Micah

using System;
using System.Runtime.InteropServices;

namespace MyDirect3D9
{
    public unsafe class IDirect3D9 : IDisposable
    {
        // A pointer to the native IDirect3D9 object that we are providing overrides for.
        public Win32.D3D9.IDirect3D9* NativeIDirect3D9
        {
            get;
            private set;
        }
        // A pointer to the original array of virtual functions.  We keep this around so we can call the originals.
        private IntPtr* OriginalVFTable = null;

        #region Construction
        // For the case where we already have a native IDirect3D9 object and we want to override some of it's functions.
        public unsafe IDirect3D9(Win32.D3D9.IDirect3D9* InNativeIDirect3D9)
        {
            NativeIDirect3D9 = InNativeIDirect3D9;

            // Override the functions in NativeIDirect3D9 with our own.
            OverrideFunctions();
        }

        // For the case where we don't have a native IDirect3D object so we want one created for us.
        public IDirect3D9(ushort SdkVersion)
        {
            // Create the real IDirect3D9 object.
            NativeIDirect3D9 = Win32.D3D9.Direct3DCreate9(SdkVersion);

            // Override the functions in NativeIDirect3D9 with our own.
            OverrideFunctions();
        }
        #endregion

        #region Destruction
        ~IDirect3D9()
        {
            Dispose(true);
        }

        public void Dispose()
        {
            Dispose(false);
        }

        // Cleanup resources.  Destructing == true means we are getting garbage collected so don't reference any managed resources.
        private void Dispose(bool Destructing)
        {
            if (OriginalVFTable != null)
            {
                Win32.Kernel32.HeapFree(Win32.Kernel32.GetProcessHeap(), 0, *OriginalVFTable);
                OriginalVFTable = null;
            }
        }
        #endregion

        #region Virtual Function Table Management
        // Backup the original native virtual function table and overwrite the pointer to it with our own (which is a copy of the original).
        private void InitializeVFTable()
        {
            // If we don't have a real IDirect3D9 object yet then do nothing.
            if (NativeIDirect3D9 == null) return;

            // Save off the original VFTable (only if it really is the original).
            if (OriginalVFTable == null) OriginalVFTable = NativeIDirect3D9->VFTable;

            // IDirect3D9 has 17 members.
            UInt32 VFTableLength = 17;
            // Allocate space for our new VFTable.
            IntPtr* NewVFTable = (IntPtr*)Win32.Kernel32.HeapAlloc(Win32.Kernel32.GetProcessHeap(), 0, (UIntPtr)(VFTableLength * sizeof(IntPtr)));

            // Copy all of the original function pointers into our new VFTable.
            for (int i = 0; i < VFTableLength; i++)
            {
                NewVFTable[i] = OriginalVFTable[i];
            }

            // Set the Real IDirect3D9 implementation's VFTable to point at our custom one.
            NativeIDirect3D9->VFTable = NewVFTable;
        }

        // Reset the native virtual function table to point back at the original.
        private void ResetVFTable()
        {
            // If the original table is not defined do nothing.
            if (OriginalVFTable == null) return;
            // If the original table points to the same place as the current one do nothing.
            if (OriginalVFTable == NativeIDirect3D9->VFTable) return;
            // Cleanup memory allocated for our custom VFTable.
            Win32.Kernel32.HeapFree(Win32.Kernel32.GetProcessHeap(), 0, *NativeIDirect3D9->VFTable);
            // Set the VFTable back to the original.
            NativeIDirect3D9->VFTable = OriginalVFTable;
            // Set the original VFTable back to null.
            OriginalVFTable = null;
        }

        private void OverrideFunctions()
        {
            InitializeVFTable();

