/// <summary>
/// Split an Icon (that contains multiple icons) into an array of Icon each rapresenting a single icons.
/// </summary>
/// <param name="icon"> Instance value. </param>
/// <returns> An array of <see cref="System.Drawing.Icon" /> objects. </returns>
public static Icon[] SplitIcon(this Icon icon)
{
icon.ExceptionIfNull("Can't split the icon. Icon is null.", "icon");
// Get multiple .ico file image.
var srcBuf = default(byte[]);
using (var stream = new MemoryStream())
{
icon.Save(stream);
srcBuf = stream.ToArray();
}
var splitIcons = new List <Icon>();
const int sizeIconDir = 6; // sizeof(IconDir)
const int sizeIconDirEntry = 16; // sizeof(IconDirEntry)
var count = BitConverter.ToInt16(srcBuf, 4); // ICONDIR.idCount
for (var i = 0; i < count; ++i)
{
using (var stream = new MemoryStream())
using (var writer = new BinaryWriter(stream))
{
// Copy IconDir and IconDirEntry.
writer.Write(srcBuf, 0, sizeIconDir - 2);
writer.Write((short)1); // IconDir.idCount == 1;
writer.Write(srcBuf, sizeIconDir + sizeIconDirEntry * i, sizeIconDirEntry - 4);
writer.Write(sizeIconDir + sizeIconDirEntry);
// IconDirEntry.dwImageOffset = sizeof(IconDir) + sizeof(IconDirEntry)
// Copy picture and mask data.
var sizeImg = BitConverter.ToInt32(srcBuf, sizeIconDir + sizeIconDirEntry * i + 8);
// IconDirEntry.dwBytesInRes
var offsetImg = BitConverter.ToInt32(srcBuf, sizeIconDir + sizeIconDirEntry * i + 12);
// IconDirEntry.dwImageOffset
writer.Write(srcBuf, offsetImg, sizeImg);
// Create new icon.
stream.Seek(0, SeekOrigin.Begin);
splitIcons.Add(new Icon(stream));
}
}
return(splitIcons.ToArray());
}
