如何获取文件缩略图(C#和C++实现)

在C++中，可以有以下两种办法

使用COM接口IThumbnailCache

文档链接：IThumbnailCache (thumbcache.h) - Win32 apps | Microsoft Learn

示例代码如下：

VOID GetFileThumbnail(PCWSTR path) {     HRESULT hr = CoInitialize(nullptr);      IShellItem* item = nullptr;     hr = SHCreateItemFromParsingName(path, nullptr, IID_PPV_ARGS(&item));      IThumbnailCache* cache = nullptr;     hr = CoCreateInstance(         CLSID_LocalThumbnailCache,         nullptr,         CLSCTX_INPROC,         IID_PPV_ARGS(&cache));      WTS_CACHEFLAGS flags = WTS_LOWQUALITY;     ISharedBitmap* shared_bitmap;     hr = cache->GetThumbnail(         item,         12*16,         WTS_EXTRACT,         &shared_bitmap,         nullptr,         nullptr);      HBITMAP hbitmap = NULL;     hr = shared_bitmap->GetSharedBitmap(&hbitmap);     shared_bitmap->Release();     cache->Release();     CoUninitialize();      //使用hbitmap，使用完成后调用DeleteObject     DeleteObject(hbitmap);  }

前面我一直使用的这种方式，但是最近系统升级后，会报 Generic Error in GDI+ 

后面我升级成了下面这种方式

使用IShellItemImageFactory接口

文档链接：IShellItemImageFactory (shobjidl_core.h) - Win32 apps | Microsoft Learn

官方示例代码：Windows-classic-samples/Samples/Win7Samples/winui/shell/appplatform/UsingImageFactory/ImageFactorySample.cpp at main · microsoft/Windows-classic-samples · GitHub

HRESULT hr = CoInitializeEx(NULL, COINIT_APARTMENTTHREADED | COINIT_DISABLE_OLE1DDE);     HBITMAP hbmp = NULL;      if (SUCCEEDED(hr))     {         IShellItemImageFactory* pImageFactory;         hr = SHCreateItemFromParsingName(path, NULL, IID_PPV_ARGS(&pImageFactory));         if (SUCCEEDED(hr))         {             SIZE size = { 256, 256 };  //图像大小             hr = pImageFactory->GetImage(size, SIIGBF_THUMBNAILONLY, &hbmp);             pImageFactory->Release();         }         CoUninitialize();          //使用hbmp,使用完成后调用DeleteObject         DeleteObject(hbmp);     }

在C#中使用，可以直接nuget引用  WindowsAPICodePack-Shell  包

PM> NuGet\Install-Package WindowsAPICodePack-Shell -Version 1.1.1

然后用下面的代码就可以获取文件缩略图

ShellFile shellFile = ShellFile.FromFilePath(filepath); Bitmap shellThumb = shellFile.Thumbnail.ExtraLargeBitmap;