How to automatically choose most suitable font for different language?

Question

I need to get the most suitable font for different language. So I could draw different language's text without using GDI text out API such as TextOut.

Actually, the api TextOut does it.

    HFONT hFont = NULL;
    LOGFONT lg = {0};
    lg.lfHeight = 14;
    lg.lfWeight = FW_NORMAL;
    wcscpy_s(lg.lfFaceName, LF_FACESIZE ,L"Arial");
    hFont = CreateFontIndirect(&lg);
    SelectObject(hdc,hFont);
    TextOut(hdc, 0, 50, L"abc我爱", 5);

Because the Arial font does not support Chinese, TextOut should not be able to draw the Chinese '我爱'. But it does and choose a suitable font, a normal font rather than some kind of art font, for it.

How could I simulate what TextOut does, or is there any other way to figure out the best suitable font for one language under Windows?

Answer 1

Yes, it is possible to do this. Here is the slight modified code snippet from chrome project,

// Callback to |EnumEnhMetaFile()| to intercept font creation.
int CALLBACK MetaFileEnumProc(HDC hdc,
                              HANDLETABLE* table,
                              CONST ENHMETARECORD* record,
                              int table_entries,
                              LPARAM log_font)
{
    if (record->iType == EMR_EXTCREATEFONTINDIRECTW) {
        const EMREXTCREATEFONTINDIRECTW* create_font_record =
            reinterpret_cast<const EMREXTCREATEFONTINDIRECTW*>(record);
        *reinterpret_cast<LOGFONT*>(log_font) = create_font_record->elfw.elfLogFont;
    }
    return 1;
}

// Finds a fallback font to use to render the specified |text| with respect to
// an initial |font|. Returns the resulting font via out param |result|. Returns
// |true| if a fallback font was found.
// Adapted from WebKit's |FontCache::GetFontDataForCharacters()|.
// TODO(asvitkine): This should be moved to font_fallback_win.cc.
bool ChooseFallbackFont(HDC hdc,
                        HFONT font,
                        const wchar_t* text,
                        int text_length,
                        LOGFONT* result)
{
    // Use a meta file to intercept the fallback font chosen by Uniscribe.
    HDC meta_file_dc = CreateEnhMetaFile(hdc, NULL, NULL, NULL);
    if (!meta_file_dc)
        return false;

    if (font)
        SelectObject(meta_file_dc, font);

    SCRIPT_STRING_ANALYSIS script_analysis;
    HRESULT hresult =
        ScriptStringAnalyse(meta_file_dc, text, text_length, 0, -1,
        SSA_METAFILE | SSA_FALLBACK | SSA_GLYPHS | SSA_LINK,
        0, NULL, NULL, NULL, NULL, NULL, &script_analysis);

    if (SUCCEEDED(hresult)) {
        hresult = ScriptStringOut(script_analysis, 0, 0, 0, NULL, 0, 0, FALSE);
        ScriptStringFree(&script_analysis);
    }

    bool found_fallback = false;
    HENHMETAFILE meta_file = CloseEnhMetaFile(meta_file_dc);
    if (SUCCEEDED(hresult)) {
        LOGFONT log_font;
        log_font.lfFaceName[0] = 0;
        EnumEnhMetaFile(0, meta_file, MetaFileEnumProc, &log_font, NULL);
        if (log_font.lfFaceName[0]) {
            *result = log_font;
            found_fallback = true;
        }
    }
    DeleteEnhMetaFile(meta_file);

    return found_fallback;
}

Sample code:

                std::wstring arabicStr = L"ششش";
        hdc = BeginPaint(hWnd, &ps);
        LOGFONT logFont = {0};
        wcscpy_s(logFont.lfFaceName, L"微软雅黑");
        HFONT hFont = CreateFontIndirect(&logFont);
        ChooseFallbackFont(hdc, hFont, arabicStr.c_str(), arabicStr.length(), &logFont);
        ATLTRACE(logFont.lfFaceName);
        HFONT hFontNew = CreateFontIndirect(&logFont);
        HFONT hFontOld = (HFONT)SelectObject(hdc, hFontNew);
        wchar_t glyphs[10] = {0}; 
        GCP_RESULTS gcpRet = {0};
        gcpRet.lStructSize = sizeof(gcpRet);
        gcpRet.lpGlyphs = glyphs;
        gcpRet.nGlyphs = 10;
        ATLASSERT(GetCharacterPlacement(hdc, arabicStr.c_str(), arabicStr.length(), GCP_MAXEXTENT, &gcpRet, 
            GCP_DISPLAYZWG | GCP_GLYPHSHAPE | GCP_REORDER ));
        RECT rcClient;
        GetClientRect(hWnd, &rcClient);
        ExtTextOut(hdc, 200, 200, ETO_GLYPH_INDEX | ETO_RTLREADING, &rcClient, gcpRet.lpGlyphs, gcpRet.nGlyphs, NULL);
        SelectObject(hdc, hFontOld);
        DeleteObject(hFontNew);
        DeleteObject(hFont);
        EndPaint(hWnd, &ps);

微软雅黑 is a font which does not support arabic, so we need a fallback font for the arabic. In my box, GDI automatically choose Microsoft Sans Serif for the arabic.