3rdparty/libwebp/mux/muxedit.c

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This source file includes following definitions.
MuxInit
WebPNewInternal
DeleteAllChunks
MuxRelease
WebPMuxDelete
MuxSet
MuxAddChunk
CreateFrameFragmentData
GetImageData
DeleteChunks
MuxDeleteAllNamedData
WebPMuxSetChunk
AddDataToChunkList
SetAlphaAndImageChunks
WebPMuxSetImage
WebPMuxPushFrame
WebPMuxSetAnimationParams
WebPMuxDeleteChunk
WebPMuxDeleteFrame
GetFrameFragmentInfo
MuxGetImageWidthHeight
GetImageInfo
GetImageCanvasWidthHeight
CreateVP8XChunk
MuxCleanup
WebPMuxAssemble
// Copyright 2011 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// Set and delete APIs for mux.
//
// Authors: Urvang (urvang@google.com)
//          Vikas (vikasa@google.com)

#include <assert.h>
#include "./muxi.h"
#include "../utils/utils.h"

#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif

//------------------------------------------------------------------------------
// Life of a mux object.

static void MuxInit(WebPMux* const mux) {
  if (mux == NULL) return;
  memset(mux, 0, sizeof(*mux));
}

WebPMux* WebPNewInternal(int version) {
  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_MUX_ABI_VERSION)) {
    return NULL;
  } else {
    WebPMux* const mux = (WebPMux*)malloc(sizeof(WebPMux));
    // If mux is NULL MuxInit is a noop.
    MuxInit(mux);
    return mux;
  }
}

static void DeleteAllChunks(WebPChunk** const chunk_list) {
  while (*chunk_list) {
    *chunk_list = ChunkDelete(*chunk_list);
  }
}

static void MuxRelease(WebPMux* const mux) {
  if (mux == NULL) return;
  MuxImageDeleteAll(&mux->images_);
  DeleteAllChunks(&mux->vp8x_);
  DeleteAllChunks(&mux->iccp_);
  DeleteAllChunks(&mux->anim_);
  DeleteAllChunks(&mux->exif_);
  DeleteAllChunks(&mux->xmp_);
  DeleteAllChunks(&mux->unknown_);
}

void WebPMuxDelete(WebPMux* mux) {
  // If mux is NULL MuxRelease is a noop.
  MuxRelease(mux);
  free(mux);
}

//------------------------------------------------------------------------------
// Helper method(s).

// Handy MACRO, makes MuxSet() very symmetric to MuxGet().
#define SWITCH_ID_LIST(INDEX, LIST)                                            \
  if (idx == (INDEX)) {                                                        \
    err = ChunkAssignData(&chunk, data, copy_data, kChunks[(INDEX)].tag);      \
    if (err == WEBP_MUX_OK) {                                                  \
      err = ChunkSetNth(&chunk, (LIST), nth);                                  \
    }                                                                          \
    return err;                                                                \
  }

static WebPMuxError MuxSet(WebPMux* const mux, CHUNK_INDEX idx, uint32_t nth,
                           const WebPData* const data, int copy_data) {
  WebPChunk chunk;
  WebPMuxError err = WEBP_MUX_NOT_FOUND;
  assert(mux != NULL);
  assert(!IsWPI(kChunks[idx].id));

  ChunkInit(&chunk);
  SWITCH_ID_LIST(IDX_VP8X, &mux->vp8x_);
  SWITCH_ID_LIST(IDX_ICCP, &mux->iccp_);
  SWITCH_ID_LIST(IDX_ANIM, &mux->anim_);
  SWITCH_ID_LIST(IDX_EXIF, &mux->exif_);
  SWITCH_ID_LIST(IDX_XMP,  &mux->xmp_);
  if (idx == IDX_UNKNOWN && data->size > TAG_SIZE) {
    // For raw-data unknown chunk, the first four bytes should be the tag to be
    // used for the chunk.
    const WebPData tmp = { data->bytes + TAG_SIZE, data->size - TAG_SIZE };
    err = ChunkAssignData(&chunk, &tmp, copy_data, GetLE32(data->bytes + 0));
    if (err == WEBP_MUX_OK)
      err = ChunkSetNth(&chunk, &mux->unknown_, nth);
  }
  return err;
}
#undef SWITCH_ID_LIST

static WebPMuxError MuxAddChunk(WebPMux* const mux, uint32_t nth, uint32_t tag,
                                const uint8_t* data, size_t size,
                                int copy_data) {
  const CHUNK_INDEX idx = ChunkGetIndexFromTag(tag);
  const WebPData chunk_data = { data, size };
  assert(mux != NULL);
  assert(size <= MAX_CHUNK_PAYLOAD);
  assert(idx != IDX_NIL);
  return MuxSet(mux, idx, nth, &chunk_data, copy_data);
}

