/// <summary>
/// Saves the specified <see cref="Bitmap"/> objects as a single
/// icon into the output stream.
/// </summary>
/// <param name="images">The bitmaps to save as an icon.</param>
/// <param name="stream">The output stream.</param>
/// <remarks>
/// The expected input for the <paramref name="images"/> parameter are
/// portable network graphic files that have a <see cref="Image.PixelFormat"/>
/// of <see cref="PixelFormat.Format32bppArgb"/> and where the
/// width is less than or equal to <see cref="IconFactory.MaxIconWidth"/> and the
/// height is less than or equal to <see cref="MaxIconHeight"/>.
/// </remarks>
/// <exception cref="InvalidOperationException">
/// Occurs if any of the input images do
/// not follow the required image format. See remarks for details.
/// </exception>
/// <exception cref="ArgumentNullException">
/// Occurs if any of the arguments are null.
/// </exception>
public static void SavePngsAsIcon(IEnumerable <Bitmap> images, Stream stream)
{
if (images == null)
{
throw new ArgumentNullException("images");
}
if (stream == null)
{
throw new ArgumentNullException("stream");
}
// validates the pngs
IconFactory.ThrowForInvalidPngs(images);
Bitmap[] orderedImages = images.OrderBy(i => i.Width)
.ThenBy(i => i.Height)
.ToArray();
using (var writer = new BinaryWriter(stream))
{
// write the header
writer.Write(IconFactory.HeaderReserved);
writer.Write(IconFactory.HeaderIconType);
writer.Write((ushort)orderedImages.Length);
// save the image buffers and offsets
Dictionary <uint, byte[]> buffers = new Dictionary <uint, byte[]>();
// tracks the length of the buffers as the iterations occur
// and adds that to the offset of the entries
uint lengthSum = 0;
uint baseOffset = (uint)(IconFactory.HeaderLength +
IconFactory.EntryLength * orderedImages.Length);
for (int i = 0; i < orderedImages.Length; i++)
{
Bitmap image = orderedImages[i];
// creates a byte array from an image
byte[] buffer = IconFactory.CreateImageBuffer(image);
// calculates what the offset of this image will be
// in the stream
uint offset = (baseOffset + lengthSum);
// writes the image entry
writer.Write(IconFactory.GetIconWidth(image));
writer.Write(IconFactory.GetIconHeight(image));
writer.Write(IconFactory.PngColorsInPalette);
writer.Write(IconFactory.EntryReserved);
writer.Write(IconFactory.PngColorPlanes);
writer.Write((ushort)Image.GetPixelFormatSize(image.PixelFormat));
writer.Write((uint)buffer.Length);
writer.Write(offset);
lengthSum += (uint)buffer.Length;
// adds the buffer to be written at the offset
buffers.Add(offset, buffer);
}
// writes the buffers for each image
foreach (var kvp in buffers)
{
// seeks to the specified offset required for the image buffer
writer.BaseStream.Seek(kvp.Key, SeekOrigin.Begin);
// writes the buffer
writer.Write(kvp.Value);
}
}
}
