load a ttf font with the Windows API

Question

With CreateFont one can specify font name and a bunch of other properties. However, what if I have a font.ttf file, and I want that particular font to be loaded by windows? How do I specify that specific file to be used?

Answer 1

It's admittedly rather indirect, but you could utilize GDI interop with DWrite when running on Windows 7+.

#include <Windows.h>
#include <WindowsX.h>
#include <DWrite.h>

...

// Make the font file visible to GDI.
AddFontResourceEx(fontFileName, FR_PRIVATE, 0);
if (SUCCEEDED(GetLogFontFromFileName(fontFileName, &logFont)))
{
    logFont.lfHeight = -long(desiredPpem);
    HFONT hf = CreateFontIndirect(&logFont);
    HFONT oldFont = SelectFont(hdc, hf);
    ...
    // Do stuff...
    ...
    SelectFont(hdc, oldFont);
}
RemoveFontResource(fontFileName);

....

HRESULT GetLogFontFromFileName(_In_z_ wchar const* fontFileName, _Out_ LOGFONT* logFont)
{
    // DWrite objects
    ComPtr<IDWriteFactory> dwriteFactory;
    ComPtr<IDWriteFontFace> fontFace;
    ComPtr<IDWriteFontFile> fontFile;
    ComPtr<IDWriteGdiInterop> gdiInterop;

    // Set up our DWrite factory and interop interface.
    IFR(DWriteCreateFactory(
        DWRITE_FACTORY_TYPE_SHARED,
        __uuidof(IDWriteFactory),
        reinterpret_cast<IUnknown**>(&dwriteFactory)
        );
    IFR(g_dwriteFactory->GetGdiInterop(&gdiInterop));

    // Open the file and determine the font type.
    IFR(g_dwriteFactory->CreateFontFileReference(fontFileName, nullptr, &fontFile));
    BOOL isSupportedFontType = false;
    DWRITE_FONT_FILE_TYPE fontFileType;
    DWRITE_FONT_FACE_TYPE fontFaceType;
    UINT32 numberOfFaces = 0;
    IFR(fontFile->Analyze(&isSupportedFontType, &fontFileType, &fontFaceType, &numberOfFaces));

    if (!isSupportedFontType)
        return DWRITE_E_FILEFORMAT;

    // Set up a font face from the array of font files (just one)
    ComPtr<IDWriteFontFile> fontFileArray[] = {fontFile};
    IFR(g_dwriteFactory->CreateFontFace(
        fontFaceType,
        ARRAYSIZE(fontFileArray), // file count
        &fontFileArray[0], // or GetAddressOf if WRL ComPtr
        0, // faceIndex
        DWRITE_FONT_SIMULATIONS_NONE,
        &fontFace
        );

    // Get the necessary logical font information.
    IFR(gdiInterop->ConvertFontFaceToLOGFONT(fontFace, OUT logFont));

    return S_OK;
}

Where IFR is just a failure macro that returns on a FAILED HRESULT, and ComPtr is a helper smart pointer class (substitute with your own, or ATL CComPtr, WinRT ComPtr, VS2013 _com_ptr_t...).

Answer 2

I'm pretty sure you can't. All requests for fonts go through the font mapper, and it picks out the font file that comes the closest to meeting the specifications you've given. Though I'm not sure it even does in reality, it could at least theoretically use (for example) data from two entirely separate font files to create one logical font.