Class GraphicsContext

Represents and provides methods to manipulate an OpenGL render context.

Inheritance

Object

GraphicsContext

Implements

IGraphicsContext

IDisposable

IGraphicsContextInternal

Inherited Members

Object.Equals(Object, Object)

Object.ReferenceEquals(Object, Object)

Object.GetType()

Object.MemberwiseClone()

Namespace: OpenTK.Graphics

Assembly: OpenTK.dll

Syntax

public sealed class GraphicsContext : IGraphicsContext, IDisposable, IGraphicsContextInternal

Constructors

GraphicsContext(ContextHandle, GraphicsContext.GetAddressDelegate, GraphicsContext.GetCurrentContextDelegate)

Initializes a new instance of the GraphicsContext class using an external context handle that was created by a third-party library.

Declaration

public GraphicsContext(ContextHandle handle, GraphicsContext.GetAddressDelegate getAddress, GraphicsContext.GetCurrentContextDelegate getCurrent)

Parameters

Type	Name	Description
ContextHandle	handle	A valid, unique handle for an external OpenGL context, or ContextHandle.Zero to use the current context. It is an error to specify a handle that has been created through OpenTK or that has been passed to OpenTK before.
GraphicsContext.GetAddressDelegate	getAddress	A GetAddressDelegate instance that accepts the name of an OpenGL function and returns a valid function pointer, or IntPtr.Zero if that function is not supported. This delegate should be implemented using the same toolkit that created the OpenGL context (i.e. if the context was created with SDL_GL_CreateContext(), then this delegate should use SDL_GL_GetProcAddress() to retrieve function pointers.)
GraphicsContext.GetCurrentContextDelegate	getCurrent	A GetCurrentContextDelegate instance that returns the handle of the current OpenGL context, or IntPtr.Zero if no context is current on the calling thread. This delegate should be implemented using the same toolkit that created the OpenGL context (i.e. if the context was created with SDL_GL_CreateContext(), then this delegate should use SDL_GL_GetCurrentContext() to retrieve the current context.)

GraphicsContext(ContextHandle, IWindowInfo)

Constructs a new GraphicsContext from a pre-existing context created outside of OpenTK. A dummy context will be created if both the handle and the window are null.

Declaration

public GraphicsContext(ContextHandle handle, IWindowInfo window)

Parameters

Type	Name	Description
ContextHandle	handle	The handle of the existing context. This must be a valid, unique handle that is not known to OpenTK.
IWindowInfo	window	This parameter is reserved.

GraphicsContext(ContextHandle, IWindowInfo, IGraphicsContext, Int32, Int32, GraphicsContextFlags)

Constructs a new GraphicsContext from a pre-existing context created outside of OpenTK.

Declaration

public GraphicsContext(ContextHandle handle, IWindowInfo window, IGraphicsContext shareContext, int major, int minor, GraphicsContextFlags flags)

Parameters

Type	Name	Description
ContextHandle	handle	The handle of the existing context. This must be a valid, unique handle that is not known to OpenTK.
IWindowInfo	window	This parameter is reserved.
IGraphicsContext	shareContext	This parameter is reserved.
Int32	major	This parameter is reserved.
Int32	minor	This parameter is reserved.
GraphicsContextFlags	flags	This parameter is reserved..

GraphicsContext(GraphicsMode, IWindowInfo)

Constructs a new GraphicsContext with the specified GraphicsMode and attaches it to the specified window.

Declaration

public GraphicsContext(GraphicsMode mode, IWindowInfo window)

Parameters

Type	Name	Description
GraphicsMode	mode	The OpenTK.Graphics.GraphicsMode of the GraphicsContext.
IWindowInfo	window	The OpenTK.Platform.IWindowInfo to attach the GraphicsContext to.

GraphicsContext(GraphicsMode, IWindowInfo, IGraphicsContext, Int32, Int32, GraphicsContextFlags)

Constructs a new GraphicsContext with the specified GraphicsMode, version and flags, and attaches it to the specified window. A dummy context will be created if both the handle and the window are null.

