root/3rdparty/libwebp/dec/webp.c

DEFINITIONS

1. get_le24
2. get_le32
3. ParseRIFF
4. ParseVP8X
5. ParseOptionalChunks
6. ParseVP8Header
7. ParseHeadersInternal
8. WebPParseHeaders
9. WebPResetDecParams
10. DecodeInto
11. DecodeIntoRGBABuffer
12. WebPDecodeRGBInto
13. WebPDecodeRGBAInto
14. WebPDecodeARGBInto
15. WebPDecodeBGRInto
16. WebPDecodeBGRAInto
17. WebPDecodeYUVInto
18. Decode
19. WebPDecodeRGB
20. WebPDecodeRGBA
21. WebPDecodeARGB
22. WebPDecodeBGR
23. WebPDecodeBGRA
24. WebPDecodeYUV
25. DefaultFeatures
26. GetFeatures
27. WebPGetInfo
28. WebPInitDecoderConfigInternal
29. WebPGetFeaturesInternal
30. WebPDecode
31. WebPIoInitFromOptions

// Copyright 2010 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.
// -----------------------------------------------------------------------------
//
// Main decoding functions for WEBP images.
//
// Author: Skal (pascal.massimino@gmail.com)

#include <stdlib.h>

#include "./vp8i.h"
#include "./vp8li.h"
#include "./webpi.h"
#include "../webp/mux_types.h"  // ALPHA_FLAG

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

//------------------------------------------------------------------------------
// RIFF layout is:
//   Offset  tag
//   0...3   "RIFF" 4-byte tag
//   4...7   size of image data (including metadata) starting at offset 8
//   8...11  "WEBP"   our form-type signature
// The RIFF container (12 bytes) is followed by appropriate chunks:
//   12..15  "VP8 ": 4-bytes tags, signaling the use of VP8 video format
//   16..19  size of the raw VP8 image data, starting at offset 20
//   20....  the VP8 bytes
// Or,
//   12..15  "VP8L": 4-bytes tags, signaling the use of VP8L lossless format
//   16..19  size of the raw VP8L image data, starting at offset 20
//   20....  the VP8L bytes
// Or,
//   12..15  "VP8X": 4-bytes tags, describing the extended-VP8 chunk.
//   16..19  size of the VP8X chunk starting at offset 20.
//   20..23  VP8X flags bit-map corresponding to the chunk-types present.
//   24..26  Width of the Canvas Image.
//   27..29  Height of the Canvas Image.
// There can be extra chunks after the "VP8X" chunk (ICCP, FRGM, ANMF, VP8,
// VP8L, XMP, EXIF  ...)
// All sizes are in little-endian order.
// Note: chunk data size must be padded to multiple of 2 when written.

static WEBP_INLINE uint32_t get_le24(const uint8_t* const data) {
  return data[0] | (data[1] << 8) | (data[2] << 16);
}

static WEBP_INLINE uint32_t get_le32(const uint8_t* const data) {
  return (uint32_t)get_le24(data) | (data[3] << 24);
}

// Validates the RIFF container (if detected) and skips over it.
// If a RIFF container is detected,
// Returns VP8_STATUS_BITSTREAM_ERROR for invalid header, and
//         VP8_STATUS_OK otherwise.
// In case there are not enough bytes (partial RIFF container), return 0 for
// *riff_size. Else return the RIFF size extracted from the header.
static VP8StatusCode ParseRIFF(const uint8_t** const data,
                               size_t* const data_size,
                               size_t* const riff_size) {
  assert(data != NULL);
  assert(data_size != NULL);
  assert(riff_size != NULL);

