如何在 DirectWrite 中使用默认 UI 字体绘制文本？

Question

CreateTextFormat 方法需要 fontFamilyName 参数。如何创建使用默认 UI 字体的 IDWriteTextFormat？

Answer 1

请注意，这里的所有代码都是在没有任何检查的情况下完成的（这里的方法太多 return HRESULT，会破坏这个例子！）。

要获得系统范围的字体，你应该使用这个：

（这是来自另一个Whosebug问题！）

NONCLIENTMETRICS ncm;
ncm.cbSize = sizeof(ncm);
SystemParametersInfo(SPI_GETNONCLIENTMETRICS, ncm.cbSize, &ncm, 0);
HFONT hFont = CreateFontIndirect(&(ncm.lfMessageFont)); //

油漆现在用这个：

HDC hdc = BeginPaint(...); //Creates a device context
SelectObject(hdc, hFont);
//Your font is now set for the current device context
//do something

DeleteObject(hFont); //Don't forget to do this at the end!

与 this 问题有点不同！

这个解决方案真的很原始，在我看来很丑陋。

获得 IDWriteFont 的替代解决方案（看起来很丑但很好）：

//just the same as above except the hfont, instead use
NONCLIENTMETRICS ncm;

ncm.cbSize = sizeof(ncm);
SystemParametersInfo(SPI_GETNONCLIENTMETRICS, ncm.cbSize, &ncm, 0);

IDWriteFactory *dwriteFactory_;
DWriteCreateFactory(
    DWRITE_FACTORY_TYPE_SHARED,
    __uuidof(IDWriteFactory),
    reinterpret_cast<IUnknown**>(&dwriteFactory_)
);

IDWriteGdiInterop* gdiInterop = NULL;
dwriteFactory_->GetGdiInterop(&gdiInterop);

IDWriteFont* sys_font = nullptr;
gdiInterop->CreateFontFromLOGFONT(&ncm.lfMessageFont, &sys_font); //Now we have it!

//The text format can now be aquired like this
//We need the font family of our font
IDWriteFontFamily* family = nullptr;
sys_font->GetFontFamily(&family);

//Now we have to get the "localized" name of our family
IDWriteLocalizedStrings* font_family_name = nullptr;
family->GetFamilyNames(&font_family_name);
UINT32 index = 0;
UINT32 length = 0;
BOOL exists = false;
font_family_name->FindLocaleName(L"en-us", &index, &exists);
font_family_name->GetStringLength(index, &length);
wchar_t* name = new wchar_t[length + 1];
font_family_name->GetString(index, name, length + 1);
wprintf(L"%s\n", name);

//Some user defined stuff
DWRITE_FONT_WEIGHT font_weight = DWRITE_FONT_WEIGHT_BLACK;
DWRITE_FONT_STYLE font_style = DWRITE_FONT_STYLE_ITALIC;
DWRITE_FONT_STRETCH font_stretch = DWRITE_FONT_STRETCH_EXPANDED;

IDWriteTextFormat* text_format = nullptr;
dwriteFactory_->CreateTextFormat(name, nullptr, font_weight, font_style, font_stretch, 10.0, L"en-us", &text_format);

即使没有检查，代码在我的电脑上运行也没有任何问题，并给我与第一个解决方案相同的结果（Windows 10，字体系列名称是 Segoe UI ).

来源： General Microsoft DirectWrite API documentation

CreateIndirectFont Documentation

How to enumerate font families, Microsoft documentation

如何在 DirectWrite 中使用默认 UI 字体绘制文本？

How to draw text with the default UI font in DirectWrite?

c++

windows

winapi

fonts

directwrite