WIP: DirectWrite font manager

Untested, will not compile and leaks memory left and right. Putting it
here so I don’t lose it, and in case someone else might be interested in
it.

src/winfonts.cc

@@ -0,0 +1,221 @@
+#include <dwrite.h>
+#include <wchar.h>
+#include <lua.h>
+#include <lauxlib.h>
+#include <lualib.h>
+
+#if !defined LUA_VERSION_NUM
+/* Lua 5.0 */
+#define luaL_Reg luaL_reg
+#endif
+
+#if !defined LUA_VERSION_NUM || LUA_VERSION_NUM==501
+/*
+** Adapted from Lua 5.2.0
+*/
+static void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup) {
+  luaL_checkstack(L, nup+1, "too many upvalues");
+  for (; l->name != nullptr; l++) {  /* fill the table with given functions */
+    int i;
+    lua_pushstring(L, l->name);
+    for (i = 0; i < nup; i++)  /* copy upvalues to the top */
+      lua_pushvalue(L, -(nup+1));
+    lua_pushcclosure(L, l->func, nup);  /* closure with those upvalues */
+    lua_settable(L, -(nup + 3));
+  }
+  lua_pop(L, nup);  /* remove upvalues */
+}
+#endif
+
+WCHAR* toW(const char* c) {
+  const size_t l = mbsrtowcs(nullptr, &c, 0, nullptr) + 1;
+  WCHAR* w = new WCHAR[l];
+  mbsrtowcs(w, &c, l, nullptr);
+  return w;
+}
+
+char* toC(const WCHAR* w) {
+  const size_t l = wcsrtombs(nullptr, &w, 0, nullptr) + 1;
+  char* c = new char[l];
+  wcsrtombs(c, &w, l, nullptr);
+  return c;
+}
+
+int face_from_options(lua_State* L) {
+  int index = 0;
+  const char* filename = nullptr;
+  double pointsize = 12;
+  const char* family = "Gentium";
+  int weight = 400;
+  const char* style = "regular";
+
+  if (!lua_istable(L, 1)) return 0;
+
+  lua_pushstring(L, "size");
+  lua_gettable(L, -2);
+  if (lua_isnumber(L, -1)) { pointsize = lua_tonumber(L, -1); }
+  lua_pop(L,1);
+
+  lua_pushstring(L, "filename");
+  lua_gettable(L, -2);
+  if (lua_isstring(L, -1)) {
+    filename = lua_tostring(L, -1);
+    lua_pop(L,1);
+    lua_newtable(L);
+    lua_pushstring(L, "filename");
+    lua_pushstring(L, (char*)filename);
+    lua_settable(L, -3);
+  }
+  lua_pop(L,1);
+
+  if (filename == NULL) {
+    lua_pushstring(L, "family");
+    lua_gettable(L, -2);
+    if (lua_isstring(L, -1)) { family = lua_tostring(L, -1); }
+    lua_pop(L,1);
+
+    lua_pushstring(L, "weight");
+    lua_gettable(L, -2);
+    if (lua_isnumber(L, -1)) { weight = lua_tointeger(L, -1); }
+    lua_pop(L,1);
+
+    lua_pushstring(L, "style");
+    lua_gettable(L, -2);
+    if (lua_isstring(L, -1)) { style = lua_tostring(L, -1); }
+    lua_pop(L,1);
+
+    DWRITE_FONT_WEIGHT dwWeight;
+    if      (weight <= 100) dwWeight = DWRITE_FONT_WEIGHT_THIN;
+    else if (weight <= 200) dwWeight = DWRITE_FONT_WEIGHT_ULTRA_LIGHT;
+    else if (weight <= 300) dwWeight = DWRITE_FONT_WEIGHT_LIGHT;
+    else if (weight <= 350) dwWeight = DWRITE_FONT_WEIGHT_SEMI_LIGHT;
+    else if (weight <= 400) dwWeight = DWRITE_FONT_WEIGHT_NORMAL;
+    else if (weight <= 500) dwWeight = DWRITE_FONT_WEIGHT_MEDIUM;
+    else if (weight <= 600) dwWeight = DWRITE_FONT_WEIGHT_SEMI_BOLD;
+    else if (weight <= 700) dwWeight = DWRITE_FONT_WEIGHT_BOLD;
+    else if (weight <= 800) dwWeight = DWRITE_FONT_WEIGHT_ULTRA_BOLD;
+    else if (weight <= 900) dwWeight = DWRITE_FONT_WEIGHT_BLACK;
+    else                    dwWeight = DWRITE_FONT_WEIGHT_ULTRA_BLACK;
+
+    DWRITE_FONT_STRETCH dwStretch = DWRITE_FONT_STRETCH_NORMAL;
+
+    // TODO: what are the other possible styles?
+    DWRITE_FONT_STYLE dwStyle;
+    if (strcasecmp(style, "italic") == 0)
+      dwStyle = DWRITE_FONT_STYLE_ITALIC;