// Create data for frame/fragment given image data, offsets and duration.
static WebPMuxError CreateFrameFragmentData(
    const WebPData* const image, int x_offset, int y_offset, int duration,
    WebPMuxAnimDispose dispose_method, int is_lossless, int is_frame,
    WebPData* const frame_frgm) {
  int width;
  int height;
  uint8_t* frame_frgm_bytes;
  const size_t frame_frgm_size = kChunks[is_frame ? IDX_ANMF : IDX_FRGM].size;

  const int ok = is_lossless ?
      VP8LGetInfo(image->bytes, image->size, &width, &height, NULL) :
      VP8GetInfo(image->bytes, image->size, image->size, &width, &height);
  if (!ok) return WEBP_MUX_INVALID_ARGUMENT;

  assert(width > 0 && height > 0 && duration >= 0);
  assert(dispose_method == (dispose_method & 1));
  // Note: assertion on upper bounds is done in PutLE24().

  frame_frgm_bytes = (uint8_t*)malloc(frame_frgm_size);
  if (frame_frgm_bytes == NULL) return WEBP_MUX_MEMORY_ERROR;

  PutLE24(frame_frgm_bytes + 0, x_offset / 2);
  PutLE24(frame_frgm_bytes + 3, y_offset / 2);

  if (is_frame) {
    PutLE24(frame_frgm_bytes + 6, width - 1);
    PutLE24(frame_frgm_bytes + 9, height - 1);
    PutLE24(frame_frgm_bytes + 12, duration);
    frame_frgm_bytes[15] = (dispose_method & 1);
  }

  frame_frgm->bytes = frame_frgm_bytes;
  frame_frgm->size = frame_frgm_size;
  return WEBP_MUX_OK;
}

// Outputs image data given a bitstream. The bitstream can either be a
// single-image WebP file or raw VP8/VP8L data.
// Also outputs 'is_lossless' to be true if the given bitstream is lossless.
static WebPMuxError GetImageData(const WebPData* const bitstream,
                                 WebPData* const image, WebPData* const alpha,
                                 int* const is_lossless) {
  WebPDataInit(alpha);  // Default: no alpha.
  if (bitstream->size < TAG_SIZE ||
      memcmp(bitstream->bytes, "RIFF", TAG_SIZE)) {
    // It is NOT webp file data. Return input data as is.
    *image = *bitstream;
  } else {
    // It is webp file data. Extract image data from it.
    const WebPMuxImage* wpi;
    WebPMux* const mux = WebPMuxCreate(bitstream, 0);
    if (mux == NULL) return WEBP_MUX_BAD_DATA;
    wpi = mux->images_;
    assert(wpi != NULL && wpi->img_ != NULL);
    *image = wpi->img_->data_;
    if (wpi->alpha_ != NULL) {
      *alpha = wpi->alpha_->data_;
    }
    WebPMuxDelete(mux);
  }
  *is_lossless = VP8LCheckSignature(image->bytes, image->size);
  return WEBP_MUX_OK;
}

static WebPMuxError DeleteChunks(WebPChunk** chunk_list, uint32_t tag) {
  WebPMuxError err = WEBP_MUX_NOT_FOUND;
  assert(chunk_list);
  while (*chunk_list) {
    WebPChunk* const chunk = *chunk_list;
    if (chunk->tag_ == tag) {
      *chunk_list = ChunkDelete(chunk);
      err = WEBP_MUX_OK;
    } else {
      chunk_list = &chunk->next_;
    }
  }
  return err;
}

static WebPMuxError MuxDeleteAllNamedData(WebPMux* const mux, uint32_t tag) {
  const WebPChunkId id = ChunkGetIdFromTag(tag);
  WebPChunk** chunk_list;

  assert(mux != NULL);
  if (IsWPI(id)) return WEBP_MUX_INVALID_ARGUMENT;

  chunk_list = MuxGetChunkListFromId(mux, id);
  if (chunk_list == NULL) return WEBP_MUX_INVALID_ARGUMENT;

  return DeleteChunks(chunk_list, tag);
}

//------------------------------------------------------------------------------
// Set API(s).

