b9f57ba4d2
Most OpenGL versions work with single-byte ASCII strings exclusively. OpenGL 4.2 adds UTF8 encoded comments to GLSL shaders. Unfortunately, UTF16 (.Net) to UTF8 conversions will usually modify the length of the resulting byte array. This is not currently possible to implement inside OpenTK, since the binding generator does not know which length parameter corresponds to a string parameter. For this reason, and to maintain compatibility with older OpenGL versions, we perform a destructive UTF16-to-ASCII encoding, which replaces unsupported characters by '?'. This allows multi-byte post-4.2. GLSL shaders to work as expected. If non-destructive round-tripping of strings is required, the user will have to use the IntPtr overload for string parameters and perform the UTF16-to-UTF8 encoding/decoding manually. This need is very unlikely to arise in practice.
345 lines
12 KiB
C#
345 lines
12 KiB
C#
#region License
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//
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// The Open Toolkit Library License
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//
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// Copyright (c) 2006 - 2009 the Open Toolkit library.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights to
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// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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// the Software, and to permit persons to whom the Software is furnished to do
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// so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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// OTHER DEALINGS IN THE SOFTWARE.
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//
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#endregion
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using System;
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using System.Collections.Generic;
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using System.Text;
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using System.Reflection;
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using System.Runtime.InteropServices;
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using System.Diagnostics;
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namespace OpenTK
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{
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/// <summary>
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/// Provides a common foundation for all flat API bindings and implements the extension loading interface.
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/// </summary>
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public abstract class BindingsBase
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{
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#region Fields
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/// <summary>
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/// A reflection handle to the nested type that contains the function delegates.
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/// </summary>
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readonly protected Type DelegatesClass;
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/// <summary>
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/// A refection handle to the nested type that contains core functions (i.e. not extensions).
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/// </summary>
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readonly protected Type CoreClass;
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/// <summary>
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/// A mapping of core function names to MethodInfo handles.
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/// </summary>
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readonly protected SortedList<string, MethodInfo> CoreFunctionMap = new SortedList<string, MethodInfo>();
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bool rebuildExtensionList = true;
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#endregion
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#region Constructors
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/// <summary>
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/// Constructs a new BindingsBase instance.
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/// </summary>
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public BindingsBase()
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{
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DelegatesClass = this.GetType().GetNestedType("Delegates", BindingFlags.Static | BindingFlags.NonPublic);
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CoreClass = this.GetType().GetNestedType("Core", BindingFlags.Static | BindingFlags.NonPublic);
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if (CoreClass != null)
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{
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MethodInfo[] methods = CoreClass.GetMethods(BindingFlags.Static | BindingFlags.NonPublic);
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CoreFunctionMap = new SortedList<string, MethodInfo>(methods.Length); // Avoid resizing
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foreach (MethodInfo m in methods)
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{
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CoreFunctionMap.Add(m.Name, m);
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}
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}
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}
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#endregion
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#region Protected Members
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/// <summary>
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/// Gets or sets a <see cref="System.Boolean"/> that indicates whether the list of supported extensions may have changed.
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/// </summary>
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protected bool RebuildExtensionList
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{
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get { return rebuildExtensionList; }
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set { rebuildExtensionList = value; }
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}
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/// <summary>
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/// Retrieves an unmanaged function pointer to the specified function.
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/// </summary>
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/// <param name="funcname">
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/// A <see cref="System.String"/> that defines the name of the function.
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/// </param>
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/// <returns>
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/// A <see cref="IntPtr"/> that contains the address of funcname or IntPtr.Zero,
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/// if the function is not supported by the drivers.
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/// </returns>
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/// <remarks>
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/// Note: some drivers are known to return non-zero values for unsupported functions.
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/// Typical values include 1 and 2 - inheritors are advised to check for and ignore these
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/// values.
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/// </remarks>
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protected abstract IntPtr GetAddress(string funcname);
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/// <summary>
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/// Gets an object that can be used to synchronize access to the bindings implementation.
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/// </summary>
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/// <remarks>This object should be unique across bindings but consistent between bindings
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/// of the same type. For example, ES10.GL, OpenGL.GL and CL10.CL should all return
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/// unique objects, but all instances of ES10.GL should return the same object.</remarks>
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protected abstract object SyncRoot { get; }
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/// <summary>
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/// Marshals a pointer to a null-terminated byte array to the specified <c>StringBuilder</c>.
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/// This method supports OpenTK and is not intended to be called by user code.
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/// </summary>
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/// <param name="ptr">A pointer to a null-terminated byte array.</param>
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/// <param name="sb">The StringBuilder to receive the contents of the pointer.</param>
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protected static void MarshalPtrToStringBuilder(IntPtr ptr, StringBuilder sb)
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{
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if (ptr == IntPtr.Zero)
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throw new ArgumentException("ptr");
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if (sb == null)
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throw new ArgumentNullException("sb");
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sb.Length = 0;
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for (int i = 0; i < sb.Capacity; i++)
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{
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byte b = Marshal.ReadByte(ptr, i);
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if (b == 0)
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{
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return;
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}
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sb.Append((char)b);
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}
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}
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/// <summary>
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/// Marshal a <c>System.String</c> to unmanaged memory.
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/// The resulting string is encoded in ASCII and must be freed
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/// with <c>FreeStringPtr</c>.
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/// </summary>
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/// <param name="str">The <c>System.String</c> to marshal.</param>
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/// <returns>
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/// An unmanaged pointer containing the marshalled string.
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/// This pointer must be freed with <c>FreeStringPtr</c>
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/// </returns>
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protected static IntPtr MarshalStringToPtr(string str)
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{
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if (String.IsNullOrEmpty(str))
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{
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return IntPtr.Zero;
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}
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// Allocate a buffer big enough to hold the marshalled string.
