From: "Joe C. Hecht" <joehecht@gte.net>
Subject: Re: Bitmaps larger than screen size
Date: 10 Jul 1999 00:00:00 GMT
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Chad Jones wrote:
>
> Joe C. Hecht wrote:
> >
> > ... but you will get
> > very reliable results if you follow the guideline
> > of not blting a section thats larger than the
> > screen, or bltting a section that requires more
> > memory than a screen load.
>
>  Thanks for clarifying that!
>
>  Up til now, I've been using a TScrollbox containing a large re-sizing
> TImage which obviously is not a good strategy.
>
>  It seems that what I'll need is a TImage based component with a
> client-area sized canvas and scrollbars which represent the larger
> virtual width/height. It would keep the full image in memory or as a
> mapped file and blt to screen only those portions which should become
> visible as scrolling takes place.

Perfect strategy.

>  Seen anything like this out there already?


Not on the market. I have been doing stuff like this since
the first verions of Windows. Its not too difficult to pull
off, but I do wish I had a good pointer to a component for
you.

Remember, blt the smaller of the screensize or the chunk
of memory used by a screenload. ie: when blitting a 24 bit
DIB to a 8 bit display, blt the chunks in 1/3 screenload
chunks, and you will be *absolutly* safe under all versions
of windows. Use this method *especially* when going to the
printer as well.

Joe
--
Joe C. Hecht
http://home1.gte.net/joehecht/index.htm