WebPMuxError WebPMuxSetChunk(WebPMux* mux, const char fourcc[4],
                             const WebPData* chunk_data, int copy_data) {
  CHUNK_INDEX idx;
  uint32_t tag;
  WebPMuxError err;
  if (mux == NULL || fourcc == NULL || chunk_data == NULL ||
      chunk_data->bytes == NULL || chunk_data->size > MAX_CHUNK_PAYLOAD) {
    return WEBP_MUX_INVALID_ARGUMENT;
  }
  idx = ChunkGetIndexFromFourCC(fourcc);
  tag = ChunkGetTagFromFourCC(fourcc);

  // Delete existing chunk(s) with the same 'fourcc'.
  err = MuxDeleteAllNamedData(mux, tag);
  if (err != WEBP_MUX_OK && err != WEBP_MUX_NOT_FOUND) return err;

  // Add the given chunk.
  return MuxSet(mux, idx, 1, chunk_data, copy_data);
}

// Creates a chunk from given 'data' and sets it as 1st chunk in 'chunk_list'.
static WebPMuxError AddDataToChunkList(
    const WebPData* const data, int copy_data, uint32_t tag,
    WebPChunk** chunk_list) {
  WebPChunk chunk;
  WebPMuxError err;
  ChunkInit(&chunk);
  err = ChunkAssignData(&chunk, data, copy_data, tag);
  if (err != WEBP_MUX_OK) goto Err;
  err = ChunkSetNth(&chunk, chunk_list, 1);
  if (err != WEBP_MUX_OK) goto Err;
  return WEBP_MUX_OK;
 Err:
  ChunkRelease(&chunk);
  return err;
}

// Extracts image & alpha data from the given bitstream and then sets wpi.alpha_
// and wpi.img_ appropriately.
static WebPMuxError SetAlphaAndImageChunks(
    const WebPData* const bitstream, int copy_data, WebPMuxImage* const wpi) {
  int is_lossless = 0;
  WebPData image, alpha;
  WebPMuxError err = GetImageData(bitstream, &image, &alpha, &is_lossless);
  const int image_tag =
      is_lossless ? kChunks[IDX_VP8L].tag : kChunks[IDX_VP8].tag;
  if (err != WEBP_MUX_OK) return err;
  if (alpha.bytes != NULL) {
    err = AddDataToChunkList(&alpha, copy_data, kChunks[IDX_ALPHA].tag,
                             &wpi->alpha_);
    if (err != WEBP_MUX_OK) return err;
  }
  return AddDataToChunkList(&image, copy_data, image_tag, &wpi->img_);
}

WebPMuxError WebPMuxSetImage(WebPMux* mux, const WebPData* bitstream,
                             int copy_data) {
  WebPMuxImage wpi;
  WebPMuxError err;

  // Sanity checks.
  if (mux == NULL || bitstream == NULL || bitstream->bytes == NULL ||
      bitstream->size > MAX_CHUNK_PAYLOAD) {
    return WEBP_MUX_INVALID_ARGUMENT;
  }

  if (mux->images_ != NULL) {
    // Only one 'simple image' can be added in mux. So, remove present images.
    MuxImageDeleteAll(&mux->images_);
  }

  MuxImageInit(&wpi);
  err = SetAlphaAndImageChunks(bitstream, copy_data, &wpi);
  if (err != WEBP_MUX_OK) goto Err;

  // Add this WebPMuxImage to mux.
  err = MuxImagePush(&wpi, &mux->images_);
  if (err != WEBP_MUX_OK) goto Err;

  // All is well.
  return WEBP_MUX_OK;

 Err:  // Something bad happened.
  MuxImageRelease(&wpi);
  return err;
}

WebPMuxError WebPMuxPushFrame(WebPMux* mux, const WebPMuxFrameInfo* frame,
                              int copy_data) {
  WebPMuxImage wpi;
  WebPMuxError err;
  int is_frame;
  const WebPData* const bitstream = &frame->bitstream;

