Rendertarget9.cs

        public Rendertarget9(Device targetDevice, Viewport dstViewport)
        {
            mViewport = dstViewport;
            mDevice = targetDevice;
            Surface backBuffer = targetDevice.GetBackBuffer(0, 0);

            mTargetTexture = new Texture(
                mDevice,
                mViewport.Width,
                mViewport.Height,
                1,
                Usage.RenderTarget,
                backBuffer.Description.Format,
                Pool.Default
            );

            backBuffer.Dispose();

            mTargetSurface = mTargetTexture.GetSurfaceLevel(0);

            mDeclaration = new VertexDeclaration(targetDevice,
                new VertexElement[]
                {
                    new VertexElement(0, 0, DeclarationType.Float3, DeclarationMethod.Default, DeclarationUsage.Position, 0),
                    new VertexElement(0, 12, DeclarationType.Color, DeclarationMethod.Default, DeclarationUsage.Color, 0),
                    new VertexElement(0, 16, DeclarationType.Float2, DeclarationMethod.Default, DeclarationUsage.TextureCoordinate, 0),
                    VertexElement.VertexDeclarationEnd
                }
            );

            mShader = new Shader9(targetDevice);
            LoadVertices();

            mScreenMatrix = Matrix.OrthoLH(mViewport.Width, mViewport.Height, 0, 1);

            mDevice.SetRenderState(RenderState.AlphaBlendEnable, true);
            mDevice.SetRenderState(RenderState.DestinationBlend, Blend.InverseSourceAlpha);
            mDevice.SetRenderState(RenderState.SourceBlend, Blend.SourceAlpha);

            mRectDrawProvider = new DrawRectangle(this, mDevice);
            mEllipseProvider = new EllipseProvider(mDevice, this);
        }

        public override void BeginUI()
        {
            if (mBaseRendertarget != null)
                mBaseRendertarget.Dispose();

            mBaseRendertarget = mDevice.GetRenderTarget(0);
            mDevice.SetRenderTarget(0, mTargetSurface);
            mDevice.Clear(ClearFlags.Target, 0, 0, 0);
        }