  *riff_size = 0;  // Default: no RIFF present.
  if (*data_size >= RIFF_HEADER_SIZE && !memcmp(*data, "RIFF", TAG_SIZE)) {
    if (memcmp(*data + 8, "WEBP", TAG_SIZE)) {
      return VP8_STATUS_BITSTREAM_ERROR;  // Wrong image file signature.
    } else {
      const uint32_t size = get_le32(*data + TAG_SIZE);
      // Check that we have at least one chunk (i.e "WEBP" + "VP8?nnnn").
      if (size < TAG_SIZE + CHUNK_HEADER_SIZE) {
        return VP8_STATUS_BITSTREAM_ERROR;
      }
      if (size > MAX_CHUNK_PAYLOAD) {
        return VP8_STATUS_BITSTREAM_ERROR;
      }
      // We have a RIFF container. Skip it.
      *riff_size = size;
      *data += RIFF_HEADER_SIZE;
      *data_size -= RIFF_HEADER_SIZE;
    }
  }
  return VP8_STATUS_OK;
}

// Validates the VP8X header and skips over it.
// Returns VP8_STATUS_BITSTREAM_ERROR for invalid VP8X header,
//         VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
//         VP8_STATUS_OK otherwise.
// If a VP8X chunk is found, found_vp8x is set to true and *width_ptr,
// *height_ptr and *flags_ptr are set to the corresponding values extracted
// from the VP8X chunk.
static VP8StatusCode ParseVP8X(const uint8_t** const data,
                               size_t* const data_size,
                               int* const found_vp8x,
                               int* const width_ptr, int* const height_ptr,
                               uint32_t* const flags_ptr) {
  const uint32_t vp8x_size = CHUNK_HEADER_SIZE + VP8X_CHUNK_SIZE;
  assert(data != NULL);
  assert(data_size != NULL);
  assert(found_vp8x != NULL);

  *found_vp8x = 0;

  if (*data_size < CHUNK_HEADER_SIZE) {
    return VP8_STATUS_NOT_ENOUGH_DATA;  // Insufficient data.
  }

  if (!memcmp(*data, "VP8X", TAG_SIZE)) {
    int width, height;
    uint32_t flags;
    const uint32_t chunk_size = get_le32(*data + TAG_SIZE);
    if (chunk_size != VP8X_CHUNK_SIZE) {
      return VP8_STATUS_BITSTREAM_ERROR;  // Wrong chunk size.
    }

    // Verify if enough data is available to validate the VP8X chunk.
    if (*data_size < vp8x_size) {
      return VP8_STATUS_NOT_ENOUGH_DATA;  // Insufficient data.
    }
    flags = get_le32(*data + 8);
    width = 1 + get_le24(*data + 12);
    height = 1 + get_le24(*data + 15);
    if (width * (uint64_t)height >= MAX_IMAGE_AREA) {
      return VP8_STATUS_BITSTREAM_ERROR;  // image is too large
    }

    if (flags_ptr != NULL) *flags_ptr = flags;
    if (width_ptr != NULL) *width_ptr = width;
    if (height_ptr != NULL) *height_ptr = height;
    // Skip over VP8X header bytes.
    *data += vp8x_size;
    *data_size -= vp8x_size;
    *found_vp8x = 1;
  }
  return VP8_STATUS_OK;
}

// Skips to the next VP8/VP8L chunk header in the data given the size of the
// RIFF chunk 'riff_size'.
// Returns VP8_STATUS_BITSTREAM_ERROR if any invalid chunk size is encountered,
//         VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
//         VP8_STATUS_OK otherwise.
// If an alpha chunk is found, *alpha_data and *alpha_size are set
// appropriately.
static VP8StatusCode ParseOptionalChunks(const uint8_t** const data,
                                         size_t* const data_size,
                                         size_t const riff_size,
                                         const uint8_t** const alpha_data,
                                         size_t* const alpha_size) {
  const uint8_t* buf;
  size_t buf_size;
  uint32_t total_size = TAG_SIZE +           // "WEBP".
                        CHUNK_HEADER_SIZE +  // "VP8Xnnnn".
                        VP8X_CHUNK_SIZE;     // data.
  assert(data != NULL);
  assert(data_size != NULL);
  buf = *data;
  buf_size = *data_size;

  assert(alpha_data != NULL);
  assert(alpha_size != NULL);
  *alpha_data = NULL;
  *alpha_size = 0;

  while (1) {
    uint32_t chunk_size;
    uint32_t disk_chunk_size;   // chunk_size with padding

