Opentk/Source/OpenTK/BindingsBase.cs
2013-11-24 13:57:08 +01:00

231 lines
7.8 KiB
C#

#region License
//
// The Open Toolkit Library License
//
// Copyright (c) 2006 - 2009 the Open Toolkit library.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do
// so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
//
#endregion
using System;
using System.Collections.Generic;
using System.Text;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Diagnostics;
namespace OpenTK
{
/// <summary>
/// Provides a common foundation for all flat API bindings and implements the extension loading interface.
/// </summary>
public abstract class BindingsBase
{
#region Fields
/// <summary>
/// A reflection handle to the nested type that contains the function delegates.
/// </summary>
readonly protected Type DelegatesClass;
/// <summary>
/// A refection handle to the nested type that contains core functions (i.e. not extensions).
/// </summary>
readonly protected Type CoreClass;
/// <summary>
/// A mapping of core function names to MethodInfo handles.
/// </summary>
readonly protected SortedList<string, MethodInfo> CoreFunctionMap = new SortedList<string, MethodInfo>();
bool rebuildExtensionList = true;
#endregion
#region Constructors
/// <summary>
/// Constructs a new BindingsBase instance.
/// </summary>
public BindingsBase()
{
DelegatesClass = this.GetType().GetNestedType("Delegates", BindingFlags.Static | BindingFlags.NonPublic);
CoreClass = this.GetType().GetNestedType("Core", BindingFlags.Static | BindingFlags.NonPublic);
if (CoreClass != null)
{
MethodInfo[] methods = CoreClass.GetMethods(BindingFlags.Static | BindingFlags.NonPublic);
CoreFunctionMap = new SortedList<string, MethodInfo>(methods.Length); // Avoid resizing
foreach (MethodInfo m in methods)
{
CoreFunctionMap.Add(m.Name, m);
}
}
}
#endregion
#region Protected Members
/// <summary>
/// Gets or sets a <see cref="System.Boolean"/> that indicates whether the list of supported extensions may have changed.
/// </summary>
protected bool RebuildExtensionList
{
get { return rebuildExtensionList; }
set { rebuildExtensionList = value; }
}
/// <summary>
/// Retrieves an unmanaged function pointer to the specified function.
/// </summary>
/// <param name="funcname">
/// A <see cref="System.String"/> that defines the name of the function.
/// </param>
/// <returns>
/// A <see cref="IntPtr"/> that contains the address of funcname or IntPtr.Zero,
/// if the function is not supported by the drivers.
/// </returns>
/// <remarks>
/// Note: some drivers are known to return non-zero values for unsupported functions.
/// Typical values include 1 and 2 - inheritors are advised to check for and ignore these
/// values.
/// </remarks>
protected abstract IntPtr GetAddress(string funcname);
/// <summary>
/// Gets an object that can be used to synchronize access to the bindings implementation.
/// </summary>
/// <remarks>This object should be unique across bindings but consistent between bindings
/// of the same type. For example, ES10.GL, OpenGL.GL and CL10.CL should all return
/// unique objects, but all instances of ES10.GL should return the same object.</remarks>
protected abstract object SyncRoot { get; }
#endregion
#region Internal Members
#region LoadEntryPoints
internal virtual void LoadEntryPoints()
{
// Using reflection is more than 3 times faster than directly loading delegates on the first
// run, probably due to code generation overhead. Subsequent runs are faster with direct loading
// than with reflection, but the first time is more significant.
int supported = 0;
FieldInfo[] delegates = DelegatesClass.GetFields(BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.Public);
if (delegates == null)
throw new InvalidOperationException("The specified type does not have any loadable extensions.");
Debug.Write("Loading extensions for " + this.GetType().FullName + "... ");
Stopwatch time = new Stopwatch();
time.Reset();
time.Start();
foreach (FieldInfo f in delegates)
{
Delegate d = LoadDelegate(f.Name, f.FieldType);
if (d != null)
++supported;
lock (SyncRoot)
{
f.SetValue(null, d);
}
}
rebuildExtensionList = true;
time.Stop();
Debug.Print("{0} extensions loaded in {1} ms.", supported, time.Elapsed.TotalMilliseconds);
time.Reset();
}
#endregion
#region LoadEntryPoint
internal virtual bool LoadEntryPoint(string function)
{
FieldInfo f = DelegatesClass.GetField(function, BindingFlags.Static | BindingFlags.NonPublic);
if (f == null)
return false;
Delegate old = f.GetValue(null) as Delegate;
Delegate @new = LoadDelegate(f.Name, f.FieldType);
lock (SyncRoot)
{
if (old.Target != @new.Target)
{
f.SetValue(null, @new);
}
}
return @new != null;
}
#endregion
#region GetExtensionDelegate
// Creates a System.Delegate that can be used to call a dynamically exported OpenGL function.
internal virtual Delegate GetExtensionDelegate(string name, Type signature)
{
IntPtr address = GetAddress(name);
if (address == IntPtr.Zero ||
address == new IntPtr(1) || // Workaround for buggy nvidia drivers which return
address == new IntPtr(2)) // 1 or 2 instead of IntPtr.Zero for some extensions.
{
return null;
}
else
{
return Marshal.GetDelegateForFunctionPointer(address, signature);
}
}
#endregion
#endregion
#region Private Members
#region LoadDelegate
// Tries to load the specified core or extension function.
Delegate LoadDelegate(string name, Type signature)
{
MethodInfo m;
return
GetExtensionDelegate(name, signature) ??
(CoreFunctionMap.TryGetValue((name.Substring(2)), out m) ?
Delegate.CreateDelegate(signature, m) : null);
}
#endregion
#endregion
}
}