Declaration

public GraphicsContext(GraphicsMode mode, IWindowInfo window, IGraphicsContext shareContext, int major, int minor, GraphicsContextFlags flags)

Parameters

Type	Name	Description
GraphicsMode	mode	The OpenTK.Graphics.GraphicsMode of the GraphicsContext.
IWindowInfo	window	The OpenTK.Platform.IWindowInfo to attach the GraphicsContext to.
IGraphicsContext	shareContext	The GraphicsContext to share resources with, or null for explicit non-sharing.
Int32	major	The major version of the new GraphicsContext.
Int32	minor	The minor version of the new GraphicsContext.
GraphicsContextFlags	flags	The GraphicsContextFlags for the GraphicsContext.

Remarks

Different hardware supports different flags, major and minor versions. Invalid parameters will be silently ignored.

GraphicsContext(GraphicsMode, IWindowInfo, Int32, Int32, GraphicsContextFlags)

Constructs a new GraphicsContext with the specified GraphicsMode, version and flags, and attaches it to the specified window.

Declaration

public GraphicsContext(GraphicsMode mode, IWindowInfo window, int major, int minor, GraphicsContextFlags flags)

Parameters

Type	Name	Description
GraphicsMode	mode	The OpenTK.Graphics.GraphicsMode of the GraphicsContext.
IWindowInfo	window	The OpenTK.Platform.IWindowInfo to attach the GraphicsContext to.
Int32	major	The major version of the new GraphicsContext.
Int32	minor	The minor version of the new GraphicsContext.
GraphicsContextFlags	flags	The GraphicsContextFlags for the GraphicsContext.

Remarks

Different hardware supports different flags, major and minor versions. Invalid parameters will be silently ignored.

Properties

CurrentContext

Gets the GraphicsContext that is current in the calling thread.

Declaration

public static IGraphicsContext CurrentContext { get; }

Property Value

Type	Description
IGraphicsContext

Remarks

Note: this property will not function correctly when both desktop and EGL contexts are available in the same process. This scenario is very unlikely to appear in practice.

CurrentContextHandle

Gets the handle of the current GraphicsContext in the calling thread.

Declaration

public static ContextHandle CurrentContextHandle { get; }

Property Value

Type	Description
ContextHandle

DirectRendering

Gets or sets a System.Boolean, indicating whether GraphicsContexts will perform direct rendering.

Declaration

public static bool DirectRendering { get; set; }

Property Value

Type	Description
Boolean

Remarks

If DirectRendering is true, new contexts will be constructed with direct rendering capabilities, if possible. If DirectRendering is false, new contexts will be constructed with indirect rendering capabilities.

This property does not affect existing GraphicsContexts, unless they are recreated.

This property is ignored on Operating Systems without support for indirect rendering, like Windows and OS X.

ErrorChecking

Gets or sets a System.Boolean, indicating whether automatic error checking should be performed. Influences the debug version of OpenTK.dll, only.

Declaration

public bool ErrorChecking { get; set; }

Property Value

Type	Description
Boolean

Remarks

Automatic error checking will clear the OpenGL error state. Set CheckErrors to false if you use the OpenGL error state in your code flow (e.g. for checking supported texture formats).

GraphicsMode

Gets the GraphicsMode of the context.

Declaration

public GraphicsMode GraphicsMode { get; }

Property Value

Type	Description
GraphicsMode

IsCurrent

Gets a Boolean indicating whether this instance is current in the calling thread.

Declaration

public bool IsCurrent { get; }

Property Value

Type	Description
Boolean

IsDisposed

Gets a Boolean indicating whether this instance has been disposed. It is an error to access any instance methods if this property returns true.

Declaration

public bool IsDisposed { get; }

Property Value

Type	Description
Boolean

ShareContexts

Gets or sets a System.Boolean, indicating whether GraphicsContext resources are shared

Declaration

public static bool ShareContexts { get; set; }

Property Value

Type	Description
Boolean

Remarks

If ShareContexts is true, new GLContexts will share resources. If this value is false, new GLContexts will not share resources.