    *data = buf;
    *data_size = buf_size;

    if (buf_size < CHUNK_HEADER_SIZE) {  // Insufficient data.
      return VP8_STATUS_NOT_ENOUGH_DATA;
    }

    chunk_size = get_le32(buf + TAG_SIZE);
    if (chunk_size > MAX_CHUNK_PAYLOAD) {
      return VP8_STATUS_BITSTREAM_ERROR;          // Not a valid chunk size.
    }
    // For odd-sized chunk-payload, there's one byte padding at the end.
    disk_chunk_size = (CHUNK_HEADER_SIZE + chunk_size + 1) & ~1;
    total_size += disk_chunk_size;

    // Check that total bytes skipped so far does not exceed riff_size.
    if (riff_size > 0 && (total_size > riff_size)) {
      return VP8_STATUS_BITSTREAM_ERROR;          // Not a valid chunk size.
    }

    // Start of a (possibly incomplete) VP8/VP8L chunk implies that we have
    // parsed all the optional chunks.
    // Note: This check must occur before the check 'buf_size < disk_chunk_size'
    // below to allow incomplete VP8/VP8L chunks.
    if (!memcmp(buf, "VP8 ", TAG_SIZE) ||
        !memcmp(buf, "VP8L", TAG_SIZE)) {
      return VP8_STATUS_OK;
    }

    if (buf_size < disk_chunk_size) {             // Insufficient data.
      return VP8_STATUS_NOT_ENOUGH_DATA;
    }

    if (!memcmp(buf, "ALPH", TAG_SIZE)) {         // A valid ALPH header.
      *alpha_data = buf + CHUNK_HEADER_SIZE;
      *alpha_size = chunk_size;
    }

    // We have a full and valid chunk; skip it.
    buf += disk_chunk_size;
    buf_size -= disk_chunk_size;
  }
}

// Validates the VP8/VP8L Header ("VP8 nnnn" or "VP8L nnnn") and skips over it.
// Returns VP8_STATUS_BITSTREAM_ERROR for invalid (chunk larger than
//         riff_size) VP8/VP8L header,
//         VP8_STATUS_NOT_ENOUGH_DATA in case of insufficient data, and
//         VP8_STATUS_OK otherwise.
// If a VP8/VP8L chunk is found, *chunk_size is set to the total number of bytes
// extracted from the VP8/VP8L chunk header.
// The flag '*is_lossless' is set to 1 in case of VP8L chunk / raw VP8L data.
static VP8StatusCode ParseVP8Header(const uint8_t** const data_ptr,
                                    size_t* const data_size,
                                    size_t riff_size,
                                    size_t* const chunk_size,
                                    int* const is_lossless) {
  const uint8_t* const data = *data_ptr;
  const int is_vp8 = !memcmp(data, "VP8 ", TAG_SIZE);
  const int is_vp8l = !memcmp(data, "VP8L", TAG_SIZE);
  const uint32_t minimal_size =
      TAG_SIZE + CHUNK_HEADER_SIZE;  // "WEBP" + "VP8 nnnn" OR
                                     // "WEBP" + "VP8Lnnnn"
  assert(data != NULL);
  assert(data_size != NULL);
  assert(chunk_size != NULL);
  assert(is_lossless != NULL);

  if (*data_size < CHUNK_HEADER_SIZE) {
    return VP8_STATUS_NOT_ENOUGH_DATA;  // Insufficient data.
  }