+    else if (strcasecmp(style, "oblique") == 0)
+      dwStyle = DWRITE_FONT_STYLE_OBLIQUE;
+    else
+      dwStyle = DWRITE_FONT_STYLE_NORMAL;
+
+    IDWriteFactory* pDWriteFactory = nullptr;
+    HRESULT hr = DWriteCreateFactory(
+              DWRITE_FACTORY_TYPE_SHARED,
+              __uuidof(IDWriteFactory),
+              reinterpret_cast<IUnknown**>(&pDWriteFactory)
+              );
+
+    IDWriteFontCollection* pFontCollection = nullptr;
+    if (SUCCEEDED(hr))
+      hr = pDWriteFactory->GetSystemFontCollection(&pFontCollection);
+
+    WCHAR* dwFamily = toW(family);
+    UINT32 dwIndex = 0;
+    BOOL dwExists = FALSE;
+    if (SUCCEEDED(hr))
+      pFontCollection->FindFamilyName(dwFamily, &dwIndex, &dwExists);
+
+    IDWriteFontFamily* pFontFamily = nullptr;
+    if (SUCCEEDED(hr) && dwExists)
+      hr = pFontCollection->GetFontFamily(dwIndex, &pFontFamily);
+
+    IDWriteFont* pFont = nullptr;
+    if (SUCCEEDED(hr))
+      hr = pFontFamily->GetFirstMatchingFont(dwWeight, dwStretch, dwStyle, &pFont);
+
+    IDWriteFontFace* pFontFace = nullptr;
+    if (SUCCEEDED(hr))
+      hr = pFont->CreateFontFace(&pFontFace);
+
+    if (SUCCEEDED(hr))
+      index = pFontFace->GetIndex();
+
+    UINT32 numberOfFiles = 0;
+    if (SUCCEEDED(hr))
+      hr = pFontFace->GetFiles(&numberOfFiles, nullptr);
+
+    IDWriteFontFile* pFontFile = nullptr;
+    if (SUCCEEDED(hr) && numberOfFiles == 1)
+      hr = pFontFace->GetFiles(&numberOfFiles, &pFontFile);
+
+    void const* pFontFileReferenceKey = nullptr;
+    UINT32 nFontFileReferenceKey = 0;
+    if (SUCCEEDED(hr))
+      hr = pFontFile->GetReferenceKey(&pFontFileReferenceKey, &nFontFileReferenceKey);
+
+    IDWriteFontFileLoader* pFontFileLoader = nullptr;
+    if (SUCCEEDED(hr))
+      hr = pFontFile->GetLoader(&pFontFileLoader);
+
+    IDWriteLocalFontFileLoader* pLocalFontFileLoader = nullptr;
+    if (SUCCEEDED(hr))
+      hr = pFontFileLoader->QueryInterface(__uuidof(IDWriteLocalFontFileLoader),
+                                           reinterpret_cast<void**>(&pLocalFontFileLoader));
+
+    UINT32 nFilePath = 0;
+    if (SUCCEEDED(hr))
+      hr = pLocalFontFileLoader->GetFilePathLengthFromKey(pFontFileReferenceKey,
+                                                          nFontFileReferenceKey,
+                                                          &nFilePath);
+
+    WCHAR* pFilePath = nullptr;
+    if (SUCCEEDED(hr)) {
+      pFilePath = new WCHAR[nFilePath + 1];
+      hr = pLocalFontFileLoader->GetFilePathFromKey(pFontFileReferenceKey,
+                                                    nFontFileReferenceKey,
+                                                    pFilePath, nFilePath);
+    }
+
+    if (SUCCEEDED(hr))
+      filename = toC(pFilePath);
+
+    // FIXME: get named instance index
+
+    lua_newtable(L);
+    lua_pushstring(L, "filename");
+    lua_pushstring(L, filename);
+    lua_settable(L, -3);
+
+    lua_pushstring(L, "family");
+    lua_pushstring(L, family);
+    lua_settable(L, -3);
+
+    delete[] dwFamily;
+    delete[] pFilePath;
+    delete[] filename;
+  }
+
+  lua_pushstring(L, "index");
+  lua_pushinteger(L, index);
+  lua_settable(L, -3);
+
+  lua_pushstring(L, "pointsize");
+  lua_pushnumber(L, pointsize);
+  lua_settable(L, -3);
+
+  return 1;
+}
+
+
+static const struct luaL_Reg lib_table [] = {
+  {"_face", face_from_options},
+  {nullptr, nullptr}
+};
+
+
+int luaopen_winfonts (lua_State* L) {
+  lua_newtable(L);
+  luaL_setfuncs(L, lib_table, 0);
+  return 1;
+}
+