            // #0: STDMETHOD(QueryInterface)(THIS_ REFIID riid, void** ppvObj) PURE;
            // #1: STDMETHOD_(ULONG,AddRef)(THIS) PURE;
            // #2: STDMETHOD_(ULONG,Release)(THIS) PURE;
            // TODO: Override this and Dispose this object if it is going to return 0.
            // #3: STDMETHOD(RegisterSoftwareDevice)(THIS_ void* pInitializeFunction) PURE;
            // #4: STDMETHOD_(UINT, GetAdapterCount)(THIS) PURE;
            DelegateGetAdapterCount MyAdapterCount = new DelegateGetAdapterCount(GetAdapterCount);
            IntPtr PointerToMyAdapterCount = Marshal.GetFunctionPointerForDelegate(MyAdapterCount);
            NativeIDirect3D9->VFTable[4] = PointerToMyAdapterCount;
            // #5: STDMETHOD(GetAdapterIdentifier)(THIS_ UINT Adapter,DWORD Flags,D3DADAPTER_IDENTIFIER9* pIdentifier) PURE;
            // #6: STDMETHOD_(UINT, GetAdapterModeCount)(THIS_ UINT Adapter,D3DFORMAT Format) PURE;
            // #7: STDMETHOD(EnumAdapterModes)(THIS_ UINT Adapter,D3DFORMAT Format,UINT Mode,D3DDISPLAYMODE* pMode) PURE;
            // #8: STDMETHOD(GetAdapterDisplayMode)(THIS_ UINT Adapter,D3DDISPLAYMODE* pMode) PURE;
            // #9: STDMETHOD(CheckDeviceType)(THIS_ UINT Adapter,D3DDEVTYPE DevType,D3DFORMAT AdapterFormat,D3DFORMAT BackBufferFormat,BOOL bWindowed) PURE;
            // #10: STDMETHOD(CheckDeviceFormat)(THIS_ UINT Adapter,D3DDEVTYPE DeviceType,D3DFORMAT AdapterFormat,DWORD Usage,D3DRESOURCETYPE RType,D3DFORMAT CheckFormat) PURE;
            // #11: STDMETHOD(CheckDeviceMultiSampleType)(THIS_ UINT Adapter,D3DDEVTYPE DeviceType,D3DFORMAT SurfaceFormat,BOOL Windowed,D3DMULTISAMPLE_TYPE MultiSampleType,DWORD* pQualityLevels) PURE;
            // #12: STDMETHOD(CheckDepthStencilMatch)(THIS_ UINT Adapter,D3DDEVTYPE DeviceType,D3DFORMAT AdapterFormat,D3DFORMAT RenderTargetFormat,D3DFORMAT DepthStencilFormat) PURE;
            // #13: STDMETHOD(CheckDeviceFormatConversion)(THIS_ UINT Adapter,D3DDEVTYPE DeviceType,D3DFORMAT SourceFormat,D3DFORMAT TargetFormat) PURE;
            // #14: STDMETHOD(GetDeviceCaps)(THIS_ UINT Adapter,D3DDEVTYPE DeviceType,D3DCAPS9* pCaps) PURE;
            // #15: STDMETHOD_(HMONITOR, GetAdapterMonitor)(THIS_ UINT Adapter) PURE;
            // #16: STDMETHOD(CreateDevice)(THIS_ UINT Adapter,D3DDEVTYPE DeviceType,HWND hFocusWindow,DWORD BehaviorFlags,D3DPRESENT_PARAMETERS* pPresentationParameters,IDirect3DDevice9** ppReturnedDeviceInterface) PURE;
        }
        #endregion

        #region IDirect3D9 Interface Function Implementations
        public delegate uint DelegateGetAdapterCount(Win32.D3D9.IDirect3D9* This);
        public uint GetAdapterCount(Win32.D3D9.IDirect3D9* This)
        {
            DelegateGetAdapterCount RealGetAdapterCount = (DelegateGetAdapterCount)Marshal.GetDelegateForFunctionPointer(OriginalVFTable[4], typeof(DelegateGetAdapterCount));
            uint AdapterCount = RealGetAdapterCount(This);
            // TODO: Send the AdapterCount to the profiling application via remoting.
            return AdapterCount;
        }
        #endregion
    }
}