  if (is_vp8 || is_vp8l) {
    // Bitstream contains VP8/VP8L header.
    const uint32_t size = get_le32(data + TAG_SIZE);
    if ((riff_size >= minimal_size) && (size > riff_size - minimal_size)) {
      return VP8_STATUS_BITSTREAM_ERROR;  // Inconsistent size information.
    }
    // Skip over CHUNK_HEADER_SIZE bytes from VP8/VP8L Header.
    *chunk_size = size;
    *data_ptr += CHUNK_HEADER_SIZE;
    *data_size -= CHUNK_HEADER_SIZE;
    *is_lossless = is_vp8l;
  } else {
    // Raw VP8/VP8L bitstream (no header).
    *is_lossless = VP8LCheckSignature(data, *data_size);
    *chunk_size = *data_size;
  }

  return VP8_STATUS_OK;
}

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

// Fetch '*width', '*height', '*has_alpha' and fill out 'headers' based on
// 'data'. All the output parameters may be NULL. If 'headers' is NULL only the
// minimal amount will be read to fetch the remaining parameters.
// If 'headers' is non-NULL this function will attempt to locate both alpha
// data (with or without a VP8X chunk) and the bitstream chunk (VP8/VP8L).
// Note: The following chunk sequences (before the raw VP8/VP8L data) are
// considered valid by this function:
// RIFF + VP8(L)
// RIFF + VP8X + (optional chunks) + VP8(L)
// ALPH + VP8 <-- Not a valid WebP format: only allowed for internal purpose.
// VP8(L)     <-- Not a valid WebP format: only allowed for internal purpose.
static VP8StatusCode ParseHeadersInternal(const uint8_t* data,
                                          size_t data_size,
                                          int* const width,
                                          int* const height,
                                          int* const has_alpha,
                                          int* const has_animation,
                                          WebPHeaderStructure* const headers) {
  int found_riff = 0;
  int found_vp8x = 0;
  VP8StatusCode status;
  WebPHeaderStructure hdrs;

  if (data == NULL || data_size < RIFF_HEADER_SIZE) {
    return VP8_STATUS_NOT_ENOUGH_DATA;
  }
  memset(&hdrs, 0, sizeof(hdrs));
  hdrs.data = data;
  hdrs.data_size = data_size;

  // Skip over RIFF header.
  status = ParseRIFF(&data, &data_size, &hdrs.riff_size);
  if (status != VP8_STATUS_OK) {
    return status;   // Wrong RIFF header / insufficient data.
  }
  found_riff = (hdrs.riff_size > 0);

  // Skip over VP8X.
  {
    uint32_t flags = 0;
    status = ParseVP8X(&data, &data_size, &found_vp8x, width, height, &flags);
    if (status != VP8_STATUS_OK) {
      return status;  // Wrong VP8X / insufficient data.
    }
    if (!found_riff && found_vp8x) {
      // Note: This restriction may be removed in the future, if it becomes
      // necessary to send VP8X chunk to the decoder.
      return VP8_STATUS_BITSTREAM_ERROR;
    }
    if (has_alpha != NULL) *has_alpha = !!(flags & ALPHA_FLAG);
    if (has_animation != NULL) *has_animation = !!(flags & ANIMATION_FLAG);
    if (found_vp8x && headers == NULL) {
      return VP8_STATUS_OK;  // Return features from VP8X header.
    }
  }

  if (data_size < TAG_SIZE) return VP8_STATUS_NOT_ENOUGH_DATA;

  // Skip over optional chunks if data started with "RIFF + VP8X" or "ALPH".
  if ((found_riff && found_vp8x) ||
      (!found_riff && !found_vp8x && !memcmp(data, "ALPH", TAG_SIZE))) {
    status = ParseOptionalChunks(&data, &data_size, hdrs.riff_size,
                                 &hdrs.alpha_data, &hdrs.alpha_data_size);
    if (status != VP8_STATUS_OK) {
      return status;  // Found an invalid chunk size / insufficient data.
    }
  }

