protected override void WndProc(ref Message m)
{
// intercept the message that sets the state image list, and pass on a fixed image list
// instead of the modified 16x16 version. the control will take care of the internal
// modified image list it created - we just need to handle disposal for our own image list
const int TVSIL_STATE = 2;
if (m.Msg == (int) WindowsMessages.TVM_SETIMAGELIST)
{
if (_fixedInternalStateImageList != null)
{
DisposeAll(_fixedInternalStateImageList.Images);
_fixedInternalStateImageList.Dispose();
_fixedInternalStateImageList = null;
}
if (m.WParam.ToInt32() == TVSIL_STATE && m.LParam != IntPtr.Zero && this.StateImageList != null)
{
// setup a new image list as a rough clone of the real one
_fixedInternalStateImageList = new ImageList();
_fixedInternalStateImageList.ColorDepth = this.StateImageList.ColorDepth;
_fixedInternalStateImageList.ImageSize = this.StateImageList.ImageSize;
_fixedInternalStateImageList.TransparentColor = this.StateImageList.TransparentColor;
// add the dummy image (we still need to do this because otherwise the image indexes are shifted by 1)
_fixedInternalStateImageList.Images.Add(string.Empty, new Bitmap(1, 1));
// copy over the original images
for (int n = 0; n < this.StateImageList.Images.Count; n++)
_fixedInternalStateImageList.Images.Add((Image) this.StateImageList.Images[n].Clone());
m.LParam = _fixedInternalStateImageList.Handle;
}
}
base.WndProc(ref m);
}
}