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// GetMaxByteCount() appears to allocate space for the final NUL
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// character, but allocate an extra one just in case (who knows
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// what old Mono version would do here.)
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int max_count = Encoding.ASCII.GetMaxByteCount(str.Length) + 1;
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IntPtr ptr = Marshal.AllocHGlobal(max_count);
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if (ptr == IntPtr.Zero)
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{
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throw new OutOfMemoryException();
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}
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// Pin the managed string and convert it to ASCII using
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// the pointer overload of System.Encoding.ASCII.GetBytes().
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unsafe
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{
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fixed (char* pstr = str)
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{
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int actual_count = Encoding.ASCII.GetBytes(pstr, str.Length, (byte*)ptr, max_count);
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Marshal.WriteByte(ptr, actual_count, 0); // Append '\0' at the end of the string
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return ptr;
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}
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}
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}
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/// <summary>
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/// Frees a marshalled string that allocated by <c>MarshalStringToPtr</c>.
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/// </summary>
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/// <param name="ptr">An unmanaged pointer allocated with <c>MarshalStringToPtr</param>
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protected static void FreeStringPtr(IntPtr ptr)
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{
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Marshal.FreeHGlobal(ptr);
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}
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/// <summary>
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/// Marshals a <c>System.String</c> array to unmanaged memory by calling
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/// Marshal.AllocHGlobal for each element.
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/// </summary>
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/// <returns>An unmanaged pointer to an array of null-terminated strings</returns>
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/// <param name="str_array">The string array to marshal.</param>
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protected static IntPtr MarshalStringArrayToPtr(string[] str_array)
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{
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IntPtr ptr = IntPtr.Zero;
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if (str_array != null && str_array.Length != 0)
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{
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ptr = Marshal.AllocHGlobal(str_array.Length * IntPtr.Size);
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if (ptr == IntPtr.Zero)
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{
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throw new OutOfMemoryException();
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}
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for (int i = 0; i < str_array.Length; i++)
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{
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IntPtr str = MarshalStringToPtr(str_array[i]);
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Marshal.WriteIntPtr(ptr, i * IntPtr.Size, str);
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}
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}
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return ptr;
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}
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/// <summary>
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/// Frees a marshalled string that allocated by <c>MarshalStringArrayToPtr</c>.
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/// </summary>
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/// <param name="ptr">An unmanaged pointer allocated with <c>MarshalStringArrayToPtr</c></param>
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/// <param name="length">The length of the string array.</param>
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protected static void FreeStringArrayPtr(IntPtr ptr, int length)
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{
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for (int i = 0; i < length; i++)
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{
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Marshal.FreeHGlobal(Marshal.ReadIntPtr(ptr, length * IntPtr.Size));
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}
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Marshal.FreeHGlobal(ptr);
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}
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#endregion
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#region Internal Members
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#region LoadEntryPoints
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internal virtual void LoadEntryPoints()
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{
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// Using reflection is more than 3 times faster than directly loading delegates on the first
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// run, probably due to code generation overhead. Subsequent runs are faster with direct loading
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// than with reflection, but the first time is more significant.
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int supported = 0;
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FieldInfo[] delegates = DelegatesClass.GetFields(BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.Public);
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if (delegates == null)
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throw new InvalidOperationException("The specified type does not have any loadable extensions.");
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Debug.Write("Loading extensions for " + this.GetType().FullName + "... ");
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Stopwatch time = new Stopwatch();
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time.Reset();
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time.Start();
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foreach (FieldInfo f in delegates)
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{
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Delegate d = LoadDelegate(f.Name, f.FieldType);
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if (d != null)
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++supported;
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lock (SyncRoot)
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{
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f.SetValue(null, d);
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}
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}
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rebuildExtensionList = true;
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time.Stop();
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Debug.Print("{0} extensions loaded in {1} ms.", supported, time.Elapsed.TotalMilliseconds);
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time.Reset();
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}
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#endregion
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#region LoadEntryPoint
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internal virtual bool LoadEntryPoint(string function)
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{
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FieldInfo f = DelegatesClass.GetField(function, BindingFlags.Static | BindingFlags.NonPublic);
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if (f == null)
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return false;
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Delegate old = f.GetValue(null) as Delegate;
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Delegate @new = LoadDelegate(f.Name, f.FieldType);
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lock (SyncRoot)
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{
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if (old.Target != @new.Target)
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{
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f.SetValue(null, @new);
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}
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}
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return @new != null;
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}
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#endregion
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#region GetExtensionDelegate
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// Creates a System.Delegate that can be used to call a dynamically exported OpenGL function.
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internal virtual Delegate GetExtensionDelegate(string name, Type signature)
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{
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IntPtr address = GetAddress(name);
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if (address == IntPtr.Zero ||
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address == new IntPtr(1) || // Workaround for buggy nvidia drivers which return
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address == new IntPtr(2)) // 1 or 2 instead of IntPtr.Zero for some extensions.
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{
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return null;
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}
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else
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{
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return Marshal.GetDelegateForFunctionPointer(address, signature);
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}
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}
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#endregion
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#endregion
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#region Private Members
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#region LoadDelegate
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// Tries to load the specified core or extension function.
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Delegate LoadDelegate(string name, Type signature)
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{
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MethodInfo m;
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return
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GetExtensionDelegate(name, signature) ??
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(CoreFunctionMap.TryGetValue((name.Substring(2)), out m) ?
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Delegate.CreateDelegate(signature, m) : null);
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}
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#endregion
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#endregion
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}
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}
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