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src/Source/LibWebP/src/mux/mux.muxedit.c  view on Meta::CPAN

    int max_y = 0;
    int64_t image_area = 0;
    // if we have a chain of wpi's, header_ is necessarily set
    assert(wpi->header_ != NULL);
    // 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, canvas dimensions are same as image dimensions.
    *width = wpi->width_;
    *height = wpi->height_;
  }
  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 WebPData vp8x = { data, 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.
  }

  err = GetAdjustedCanvasSize(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 (mux->canvas_width_ != 0 || mux->canvas_height_ != 0) {
    if (width > mux->canvas_width_ || height > mux->canvas_height_) {
      return WEBP_MUX_INVALID_ARGUMENT;
    }
    width = mux->canvas_width_;
    height = mux->canvas_height_;
  }

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

  if (MuxHasAlpha(images)) {
    // This means some frames explicitly/implicitly contain alpha.
    // 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.