 1;
 }
 
-// Frees data allocated by WebPDataCopy.
-static void WebPDataFree(WebPData* const webpdata) {
-  free((void*)webpdata->bytes_);
-  memset(webpdata, 0, sizeof(*webpdata));
-}
-
 #define RETURN_IF_ERROR(ERR_MSG)                                     \
   if (err != WEBP_MUX_OK) {                                          \
     fprintf(stderr, ERR_MSG);                                        \
@@ -370,8 +364,8 @@ static int ReadImage(const char* filename,
     if (!ok) {
       fprintf(stderr, "Error allocating storage for image (%zu bytes) "
               "and alpha (%zu bytes) data\n", image.size_, alpha.size_);
-      WebPDataFree(image_ptr);
+      WebPDataClear(image_ptr);
-      WebPDataFree(alpha_ptr);
+      WebPDataClear(alpha_ptr);
     }
   } else {
     fprintf(stderr, "Failed to extract image data from file %s. Error: %d\n",
@@ -399,17 +393,15 @@ static int WriteData(const char* filename, const WebPData* const webpdata) {
 }
 
 static int WriteWebP(WebPMux* const mux, const char* filename) {
-  WebPData webpdata;
   int ok;
-
+  WebPData webp_data;
-  const WebPMuxError err = WebPMuxAssemble(
+  const WebPMuxError err = WebPMuxAssemble(mux, &webp_data);
-      mux, (uint8_t**)&webpdata.bytes_, &webpdata.size_);
   if (err != WEBP_MUX_OK) {
     fprintf(stderr, "Error (%d) assembling the WebP file.\n", err);
     return 0;
   }
-  ok = WriteData(filename, &webpdata);
+  ok = WriteData(filename, &webp_data);
-  WebPDataFree(&webpdata);
+  WebPDataClear(&webp_data);
   return ok;
 }
 
@@ -862,14 +854,14 @@ static int Process(const WebPMuxConfig* config) {
               ok = ParseFrameArgs(feature->args_[index].params_,
                                   &x_offset, &y_offset, &duration);
               if (!ok) {
-                WebPDataFree(&image);
+                WebPDataClear(&image);
-                WebPDataFree(&alpha);
+                WebPDataClear(&alpha);
                 ERROR_GOTO1("ERROR: Could not parse frame properties.\n", Err2);
               }
               err = WebPMuxSetFrame(mux, 0, &image, &alpha,
                                     x_offset, y_offset, duration, 1);
-              WebPDataFree(&image);
+              WebPDataClear(&image);
-              WebPDataFree(&alpha);
+              WebPDataClear(&alpha);
               if (err != WEBP_MUX_OK) {
                 ERROR_GOTO3("ERROR#%d: Could not add a frame at index %d.\n",
                             err, index, Err2);
@@ -893,13 +885,13 @@ static int Process(const WebPMuxConfig* config) {
             ok = ParseTileArgs(feature->args_[index].params_, &x_offset,
                                &y_offset);
             if (!ok) {
-              WebPDataFree(&image);
+              WebPDataClear(&image);
-              WebPDataFree(&alpha);
+              WebPDataClear(&alpha);
               ERROR_GOTO1("ERROR: Could not parse tile properties.\n", Err2);
             }
             err = WebPMuxSetTile(mux, 0, &image, &alpha, x_offset, y_offset, 1);
-            WebPDataFree(&image);
+            WebPDataClear(&image);
-            WebPDataFree(&alpha);
+            WebPDataClear(&alpha);
             if (err != WEBP_MUX_OK) {
               ERROR_GOTO3("ERROR#%d: Could not add a tile at index %d.\n",
                           err, index, Err2);

src/mux/muxedit.c

@@ -270,7 +270,8 @@ WebPMuxError WebPMuxSetImage(WebPMux* const mux,
 
   // Add image chunk.
   ChunkInit(&chunk);
-  err = ChunkAssignDataImageInfo(&chunk, &image_raw, NULL, copy_data, image_tag);
+  err = ChunkAssignDataImageInfo(&chunk, &image_raw, NULL, copy_data,
+                                 image_tag);
   if (err != WEBP_MUX_OK) return err;
   err = ChunkSetNth(&chunk, &wpi.img_, 1);
   if (err != WEBP_MUX_OK) return err;
@@ -645,7 +646,7 @@ static WebPMuxError CreateVP8XChunk(WebPMux* const mux) {
 }
 
