GLContext

open class GLContext : DrawContext, GLContextProtocol

The GLContext type acts as a reference-counted owner of an underlying GdkGLContext instance. It provides the methods that can operate on this data type through GLContextProtocol conformance. Use GLContext as a strong reference or owner of a GdkGLContext instance.

GdkGLContext is an object representing a platform-specific OpenGL draw context.

GdkGLContexts are created for a surface using [methodGdk.Surface.create_gl_context], and the context will match the the characteristics of the surface.

A GdkGLContext is not tied to any particular normal framebuffer. For instance, it cannot draw to the surface back buffer. The GDK repaint system is in full control of the painting to that. Instead, you can create render buffers or textures and use [funccairo_draw_from_gl] in the draw function of your widget to draw them. Then GDK will handle the integration of your rendering with that of other widgets.

Support for GdkGLContext is platform-specific and context creation can fail, returning nil context.

A GdkGLContext has to be made “current” in order to start using it, otherwise any OpenGL call will be ignored.

Creating a new OpenGL context

In order to create a new GdkGLContext instance you need a GdkSurface, which you typically get during the realize call of a widget.

A GdkGLContext is not realized until either [methodGdk.GLContext.make_current] or [methodGdk.GLContext.realize] is called. It is possible to specify details of the GL context like the OpenGL version to be used, or whether the GL context should have extra state validation enabled after calling [methodGdk.Surface.create_gl_context] by calling [methodGdk.GLContext.realize]. If the realization fails you have the option to change the settings of the GdkGLContext and try again.

Using a GdkGLContext

You will need to make the GdkGLContext the current context before issuing OpenGL calls; the system sends OpenGL commands to whichever context is current. It is possible to have multiple contexts, so you always need to ensure that the one which you want to draw with is the current one before issuing commands:

gdk_gl_context_make_current (context);

You can now perform your drawing using OpenGL commands.

You can check which GdkGLContext is the current one by using [funcGdk.GLContext.get_current]; you can also unset any GdkGLContext that is currently set by calling [funcGdk.GLContext.clear_current].

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  • Designated initialiser from the underlying `C` data type.

    This creates an instance without performing an unbalanced retain i.e., ownership is transferred to the GLContext instance.

    Declaration

    Swift

    @inlinable
public init(_ op: UnsafeMutablePointer<GdkGLContext>)

    Parameters

    op

    pointer to the underlying object
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  • Designated initialiser from a constant pointer to the underlying C data type. This creates an instance without performing an unbalanced retain i.e., ownership is transferred to the GLContext instance.

    Declaration

    Swift

    @inlinable
public init(_ op: UnsafePointer<GdkGLContext>)

    Parameters

    op

    pointer to the underlying object
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  • Optional initialiser from a non-mutating gpointer to the underlying C data type. This creates an instance without performing an unbalanced retain i.e., ownership is transferred to the GLContext instance.

    Declaration

    Swift

    @inlinable
override public init!(gpointer op: gpointer?)

    Parameters

    op

    gpointer to the underlying object
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  • Optional initialiser from a non-mutating gconstpointer to the underlying C data type. This creates an instance without performing an unbalanced retain i.e., ownership is transferred to the GLContext instance.

    Declaration

    Swift

    @inlinable
override public init!(gconstpointer op: gconstpointer?)

    Parameters

    op

    pointer to the underlying object
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  • Optional initialiser from a constant pointer to the underlying C data type. This creates an instance without performing an unbalanced retain i.e., ownership is transferred to the GLContext instance.

    Declaration

    Swift

    @inlinable
public init!(_ op: UnsafePointer<GdkGLContext>?)

    Parameters

    op

    pointer to the underlying object
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  • Optional initialiser from the underlying C data type. This creates an instance without performing an unbalanced retain i.e., ownership is transferred to the GLContext instance.

    Declaration

    Swift

    @inlinable
public init!(_ op: UnsafeMutablePointer<GdkGLContext>?)

    Parameters

    op

    pointer to the underlying object
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  • Designated initialiser from the underlying C data type. Will retain GdkGLContext. i.e., ownership is transferred to the GLContext instance.

    Declaration

    Swift

    @inlinable
public init(retaining op: UnsafeMutablePointer<GdkGLContext>)

    Parameters

    op

    pointer to the underlying object
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  • Reference intialiser for a related type that implements GLContextProtocol Will retain GdkGLContext.

    Declaration

    Swift

    @inlinable
public init<T>(gLContext other: T) where T : GLContextProtocol

    Parameters

    other

    an instance of a related type that implements GLContextProtocol
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  • Unsafe typed initialiser. Do not use unless you know the underlying data type the pointer points to conforms to GLContextProtocol.

    Declaration

    Swift

    @inlinable
override public init<T>(cPointer p: UnsafeMutablePointer<T>)

    Parameters

    cPointer

    pointer to the underlying object
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  • Unsafe typed, retaining initialiser. Do not use unless you know the underlying data type the pointer points to conforms to GLContextProtocol.

    Declaration

    Swift

    @inlinable
override public init<T>(retainingCPointer cPointer: UnsafeMutablePointer<T>)

    Parameters

    cPointer

    pointer to the underlying object
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  • Unsafe untyped initialiser. Do not use unless you know the underlying data type the pointer points to conforms to GLContextProtocol.

    Declaration

    Swift

    @inlinable
override public init(raw p: UnsafeRawPointer)

    Parameters

    p

    raw pointer to the underlying object
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  • Unsafe untyped, retaining initialiser. Do not use unless you know the underlying data type the pointer points to conforms to GLContextProtocol.

    Declaration

    Swift

    @inlinable
override public init(retainingRaw raw: UnsafeRawPointer)
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  • Unsafe untyped initialiser. Do not use unless you know the underlying data type the pointer points to conforms to GLContextProtocol.

    Declaration

    Swift

    @inlinable
public required init(raw p: UnsafeMutableRawPointer)

    Parameters

    p

    mutable raw pointer to the underlying object
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  • Unsafe untyped, retaining initialiser. Do not use unless you know the underlying data type the pointer points to conforms to GLContextProtocol.

    Declaration

    Swift

    @inlinable
required public init(retainingRaw raw: UnsafeMutableRawPointer)

    Parameters

    raw

    mutable raw pointer to the underlying object
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  • Unsafe untyped initialiser. Do not use unless you know the underlying data type the pointer points to conforms to GLContextProtocol.

    Declaration

    Swift

    @inlinable
override public init(opaquePointer p: OpaquePointer)

    Parameters

    p

    opaque pointer to the underlying object
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  • Unsafe untyped, retaining initialiser. Do not use unless you know the underlying data type the pointer points to conforms to GLContextProtocol.

    Declaration

    Swift

    @inlinable
override public init(retainingOpaquePointer p: OpaquePointer)

    Parameters

    p

    opaque pointer to the underlying object
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  • Retrieves the current GdkGLContext.

    Declaration

    Swift

    @inlinable
public static func getCurrent() -> GLContext!
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