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A simple class that converts a image to a icon in c# without losing image color data, unlike System.Drawing.Icon; ico with png data requires Windows Vista or above
class PngIconConverter
{
/* input image with width = height is suggested to get the best result */
/* png support in icon was introduced in Windows Vista */
public static bool Convert(System.IO.Stream input_stream, System.IO.Stream output_stream, int size, bool keep_aspect_ratio = false)
{
System.Drawing.Bitmap input_bit = (System.Drawing.Bitmap)System.Drawing.Bitmap.FromStream(input_stream);
if (input_bit != null)
{
int width, height;
if (keep_aspect_ratio)
{
width = size;
height = input_bit.Height / input_bit.Width * size;
}
else
{
width = height = size;
}
System.Drawing.Bitmap new_bit = new System.Drawing.Bitmap(input_bit, new System.Drawing.Size(width, height));
if (new_bit != null)
{
// save the resized png into a memory stream for future use
System.IO.MemoryStream mem_data = new System.IO.MemoryStream();
new_bit.Save(mem_data, System.Drawing.Imaging.ImageFormat.Png);
System.IO.BinaryWriter icon_writer = new System.IO.BinaryWriter(output_stream);
if (output_stream != null && icon_writer != null)
{
// 0-1 reserved, 0
icon_writer.Write((byte)0);
icon_writer.Write((byte)0);
// 2-3 image type, 1 = icon, 2 = cursor
icon_writer.Write((short)1);
// 4-5 number of images
icon_writer.Write((short)1);
// image entry 1
// 0 image width
icon_writer.Write((byte)width);
// 1 image height
icon_writer.Write((byte)height);
// 2 number of colors
icon_writer.Write((byte)0);
// 3 reserved
icon_writer.Write((byte)0);
// 4-5 color planes
icon_writer.Write((short)0);
// 6-7 bits per pixel
icon_writer.Write((short)32);
// 8-11 size of image data
icon_writer.Write((int)mem_data.Length);
// 12-15 offset of image data
icon_writer.Write((int)(6 + 16));
// write image data
// png data must contain the whole png data file
icon_writer.Write(mem_data.ToArray());
icon_writer.Flush();
return true;
}
}
return false;
}
return false;
}
public static bool Convert(string input_image, string output_icon, int size, bool keep_aspect_ratio = false)
{
System.IO.FileStream input_stream = new System.IO.FileStream(input_image, System.IO.FileMode.Open);
System.IO.FileStream output_stream = new System.IO.FileStream(output_icon, System.IO.FileMode.OpenOrCreate);
bool result = Convert(input_stream, output_stream, size, keep_aspect_ratio);
input_stream.Close();
output_stream.Close();
return result;
}
}
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