DWRITE_FACTORY_TYPE enumeration (dwrite.h)

Specifies the type of DirectWrite factory object.

Important

This API is available as part of the DWriteCore implementation of DirectWrite. For more info, and code examples, see DWriteCore overview.

Syntax

typedef enum DWRITE_FACTORY_TYPE {
  DWRITE_FACTORY_TYPE_SHARED,
  DWRITE_FACTORY_TYPE_ISOLATED,
  DWRITE_FACTORY_TYPE_ISOLATED2
} ;

Constants

DWRITE_FACTORY_TYPE_SHARED Indicates that the DirectWrite factory is a shared factory and that it allows for the reuse of cached font data across multiple in-process components. Such factories also take advantage of cross process font caching components for better performance.
DWRITE_FACTORY_TYPE_ISOLATED Indicates that the DirectWrite factory object is isolated. Objects created from the isolated factory do not interact with internal DirectWrite state from other components.
DWRITE_FACTORY_TYPE_ISOLATED2 Indicates that the DirectWrite factory object is restricted. Objects created from a restricted factory don't use nor modify internal state or cached data used by other factories. In addition, the system font collection contains only well-known fonts. ## Examples See the DWriteCore overview topic, and the DWriteCoreGallery sample app.

Remarks

A DirectWrite factory object contains information about its internal state, such as font loader registration and cached font data. In most cases you should use the shared factory object, because it allows multiple components that use DirectWrite to share internal DirectWrite state information, thereby reducing memory usage. However, there are cases when it is desirable to reduce the impact of a component on the rest of the process, such as a plug-in from an untrusted source, by sandboxing and isolating it from the rest of the process components. In such cases, you should use an isolated factory for the sandboxed component.

A restricted factory is more locked down than an isolated factory. It doesn't interact with a cross-process nor persistent font cache in any way. In addition, the system font collection returned from this factory includes only well-known fonts. If you pass DWRITE_FACTORY_TYPE_ISOLATED2 to a version of DWrite that's older than DWriteCore, then DWriteCreateFactory returns E_INVALIDARG.

Requirements

Requirement	Value
Minimum supported client	Windows 10, version 1809 (with Windows App SDK 0.5 or later)
Header	dwrite.h

See also

DWriteCore

DWriteCoreGallery sample