  // Skip over VP8/VP8L header.
  status = ParseVP8Header(&data, &data_size, hdrs.riff_size,
                          &hdrs.compressed_size, &hdrs.is_lossless);
  if (status != VP8_STATUS_OK) {
    return status;  // Wrong VP8/VP8L chunk-header / insufficient data.
  }
  if (hdrs.compressed_size > MAX_CHUNK_PAYLOAD) {
    return VP8_STATUS_BITSTREAM_ERROR;
  }

  if (!hdrs.is_lossless) {
    if (data_size < VP8_FRAME_HEADER_SIZE) {
      return VP8_STATUS_NOT_ENOUGH_DATA;
    }
    // Validates raw VP8 data.
    if (!VP8GetInfo(data, data_size,
                    (uint32_t)hdrs.compressed_size, width, height)) {
      return VP8_STATUS_BITSTREAM_ERROR;
    }
  } else {
    if (data_size < VP8L_FRAME_HEADER_SIZE) {
      return VP8_STATUS_NOT_ENOUGH_DATA;
    }
    // Validates raw VP8L data.
    if (!VP8LGetInfo(data, data_size, width, height, has_alpha)) {
      return VP8_STATUS_BITSTREAM_ERROR;
    }
  }

  if (has_alpha != NULL) {
    // If the data did not contain a VP8X/VP8L chunk the only definitive way
    // to set this is by looking for alpha data (from an ALPH chunk).
    *has_alpha |= (hdrs.alpha_data != NULL);
  }
  if (headers != NULL) {
    *headers = hdrs;
    headers->offset = data - headers->data;
    assert((uint64_t)(data - headers->data) < MAX_CHUNK_PAYLOAD);
    assert(headers->offset == headers->data_size - data_size);
  }
  return VP8_STATUS_OK;  // Return features from VP8 header.
}

VP8StatusCode WebPParseHeaders(WebPHeaderStructure* const headers) {
  VP8StatusCode status;
  int has_animation = 0;
  assert(headers != NULL);
  // fill out headers, ignore width/height/has_alpha.
  status = ParseHeadersInternal(headers->data, headers->data_size,
                                NULL, NULL, NULL, &has_animation, headers);
  if (status == VP8_STATUS_OK || status == VP8_STATUS_NOT_ENOUGH_DATA) {
    // TODO(jzern): full support of animation frames will require API additions.
    if (has_animation) {
      status = VP8_STATUS_UNSUPPORTED_FEATURE;
    }
  }
  return status;
}

//------------------------------------------------------------------------------
// WebPDecParams

void WebPResetDecParams(WebPDecParams* const params) {
  if (params) {
    memset(params, 0, sizeof(*params));
  }
}

//------------------------------------------------------------------------------
// "Into" decoding variants

// Main flow
static VP8StatusCode DecodeInto(const uint8_t* const data, size_t data_size,
                                WebPDecParams* const params) {
  VP8StatusCode status;
  VP8Io io;
  WebPHeaderStructure headers;

  headers.data = data;
  headers.data_size = data_size;
  status = WebPParseHeaders(&headers);   // Process Pre-VP8 chunks.
  if (status != VP8_STATUS_OK) {
    return status;
  }

  assert(params != NULL);
  VP8InitIo(&io);
  io.data = headers.data + headers.offset;
  io.data_size = headers.data_size - headers.offset;
  WebPInitCustomIo(params, &io);  // Plug the I/O functions.

  if (!headers.is_lossless) {
    VP8Decoder* const dec = VP8New();
    if (dec == NULL) {
      return VP8_STATUS_OUT_OF_MEMORY;
    }
#ifdef WEBP_USE_THREAD
    dec->use_threads_ = params->options && (params->options->use_threads > 0);
#else
    dec->use_threads_ = 0;
#endif
    dec->alpha_data_ = headers.alpha_data;
    dec->alpha_data_size_ = headers.alpha_data_size;

