Mux: only allow adding frame/tiles at the end.

Change-Id: I5d685628da8c8ac85144cee2e5808b30ec79fef9

examples/webpmux.c

@@ -797,7 +797,7 @@ static int Process(const WebPMuxConfig* config) {
                 WebPDataClear(&webpdata);
                 ERROR_GOTO1("ERROR: Could not parse frame properties.\n", Err2);
               }
-              err = WebPMuxSetFrame(mux, 0, &webpdata, x_offset, y_offset,
+              err = WebPMuxPushFrame(mux, &webpdata, x_offset, y_offset,
                                     duration, 1);
               WebPDataClear(&webpdata);
               if (err != WEBP_MUX_OK) {
@@ -825,7 +825,7 @@ static int Process(const WebPMuxConfig* config) {
               WebPDataClear(&webpdata);
               ERROR_GOTO1("ERROR: Could not parse tile properties.\n", Err2);
             }
-            err = WebPMuxSetTile(mux, 0, &webpdata, x_offset, y_offset, 1);
+            err = WebPMuxPushTile(mux, &webpdata, x_offset, y_offset, 1);
             WebPDataClear(&webpdata);
             if (err != WEBP_MUX_OK) {
               ERROR_GOTO3("ERROR#%d: Could not add a tile at index %d.\n",

src/mux/muxedit.c

@@ -273,7 +273,7 @@ WebPMuxError WebPMuxSetImage(WebPMux* const mux,
   if (err != WEBP_MUX_OK) goto Err;
 
   // Add this image to mux.
-  err = MuxImageSetNth(&wpi, &mux->images_, 1);
+  err = MuxImagePush(&wpi, &mux->images_);
   if (err != WEBP_MUX_OK) goto Err;
 
   // All OK.
@@ -343,10 +343,9 @@ WebPMuxError WebPMuxSetLoopCount(WebPMux* const mux, uint32_t loop_count) {
   return err;
 }
 
-static WebPMuxError MuxSetFrameTileInternal(
+static WebPMuxError MuxPushFrameTileInternal(
-    WebPMux* const mux, uint32_t nth, const WebPData* const bitstream,
+    WebPMux* const mux, const WebPData* const bitstream, uint32_t x_offset,
-    uint32_t x_offset, uint32_t y_offset, uint32_t duration,
+    uint32_t y_offset, uint32_t duration, int copy_data, uint32_t tag) {
-    int copy_data, uint32_t tag) {
   WebPChunk chunk;
   WebPData image;
   WebPData alpha;
@@ -418,7 +417,7 @@ static WebPMuxError MuxSetFrameTileInternal(
   ChunkInit(&chunk);  // chunk owned by wpi.header_ now.
 
   // Add this WebPMuxImage to mux.
-  err = MuxImageSetNth(&wpi, &mux->images_, nth);
+  err = MuxImagePush(&wpi, &mux->images_);
   if (err != WEBP_MUX_OK) goto Err;
 
   // All is well.
@@ -432,21 +431,19 @@ static WebPMuxError MuxSetFrameTileInternal(
   return err;
 }
 
-// TODO(urvang): Think about whether we need 'nth' while adding a frame or tile.
+WebPMuxError WebPMuxPushFrame(WebPMux* const mux,
-
-WebPMuxError WebPMuxSetFrame(WebPMux* const mux, uint32_t nth,
                              const WebPData* const bitstream,
                              uint32_t x_offset, uint32_t y_offset,
                              uint32_t duration, int copy_data) {
-  return MuxSetFrameTileInternal(mux, nth, bitstream, x_offset, y_offset,
+  return MuxPushFrameTileInternal(mux, bitstream, x_offset, y_offset,
                                  duration, copy_data, kChunks[IDX_FRAME].tag);
 }
 
