Opentk/Source/OpenTK/BindingsBase.cs
thefiddler ccd1ad0fd7 [GL] Do not limit strings to StringBuilder.Capacity. Fixes issue #57
We let StringBuilder grow to fit the unmanaged string. This appears to
match the default CLR marshaling behavior, which was used in OpenTK 1.0.
2014-02-07 15:57:36 +01:00

346 lines
12 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; }
/// <summary>
/// Marshals a pointer to a null-terminated byte array to the specified <c>StringBuilder</c>.
/// This method supports OpenTK and is not intended to be called by user code.
/// </summary>
/// <param name="ptr">A pointer to a null-terminated byte array.</param>
/// <param name="sb">The StringBuilder to receive the contents of the pointer.</param>
protected static void MarshalPtrToStringBuilder(IntPtr ptr, StringBuilder sb)
{
if (ptr == IntPtr.Zero)
throw new ArgumentException("ptr");
if (sb == null)
throw new ArgumentNullException("sb");
sb.Length = 0;
for (int i = 0; ; i++)
{
byte b = Marshal.ReadByte(ptr, i);
if (b == 0)
{
return;
}
sb.Append((char)b);
}
}
/// <summary>
/// Marshal a <c>System.String</c> to unmanaged memory.
/// The resulting string is encoded in ASCII and must be freed
/// with <c>FreeStringPtr</c>.
/// </summary>
/// <param name="str">The <c>System.String</c> to marshal.</param>
/// <returns>
/// An unmanaged pointer containing the marshalled string.
/// This pointer must be freed with <c>FreeStringPtr</c>
/// </returns>
protected static IntPtr MarshalStringToPtr(string str)
{
if (String.IsNullOrEmpty(str))
{
return IntPtr.Zero;
}
// Allocate a buffer big enough to hold the marshalled string.
// GetMaxByteCount() appears to allocate space for the final NUL
// character, but allocate an extra one just in case (who knows
// what old Mono version would do here.)
int max_count = Encoding.ASCII.GetMaxByteCount(str.Length) + 1;
IntPtr ptr = Marshal.AllocHGlobal(max_count);
if (ptr == IntPtr.Zero)
{
throw new OutOfMemoryException();
}
// Pin the managed string and convert it to ASCII using
// the pointer overload of System.Encoding.ASCII.GetBytes().
unsafe
{
fixed (char* pstr = str)
{
int actual_count = Encoding.ASCII.GetBytes(pstr, str.Length, (byte*)ptr, max_count);
Marshal.WriteByte(ptr, actual_count, 0); // Append '\0' at the end of the string
return ptr;
}
}
}
/// <summary>
/// Frees a marshalled string that allocated by <c>MarshalStringToPtr</c>.
/// </summary>
/// <param name="ptr">An unmanaged pointer allocated with <c>MarshalStringToPtr</param>
protected static void FreeStringPtr(IntPtr ptr)
{
Marshal.FreeHGlobal(ptr);
}
/// <summary>
/// Marshals a <c>System.String</c> array to unmanaged memory by calling
/// Marshal.AllocHGlobal for each element.
/// </summary>
/// <returns>An unmanaged pointer to an array of null-terminated strings</returns>
/// <param name="str_array">The string array to marshal.</param>
protected static IntPtr MarshalStringArrayToPtr(string[] str_array)
{
IntPtr ptr = IntPtr.Zero;
if (str_array != null && str_array.Length != 0)
{
ptr = Marshal.AllocHGlobal(str_array.Length * IntPtr.Size);
if (ptr == IntPtr.Zero)
{
throw new OutOfMemoryException();
}
for (int i = 0; i < str_array.Length; i++)
{
IntPtr str = MarshalStringToPtr(str_array[i]);
Marshal.WriteIntPtr(ptr, i * IntPtr.Size, str);
}
}
return ptr;
}
/// <summary>
/// Frees a marshalled string that allocated by <c>MarshalStringArrayToPtr</c>.
/// </summary>
/// <param name="ptr">An unmanaged pointer allocated with <c>MarshalStringArrayToPtr</c></param>
/// <param name="length">The length of the string array.</param>
protected static void FreeStringArrayPtr(IntPtr ptr, int length)
{
for (int i = 0; i < length; i++)
{
Marshal.FreeHGlobal(Marshal.ReadIntPtr(ptr, length * IntPtr.Size));
}
Marshal.FreeHGlobal(ptr);
}
#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
}
}