How can I use SetCurrentConsoleFontEx with fonts loaded by AddFontMemResourceEx? - c++

Question

My main goal is to set the console font to Unifont using windows API functions. I can successfully do this by calling AddFontResource with the filename. I would rather use AddFontMemResourceEx because then I can load the font from a Resource.
I tested a variety of calls to load the font, and here are the results:
AddFontResource(filename); //works
AddFontResourceEx(filename, FR_PRIVATE, NULL); //does not work
AddFontResourceEx(filename, FR_NOT_ENUM, NULL); //works
AddFontMemResourceEx(valid_pointer, data_size, NULL, &font_count); //does not work
I tested these with two fonts, Unifont, and Fira Code (the only other font I could find that would display on the terminal).
I wrote this program to cut out possible issues with loading the font as a resource.
#include <windows.h>
#include <iostream>
#include <fstream>
#include <filesystem>
int main() {
std::string filename = "unifont-13.0.04.ttf";
std::wstring fontname = L"Unifont";
auto fileSize = std::filesystem::file_size(filename);
std::ifstream in(filename, std::ifstream::binary);
char* data = new char[fileSize];
in.read(data, fileSize);
in.close();
DWORD loadedFonts = 0;
AddFontMemResourceEx(reinterpret_cast<PVOID>(data), fileSize, NULL, &loadedFonts);
CONSOLE_FONT_INFOEX cfi;
cfi.cbSize = sizeof(cfi);
cfi.nFont = 0;
cfi.dwFontSize.X = 0;
cfi.dwFontSize.Y = 16;
cfi.FontFamily = FF_DONTCARE;
cfi.FontWeight = FW_NORMAL;
wcscpy_s(cfi.FaceName, fontname.c_str());
SetCurrentConsoleFontEx(GetStdHandle(STD_OUTPUT_HANDLE), FALSE, &cfi);
std::wcout << "I found " << loadedFonts << " fonts.";
std::wcin.ignore();
delete[] data;
}
With unifont, AddFontMemResourceEx will set loadedFonts to two, indicating it did find and load two fonts, and did not fail.
Worth noting, the HANDLE returned by SetCurrentConsoleFontEx is entirely useless for doing anything except calling RemoveFontMemResourceEx, which you don't even need to do in most cases because the fonts will be unloaded when the process ends.
Why does SetCurrentConsoleFontEx work with AddFontResource but not with AddFontMemResourceEx?

Answer 1

From the doc,
This function allows an application to get a font that is embedded in
a document or a webpage. A font that is added by AddFontMemResourceEx
is always private to the process that made the call and is not
enumerable.
For other content, please refer to zett42's answer,
You are calling AddFontResourceEx() with FR_PRIVATE flag, which means
the font is available only to your process.
Unfortunately, the console window is not part of your process
(GetWindowThreadProcessId() lies in this regard!). It is hosted by a
system process ("csrss.exe" before Win 7, "conhost.exe" since then).