Anyone know about CachedBitmap?

[aewarnick]

I have been trying to make it work but am having weird unconsistant problems and cannot find any useful documentation on the CachedBitmap. Can someone point me to a site or something that teaches about this?

[DllImport("gdiplus.dll")]
			public static extern int GdipCreateCachedBitmap(IntPtr pBmp, IntPtr pGraphics, ref IntPtr pCatchedBmp);
			[DllImport("gdiplus.dll")]
			public static extern int GdipDrawCachedBitmap(IntPtr pGraphics, IntPtr pCatchedBmp, int x, int y);
			[DllImport("gdiplus.dll")]
			public static extern int GdipDeleteCachedBitmap(IntPtr pCatchedBmp);

			public class CachedBmp
			{
				Bitmap cachedBmp;
				IntPtr pCachedBmp;
				IntPtr pGrfi;

				public CachedBmp(Bitmap b, Graphics g)
				{
					this.cachedBmp= b;
					FieldInfo Bmpfi= typeof(Bitmap).GetField("nativeImage", BindingFlags.Instance | BindingFlags.NonPublic);
					IntPtr pBmpfi= (IntPtr)Bmpfi.GetValue(this.cachedBmp);
					FieldInfo Grfi= typeof(Graphics).GetField("nativeGraphics", BindingFlags.Instance | BindingFlags.NonPublic);
					pGrfi= (IntPtr)Grfi.GetValue(g);
					GdipCreateCachedBitmap(pBmpfi, pGrfi, ref pCachedBmp);
				}

				public int Draw(int x, int y)
				{
					return GdipDrawCachedBitmap(this.pGrfi, this.pCachedBmp, x, y);
				}

				public void Delete()
				{
					GdipDeleteCachedBitmap(this.pCachedBmp);
				}
			}