-WebPMuxError WebPMuxSetTile(WebPMux* const mux, uint32_t nth,
+WebPMuxError WebPMuxPushTile(WebPMux* const mux,
                             const WebPData* const bitstream,
                             uint32_t x_offset, uint32_t y_offset,
                             int copy_data) {
-  return MuxSetFrameTileInternal(mux, nth, bitstream, x_offset, y_offset,
+  return MuxPushFrameTileInternal(mux, bitstream, x_offset, y_offset,
                                  1 /* unused duration*/, copy_data,
                                  kChunks[IDX_TILE].tag);
 }

src/mux/muxi.h

@@ -215,10 +215,8 @@ static WEBP_INLINE WebPChunk** MuxImageGetListFromId(WebPMuxImage* wpi,
   }
 }
 
-// Sets 'wpi' at nth position in the 'wpi_list'.
+// Pushes 'wpi' at the end of 'wpi_list'.
-// nth = 0 has the special meaning "last of the list".
+WebPMuxError MuxImagePush(const WebPMuxImage* wpi, WebPMuxImage** wpi_list);
-WebPMuxError MuxImageSetNth(const WebPMuxImage* wpi, WebPMuxImage** wpi_list,
-                            uint32_t nth);
 
 // Delete nth image in the image list with given tag id.
 WebPMuxError MuxImageDeleteNth(WebPMuxImage** wpi_list, uint32_t nth,

src/mux/muxinternal.c

@@ -275,27 +275,6 @@ int MuxImageCount(WebPMuxImage* const wpi_list, WebPChunkId id) {
   return count;
 }
 
-// Outputs a pointer to 'prev_wpi->next_',
-//   where 'prev_wpi' is the pointer to the image at position (nth - 1).
-// Returns 1 if nth image was found, 0 otherwise.
-static int SearchImageToSet(WebPMuxImage** wpi_list, uint32_t nth,
-                            WebPMuxImage*** const location) {
-  uint32_t count = 0;
-  assert(wpi_list);
-  *location = wpi_list;
-
-  while (*wpi_list) {
-    WebPMuxImage* const cur_wpi = *wpi_list;
-    ++count;
-    if (count == nth) return 1;  // Found.
-    wpi_list = &cur_wpi->next_;
-    *location = wpi_list;
-  }
-
-  // *chunk_list is ok to be NULL if adding at last location.
-  return (nth == 0 || (count == nth - 1)) ? 1 : 0;
-}
-
 // Outputs a pointer to 'prev_wpi->next_',
 //   where 'prev_wpi' is the pointer to the image at position (nth - 1).
 // Returns 1 if nth image with given id was found, 0 otherwise.
@@ -335,19 +314,25 @@ static int SearchImageToGetOrDelete(WebPMuxImage** wpi_list, uint32_t nth,
 //------------------------------------------------------------------------------
 // MuxImage writer methods.
 
-WebPMuxError MuxImageSetNth(const WebPMuxImage* wpi, WebPMuxImage** wpi_list,
+WebPMuxError MuxImagePush(const WebPMuxImage* wpi, WebPMuxImage** wpi_list) {
-                            uint32_t nth) {
   WebPMuxImage* new_wpi;
 
-  if (!SearchImageToSet(wpi_list, nth, &wpi_list)) {
+  while (*wpi_list != NULL) {
-    return WEBP_MUX_NOT_FOUND;
+    WebPMuxImage* const cur_wpi = *wpi_list;
+    if (cur_wpi->next_ == NULL) break;
+    wpi_list = &cur_wpi->next_;
   }
 
   new_wpi = (WebPMuxImage*)malloc(sizeof(*new_wpi));
   if (new_wpi == NULL) return WEBP_MUX_MEMORY_ERROR;
   *new_wpi = *wpi;
-  new_wpi->next_ = *wpi_list;
+  new_wpi->next_ = NULL;
+
+  if (*wpi_list != NULL) {
+    (*wpi_list)->next_ = new_wpi;
+  } else {
   *wpi_list = new_wpi;
+  }
   return WEBP_MUX_OK;
 }
 

src/mux/muxread.c

@@ -151,7 +151,7 @@ WebPMux* WebPMuxCreateInternal(const WebPData* const bitstream, int copy_data,
       if (id == WEBP_CHUNK_IMAGE) {
         wpi->is_partial_ = 0;  // wpi is completely filled.
         // Add this to mux->images_ list.
-        if (MuxImageSetNth(wpi, &mux->images_, 0) != WEBP_MUX_OK) goto Err;
+        if (MuxImagePush(wpi, &mux->images_) != WEBP_MUX_OK) goto Err;
         MuxImageInit(wpi);  // Reset for reading next image.
       } else {
         wpi->is_partial_ = 1;  // wpi is only partially filled.

