CSS Image Sprite Packer

PackImages.cs

using System;
using System.IO;
using System.Collections;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;

public class PackImagesApplication
{
    private static string cssFormat =
@"#{0}_{1} {{
    width: {2}px;
    height: {3}px;
    background-position: -{4}px -{5}px;
    background-image: url({6});
}}
#{0}_{1}_half {{
    width: {7}px;
    height: {8}px;
    background-position: -{9}px -{10}px;
    background-image: url({6});
    background-size: {11}px {12}px
}}
#{0}_{1}_double {{
    width: {13}px;
    height: {14}px;
    background-position: -{15}px -{16}px;
    background-image: url({6});
    background-size: {17}px {18}px
}}";

    public class Run
    {
        public List<Image> Images = new List<Image>();
        public long RunHeight;
        public long RunWidth;
    }

    private static void Main(string[] args)
    {
        uint maximumWidth = 1024;
        uint maximumHeight = 1024;
        long fileSize = 0;

        List<string> importDirectories = new List<string>();
        string outputFile = null;
        string cssFile = null;

        for(int i = 0; i < args.Length; i++)
        {
            string arg = args[i];
            if ( arg.StartsWith("/o:") )
            {
                outputFile = arg.Substring(3);
            }
            else if ( arg.StartsWith("/h:") )
            {
                maximumHeight = uint.Parse(arg.Substring(3));
            }
            else if ( arg.StartsWith("/w:") )
            {
                maximumWidth = uint.Parse(arg.Substring(3));
            }
            else if ( arg.StartsWith("/css:") )
            {
                cssFile = arg.Substring(5);
            }
            else
            {
                importDirectories.Add(arg);
            }
        }

        if ( outputFile == null )
        {
            Console.WriteLine("Usage: PackImages /o:out.png [/h:maxHeight] [/w:maxWidth] [/css:out.css] [dirs...]");
            return;
        }

        if ( cssFile == null )
        {
            cssFile = Path.ChangeExtension(outputFile, ".css");
        }

        List<Image> images = new List<Image>();
        if ( outputFile != null )
        {
            for(int i = 0; i < importDirectories.Count; i++)
            {
                DirectoryInfo di = new DirectoryInfo(importDirectories[i]);
                if ( !di.Exists )
                {
                    throw new Exception("Directory doesn't exist " + importDirectories[i]);
                }

                FileInfo[] fis = di.GetFiles("*.png");
                foreach(FileInfo fi in fis)
                {
                    fileSize += fi.Length;
                    Image image = Image.FromFile(fi.FullName);
                    image.Tag = fi.FullName;
                    images.Add(image);
                }
            }
        }

        List<Run> ImageRuns = new List<Run>();

        long totalImageHeight = 0;
        long totalImageWidth = 0;

        images.Sort((x,y) => { return x.Width.CompareTo(y.Width); });
        Run currentRun = new Run();
        long currentWidth = 0;
        foreach(Image image in images)
        {
            if ( currentWidth + image.Width >= maximumWidth )
            {
                if (currentRun.Images.Count == 0)
                {
                    throw new Exception("An image is too large for spriting");
                }
                currentRun.RunWidth = currentWidth;
                totalImageWidth = Math.Max(currentRun.RunWidth, totalImageWidth);
                totalImageHeight += currentRun.RunHeight;
                ImageRuns.Add(currentRun);

                currentRun = new Run();
                currentWidth = 0;
            }

            currentRun.Images.Add(image);
            currentRun.RunHeight = Math.Max(currentRun.RunHeight, image.Height);
            currentWidth += image.Width;
        }

        if (currentRun.Images.Count > 0)
        {
            currentRun.RunWidth = currentWidth;
            totalImageWidth = Math.Max(currentRun.RunWidth, totalImageWidth);
            totalImageHeight += currentRun.RunHeight;
            ImageRuns.Add(currentRun);
        }

        Console.WriteLine("Size before pack is {0}", fileSize);
        Console.WriteLine("Final image size is {0},{1} with {2} images in {3} runs", totalImageWidth, totalImageHeight, images.Count, ImageRuns.Count);

        string debugHtmlFile = Path.ChangeExtension(cssFile, ".htm");
        using(StreamWriter swDebug = new StreamWriter(debugHtmlFile))
        {
            swDebug.WriteLine("<!DOCTYPE HTML><html><head><link rel=\"stylesheet\" type=\"text/css\" href=\"{0}\" /></head><body>", Path.GetFileName(cssFile));
            using(StreamWriter sw = new StreamWriter(cssFile))
            {
                Bitmap bmpPack = new Bitmap((int) totalImageWidth, (int) totalImageHeight);
                using(Graphics gfx = Graphics.FromImage(bmpPack))
                {
                    long currentY = 0;
                    foreach(Run imageRun in ImageRuns)
                    {
                        long currentX = 0;
                        foreach(Image image in imageRun.Images)
                        {
                            // Render the image
                            gfx.DrawImage(image, currentX, currentY);

                            // Build the CSS for this image
                            string fileName = image.Tag as string;
                            if ( fileName != null )
                            {
                                string imageName = Path.GetFileNameWithoutExtension(fileName);
                                string imagePack = Path.GetFileNameWithoutExtension(outputFile);
                                string imageUrl = Path.GetFileName(outputFile);

                                sw.WriteLine(cssFormat,
                                    imagePack, imageName, image.Width, image.Height, currentX, currentY, imageUrl,
                                    image.Width / 2, image.Height / 2, currentX / 2, currentY / 2, totalImageWidth / 2, totalImageHeight / 2,
                                    image.Width * 2, image.Height * 2, currentX * 2, currentY * 2, totalImageWidth * 2, totalImageHeight * 2);
                                swDebug.WriteLine("<div id=\"{0}_{1}\"></div>", imagePack, imageName);
                                swDebug.WriteLine("<div id=\"{0}_{1}_half\"></div>", imagePack, imageName);
                                swDebug.WriteLine("<div id=\"{0}_{1}_double\"></div>", imagePack, imageName);
                            }
                            else
                            {
                                throw new Exception("Image has a null tag, no name, can't emit CSS");
                            }

                            // Update our current offsets
                            currentX += image.Width;
                        }
                        currentY += imageRun.RunHeight;
                    }
                    bmpPack.Save(outputFile, ImageFormat.Png);
                }
            }
            swDebug.WriteLine("</body></html>");
        }
    }
}