  // Sanity checks.
  if (mux == NULL || frame == NULL) return WEBP_MUX_INVALID_ARGUMENT;

  is_frame = (frame->id == WEBP_CHUNK_ANMF);
  if (!(is_frame || (frame->id == WEBP_CHUNK_FRGM))) {
    return WEBP_MUX_INVALID_ARGUMENT;
  }
#ifndef WEBP_EXPERIMENTAL_FEATURES
  if (frame->id == WEBP_CHUNK_FRGM) {     // disabled for now.
    return WEBP_MUX_INVALID_ARGUMENT;
  }
#endif

  if (bitstream->bytes == NULL || bitstream->size > MAX_CHUNK_PAYLOAD) {
    return WEBP_MUX_INVALID_ARGUMENT;
  }

  if (mux->images_ != NULL) {
    const WebPMuxImage* const image = mux->images_;
    const uint32_t image_id = (image->header_ != NULL) ?
        ChunkGetIdFromTag(image->header_->tag_) : WEBP_CHUNK_IMAGE;
    if (image_id != frame->id) {
      return WEBP_MUX_INVALID_ARGUMENT;  // Conflicting frame types.
    }
  }

  MuxImageInit(&wpi);
  err = SetAlphaAndImageChunks(bitstream, copy_data, &wpi);
  if (err != WEBP_MUX_OK) goto Err;
  assert(wpi.img_ != NULL);  // As SetAlphaAndImageChunks() was successful.

  {
    const int is_lossless = (wpi.img_->tag_ == kChunks[IDX_VP8L].tag);
    const int x_offset = frame->x_offset & ~1;  // Snap offsets to even.
    const int y_offset = frame->y_offset & ~1;
    const int duration = is_frame ? frame->duration : 1 /* unused */;
    const WebPMuxAnimDispose dispose_method =
        is_frame ? frame->dispose_method : 0 /* unused */;
    const uint32_t tag = kChunks[is_frame ? IDX_ANMF : IDX_FRGM].tag;
    WebPData frame_frgm;
    if (x_offset < 0 || x_offset >= MAX_POSITION_OFFSET ||
        y_offset < 0 || y_offset >= MAX_POSITION_OFFSET ||
        (duration < 0 || duration >= MAX_DURATION) ||
        dispose_method != (dispose_method & 1)) {
      err = WEBP_MUX_INVALID_ARGUMENT;
      goto Err;
    }
    err = CreateFrameFragmentData(&wpi.img_->data_, x_offset, y_offset,
                                  duration, dispose_method, is_lossless,
                                  is_frame, &frame_frgm);
    if (err != WEBP_MUX_OK) goto Err;
    // Add frame/fragment chunk (with copy_data = 1).
    err = AddDataToChunkList(&frame_frgm, 1, tag, &wpi.header_);
    WebPDataClear(&frame_frgm);  // frame_frgm owned by wpi.header_ now.
    if (err != WEBP_MUX_OK) goto Err;
  }

  // Add this WebPMuxImage to mux.
  err = MuxImagePush(&wpi, &mux->images_);
  if (err != WEBP_MUX_OK) goto Err;

  // All is well.
  return WEBP_MUX_OK;

 Err:  // Something bad happened.
  MuxImageRelease(&wpi);
  return err;
}

WebPMuxError WebPMuxSetAnimationParams(WebPMux* mux,
                                       const WebPMuxAnimParams* params) {
  WebPMuxError err;
  uint8_t data[ANIM_CHUNK_SIZE];

  if (mux == NULL || params == NULL) return WEBP_MUX_INVALID_ARGUMENT;
  if (params->loop_count < 0 || params->loop_count >= MAX_LOOP_COUNT) {
    return WEBP_MUX_INVALID_ARGUMENT;
  }

  // Delete any existing ANIM chunk(s).
  err = MuxDeleteAllNamedData(mux, kChunks[IDX_ANIM].tag);
  if (err != WEBP_MUX_OK && err != WEBP_MUX_NOT_FOUND) return err;

  // Set the animation parameters.
  PutLE32(data, params->bgcolor);
  PutLE16(data + 4, params->loop_count);
  return MuxAddChunk(mux, 1, kChunks[IDX_ANIM].tag, data, sizeof(data), 1);
}

//------------------------------------------------------------------------------
// Delete API(s).

