/// <summary>
/// Write the images to the stream as icon
/// Every image is resized to 256x256 (but the content maintains the aspect ratio)
/// </summary>
/// <param name="stream">Stream to write to</param>
/// <param name="images">List of images</param>
public static void WriteIcon(Stream stream, IList <Image> images)
{
var binaryWriter = new BinaryWriter(stream);
//
// ICONDIR structure
//
binaryWriter.Write((short)0); // reserved
binaryWriter.Write((short)1); // image type (icon)
binaryWriter.Write((short)images.Count); // number of images
IList <Size> imageSizes = new List <Size>();
IList <MemoryStream> encodedImages = new List <MemoryStream>();
foreach (var image in images)
{
// Pick the best fit
var sizes = new[] { 16, 32, 48 };
int size = 256;
foreach (var possibleSize in sizes)
{
if (image.Width <= possibleSize && image.Height <= possibleSize)
{
size = possibleSize;
break;
}
}
var imageStream = new MemoryStream();
if (image.Width == size && image.Height == size)
{
using (var clonedImage = ImageHelper.Clone(image, PixelFormat.Format32bppArgb))
{
clonedImage.Save(imageStream, ImageFormat.Png);
imageSizes.Add(new Size(size, size));
}
}
else
{
// Resize to the specified size, first make sure the image is 32bpp
using (var clonedImage = ImageHelper.Clone(image, PixelFormat.Format32bppArgb))
{
using (var resizedImage = ImageHelper.ResizeImage(clonedImage, true, true, Color.Empty, size, size, null))
{
resizedImage.Save(imageStream, ImageFormat.Png);
imageSizes.Add(resizedImage.Size);
}
}
}
imageStream.Seek(0, SeekOrigin.Begin);
encodedImages.Add(imageStream);
}
//
// ICONDIRENTRY structure
//
const int iconDirSize = 6;
const int iconDirEntrySize = 16;
var offset = iconDirSize + (images.Count * iconDirEntrySize);
for (int i = 0; i < images.Count; i++)
{
var imageSize = imageSizes[i];
// Write the width / height, 0 means 256
binaryWriter.Write(imageSize.Width == 256 ? (byte)0 : (byte)imageSize.Width);
binaryWriter.Write(imageSize.Height == 256 ? (byte)0 : (byte)imageSize.Height);
binaryWriter.Write((byte)0); // no pallete
binaryWriter.Write((byte)0); // reserved
binaryWriter.Write((short)0); // no color planes
binaryWriter.Write((short)32); // 32 bpp
binaryWriter.Write((int)encodedImages[i].Length); // image data length
binaryWriter.Write(offset);
offset += (int)encodedImages[i].Length;
}
binaryWriter.Flush();
//
// Write image data
//
foreach (var encodedImage in encodedImages)
{
encodedImage.WriteTo(stream);
encodedImage.Dispose();
}
}
