Get a file's thumbnail or icon (Win32)

[Josh]

There are too many unknown factors to make this code part of the official API yet, so I am posting it here for now:

#include "UltraEngine.h"
#include "GetFileIcon.h"
#ifdef _WIN32
#include <commoncontrols.h>
#endif

namespace UltraEngine::Editor
{
	shared_ptr<Pixmap> GetFileIcon(const WString& file, const int size)
	{
		shared_ptr<Pixmap> pixmap;
#ifdef _WIN32
		CoInitialize(nullptr);
		WString path = RealPath(file).Replace("/", "\\");

		IShellItemImageFactory* pImageFactory;
		IShellItem* psiFile;
		LPCWSTR szFilePath = path.Data();
		auto hr = SHCreateItemFromParsingName(szFilePath, NULL, IID_PPV_ARGS(&pImageFactory));
		if (SUCCEEDED(hr))
		{
			HBITMAP hbmp;
			SIZE sz = { size,size };
			//SIIGBF_BIGGERSIZEOK
			//SIIGBF_RESIZETOFIT //this may invert some images
			hr = pImageFactory->GetImage(sz, SIIGBF_RESIZETOFIT | SIIGBF_BIGGERSIZEOK, &hbmp);
			if (SUCCEEDED(hr))
			{
				BITMAP bminfo = {};
				if (GetObjectW(hbmp, sizeof(bminfo), &bminfo) != 0)
				{
					auto hdc = GetDC(GetDesktopWindow());
					BITMAPINFO bmi = {};
					bmi.bmiHeader.biSize = sizeof(bmi.bmiHeader);					
					auto r = GetDIBits(hdc, hbmp, 0, 1, nullptr, &bmi, DIB_RGB_COLORS);
					TextureFormat format = TextureFormat(0);
					if (bminfo.bmBitsPixel == 24) format = TEXTURE_BGR;
					if (bminfo.bmBitsPixel == 32) format = TEXTURE_BGRA;
					bmi.bmiHeader.biHeight = -Abs(bmi.bmiHeader.biHeight);
					bmi.bmiHeader.biCompression = BI_RGB;
					if (format != 0)
					{
						pixmap = CreatePixmap(bminfo.bmWidth, bminfo.bmHeight, format);
						Assert(pixmap->pixels->GetSize() == bmi.bmiHeader.biSizeImage);
						auto r = GetDIBits(hdc, hbmp, 0, bminfo.bmHeight, pixmap->pixels->Data(), &bmi, DIB_RGB_COLORS);
					}
				}
				DeleteObject(hbmp);
			}
			pImageFactory->Release();
		}
#endif
		return pixmap;
	}
}

 

[Josh]

Updated to fix flipped images.