WebPMuxError WebPMuxDeleteChunk(WebPMux* mux, const char fourcc[4]) {
  if (mux == NULL || fourcc == NULL) return WEBP_MUX_INVALID_ARGUMENT;
  return MuxDeleteAllNamedData(mux, ChunkGetTagFromFourCC(fourcc));
}

WebPMuxError WebPMuxDeleteFrame(WebPMux* mux, uint32_t nth) {
  if (mux == NULL) return WEBP_MUX_INVALID_ARGUMENT;
  return MuxImageDeleteNth(&mux->images_, nth);
}

//------------------------------------------------------------------------------
// Assembly of the WebP RIFF file.

static WebPMuxError GetFrameFragmentInfo(
    const WebPChunk* const frame_frgm_chunk,
    int* const x_offset, int* const y_offset, int* const duration) {
  const uint32_t tag = frame_frgm_chunk->tag_;
  const int is_frame = (tag == kChunks[IDX_ANMF].tag);
  const WebPData* const data = &frame_frgm_chunk->data_;
  const size_t expected_data_size =
      is_frame ? ANMF_CHUNK_SIZE : FRGM_CHUNK_SIZE;
  assert(frame_frgm_chunk != NULL);
  assert(tag == kChunks[IDX_ANMF].tag || tag ==  kChunks[IDX_FRGM].tag);
  if (data->size != expected_data_size) return WEBP_MUX_INVALID_ARGUMENT;

  *x_offset = 2 * GetLE24(data->bytes + 0);
  *y_offset = 2 * GetLE24(data->bytes + 3);
  if (is_frame) *duration = GetLE24(data->bytes + 12);
  return WEBP_MUX_OK;
}

WebPMuxError MuxGetImageWidthHeight(const WebPChunk* const image_chunk,
                                    int* const width, int* const height) {
  const uint32_t tag = image_chunk->tag_;
  const WebPData* const data = &image_chunk->data_;
  int w, h;
  int ok;
  assert(image_chunk != NULL);
  assert(tag == kChunks[IDX_VP8].tag || tag ==  kChunks[IDX_VP8L].tag);
  ok = (tag == kChunks[IDX_VP8].tag) ?
      VP8GetInfo(data->bytes, data->size, data->size, &w, &h) :
      VP8LGetInfo(data->bytes, data->size, &w, &h, NULL);
  if (ok) {
    *width = w;
    *height = h;
    return WEBP_MUX_OK;
  } else {
    return WEBP_MUX_BAD_DATA;
  }
}

static WebPMuxError GetImageInfo(const WebPMuxImage* const wpi,
                                 int* const x_offset, int* const y_offset,
                                 int* const duration,
                                 int* const width, int* const height) {
  const WebPChunk* const image_chunk = wpi->img_;
  const WebPChunk* const frame_frgm_chunk = wpi->header_;

  // Get offsets and duration from ANMF/FRGM chunk.
  const WebPMuxError err =
      GetFrameFragmentInfo(frame_frgm_chunk, x_offset, y_offset, duration);
  if (err != WEBP_MUX_OK) return err;

  // Get width and height from VP8/VP8L chunk.
  return MuxGetImageWidthHeight(image_chunk, width, height);
}

static WebPMuxError GetImageCanvasWidthHeight(
    const WebPMux* const mux, uint32_t flags,
    int* const width, int* const height) {
  WebPMuxImage* wpi = NULL;
  assert(mux != NULL);
  assert(width != NULL && height != NULL);

  wpi = mux->images_;
  assert(wpi != NULL);
  assert(wpi->img_ != NULL);

  if (wpi->next_) {
    int max_x = 0;
    int max_y = 0;
    int64_t image_area = 0;
    // Aggregate the bounding box for animation frames & fragmented images.
    for (; wpi != NULL; wpi = wpi->next_) {
      int x_offset = 0, y_offset = 0, duration = 0, w = 0, h = 0;
      const WebPMuxError err = GetImageInfo(wpi, &x_offset, &y_offset,
                                            &duration, &w, &h);
      const int max_x_pos = x_offset + w;
      const int max_y_pos = y_offset + h;
      if (err != WEBP_MUX_OK) return err;
      assert(x_offset < MAX_POSITION_OFFSET);
      assert(y_offset < MAX_POSITION_OFFSET);

