/// <summary>
/// Initializes a new instance of the <see cref="PngDecoder"/> class.
/// </summary>
/// <param name="stream">
/// A <see cref="Stream"/> which contains a PNG image.
/// </param>
public PngDecoder(Stream stream)
{
this.Stream = stream ?? throw new ArgumentNullException(nameof(stream));
this.version = NativeMethods.png_get_libpng_ver(IntPtr.Zero);
this.Version = Marshal.PtrToStringAnsi(this.version);
this.errorCallback = new NativeMethods.png_error(OnError);
this.warningCallback = new NativeMethods.png_error(OnWarning);
this.pngPtr = NativeMethods.png_create_read_struct(this.version, new IntPtr(1), this.errorCallback, this.warningCallback);
ThrowOnZero(this.pngPtr);
this.infoPtr = NativeMethods.png_create_info_struct(this.pngPtr);
ThrowOnZero(this.infoPtr);
// Set the callback function
this.readCallback = new NativeMethods.png_rw(this.Read);
NativeMethods.png_set_read_fn(this.pngPtr, IntPtr.Zero, this.readCallback);
// Get basic image properties.
// This will process all chunks up to but not including the image data.
NativeMethods.png_read_info(this.pngPtr, this.infoPtr);
this.RefreshProperties();
}
/// <summary>
/// Initializes a new instance of the <see cref="PngReader"/> class.
/// </summary>
/// <param name="stream">
/// A <see cref="pngStream"/> which contains a PNG image.
/// </param>
public PngReader(String FileName)
{
using (Stream stream = File.OpenRead(FileName))
{
pngStream = stream ?? throw new ArgumentNullException(nameof(stream));
Version = Marshal.PtrToStringAnsi(verPtr = NativeMethods.png_get_libpng_ver(IntPtr.Zero));
errorCallback = new NativeMethods.png_error(OnError);
warningCallback = new NativeMethods.png_error(OnWarning);
// Creat structures
ThrowOnZero(pngPtr = NativeMethods.png_create_read_struct(verPtr, IntPtr.Zero, errorCallback, warningCallback)); // ?IntPtr(1)?
ThrowOnZero(infoPtr = NativeMethods.png_create_info_struct(pngPtr));
// Set the callback function
NativeMethods.png_set_read_fn(pngPtr, IntPtr.Zero, readCallback = new NativeMethods.png_rw(ReadBlock));
// Get basic image properties
try
{
NativeMethods.png_read_info(pngPtr, infoPtr);
Width = (int)NativeMethods.png_get_image_width(pngPtr, infoPtr);
Height = (int)NativeMethods.png_get_image_height(pngPtr, infoPtr);
BitDepth = NativeMethods.png_get_bit_depth(pngPtr, infoPtr);
Channels = NativeMethods.png_get_channels(pngPtr, infoPtr);
BytesPerRow = (int)NativeMethods.png_get_rowbytes(pngPtr, infoPtr);
ColorType = NativeMethods.png_get_color_type(pngPtr, infoPtr);
DecompressedSize = BytesPerRow * Height;
// Get image data
ScanLine = new byte[DecompressedSize];
fixed(byte *ptr = ScanLine)
{
IntPtr[] rowPtrs = new IntPtr[Height];
IntPtr rowPtr = (IntPtr)ptr;
for (int i = 0; i < Height; i++)
{
rowPtrs[i] = rowPtr;
rowPtr += BytesPerRow;
}
NativeMethods.png_read_image(pngPtr, rowPtrs);
}
// Read the end_info data
NativeMethods.png_read_end(pngPtr, endInfoPtr);
}
catch (Exception exc)
{
throw exc;
}
}
}
public PngWriter(String FileName, byte[] ScanLine, int Width, int Height, int Channels, int BitDepth, PngColorType ColorType)
{
if (ScanLine == null)
{
throw
new ArgumentNullException(nameof(ScanLine));
}
using (Stream stream = File.OpenWrite(FileName))
{
BytesPerRow = Width * Channels * BitDepth / 8;
pngStream = stream ?? throw new ArgumentNullException(nameof(stream));
Version = Marshal.PtrToStringAnsi(verPtr = NativeMethods.png_get_libpng_ver(IntPtr.Zero));
errorCallback = new NativeMethods.png_error(OnError);
warningCallback = new NativeMethods.png_error(OnWarning);
// Creat structures
ThrowOnZero(pngPtr = NativeMethods.png_create_write_struct(verPtr, IntPtr.Zero, errorCallback, warningCallback));
ThrowOnZero(infoPtr = NativeMethods.png_create_info_struct(pngPtr));
// Set the callback function
NativeMethods.png_set_write_fn(pngPtr, IntPtr.Zero, writeCallback = new NativeMethods.png_rw(WriteBlock), flushCallback = new NativeMethods.png_flush(FlushBlock));
// Init image
NativeMethods.png_set_IHDR(pngPtr, infoPtr, Width, Height, BitDepth, ColorType, PngInterlaceType.None, PngCompressionType.Base, PngFillerFlags.Before);
// Write basic image properties
NativeMethods.png_write_info(pngPtr, infoPtr);
// Write image data
fixed(byte *ptr = ScanLine)
{
IntPtr[] rowPtrs = new IntPtr[Height];
IntPtr rowPtr = (IntPtr)ptr;
for (int i = 0; i < Height; i++)
{
rowPtrs[i] = rowPtr;
rowPtr += BytesPerRow;
}
NativeMethods.png_write_image(pngPtr, rowPtrs);
}
// Write end_info data
NativeMethods.png_write_end(pngPtr, endInfoPtr);
}
}
