private static IconData BuildIconData(Stream source, IconHeader header, IconEntry entry)
{
using (var stream = new MemoryStream())
{
using (var writer = new BinaryWriter(stream, System.Text.Encoding.UTF8, true))
{
/* I’m not recreating an icon file here, just one icon at a time in the icon file format.
* Therefore write the count as 1, and the offset as sizeof(header) + sizeof(entry). */
const short number = 1;
var offset = Marshal.SizeOf(typeof(IconHeader)) + Marshal.SizeOf(typeof(IconEntry));
writer.Write(header.Reserved);
writer.Write(header.Type);
writer.Write(number);
writer.Write((byte)entry.Width);
writer.Write((byte)entry.Height);
writer.Write(entry.ColorCount);
writer.Write(entry.Reserved);
writer.Write(entry.Planes);
writer.Write(entry.BitCount);
writer.Write(entry.BytesInRes);
writer.Write(offset);
var buffer = new byte[entry.BytesInRes];
source.Position = entry.ImageOffset;
source.Read(buffer, 0, entry.BytesInRes);
writer.Write(buffer);
/* While this shouldn’t always be necessary, the managed Icon type will throw an exception when, for example,
* trying to create an icon from any .png image that was just loaded from the file, whether it is 256×256
* (0x0 in the entry), or smaller, whereas this way always seems to work. */
using (var image = Image.FromStream(stream) as Bitmap)
{
Icon temp = null;
try
{
temp = Icon.FromHandle(image.GetHicon());
/* Use the dimensions we got from the GDI icon, so we
* don’t have to worry about double-height bitmaps etc.*/
return(new IconData {
Icon = new Icon(temp, temp.Width, temp.Height), BitDepth = entry.BitCount
});
}
finally
{
if (temp != null)
{
NativeMethods.DestroyIcon(temp.Handle);
}
}
}
}
}
}
private static IEnumerable <IIconData> ReadStream(Stream stream)
{
using (var reader = new BinaryReader(stream, System.Text.Encoding.UTF8, true))
{
var header = new IconHeader(reader);
var entries = new IconEntry[header.Count];
for (var i = 0; i < header.Count; i++)
{
entries[i] = new IconEntry(reader);
}
var imageData = new IconData[header.Count];
for (var i = 0; i < header.Count; i++)
{
try
{
imageData[i] = BuildIconData(stream, header, entries[i]);
}
catch { }
}
/* Sort the results; by bit-depth, then size; descending, so that the
* first icon found will be the largest resolution and highest bit depth. */
var bitDepths = imageData.Select(b => b.BitDepth).Distinct().ToList();
bitDepths.Sort();
var result = new List <IIconData>();
foreach (var i in bitDepths)
{
result.AddRange(imageData.Where(b => b.BitDepth == i).OrderBy(b => b.Icon.Width));
}
result.Reverse();
return(result);
}
}