ClassiCube/OpenTK/Graphics/GraphicsContext.cs
2015-06-07 08:53:12 +10:00

335 lines
11 KiB
C#

#region --- License ---
/* Licensed under the MIT/X11 license.
* Copyright (c) 2006-2008 the OpenTK Team.
* This notice may not be removed from any source distribution.
* See license.txt for licensing detailed licensing details.
*/
#endregion
using System;
using System.Collections.Generic;
using System.Text;
using System.Diagnostics;
using OpenTK.Platform;
namespace OpenTK.Graphics
{
/// <summary>
/// Represents and provides methods to manipulate an OpenGL render context.
/// </summary>
public sealed class GraphicsContext : IGraphicsContext, IGraphicsContextInternal
{
#region --- Fields ---
IGraphicsContext implementation; // The actual render context implementation for the underlying platform.
bool disposed;
readonly static object SyncRoot = new object();
// Maps OS-specific context handles to GraphicsContext weak references.
readonly static Dictionary<ContextHandle, WeakReference> available_contexts = new Dictionary<ContextHandle, WeakReference>();
#endregion
#region --- Constructors ---
/// <summary>
/// Constructs a new GraphicsContext with the specified GraphicsMode and attaches it to the specified window.
/// </summary>
/// <param name="mode">The OpenTK.Graphics.GraphicsMode of the GraphicsContext.</param>
/// <param name="window">The OpenTK.Platform.IWindowInfo to attach the GraphicsContext to.</param>
public GraphicsContext(GraphicsMode mode, IWindowInfo window)
: this(mode, window, 1, 0)
{ }
/// <summary>
/// Constructs a new GraphicsContext with the specified GraphicsMode, version and flags, and attaches it to the specified window.
/// </summary>
/// <param name="mode">The OpenTK.Graphics.GraphicsMode of the GraphicsContext.</param>
/// <param name="window">The OpenTK.Platform.IWindowInfo to attach the GraphicsContext to.</param>
/// <param name="major">The major version of the new GraphicsContext.</param>
/// <param name="minor">The minor version of the new GraphicsContext.</param>
/// <param name="flags">The GraphicsContextFlags for the GraphicsContext.</param>
/// <remarks>
/// Different hardware supports different flags, major and minor versions. Invalid parameters will be silently ignored.
/// </remarks>
public GraphicsContext(GraphicsMode mode, IWindowInfo window, int major, int minor)
{
lock (SyncRoot)
{
if (mode == null) throw new ArgumentNullException("mode", "Must be a valid GraphicsMode.");
if (window == null) throw new ArgumentNullException("window", "Must point to a valid window.");
// Silently ignore invalid major and minor versions.
if (major <= 0) major = 1;
if (minor < 0) minor = 0;
Debug.Print("Creating GraphicsContext.");
try
{
Debug.Indent();
Debug.Print("GraphicsMode: {0}", mode);
Debug.Print("IWindowInfo: {0}", window);
Debug.Print("Requested version: {0}.{1}", major, minor);
IPlatformFactory factory = Factory.Default;
implementation = factory.CreateGLContext(mode, window, major, minor);
// Note: this approach does not allow us to mix native and EGL contexts in the same process.
// This should not be a problem, as this use-case is not interesting for regular applications.
// Note 2: some platforms may not support a direct way of getting the current context
// (this happens e.g. with DummyGLContext). In that case, we use a slow fallback which
// iterates through all known contexts and checks if any is current (check GetCurrentContext
// declaration).
if (GetCurrentContext == null)
{
GetCurrentContextDelegate temp = factory.CreateGetCurrentGraphicsContext();
if (temp != null)
{
GetCurrentContext = temp;
}
}
available_contexts.Add((this as IGraphicsContextInternal).Context, new WeakReference(this));
}
finally
{
Debug.Unindent();
}
}
}
#endregion
#region Private Members
#endregion
#region --- Static Members ---
#region public static void Assert()
/// <summary>
/// Checks if a GraphicsContext exists in the calling thread and throws a GraphicsContextMissingException if it doesn't.
/// </summary>
/// <exception cref="GraphicsContextMissingException">Generated when no GraphicsContext is current in the calling thread.</exception>
public static void Assert()
{
if (GraphicsContext.CurrentContext == null)
throw new GraphicsContextMissingException();
}
#endregion
#region public static IGraphicsContext CurrentContext
internal delegate ContextHandle GetCurrentContextDelegate();
internal static GetCurrentContextDelegate GetCurrentContext = delegate
{
// Note: this is a slow, generic fallback for use with DummyGLContext.
// Most other platforms can query the current context directly (via
// [Wgl|Glx|Agl|Egl].GetCurrentContext()) so the GraphicsContext
// constructor will replace this implementation with a platform-specific
// one, if it exists.
foreach (WeakReference weak_ref in available_contexts.Values)
{
IGraphicsContext context = (IGraphicsContext)weak_ref.Target;
if (context.IsCurrent)
{
return (context as IGraphicsContextInternal).Context;
}
}
return ContextHandle.Zero;
};
/// <summary>
/// Gets the GraphicsContext that is current in the calling thread.
