/// <summary>
/// Tries to match imageHeaderByte and headerSize against every known
/// image format. If any match succeeds, corresponding ImageFormat
/// is returned.
/// </summary>
/// <returns>
/// ImageFormat for given imageHeaderBytes or UNKNOWN if no such type
/// could be recognized.
/// </returns>
private static ImageFormat DoGetImageFormat(
byte[] imageHeaderBytes,
int headerSize)
{
Preconditions.CheckNotNull(imageHeaderBytes);
if (WebpSupportStatus.IsWebpHeader(imageHeaderBytes, 0, headerSize))
{
return(GetWebpFormat(imageHeaderBytes, headerSize));
}
if (IsJpegHeader(imageHeaderBytes, headerSize))
{
return(ImageFormat.JPEG);
}
if (IsPngHeader(imageHeaderBytes, headerSize))
{
return(ImageFormat.PNG);
}
if (IsGifHeader(imageHeaderBytes, headerSize))
{
return(ImageFormat.GIF);
}
if (IsBmpHeader(imageHeaderBytes, headerSize))
{
return(ImageFormat.BMP);
}
return(ImageFormat.UNKNOWN);
}
/// <summary>
/// Determines type of WebP image. imageHeaderBytes has to be header
/// of a WebP image.
/// </summary>
private static ImageFormat GetWebpFormat(byte[] imageHeaderBytes, int headerSize)
{
Preconditions.CheckArgument(WebpSupportStatus.IsWebpHeader(imageHeaderBytes, 0, headerSize));
if (WebpSupportStatus.IsSimpleWebpHeader(imageHeaderBytes, 0))
{
return(ImageFormat.WEBP_SIMPLE);
}
if (WebpSupportStatus.IsLosslessWebpHeader(imageHeaderBytes, 0))
{
return(ImageFormat.WEBP_LOSSLESS);
}
if (WebpSupportStatus.IsExtendedWebpHeader(imageHeaderBytes, 0, headerSize))
{
if (WebpSupportStatus.IsAnimatedWebpHeader(imageHeaderBytes, 0))
{
return(ImageFormat.WEBP_ANIMATED);
}
if (WebpSupportStatus.IsExtendedWebpHeaderWithAlpha(imageHeaderBytes, 0))
{
return(ImageFormat.WEBP_EXTENDED_WITH_ALPHA);
}
return(ImageFormat.WEBP_EXTENDED);
}
return(ImageFormat.UNKNOWN);
}
