[Lazarus] TPicture beginupdate or similar

[Leonardo M. Ramé]

Hi again, I'm doing some transformations on a TImage using
Canvas.CopyRect and don't want to show intermediate steps before the final one is done, 
I need to do something similar to TListView's Items.BeginUpdate - Items.EndUpdate.

What I have is a big image on background, and in the OnMouseMove
event I copy the area surrounding the mouse to a temporal bitmap, then
draw over the original image on that area. When the user moves the mouse
again, before doing anithing, I paint the original area with the
temporary bitmap to obtain the original image, then re-draw on the new
area. This causes flickering, and I thing it can be avoided using
something like BeginUpdate at the beginning of my method and EndUpdate
at the end.

Any hint?.

-- 
Leonardo M. Ramé
http://leonardorame.blogspot.com