#719 – ASCII Art Generator

Here’s a WPF-based ASCII Art generator that I wrote.  Merry Christmas!

The GUI just consists of a button for selecting a file and a label indicating the file that was selected.

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition />
            <ColumnDefinition/>
        </Grid.ColumnDefinitions>

        <Label Content="{Binding InputFile}"
               HorizontalAlignment="Left" VerticalAlignment="Center"
               Margin="10"/>
        <Button Content="Select File" Grid.Column="1"
                HorizontalAlignment="Left" VerticalAlignment="Center"
                Padding="10,5" Margin="10"
                Click="btnSelectFile_Click"/>
    </Grid>

In the code-behind, we generate an output file name and load the input file into a Bitmap before calling the main ASCII Art generation method.

    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        public MainWindow()
        {
            InitializeComponent();
            this.DataContext = this;

            inputFile = "Select an image file to use for ASCII Art";
        }

        private string inputFile;
        public string InputFile
        {
            get { return inputFile; }
            set
            {
                if (value != inputFile)
                {
                    inputFile = value;
                    RaisePropertyChanged("InputFile");
                }
            }
        }

        async private void btnSelectFile_Click(object sender, RoutedEventArgs e)
        {
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.Filter = "Image Files (*.jpg, *.png)|*.jpg;*.png;";
            ofd.Title = "Select an image file to convert";

            try
            {
                bool? bResult = ofd.ShowDialog();
                if (bResult.HasValue && (bool)bResult)
                {
                    InputFile = ofd.FileName;
                    await Task.Run(() => DoGenerate(InputFile));
                }
            }
            catch (Exception xx)
            {
                MessageBox.Show(string.Format("Fatal Error: {0}", xx.ToString()), "Fatal Error", MessageBoxButton.OK, MessageBoxImage.Error);
            }
        }

        private void DoGenerate(string inputFile)
        {
            int outputWidth = 100;

            FileInfo fi = new FileInfo(inputFile);
            if (!fi.Exists)
                throw new Exception(string.Format("File {0} not found", inputFile));
            string outputFile = Path.Combine(fi.DirectoryName, Path.GetFileNameWithoutExtension(inputFile) + ".txt");

            Bitmap bmInput = new Bitmap(inputFile);

            if (outputWidth > bmInput.Width)
                throw new Exception("Output width must be <= pixel width of image");

            // Generate the ASCII art
            AscArt.GenerateAsciiArt(bmInput, outputFile, outputWidth);

            // This will fire up default app for .txt files
            Process.Start(outputFile);
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void RaisePropertyChanged(string prop)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(prop));
        }
    }

Finally, here is the code for the class that generates the ASCII art.

    public static class AscArt
    {
        // Typical width/height for ASCII characters
        private const double FontAspectRatio = 0.6;

        // Available character set, ordered by decreasing intensity (brightness)
        private const string OutputCharSet = "@%#*+=-:. ";

        // Alternate char set uses more chars, but looks less realistic
        private const string OutputCharSetAlternate = "$@B%8&WM#*oahkbdpqwmZO0QLCJUYXzcvunxrjft/\\|()1{}[]?-_+~<>i!lI;:,\"^`'. ";

        public static void GenerateAsciiArt(Bitmap bmInput, string outputFile, int outputWidth)
        {
            // pixelChunkWidth/pixelChunkHeight - size of a chunk of pixels that will
            // map to 1 character.  These are doubles to avoid progressive rounding
            // error.
            double pixelChunkWidth = (double)bmInput.Width / (double)outputWidth;
            double pixelChunkHeight = pixelChunkWidth / FontAspectRatio;

            // Calculate output height to capture entire image
            int outputHeight = (int)Math.Round((double)bmInput.Height / pixelChunkHeight);

            // Generate output image, row by row
            double pixelOffSetTop = 0.0;
            StringBuilder sbOutput = new StringBuilder();

            for (int row = 1; row <= outputHeight; row++)
            {
                double pixelOffSetLeft = 0.0;

                for (int col = 1; col <= outputWidth; col++)
                {
                    // Calculate brightness for this set of pixels by averaging
                    // brightness across all pixels in this pixel chunk
                    double brightSum = 0.0;
                    int pixelCount = 0;
                    for (int pixelLeftInd = 0; pixelLeftInd < (int)pixelChunkWidth; pixelLeftInd++)
                        for (int pixelTopInd = 0; pixelTopInd < (int)pixelChunkHeight; pixelTopInd++)
                        {
                            // Each call to GetBrightness returns value between 0.0 and 1.0
                            int x = (int)pixelOffSetLeft + pixelLeftInd;
                            int y = (int)pixelOffSetTop + pixelTopInd;
                            if ((x < bmInput.Width) && (y < bmInput.Height))
                            {
                                brightSum += bmInput.GetPixel(x, y).GetBrightness();
                                pixelCount++;
                            }
                        }

                    // Average brightness for this entire pixel chunk, between 0.0 and 1.0
                    double pixelChunkBrightness = brightSum / pixelCount;

                    // Target character is just relative position in ordered set of output characters
                    int outputIndex = (int)Math.Floor(pixelChunkBrightness * OutputCharSet.Length);
                    if (outputIndex == OutputCharSet.Length)
                        outputIndex--;

                    char targetChar = OutputCharSet[outputIndex];

                    sbOutput.Append(targetChar);

                    pixelOffSetLeft += pixelChunkWidth;
                }
                sbOutput.AppendLine();
                pixelOffSetTop += pixelChunkHeight;
            }

            // Dump output string to file
            File.WriteAllText(outputFile, sbOutput.ToString());
        }
    }

719-001

 

Full solution available here.

About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

One Response to #719 – ASCII Art Generator

  1. Pingback: Dew Drop – December 26, 2012 (#1,470) | Alvin Ashcraft's Morning Dew

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