基于C#和PDFSharp实现高效图片转PDF工具

private async void LoadImagesAsync(string folderPath)
{
    var files = Directory.GetFiles(folderPath, "*.jpg");
    foreach (var file in files)
    {
        await Task.Run(() => ProcessImage(file));
        UpdateProgressBar();
    }
}

using PdfSharp.Pdf;
using PdfSharp.Drawing;

var document = new PdfDocument();
var page = document.AddPage();
var gfx = XGraphics.FromPdfPage(page);

gfx.DrawString("Hello, PDF!", 
               new XFont("Arial", 20), 
               XBrushes.Black, 
               new XRect(0, 0, page.Width, page.Height),
               XStringFormats.Center);

document.Save("output.pdf");

gfx.DrawImage(xImage, x, y, width, height);

double dpi = 96; // 假设图像来自96DPI屏幕
double widthInPoints = (image.Width / dpi) * 72;
double heightInPoints = (image.Height / dpi) * 72;

gfx.DrawImage(xImage, 
              (page.Width - widthInPoints) / 2,
              (page.Height - heightInPoints) / 2);

var xImage = XImage.FromFile("photo.jpg"); // 自动识别为JPEG

Bitmap ConvertToGrayscale(Bitmap src)
{
    var gray = new Bitmap(src.Width, src.Height, PixelFormat.Format8bppIndexed);
    using (var g = Graphics.FromImage(gray))
    {
        var cm = new ColorMatrix { Matrix = new float[][] {
            new float[] {0.3f, 0.3f, 0.3f, 0, 0},
            new float[] {0.59f,0.59f,0.59f,0,0},
            new float[] {0.11f,0.11f,0.11f,0,0},
            new float[] {0,0,0,1,0},
            new float[] {0,0,0,0,1}
        }};
        var ia = new ImageAttributes();
        ia.SetColorMatrix(cm);
        g.DrawImage(src, new Rectangle(0,0,gray.Width,gray.Height),
                    0,0,src.Width,src.Height, GraphicsUnit.Pixel, ia);
    }
    return gray;
}

public class ConversionController
{
    private readonly IFileReader _fileReader;
    private readonly IImageProcessor _imageProcessor;
    private readonly IPdfGenerator _pdfGenerator;

    public ConversionController(IFileReader fileReader, 
                               IImageProcessor imageProcessor, 
                               IPdfGenerator pdfGenerator)
    {
        _fileReader = fileReader;
        _imageProcessor = imageProcessor;
        _pdfGenerator = pdfGenerator;
    }

    public async Task<bool> StartConversion(string[] imagePaths, string outputPath)
    {
        try
        {
            var images = await _fileReader.ReadImagesAsync(imagePaths);
            var processedImages = _imageProcessor.ProcessBatch(images);
            return await _pdfGenerator.GeneratePdfAsync(processedImages, outputPath);
        }
        catch (Exception ex)
        {
            Logger.LogError($"转换失败: {ex.Message}");
            return false;
        }
    }
}

public static List<string> GetImageFiles(string rootPath, bool recursive = true)
{
    var searchOption = recursive ? SearchOption.AllDirectories : SearchOption.TopDirectoryOnly;
    var extensions = new[] { ".jpg", ".jpeg", ".png", ".bmp", ".gif", ".tiff", ".webp" };
    var imageFiles = new List<string>();

    foreach (var ext in extensions)
    {
        try
        {
            var files = Directory.GetFiles(rootPath, "*" + ext, searchOption);
            imageFiles.AddRange(files.Where(File.Exists));
        }
        catch (UnauthorizedAccessException) { continue; }
        catch (IOException) { continue; }
    }

    return imageFiles.OrderBy(f => f).ToList();
}

public static List<ImageFileInfo> LoadImagesParallel(List<string> paths)
{
    var results = new ConcurrentBag<ImageFileInfo>();
    Parallel.ForEach(paths, path =>
    {
        try
        {
            var info = new FileInfo(path);
            using (var img = Image.FromFile(path))
            {
                results.Add(new ImageFileInfo
                {
                    FilePath = path,
                    Resolution = img.Size,
                    FileSize = info.Length,
                    Format = img.RawFormat
                });
            }
        }
        catch { /* 记录日志即可 */ }
    });

    return results.ToList();
}

public static PdfPage CreateAutoSizePage(Bitmap bitmap, double marginInch = 0.5)
{
    var dpi = bitmap.HorizontalResolution;
    var widthPt = (bitmap.Width / dpi) * 72;
    var heightPt = (bitmap.Height / dpi) * 72;

    var page = new PdfPage
    {
        Width = widthPt + marginInch * 72 * 2,
        Height = heightPt + marginInch * 72 * 2
    };

    return page;
}

public enum PaperSizeType
{
    A4,
    Letter,
    Legal,
    Custom
}

public static XRect GetPaperDimensions(PaperSizeType type)
{
    return type switch
    {
        PaperSizeType.A4 => new XRect(0, 0, 595.276, 841.89),
        PaperSizeType.Letter => new XRect(0, 0, 612, 792),
        PaperSizeType.Legal => new XRect(0, 0, 612, 1008),
        _ => throw new ArgumentOutOfRangeException(nameof(type))
    };
}

gfx.InterpolationMode = XInterpolationMode.HighQualityBicubic;
gfx.SmoothingMode = XSmoothingMode.AntiAlias;

<Grid>
    <Border BorderBrush="Gray" BorderThickness="2" 
            AllowDrop="True" Drop="OnDropHandler">
        <TextBlock Text="将图片拖拽至此区域" HorizontalAlignment="Center" VerticalAlignment="Center"/>
    </Border>
    <ListBox ItemsSource="{Binding ImageList}" Margin="10" Height="150" />
    <ProgressBar Value="{Binding Progress}" Visibility="{Binding IsProcessing, Converter={StaticResource BoolToVisibility}}"/>
    <Button Content="生成PDF" Command="{Binding GeneratePdfCommand}" HorizontalAlignment="Right" Margin="10"/>
</Grid>

using (var img = Image.FromFile(path))
{
    ImageExtensions.RotateImageByExifOrientation(ref img);
    var ximage = XImage.FromGdiPlusImage(img);
    graphics.DrawImage(ximage, 0, 0, page.Width, page.Height);
}

document.SecuritySettings.OwnerPassword = "admin123";
document.SecuritySettings.UserPassword = ""; 
document.SecuritySettings.Revisions = PdfStandardSecurityHandler.EncryptionAlgorithm.RC4_128;

using var watcher = new FileSystemWatcher(@"C:\Incoming\Images");
watcher.Created += async (s, e) =>
{
    await Task.Delay(2000); 
    if (IsImageFile(e.Name))
        await ProcessAndExportAsPdf(e.FullPath);
};
watcher.EnableRaisingEvents = true;