    // Decode bitstream header, update io->width/io->height.
    if (!VP8GetHeaders(dec, &io)) {
      status = dec->status_;   // An error occurred. Grab error status.
    } else {
      // Allocate/check output buffers.
      status = WebPAllocateDecBuffer(io.width, io.height, params->options,
                                     params->output);
      if (status == VP8_STATUS_OK) {  // Decode
        if (!VP8Decode(dec, &io)) {
          status = dec->status_;
        }
      }
    }
    VP8Delete(dec);
  } else {
    VP8LDecoder* const dec = VP8LNew();
    if (dec == NULL) {
      return VP8_STATUS_OUT_OF_MEMORY;
    }
    if (!VP8LDecodeHeader(dec, &io)) {
      status = dec->status_;   // An error occurred. Grab error status.
    } else {
      // Allocate/check output buffers.
      status = WebPAllocateDecBuffer(io.width, io.height, params->options,
                                     params->output);
      if (status == VP8_STATUS_OK) {  // Decode
        if (!VP8LDecodeImage(dec)) {
          status = dec->status_;
        }
      }
    }
    VP8LDelete(dec);
  }

  if (status != VP8_STATUS_OK) {
    WebPFreeDecBuffer(params->output);
  }
  return status;
}

// Helpers
static uint8_t* DecodeIntoRGBABuffer(WEBP_CSP_MODE colorspace,
                                     const uint8_t* const data,
                                     size_t data_size,
                                     uint8_t* const rgba,
                                     int stride, size_t size) {
  WebPDecParams params;
  WebPDecBuffer buf;
  if (rgba == NULL) {
    return NULL;
  }
  WebPInitDecBuffer(&buf);
  WebPResetDecParams(&params);
  params.output = &buf;
  buf.colorspace    = colorspace;
  buf.u.RGBA.rgba   = rgba;
  buf.u.RGBA.stride = stride;
  buf.u.RGBA.size   = size;
  buf.is_external_memory = 1;
  if (DecodeInto(data, data_size, &params) != VP8_STATUS_OK) {
    return NULL;
  }
  return rgba;
}

uint8_t* WebPDecodeRGBInto(const uint8_t* data, size_t data_size,
                           uint8_t* output, size_t size, int stride) {
  return DecodeIntoRGBABuffer(MODE_RGB, data, data_size, output, stride, size);
}

uint8_t* WebPDecodeRGBAInto(const uint8_t* data, size_t data_size,
                            uint8_t* output, size_t size, int stride) {
  return DecodeIntoRGBABuffer(MODE_RGBA, data, data_size, output, stride, size);
}

uint8_t* WebPDecodeARGBInto(const uint8_t* data, size_t data_size,
                            uint8_t* output, size_t size, int stride) {
  return DecodeIntoRGBABuffer(MODE_ARGB, data, data_size, output, stride, size);
}

uint8_t* WebPDecodeBGRInto(const uint8_t* data, size_t data_size,
                           uint8_t* output, size_t size, int stride) {
  return DecodeIntoRGBABuffer(MODE_BGR, data, data_size, output, stride, size);
}

uint8_t* WebPDecodeBGRAInto(const uint8_t* data, size_t data_size,
                            uint8_t* output, size_t size, int stride) {
  return DecodeIntoRGBABuffer(MODE_BGRA, data, data_size, output, stride, size);
}

uint8_t* WebPDecodeYUVInto(const uint8_t* data, size_t data_size,
                           uint8_t* luma, size_t luma_size, int luma_stride,
                           uint8_t* u, size_t u_size, int u_stride,
                           uint8_t* v, size_t v_size, int v_stride) {
  WebPDecParams params;
  WebPDecBuffer output;
  if (luma == NULL) return NULL;
  WebPInitDecBuffer(&output);
  WebPResetDecParams(&params);
  params.output = &output;
  output.colorspace      = MODE_YUV;
  output.u.YUVA.y        = luma;
  output.u.YUVA.y_stride = luma_stride;
  output.u.YUVA.y_size   = luma_size;
  output.u.YUVA.u        = u;
  output.u.YUVA.u_stride = u_stride;
  output.u.YUVA.u_size   = u_size;
  output.u.YUVA.v        = v;
  output.u.YUVA.v_stride = v_stride;
  output.u.YUVA.v_size   = v_size;
  output.is_external_memory = 1;
  if (DecodeInto(data, data_size, &params) != VP8_STATUS_OK) {
    return NULL;
  }
  return luma;
}

