声明：此方法只适用于windows系统

利用freetype的时候，需要传入字体的路径，找了半天找不到一个合适的方法，经指导研究，找到一种合适的方法，

贴出来共享。

#include<dwrite.h>
#pragma once dwrite.libvoid GetSystemFont(){std::map<std::wstring, std::wstring> m_systemFonts  ;m_systemFonts.clear();IDWriteFontCollection* pFontCollection = NULL;// Get the system font collection.HRESULT hr = S_OK;IDWriteFactory* pDWriteFactory = NULL;if (SUCCEEDED(hr)){hr = DWriteCreateFactory(DWRITE_FACTORY_TYPE_SHARED,__uuidof(IDWriteFactory),reinterpret_cast<IUnknown**>(&pDWriteFactory));}// Get the system font collection.if (SUCCEEDED(hr)){hr = pDWriteFactory->GetSystemFontCollection(&pFontCollection);}UINT32 familyCount = 0;// Get the number of font families in the collection.if (SUCCEEDED(hr)){familyCount = pFontCollection->GetFontFamilyCount();}for (UINT32 i = 0; i < familyCount; ++i) {IDWriteFontFamily* pFontFamily = NULL;// Get the font family.if (SUCCEEDED(hr)){IDWriteLocalizedStrings* pFamilyNames = NULL;hr = pFontCollection->GetFontFamily(i, &pFontFamily);// Get a list of localized strings for the family name.if (SUCCEEDED(hr)){hr = pFontFamily->GetFamilyNames(&pFamilyNames);}UINT32 index = 0;BOOL exists = false;if (!exists)index = 0;UINT32 length = 0;// Get the string length.if (SUCCEEDED(hr)){hr = pFamilyNames->GetStringLength(index, &length);}// Allocate a string big enough to hold the name.wchar_t* name = new wchar_t[length + 1];std::wstring sname;std::wstring sname_unicode;std::wstring fpath;// Get the family name.if (SUCCEEDED(hr)){hr = pFamilyNames->GetString(index, name, length + 1);//sname 为英文名sname = std::wstring(name);fpath = GetSystemFontFile(sname);if (fpath.empty()) {continue;}}wchar_t localeName[LOCALE_NAME_MAX_LENGTH];if (SUCCEEDED(hr)){// Get the default locale for this user.int defaultLocaleSuccess = GetUserDefaultLocaleName(localeName, LOCALE_NAME_MAX_LENGTH);//If the default locale is returned, find that locale name, otherwise use "en-us".if (defaultLocaleSuccess){hr = pFamilyNames->FindLocaleName(localeName, &index, &exists);}if (SUCCEEDED(hr) && !exists) // if the above find did not find a match, retry with US English{hr = pFamilyNames->FindLocaleName(L"en-us", &index, &exists);}}// If the specified locale doesn't exist, select the first on the list.if (!exists)index = 0;length = 0;// Get the string length.if (SUCCEEDED(hr)){hr = pFamilyNames->GetStringLength(index, &length);}// Get the family name.if (SUCCEEDED(hr)){hr = pFamilyNames->GetString(index, name, length + 1);//sname_unicode为对应的中文名sname_unicode = std::wstring(name);m_systemFonts[sname_unicode] = fpath;}delete[]name;if (pFontFamily){pFontFamily->Release();pFontFamily = NULL;}if (pFamilyNames){pFamilyNames->Release();pFamilyNames = NULL;}}}if (pFontCollection){pFontCollection->Release();pFontCollection = NULL;}if (pDWriteFactory){pDWriteFactory->Release();pDWriteFactory = NULL;}}}
std::wstring GetSystemFontFile(const std::wstring &faceName) {std::wstring wsFontFile;static const LPWSTR fontRegistryPath = L"Software\\Microsoft\\Windows NT\\CurrentVersion\\Fonts";HKEY hKey;LONG result;std::wstring wsFaceName(faceName.begin(), faceName.end());// Open Windows font registry keyresult = RegOpenKeyEx(HKEY_LOCAL_MACHINE, fontRegistryPath, 0, KEY_READ, &hKey);if (result != ERROR_SUCCESS) {return L"";}DWORD maxValueNameSize, maxValueDataSize;result = RegQueryInfoKey(hKey, 0, 0, 0, 0, 0, 0, 0, &maxValueNameSize, &maxValueDataSize, 0, 0);if (result != ERROR_SUCCESS) {return L"";}DWORD valueIndex = 0;LPWSTR valueName = new WCHAR[maxValueNameSize];LPBYTE valueData = new BYTE[maxValueDataSize];DWORD valueNameSize, valueDataSize, valueType;// Look for a matching font namedo {wsFontFile.clear();valueDataSize = maxValueDataSize;valueNameSize = maxValueNameSize;result = RegEnumValue(hKey, valueIndex, valueName, &valueNameSize, 0, &valueType, valueData, &valueDataSize);valueIndex++;if (result != ERROR_SUCCESS || valueType != REG_SZ) {continue;}std::wstring wsValueName(valueName, valueNameSize);// Found a matchif (_wcsnicmp(wsFaceName.c_str(), wsValueName.c_str(), wsFaceName.length()) == 0) {wsFontFile.assign((LPWSTR)valueData, valueDataSize);break;}} while (result != ERROR_NO_MORE_ITEMS);delete[] valueName;delete[] valueData;RegCloseKey(hKey);if (wsFontFile.empty()) {return L"";}// Build full font file pathWCHAR winDir[MAX_PATH];GetWindowsDirectory(winDir, MAX_PATH);std::wstringstream ss;ss << winDir << "\\Fonts\\" << wsFontFile;wsFontFile = ss.str();return wsFontFile;
}