/// <summary>
/// Decompress a JPEG image.
/// </summary>
/// <param name="jpegBuf">Pointer to a buffer containing the JPEG image to decompress. This buffer is not modified.</param>
/// <param name="jpegBufSize">Size of the JPEG image (in bytes).</param>
/// <param name="destPixelFormat">Pixel format of the destination image (see <see cref="SKColorType"/> "Pixel formats".)</param>
/// <param name="flags">The bitwise OR of one or more of the <see cref="TJFlags"/> "flags".</param>
/// <returns>Decompressed image of specified format.</returns>
/// <exception cref="TJException">Throws if underlying decompress function failed.</exception>
/// <exception cref="ObjectDisposedException">Object is disposed and can not be used anymore.</exception>
/// <exception cref="NotSupportedException">Convertion to the requested pixel format can not be performed.</exception>
public static SKBitmap Decompress(this TJDecompressor @this, IntPtr jpegBuf, ulong jpegBufSize, SKColorType destPixelFormat, TJFlags flags)
{
_ = @this ?? throw new ArgumentNullException(nameof(@this));
var targetFormat = TJSkiaUtils.ConvertPixelFormat(destPixelFormat);
@this.GetImageInfo(jpegBuf, jpegBufSize, targetFormat, out var width, out var height, out var stride, out var outBufSize);
var info = new SKImageInfo(width, height, destPixelFormat);
if (info.RowBytes != stride)
{
throw new NotSupportedException($"Skia expected the RowBytes/stride to be {info.RowBytes} for the given parameters but MozJPEG returns {stride}. Those values need to be equal.");
}
if (info.BytesSize != outBufSize)
{
throw new NotSupportedException($"Skia expected the BytesSize/number of bytes required to store the bitmap data to be {info.BytesSize} for the given parameters but MozJPEG returns {outBufSize}. Those values need to be equal.");
}
var dst = new SKBitmap(info);
var dstPtr = dst.GetPixels();
@this.Decompress(jpegBuf, jpegBufSize, dstPtr, outBufSize, targetFormat, flags, out _, out _, out _);
return(dst);
}
/// <summary>
/// Decompress a JPEG image to an RGB, grayscale, or CMYK image.
/// </summary>
/// <param name="jpegBuf">A buffer containing the JPEG image to decompress. This buffer is not modified.</param>
/// <param name="destPixelFormat">Pixel format of the destination image (see <see cref="PixelFormat"/> "Pixel formats".)</param>
/// <param name="flags">The bitwise OR of one or more of the <see cref="TJFlags"/> "flags".</param>
/// <returns>Decompressed image of specified format.</returns>
/// <exception cref="TJException">Throws if underlying decompress function failed.</exception>
/// <exception cref="ObjectDisposedException">Object is disposed and can not be used anymore.</exception>
/// <exception cref="NotSupportedException">Convertion to the requested pixel format can not be performed.</exception>
public static unsafe Bitmap Decompress(this TJDecompressor @this, byte[] jpegBuf, PixelFormat destPixelFormat, TJFlags flags)
{
var jpegBufSize = (ulong)jpegBuf.Length;
fixed(byte *jpegPtr = jpegBuf)
{
return(@this.Decompress((IntPtr)jpegPtr, jpegBufSize, destPixelFormat, flags));
}
}
public static byte[] Recompress(
ReadOnlySpan <byte> jpegBytes,
int quality = 70,
TJSubsamplingOption subsampling = TJSubsamplingOption.Chrominance420,
TJFlags flags = TJFlags.None)
{
var pixelFormat = TJPixelFormat.BGRA;
using var decr = new TJDecompressor();
var raw = decr.Decompress(jpegBytes, pixelFormat, flags, out var width, out var height, out var stride);
decr.Dispose();
using var compr = new TJCompressor();
var compressed = compr.Compress(raw, stride, width, height, pixelFormat, subsampling, quality, flags);
return(compressed);
}
/// <summary>
/// Decompress a JPEG image.
/// </summary>
/// <param name="jpegBuf">A buffer containing the JPEG image to decompress. This buffer is not modified.</param>
/// <param name="destPixelFormat">Pixel format of the destination image (see <see cref="SKColorType"/> "Pixel formats".)</param>
/// <param name="flags">The bitwise OR of one or more of the <see cref="TJFlags"/> "flags".</param>
/// <returns>Decompressed image of specified format.</returns>
/// <exception cref="TJException">Throws if underlying decompress function failed.</exception>
/// <exception cref="ObjectDisposedException">Object is disposed and can not be used anymore.</exception>
/// <exception cref="NotSupportedException">Convertion to the requested pixel format can not be performed.</exception>
public static SKBitmap Decompress(this TJDecompressor @this, ReadOnlySpan <byte> jpegBuf, SKColorType destPixelFormat, TJFlags flags)
{
_ = @this ?? throw new ArgumentNullException(nameof(@this));
// see https://stackoverflow.com/questions/537573/how-to-get-intptr-from-byte-in-c-sharp
var pinnedArray = GCHandle.Alloc(jpegBuf.GetPinnableReference(), GCHandleType.Pinned);
try
{
IntPtr pointer = pinnedArray.AddrOfPinnedObject();
var jpegBufSize = (ulong)jpegBuf.Length;
return(@this.Decompress(pointer, jpegBufSize, destPixelFormat, flags));
}
finally
{
pinnedArray.Free();
}
}
/// <summary>
/// Decompress a JPEG image to an RGB, grayscale, or CMYK image.
/// </summary>
/// <param name="jpegBuf">Pointer to a buffer containing the JPEG image to decompress. This buffer is not modified.</param>
/// <param name="jpegBufSize">Size of the JPEG image (in bytes).</param>
/// <param name="destPixelFormat">Pixel format of the destination image (see <see cref="PixelFormat"/> "Pixel formats".)</param>
/// <param name="flags">The bitwise OR of one or more of the <see cref="TJFlags"/> "flags".</param>
/// <returns>Decompressed image of specified format.</returns>
/// <exception cref="TJException">Throws if underlying decompress function failed.</exception>
/// <exception cref="ObjectDisposedException">Object is disposed and can not be used anymore.</exception>
/// <exception cref="NotSupportedException">Convertion to the requested pixel format can not be performed.</exception>
public static unsafe Bitmap Decompress(this TJDecompressor @this, IntPtr jpegBuf, ulong jpegBufSize, PixelFormat destPixelFormat, TJFlags flags)
{
var targetFormat = TJGdiPlusUtils.ConvertPixelFormat(destPixelFormat);
int width;
int height;
int stride;
var buffer = @this.Decompress(jpegBuf, jpegBufSize, targetFormat, flags, out width, out height, out stride);
Bitmap result;
fixed(byte *bufferPtr = buffer)
{
result = new Bitmap(width, height, stride, destPixelFormat, (IntPtr)bufferPtr);
if (destPixelFormat == PixelFormat.Format8bppIndexed)
{
result.Palette = TJGdiPlusUtils.FixPaletteToGrayscale(result.Palette);
}
}
return(result);
}