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

static uint8_t* Decode(WEBP_CSP_MODE mode, const uint8_t* const data,
                       size_t data_size, int* const width, int* const height,
                       WebPDecBuffer* const keep_info) {
  WebPDecParams params;
  WebPDecBuffer output;

  WebPInitDecBuffer(&output);
  WebPResetDecParams(&params);
  params.output = &output;
  output.colorspace = mode;

  // Retrieve (and report back) the required dimensions from bitstream.
  if (!WebPGetInfo(data, data_size, &output.width, &output.height)) {
    return NULL;
  }
  if (width != NULL) *width = output.width;
  if (height != NULL) *height = output.height;

  // Decode
  if (DecodeInto(data, data_size, &params) != VP8_STATUS_OK) {
    return NULL;
  }
  if (keep_info != NULL) {    // keep track of the side-info
    WebPCopyDecBuffer(&output, keep_info);
  }
  // return decoded samples (don't clear 'output'!)
  return WebPIsRGBMode(mode) ? output.u.RGBA.rgba : output.u.YUVA.y;
}

uint8_t* WebPDecodeRGB(const uint8_t* data, size_t data_size,
                       int* width, int* height) {
  return Decode(MODE_RGB, data, data_size, width, height, NULL);
}

uint8_t* WebPDecodeRGBA(const uint8_t* data, size_t data_size,
                        int* width, int* height) {
  return Decode(MODE_RGBA, data, data_size, width, height, NULL);
}

uint8_t* WebPDecodeARGB(const uint8_t* data, size_t data_size,
                        int* width, int* height) {
  return Decode(MODE_ARGB, data, data_size, width, height, NULL);
}

uint8_t* WebPDecodeBGR(const uint8_t* data, size_t data_size,
                       int* width, int* height) {
  return Decode(MODE_BGR, data, data_size, width, height, NULL);
}

uint8_t* WebPDecodeBGRA(const uint8_t* data, size_t data_size,
                        int* width, int* height) {
  return Decode(MODE_BGRA, data, data_size, width, height, NULL);
}

uint8_t* WebPDecodeYUV(const uint8_t* data, size_t data_size,
                       int* width, int* height, uint8_t** u, uint8_t** v,
                       int* stride, int* uv_stride) {
  WebPDecBuffer output;   // only to preserve the side-infos
  uint8_t* const out = Decode(MODE_YUV, data, data_size,
                              width, height, &output);

  if (out != NULL) {
    const WebPYUVABuffer* const buf = &output.u.YUVA;
    *u = buf->u;
    *v = buf->v;
    *stride = buf->y_stride;
    *uv_stride = buf->u_stride;
    assert(buf->u_stride == buf->v_stride);
  }
  return out;
}

static void DefaultFeatures(WebPBitstreamFeatures* const features) {
  assert(features != NULL);
  memset(features, 0, sizeof(*features));
  features->bitstream_version = 0;
}

static VP8StatusCode GetFeatures(const uint8_t* const data, size_t data_size,
                                 WebPBitstreamFeatures* const features) {
  if (features == NULL || data == NULL) {
    return VP8_STATUS_INVALID_PARAM;
  }
  DefaultFeatures(features);

  // Only parse enough of the data to retrieve the features.
  return ParseHeadersInternal(data, data_size,
                              &features->width, &features->height,
                              &features->has_alpha, &features->has_animation,
                              NULL);
}

