Font Management

DirectWrite provides a comprehensive set of interfaces for locating, enumerating, and managing fonts. This article outlines the primary concepts, key interfaces, and best practices for working with font collections and font families.

Key Concepts

• Font collection: A group of font families. The system font collection is accessed via IDWriteFactory::GetSystemFontCollection.
• Font family: Represents a group of typefaces that share a common design. Accessed through IDWriteFontFamily.
• Font face: A specific typeface (e.g., Regular, Bold). Represented by IDWriteFontFace.
• Custom collections: Applications can create custom font collections by implementing IDWriteFontCollectionLoader and IDWriteFontFileEnumerator.

System Font Collection

The most common scenario is to use the system font collection. Example code:

// Initialize DirectWrite factory
Microsoft::WRL::ComPtr<IDWriteFactory> factory;
DWriteCreateFactory(DWRITE_FACTORY_TYPE_SHARED, __uuidof(IDWriteFactory), &factory);

// Retrieve the system font collection
Microsoft::WRL::ComPtr<IDWriteFontCollection> systemFonts;
factory->GetSystemFontCollection(&systemFonts, FALSE);

// Enumerate font families
UINT32 familyCount = systemFonts->GetFontFamilyCount();
for (UINT32 i = 0; i < familyCount; ++i) {
    Microsoft::WRL::ComPtr<IDWriteFontFamily> family;
    systemFonts->GetFontFamily(i, &family);
    // Get family name
    Microsoft::WRL::ComPtr<IDWriteLocalizedStrings> names;
    family->GetFamilyNames(&names);
    // ... retrieve and display the name ...
}

Creating a Custom Font Collection

Custom collections enable loading fonts from memory, network, or other sources. The steps are:

1. Implement IDWriteFontFileLoader to load font data.
2. Implement IDWriteFontFileEnumerator to enumerate loaded files.
3. Register the loader with IDWriteFactory::RegisterFontFileLoader.
4. Create the collection using IDWriteFactory::CreateCustomFontCollection.

Common Methods

Related Topics

• Text Formatting
• Text Rendering
• Glyph Management
• DirectWrite Resources