what is invalidate,update methods do in VC++
c++, mfc, visual-c++, winapi, windows-services
Solution
`CWnd::Invalidate()` invalidates the entire client area of a window, which indicates that the area is out of date, and should be repainted. You would typically call this on a control that needs to be redrawn. `CWnd::InvalidateRect()` invalidates only part of the window.
With the `Invalidate` functions, the `WM_PAINT` message will posted [not strictly true; see the comments] to the message queue and handled at some point in the future. `CWnd::UpdateWindow()` sends (as opposed to posts) a `WM_PAINT` message, causing the invalidated regions to be redrawn immediately.
Really, this is all in the docs.
Problem
i have small doubt regarding the window functions in c++. what exactly `"invalidate()"` function do? what message does it sends?when we need to call this? also what is `"update()"` function? is `"invalidaterect()"` works similar to `"invalidate()"` function?. Thanks