在 C# 中将 PDF 导出为 JPG
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Export PDF to JPG(s) in C#
提问by Jason
I need to save a one page pdf document as an image for a thumbnail on a website.
我需要将一页 pdf 文档保存为网站上缩略图的图像。
I've been messing around with PDFSharp and have had no luck.
我一直在搞弄 PDFSharp 并且没有运气。
I have tried this: http://www.pdfsharp.net/wiki/ExportImages-sample.ashx?AspxAutoDetectCookieSupport=1but all it does is extract the embedded images in the PDF file which is not the desired result.
我试过这个：http: //www.pdfsharp.net/wiki/ExportImages-sample.ashx?AspxAutoDetectCookieSupport=1但它所做的只是提取 PDF 文件中的嵌入图像，这不是预期的结果。
Ideas on how to do this? Anyone know a good library that can handle this?
关于如何做到这一点的想法？任何人都知道一个可以处理这个问题的好图书馆？
Edit: Please let me know why this is such a bad question. If anyone has a good solution to this it would be a great resource for many other people. Especially since google searches come up empty.
编辑：请让我知道为什么这是一个糟糕的问题。如果有人对此有很好的解决方案，那么这对许多其他人来说将是一个很好的资源。特别是因为谷歌搜索是空的。
回答by Jason
Take a look at Ghostscript. You can render PDF to images with it.
看看 Ghostscript。您可以使用它将 PDF 渲染为图像。
http://www.mattephraim.com/blog/2009/01/06/a-simple-c-wrapper-for-ghostscript/
http://www.mattephraim.com/blog/2009/01/06/a-simple-c-wrapper-for-ghostscript/
回答by plinth
(disclaimer: I work for Atalasoft and wrote a lot of the PDF technology) If you use the PdfDecoder in AtalasoftdotImage, this is straight forward:
（免责声明：Atalasoft我的工作，写了很多的PDF技术的）如果你使用的PdfDecoder AtalasoftdotImage，这是直截了当：
public void PdfToJpegThumb(Stream srcStream, int pageNo, int maxDimension, Stream dstStream)
{
PdfDecoder decoder = new PdfDecoder();
decoder.Resolution = 96; // reduce default resolution to speed up rendering
// render page
using (AtalaImage pdfimage = decoder.read(srcStream, pageNo, null)) {
Thumbnail tn = new Thumbnail(maxDimension, maxDimension);
// make a thumbnail image
using (AtalaImage tnImage = tn.Create(pdfImage)) {
// save it
tnImage.Save(dstStream, new JpegEncoder(), null);
}
}
}
回答by AffineMesh
ABCpdf exports PDF documents to JPEG with C#. See: http://www.websupergoo.com/helppdfnet/source/4-examples/19-rendering.htm
ABCpdf 使用 C# 将 PDF 文档导出为 JPEG。请参阅：http: //www.websupergoo.com/helppdfnet/source/4-examples/19-rendering.htm
回答by CompanyDroneFromSector7G
I got this from somewhere on the web - can't remember exactly where but it works for me!
I just made it into a nice function.
It uses the GhostScript APIs (GSdll32.dll)
Examples of the imageFormat parameter are "jpeg", "tiff32nc", etc.
我从网上的某个地方得到了这个 - 不记得确切的位置，但它对我有用！
我只是把它变成了一个很好的函数。
它使用 GhostScript API (GSdll32.dll)
imageFormat 参数的示例是“jpeg”、“tiff32nc”等。
#region GhostScript API functions
[DllImport("gsdll32.dll", EntryPoint = "gsapi_new_instance")]
private static extern int CreateAPIInstance(out IntPtr pinstance,
IntPtr caller_handle);
[DllImport("gsdll32.dll", EntryPoint = "gsapi_init_with_args")]
private static extern int InitAPI(IntPtr instance, int argc, IntPtr argv);
[DllImport("gsdll32.dll", EntryPoint = "gsapi_exit")]
private static extern int ExitAPI(IntPtr instance);
[DllImport("gsdll32.dll", EntryPoint = "gsapi_delete_instance")]
private static extern void DeleteAPIInstance(IntPtr instance);
#endregion
public bool CreateImage(string inputPath, string outputPath, string imageFormat, int firstPage, int lastPage, int width, int height)
{
bool result = false;
try
{
string[] args = GetArgs(inputPath, outputPath, imageFormat, firstPage, lastPage, width, height);
var argStrHandles = new GCHandle[args.Length];
var argPtrs = new IntPtr[args.Length];
// Create a handle for each of the arguments after
// they've been converted to an ANSI null terminated
// string. Then store the pointers for each of the handles
for (int i = 0; i < args.Length; i++)
{
argStrHandles[i] = GCHandle.Alloc(StringToAnsi(args[i]), GCHandleType.Pinned);
argPtrs[i] = argStrHandles[i].AddrOfPinnedObject();
}
// Get a new handle for the array of argument pointers
var argPtrsHandle = GCHandle.Alloc(argPtrs, GCHandleType.Pinned);
// Get a pointer to an instance of the GhostScript API
// and run the API with the current arguments
IntPtr gsInstancePtr;
CreateAPIInstance(out gsInstancePtr, IntPtr.Zero);
InitAPI(gsInstancePtr, args.Length, argPtrsHandle.AddrOfPinnedObject());
// Cleanup arguments in memory
for (int i = 0; i < argStrHandles.Length; i++)
argStrHandles[i].Free();
argPtrsHandle.Free();
// Clear API
ExitAPI(gsInstancePtr);
DeleteAPIInstance(gsInstancePtr);
result = true;
}
catch(Exception e)
{
throw e;
}
return result;
}
回答by Lilith River
Ghostscript is currently the de-facto standard for rendering PDFs. It's a bit tricky to wrap, even using GhostScriptSharp.
Ghostscript 目前是渲染 PDF 的事实上的标准。即使使用 GhostScriptSharp，包装起来也有点棘手。
Jason Morse wrote a great C# wrapper for rendering PDFsas a plugin to the open-source imageresizing.net library.
Jason Morse 编写了一个很棒的 C# 包装器，用于将 PDF 渲染为开源imageresizing.net 库的插件。
If it's an asp.net application, the library allows on-the-fly rendering, so you can just add a querystring to get the jpeg/png version:
如果它是一个 asp.net 应用程序，该库允许即时渲染，因此您只需添加一个查询字符串即可获取 jpeg/png 版本：
/pdfs/letter.pdf?format=jpg&page=2
/pdfs/letter.pdf?format=jpg&page=2
You can also use the managed API instead (in any application type - not asp.net specific)
您也可以使用托管 API（在任何应用程序类型中 - 不是特定于 asp.net）
ImageBuilder.Current.Build("letter.pdf","dest.jpg",new ResizeSettings("format=jpg;page=2"));
ImageBuilder.Current.Build("letter.pdf","dest.jpg",new ResizeSettings("format=jpg;page=2"));
The PdfRenderer plugin is GPL licensed, just like Ghostscript.
PdfRenderer 插件是 GPL 许可的，就像 Ghostscript 一样。