      if (max_x_pos > max_x) max_x = max_x_pos;
      if (max_y_pos > max_y) max_y = max_y_pos;
      image_area += w * h;
    }
    *width = max_x;
    *height = max_y;
    // Crude check to validate that there are no image overlaps/holes for
    // fragmented images. Check that the aggregated image area for individual
    // fragments exactly matches the image area of the constructed canvas.
    // However, the area-match is necessary but not sufficient condition.
    if ((flags & FRAGMENTS_FLAG) && (image_area != (max_x * max_y))) {
      *width = 0;
      *height = 0;
      return WEBP_MUX_INVALID_ARGUMENT;
    }
  } else {
    // For a single image, extract the width & height from VP8/VP8L image-data.
    int w, h;
    const WebPChunk* const image_chunk = wpi->img_;
    const WebPMuxError err = MuxGetImageWidthHeight(image_chunk, &w, &h);
    if (err != WEBP_MUX_OK) return err;
    *width = w;
    *height = h;
  }
  return WEBP_MUX_OK;
}

// VP8X format:
// Total Size : 10,
// Flags  : 4 bytes,
// Width  : 3 bytes,
// Height : 3 bytes.
static WebPMuxError CreateVP8XChunk(WebPMux* const mux) {
  WebPMuxError err = WEBP_MUX_OK;
  uint32_t flags = 0;
  int width = 0;
  int height = 0;
  uint8_t data[VP8X_CHUNK_SIZE];
  const size_t data_size = VP8X_CHUNK_SIZE;
  const WebPMuxImage* images = NULL;

  assert(mux != NULL);
  images = mux->images_;  // First image.
  if (images == NULL || images->img_ == NULL ||
      images->img_->data_.bytes == NULL) {
    return WEBP_MUX_INVALID_ARGUMENT;
  }

  // If VP8X chunk(s) is(are) already present, remove them (and later add new
  // VP8X chunk with updated flags).
  err = MuxDeleteAllNamedData(mux, kChunks[IDX_VP8X].tag);
  if (err != WEBP_MUX_OK && err != WEBP_MUX_NOT_FOUND) return err;

  // Set flags.
  if (mux->iccp_ != NULL && mux->iccp_->data_.bytes != NULL) {
    flags |= ICCP_FLAG;
  }
  if (mux->exif_ != NULL && mux->exif_->data_.bytes != NULL) {
    flags |= EXIF_FLAG;
  }
  if (mux->xmp_ != NULL && mux->xmp_->data_.bytes != NULL) {
    flags |= XMP_FLAG;
  }
  if (images->header_ != NULL) {
    if (images->header_->tag_ == kChunks[IDX_FRGM].tag) {
      // This is a fragmented image.
      flags |= FRAGMENTS_FLAG;
    } else if (images->header_->tag_ == kChunks[IDX_ANMF].tag) {
      // This is an image with animation.
      flags |= ANIMATION_FLAG;
    }
  }
  if (MuxImageCount(images, WEBP_CHUNK_ALPHA) > 0) {
    flags |= ALPHA_FLAG;  // Some images have an alpha channel.
  }

  if (flags == 0) {
    // For Simple Image, VP8X chunk should not be added.
    return WEBP_MUX_OK;
  }

  err = GetImageCanvasWidthHeight(mux, flags, &width, &height);
  if (err != WEBP_MUX_OK) return err;

  if (width <= 0 || height <= 0) {
    return WEBP_MUX_INVALID_ARGUMENT;
  }
  if (width > MAX_CANVAS_SIZE || height > MAX_CANVAS_SIZE) {
    return WEBP_MUX_INVALID_ARGUMENT;
  }

  if (MuxHasLosslessImages(images)) {
    // We have a file with a VP8X chunk having some lossless images.
    // As lossless images implicitly contain alpha, force ALPHA_FLAG to be true.
    // Note: This 'flags' update must NOT be done for a lossless image
    // without a VP8X chunk!
    flags |= ALPHA_FLAG;
  }

  PutLE32(data + 0, flags);   // VP8X chunk flags.
  PutLE24(data + 4, width - 1);   // canvas width.
  PutLE24(data + 7, height - 1);  // canvas height.

