C ＃ convert PDF files into pictures

Preface

Today, a colleague told me what you got pdf The file is a little inconsistent with our existing software process , Can you take us pdf Turn the file into a picture ！ Do as you say , Because I have studied for some time before pdf Related components of the file , So I am github Before you found me on the star The warehouse of ,PdfiumViewer Open source address : https://github.com/pvginkel/PdfiumViewer：

First let's open up Nuget install PdfiumViewer and ImageResizer.Plugins.PdfiumRenderer.Pdfium.Dll.

For a demand , We should know what properties the object we operate on has ？

So we get pdf The file should know ,pdf It has attributes such as the number of pages and the height and width of the file .

For pictures , Picture has height , Width ( The resolution of the ) And horizontal resolution and vertical resolution (dpi) And other attributes are more important ！

After we understand these properties, we can start to work , The first step is to load our pdf file , Get the number of pages and size of the file .

var pdf = PdfiumViewer.PdfDocument.Load(strpdfPath);
var pdfpage = pdf.PageCount;
var pagesizes = pdf.PageSizes;

Then assemble the height, width, horizontal resolution, vertical resolution and other attributes of the picture

document.Render(pageNumber - 1, size.Width, size.Height, dpi, dpi, PdfRenderFlags.Annotations);

Finally, save the picture

image.Save(stream, ImageFormat.Jpeg);

The complete code is as follows

public class PdfToImage
{
    /// <summary>
    /// 
    /// </summary>
    /// <param name="filePath">pdf File path </param>
    /// <param name="picPath">picture File path </param>
    public  void PdfToPic(string filePath, string picPath)
    {

        var pdf = PdfiumViewer.PdfDocument.Load(filePath);
        var pdfpage = pdf.PageCount;
        var pagesizes = pdf.PageSizes;

        for (int i = 1; i <= pdfpage; i++)
        {
            Size size = new Size();
            size.Height = (int)pagesizes[(i - 1)].Height;
            size.Width = (int)pagesizes[(i - 1)].Width;
            // You can put ".jpg" Write in other forms 
            RenderPage(filePath, i, size, picPath);
        }

    }

    private void RenderPage(string pdfPath, int pageNumber, System.Drawing.Size size, string outputPath, int dpi = 300)
    {
        using (var document = PdfiumViewer.PdfDocument.Load(pdfPath))
        using (var stream = new FileStream(outputPath, FileMode.Create))
        using (var image = GetPageImage(pageNumber, size, document, dpi))
        {
            image.Save(stream, ImageFormat.Jpeg);
        }
    }
    private static System.Drawing.Image GetPageImage(int pageNumber, Size size, PdfiumViewer.PdfDocument document, int dpi)
    {
        return document.Render(pageNumber - 1, size.Width, size.Height, dpi, dpi, PdfRenderFlags.Annotations);

    }
}