Changing this value will not affect already created GLContexts.

SwapInterval

Gets or sets a positive integer in the range [1, n), indicating the number of DisplayDevice refreshes between consecutive SwapBuffers() calls. The maximum value for n is implementation-dependent. The default value is 1. Invalid values will be clamped to the valid range.

Declaration

public int SwapInterval { get; set; }

Property Value

Type	Description
Int32

Methods

Assert()

Checks if a GraphicsContext exists in the calling thread and throws a GraphicsContextMissingException if it doesn't.

Declaration

public static void Assert()

Exceptions

Type	Condition
GraphicsContextMissingException	Generated when no GraphicsContext is current in the calling thread.

Dispose()

Disposes of the GraphicsContext.

Declaration

public void Dispose()

Equals(Object)

Compares two instances.

Declaration

public override bool Equals(object obj)

Parameters

Type	Name	Description
Object	obj	The instance to compare to.

Returns

Type	Description
Boolean	True, if obj is equal to this instance; false otherwise.

Overrides

Object.Equals(Object)

Finalize()

Marks this context as deleted, but does not actually release unmanaged resources due to the threading requirements of OpenGL. Use Dispose() instead.

Declaration

protected void Finalize()

GetHashCode()

Returns the hash code for this instance.

Declaration

public override int GetHashCode()

Returns

Type	Description
Int32	A System.Int32 with the hash code of this instance.

Overrides

Object.GetHashCode()

LoadAll()

Loads all OpenGL entry points.

Declaration

public void LoadAll()

Exceptions

Type	Condition
GraphicsContextException	Occurs when this instance is not current on the calling thread.

MakeCurrent(IWindowInfo)

Makes the GraphicsContext the current rendering target.

Declaration

public void MakeCurrent(IWindowInfo window)

Parameters

Type	Name	Description
IWindowInfo	window	A valid IWindowInfo structure.

Remarks

You can use this method to bind the GraphicsContext to a different window than the one it was created from.

SwapBuffers()

Swaps buffers on a context. This presents the rendered scene to the user.

Declaration

public void SwapBuffers()

ToString()

Returns a String representing this instance.

Declaration

public override string ToString()

Returns

Type	Description
String	A String that contains a string representation of this instance.

Overrides

Object.ToString()

Update(IWindowInfo)

Updates the graphics context. This must be called when the render target is resized for proper behavior on Mac OS X.

Declaration

public void Update(IWindowInfo window)

Parameters

Type	Name	Description
IWindowInfo	window

Explicit Interface Implementations

IGraphicsContextInternal.Context

Gets a handle to the OpenGL rendering context.

Declaration

ContextHandle IGraphicsContextInternal.Context { get; }

Returns

Type	Description
ContextHandle

IGraphicsContextInternal.GetAddress(IntPtr)

Retrieves the implementation-defined address of an OpenGL function.

Declaration

IntPtr IGraphicsContextInternal.GetAddress(IntPtr function)

Parameters

Type	Name	Description
IntPtr	function	A pointer to a null-terminated buffer containing the name of the OpenGL function.

Returns

Type	Description
IntPtr	A pointer to the specified function or an invalid pointer if the function is not available in the current OpenGL context. The return value and calling convention depends on the underlying platform.

IGraphicsContextInternal.GetAddress(String)

Retrieves the implementation-defined address of an OpenGL function.

Declaration

IntPtr IGraphicsContextInternal.GetAddress(string function)

Parameters

Type	Name	Description
String	function	The name of the OpenGL function (e.g. "glGetString")

Returns

Type	Description
IntPtr	A pointer to the specified function or an invalid pointer if the function is not available in the current OpenGL context. The return value and calling convention depends on the underlying platform.

IGraphicsContextInternal.Implementation

Gets the platform-specific implementation of this IGraphicsContext.

Declaration

IGraphicsContext IGraphicsContextInternal.Implementation { get; }

Returns

Type	Description
IGraphicsContext

Implements

IGraphicsContext

System.IDisposable

IGraphicsContextInternal