 WebPMuxError WebPMuxAssemble(WebPMux* const mux,
-                             uint8_t** output_data, size_t* output_size) {
+                             WebPData* const assembled_data) {
   size_t size = 0;
   uint8_t* data = NULL;
   uint8_t* dst = NULL;
@@ -653,13 +654,10 @@ WebPMuxError WebPMuxAssemble(WebPMux* const mux,
   int num_loop_chunks;
   WebPMuxError err;
 
-  if (mux == NULL || output_data == NULL || output_size == NULL) {
+  if (mux == NULL || assembled_data == NULL) {
     return WEBP_MUX_INVALID_ARGUMENT;
   }
 
-  *output_data = NULL;
-  *output_size = 0;
-
   // Remove LOOP chunk if unnecessary.
   err = WebPMuxNumNamedElements(mux, kChunks[IDX_LOOP].name,
                                 &num_loop_chunks);
@@ -715,8 +713,8 @@ WebPMuxError WebPMuxAssemble(WebPMux* const mux,
   }
 
   // Finalize.
-  *output_data = data;
+  assembled_data->bytes_ = data;
-  *output_size = size;
+  assembled_data->size_ = size;
 
   return err;
 }

src/mux/muxinternal.c

@@ -225,6 +225,16 @@ uint8_t* ChunkListEmit(const WebPChunk* chunk_list, uint8_t* dst) {
   return dst;
 }
 
+//------------------------------------------------------------------------------
+// Life of a WebPData object.
+
+void WebPDataClear(WebPData* const webp_data) {
+  if (webp_data != NULL) {
+    free((void*)webp_data->bytes_);
+    memset(webp_data, 0, sizeof(*webp_data));
+  }
+}
+
 //------------------------------------------------------------------------------
 // Life of a MuxImage object.
 

src/webp/mux.h

@@ -24,10 +24,10 @@
 //   // ... (Prepare XMP metadata).
 //   WebPMuxSetMetadata(mux, &xmp, copy_data);
 //   // Get data from mux in WebP RIFF format.
-//   WebPMuxAssemble(mux, &output_data, &output_data_size);
+//   WebPMuxAssemble(mux, &output_data);
 //   WebPMuxDelete(mux);
-//   // ... (Consume output_data; e.g. write output_data to file).
+//   // ... (Consume output_data; e.g. write output_data.bytes_ to file).
-//   free(output_data);
+//   WebPDataClear(&output_data);
 //
 // Code Example#2: Get image & color profile data from a WebP file.
 //
@@ -88,6 +88,13 @@ typedef struct {
   size_t size_;
 } WebPData;
 
+//------------------------------------------------------------------------------
+// Life of a WebPData object.
+
+// Clears the contents of the 'webp_data' object by calling free(). Does not
+// deallocate the object itself.
+WEBP_EXTERN(void) WebPDataClear(WebPData* const webp_data);
+
 //------------------------------------------------------------------------------
 // Life of a Mux object
 
@@ -438,15 +445,15 @@ WEBP_EXTERN(WebPMuxError) WebPMuxNumNamedElements(const WebPMux* const mux,
                                                   const char* name,
                                                   int* num_elements);
 
-// Assembles all chunks in WebP RIFF format and returns in output_data.
+// Assembles all chunks in WebP RIFF format and returns in 'assembled_data'.
 // This function also validates the mux object.
-// The content of '*output_data' is allocated using malloc(), and NOT
+// Note: The content of 'assembled_data' will be ignored and overwritten.
-// owned by the 'mux' object.
+// Also, the content of 'assembled_data' is allocated using malloc(), and NOT
-// It MUST be deallocated by the caller by calling free().
+// owned by the 'mux' object. It MUST be deallocated by the caller by calling
+// WebPDataClear().
 // Parameters:
 //   mux - (in/out) object whose chunks are to be assembled
-//   output_data - (out) byte array where assembled WebP data is returned
+//   assembled_data - (out) assembled WebP data
-//   output_size - (out) size of returned data
 // Returns:
 //   WEBP_MUX_BAD_DATA - if mux object is invalid.
 //   WEBP_MUX_INVALID_ARGUMENT - if either mux, output_data or output_size is
@@ -454,8 +461,7 @@ WEBP_EXTERN(WebPMuxError) WebPMuxNumNamedElements(const WebPMux* const mux,
 //   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
 //   WEBP_MUX_OK - on success
 WEBP_EXTERN(WebPMuxError) WebPMuxAssemble(WebPMux* const mux,
-                                          uint8_t** output_data,
+                                          WebPData* const assembled_data);
-                                          size_t* output_size);
 
 //------------------------------------------------------------------------------