/// </summary>
/// <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.
/// </remarks>
public static IGraphicsContext CurrentContext
{
get
{
lock (SyncRoot)
{
if (available_contexts.Count > 0)
{
ContextHandle handle = GetCurrentContext();
if (handle.Handle != IntPtr.Zero)
return (GraphicsContext)available_contexts[handle].Target;
}
return null;
}
}
}
#endregion
#endregion
#region --- IGraphicsContext Members ---
/// <summary>
/// Creates an OpenGL context with the specified direct/indirect rendering mode and sharing state with the
/// specified IGraphicsContext.
/// </summary>
/// <param name="direct">Set to true for direct rendering or false otherwise.</param>
/// <param name="source">The source IGraphicsContext to share state from.</param>.
/// <remarks>
/// <para>
/// Direct rendering is the default rendering mode for OpenTK, since it can provide higher performance
/// in some circumastances.
/// </para>
/// <para>
/// The 'direct' parameter is a hint, and will ignored if the specified mode is not supported (e.g. setting
/// indirect rendering on Windows platforms).
/// </para>
/// </remarks>
void CreateContext(bool direct, IGraphicsContext source)
{
lock (SyncRoot)
{
available_contexts.Add((this as IGraphicsContextInternal).Context, new WeakReference(this));
}
}
/// <summary>
/// Swaps buffers on a context. This presents the rendered scene to the user.
/// </summary>
public void SwapBuffers()
{
implementation.SwapBuffers();
}
/// <summary>
/// Makes the GraphicsContext the current rendering target.
/// </summary>
/// <param name="window">A valid <see cref="OpenTK.Platform.IWindowInfo" /> structure.</param>
/// <remarks>
/// You can use this method to bind the GraphicsContext to a different window than the one it was created from.
/// </remarks>
public void MakeCurrent(IWindowInfo window)
{
implementation.MakeCurrent(window);
}
/// <summary>
/// Gets a <see cref="System.Boolean"/> indicating whether this instance is current in the calling thread.
/// </summary>
public bool IsCurrent
{
get { return implementation.IsCurrent; }
}
/// <summary>
/// Gets a <see cref="System.Boolean"/> indicating whether this instance has been disposed.
/// It is an error to access any instance methods if this property returns true.
/// </summary>
public bool IsDisposed
{
get { return disposed && implementation.IsDisposed; }
private set { disposed = value; }
}
/// <summary>
/// Gets or sets a value indicating whether VSync is enabled.
/// </summary>
public bool VSync
{
get { return implementation.VSync; }
set { implementation.VSync = value; }
}
/// <summary>
/// Updates the graphics context. This must be called when the render target
/// is resized for proper behavior on Mac OS X.
/// </summary>
/// <param name="window"></param>
public void Update(IWindowInfo window)
{
implementation.Update(window);
}
/// <summary>
/// Loads all OpenGL entry points.
/// </summary>
/// <exception cref="OpenTK.Graphics.GraphicsContextException">
/// Occurs when this instance is not current on the calling thread.
/// </exception>
public void LoadAll()
{
if (GraphicsContext.CurrentContext != this)
throw new GraphicsContextException();
implementation.LoadAll();
}
#endregion
#region --- IGraphicsContextInternal Members ---
/// <summary>
/// Gets a handle to the OpenGL rendering context.
/// </summary>
ContextHandle IGraphicsContextInternal.Context
{
get { return ((IGraphicsContextInternal)implementation).Context; }
}
/// <summary>
/// Gets the GraphicsMode of the context.
/// </summary>
public GraphicsMode GraphicsMode
{
get { return (implementation as IGraphicsContext).GraphicsMode; }
}
/// <summary>
/// Gets the address of an OpenGL extension function.
/// </summary>
/// <param name="function">The name of the OpenGL function (e.g. "glGetString")</param>
/// <returns>
/// A pointer to the specified function or IntPtr.Zero if the function isn't
/// available in the current opengl context.
/// </returns>
IntPtr IGraphicsContextInternal.GetAddress(string function)
{
return (implementation as IGraphicsContextInternal).GetAddress(function);
}
#endregion
#region --- IDisposable Members ---
/// <summary>
/// Disposes of the GraphicsContext.
/// </summary>
public void Dispose()
{
this.Dispose(true);
GC.SuppressFinalize(this);
}
void Dispose(bool manual)
{
if (!IsDisposed)
{
Debug.Print("Disposing context {0}.", (this as IGraphicsContextInternal).Context.ToString());
lock (SyncRoot)
{
available_contexts.Remove((this as IGraphicsContextInternal).Context);
}
if (manual) {
if (implementation != null)
implementation.Dispose();
}
IsDisposed = true;
}
}
#endregion
}
}