src/webp/mux.h

@@ -267,11 +267,9 @@ WEBP_EXTERN(WebPMuxError) WebPMuxDeleteColorProfile(WebPMux* const mux);
 //------------------------------------------------------------------------------
 // Animation.
 
-// Adds an animation frame to the mux object.
+// Adds an animation frame at the end of the mux object.
-// nth=0 has a special meaning - last position.
 // Parameters:
 //   mux - (in/out) object to which an animation frame is to be added
-//   nth - (in) The position at which the frame is to be added.
 //   bitstream - (in) the image data corresponding to the frame. It can either
 //               be a raw VP8/VP8L bitstream or a single-image WebP file
 //               (non-animated and non-tiled)
@@ -282,17 +280,15 @@ WEBP_EXTERN(WebPMuxError) WebPMuxDeleteColorProfile(WebPMux* const mux);
 //               value 0 indicates data will NOT be copied.
 // Returns:
 //   WEBP_MUX_INVALID_ARGUMENT - if mux is NULL or bitstream is NULL
-//   WEBP_MUX_NOT_FOUND - If we have less than (nth-1) frames before adding.
 //   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
 //   WEBP_MUX_OK - on success.
-WEBP_EXTERN(WebPMuxError) WebPMuxSetFrame(
+WEBP_EXTERN(WebPMuxError) WebPMuxPushFrame(
-    WebPMux* const mux, uint32_t nth, const WebPData* const bitstream,
+    WebPMux* const mux, const WebPData* const bitstream,
     uint32_t x_offset, uint32_t y_offset, uint32_t duration,
     int copy_data);
 
 // TODO(urvang): Create a struct as follows to reduce argument list size:
 // typedef struct {
-//  int nth;
 //  WebPData image;
 //  WebPData alpha;
 //  uint32_t x_offset, y_offset;
@@ -360,11 +356,9 @@ WEBP_EXTERN(WebPMuxError) WebPMuxGetLoopCount(const WebPMux* const mux,
 //------------------------------------------------------------------------------
 // Tiling.
 
-// Adds a tile to the mux object.
+// Adds a tile at the end of the mux object.
-// nth=0 has a special meaning - last position.
 // Parameters:
-//   mux - (in/out) object to which a tile is to be added
+//   mux - (in/out) object to which a tile is to be added.
-//   nth - (in) The position at which the tile is to be added.
 //   bitstream - (in) the image data corresponding to the frame. It can either
 //               be a raw VP8/VP8L bitstream or a single-image WebP file
 //               (non-animated and non-tiled)
@@ -374,11 +368,10 @@ WEBP_EXTERN(WebPMuxError) WebPMuxGetLoopCount(const WebPMux* const mux,
 //               value 0 indicates data will NOT be copied.
 // Returns:
 //   WEBP_MUX_INVALID_ARGUMENT - if mux is NULL or bitstream is NULL
-//   WEBP_MUX_NOT_FOUND - If we have less than (nth-1) tiles before adding.
 //   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
 //   WEBP_MUX_OK - on success.
-WEBP_EXTERN(WebPMuxError) WebPMuxSetTile(
+WEBP_EXTERN(WebPMuxError) WebPMuxPushTile(
-    WebPMux* const mux, uint32_t nth, const WebPData* const bitstream,
+    WebPMux* const mux, const WebPData* const bitstream,
     uint32_t x_offset, uint32_t y_offset, int copy_data);
 
 // Gets the nth tile from the mux object.