  err = MuxAddChunk(mux, 1, kChunks[IDX_VP8X].tag, data, data_size, 1);
  return err;
}

// Cleans up 'mux' by removing any unnecessary chunks.
static WebPMuxError MuxCleanup(WebPMux* const mux) {
  int num_frames;
  int num_fragments;
  int num_anim_chunks;

  // If we have an image with single fragment or frame, convert it to a
  // non-animated non-fragmented image (to avoid writing FRGM/ANMF chunk
  // unnecessarily).
  WebPMuxError err = WebPMuxNumChunks(mux, kChunks[IDX_ANMF].id, &num_frames);
  if (err != WEBP_MUX_OK) return err;
  err = WebPMuxNumChunks(mux, kChunks[IDX_FRGM].id, &num_fragments);
  if (err != WEBP_MUX_OK) return err;
  if (num_frames == 1 || num_fragments == 1) {
    WebPMuxImage* frame_frag;
    err = MuxImageGetNth((const WebPMuxImage**)&mux->images_, 1, &frame_frag);
    assert(err == WEBP_MUX_OK);  // We know that one frame/fragment does exist.
    if (frame_frag->header_ != NULL) {
      assert(frame_frag->header_->tag_ == kChunks[IDX_ANMF].tag ||
             frame_frag->header_->tag_ == kChunks[IDX_FRGM].tag);
      ChunkDelete(frame_frag->header_);  // Removes ANMF/FRGM chunk.
      frame_frag->header_ = NULL;
    }
    num_frames = 0;
    num_fragments = 0;
  }
  // Remove ANIM chunk if this is a non-animated image.
  err = WebPMuxNumChunks(mux, kChunks[IDX_ANIM].id, &num_anim_chunks);
  if (err != WEBP_MUX_OK) return err;
  if (num_anim_chunks >= 1 && num_frames == 0) {
    err = MuxDeleteAllNamedData(mux, kChunks[IDX_ANIM].tag);
    if (err != WEBP_MUX_OK) return err;
  }
  return WEBP_MUX_OK;
}

WebPMuxError WebPMuxAssemble(WebPMux* mux, WebPData* assembled_data) {
  size_t size = 0;
  uint8_t* data = NULL;
  uint8_t* dst = NULL;
  WebPMuxError err;

  if (mux == NULL || assembled_data == NULL) {
    return WEBP_MUX_INVALID_ARGUMENT;
  }

  // Finalize mux.
  err = MuxCleanup(mux);
  if (err != WEBP_MUX_OK) return err;
  err = CreateVP8XChunk(mux);
  if (err != WEBP_MUX_OK) return err;

  // Allocate data.
  size = ChunksListDiskSize(mux->vp8x_) + ChunksListDiskSize(mux->iccp_)
       + ChunksListDiskSize(mux->anim_) + MuxImageListDiskSize(mux->images_)
       + ChunksListDiskSize(mux->exif_) + ChunksListDiskSize(mux->xmp_)
       + ChunksListDiskSize(mux->unknown_) + RIFF_HEADER_SIZE;

  data = (uint8_t*)malloc(size);
  if (data == NULL) return WEBP_MUX_MEMORY_ERROR;

  // Emit header & chunks.
  dst = MuxEmitRiffHeader(data, size);
  dst = ChunkListEmit(mux->vp8x_, dst);
  dst = ChunkListEmit(mux->iccp_, dst);
  dst = ChunkListEmit(mux->anim_, dst);
  dst = MuxImageListEmit(mux->images_, dst);
  dst = ChunkListEmit(mux->exif_, dst);
  dst = ChunkListEmit(mux->xmp_, dst);
  dst = ChunkListEmit(mux->unknown_, dst);
  assert(dst == data + size);

  // Validate mux.
  err = MuxValidate(mux);
  if (err != WEBP_MUX_OK) {
    free(data);
    data = NULL;
    size = 0;
  }

  // Finalize data.
  assembled_data->bytes = data;
  assembled_data->size = size;

  return err;
}

//------------------------------------------------------------------------------

#if defined(__cplusplus) || defined(c_plusplus)
}    // extern "C"
#endif
/* [<][>][^][v][top][bottom][index][help] */
root/3rdparty/libwebp/mux/muxedit.c

DEFINITIONS