//------------------------------------------------------------------------------
// WebPGetInfo()

int WebPGetInfo(const uint8_t* data, size_t data_size,
                int* width, int* height) {
  WebPBitstreamFeatures features;

  if (GetFeatures(data, data_size, &features) != VP8_STATUS_OK) {
    return 0;
  }

  if (width != NULL) {
    *width  = features.width;
  }
  if (height != NULL) {
    *height = features.height;
  }

  return 1;
}

//------------------------------------------------------------------------------
// Advance decoding API

int WebPInitDecoderConfigInternal(WebPDecoderConfig* config,
                                  int version) {
  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
    return 0;   // version mismatch
  }
  if (config == NULL) {
    return 0;
  }
  memset(config, 0, sizeof(*config));
  DefaultFeatures(&config->input);
  WebPInitDecBuffer(&config->output);
  return 1;
}

VP8StatusCode WebPGetFeaturesInternal(const uint8_t* data, size_t data_size,
                                      WebPBitstreamFeatures* features,
                                      int version) {
  if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_DECODER_ABI_VERSION)) {
    return VP8_STATUS_INVALID_PARAM;   // version mismatch
  }
  if (features == NULL) {
    return VP8_STATUS_INVALID_PARAM;
  }
  return GetFeatures(data, data_size, features);
}

VP8StatusCode WebPDecode(const uint8_t* data, size_t data_size,
                         WebPDecoderConfig* config) {
  WebPDecParams params;
  VP8StatusCode status;

  if (config == NULL) {
    return VP8_STATUS_INVALID_PARAM;
  }

  status = GetFeatures(data, data_size, &config->input);
  if (status != VP8_STATUS_OK) {
    if (status == VP8_STATUS_NOT_ENOUGH_DATA) {
      return VP8_STATUS_BITSTREAM_ERROR;  // Not-enough-data treated as error.
    }
    return status;
  }

  WebPResetDecParams(&params);
  params.output = &config->output;
  params.options = &config->options;
  status = DecodeInto(data, data_size, &params);

  return status;
}

//------------------------------------------------------------------------------
// Cropping and rescaling.

int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
                          VP8Io* const io, WEBP_CSP_MODE src_colorspace) {
  const int W = io->width;
  const int H = io->height;
  int x = 0, y = 0, w = W, h = H;

  // Cropping
  io->use_cropping = (options != NULL) && (options->use_cropping > 0);
  if (io->use_cropping) {
    w = options->crop_width;
    h = options->crop_height;
    x = options->crop_left;
    y = options->crop_top;
    if (!WebPIsRGBMode(src_colorspace)) {   // only snap for YUV420 or YUV422
      x &= ~1;
      y &= ~1;    // TODO(later): only for YUV420, not YUV422.
    }
    if (x < 0 || y < 0 || w <= 0 || h <= 0 || x + w > W || y + h > H) {
      return 0;  // out of frame boundary error
    }
  }
  io->crop_left   = x;
  io->crop_top    = y;
  io->crop_right  = x + w;
  io->crop_bottom = y + h;
  io->mb_w = w;
  io->mb_h = h;

  // Scaling
  io->use_scaling = (options != NULL) && (options->use_scaling > 0);
  if (io->use_scaling) {
    if (options->scaled_width <= 0 || options->scaled_height <= 0) {
      return 0;
    }
    io->scaled_width = options->scaled_width;
    io->scaled_height = options->scaled_height;
  }

  // Filter
  io->bypass_filtering = options && options->bypass_filtering;

  // Fancy upsampler
#ifdef FANCY_UPSAMPLING
  io->fancy_upsampling = (options == NULL) || (!options->no_fancy_upsampling);
#endif

  if (io->use_scaling) {
    // disable filter (only for large downscaling ratio).
    io->bypass_filtering = (io->scaled_width < W * 3 / 4) &&
                           (io->scaled_height < H * 3 / 4);
    io->fancy_upsampling = 0;
  }
  return 1;
}

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

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