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Author Topic: Virtual TreeView paint issues (both Win and Lin)  (Read 4519 times)

tlacuache

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Virtual TreeView paint issues (both Win and Lin)
« on: November 03, 2006, 06:38:32 pm »
I've been trying to figure out what to use for a virtual table component (ie., the data for the table is only loaded up when it's needed or drawn), and have heard good things about the Virtual TreeView component (http://wiki.lazarus.freepascal.org/VirtualTreeview).

I looked at the examples on the main Virtual TreeView site and modified one of the examples about how to use the component with a database to work with my database.

I got it to compile and run, and it "works", mostly. What I mean by mostly is that I can see the event functions being called as they should when they should, but there are some really horrible issues dealing with painting:

- when I scroll the scrollbar with either the mouse or the keyboard, often times the scrollbar moves, but nothing happens. after I scroll, when I finally click in the tree view, then the component finally paints
- when i click one one of my rows and hit "home" or "end", the component jumps to the beginning or end of the list correctly, but only the selected row paints. the rest of them are still what they were before, and will only paint when i click on them individually
- the table column headers sometimes disappear or get "painted over" by data from rows as I scroll
- a lot of rows are ending up "half painted", ie., i can only see the upper half of the data

And the list goes on and on. I tried in both Windows and Linux and the symptoms are similar in both cases.

Has anyone had any real success with this port to Lazarus?

Or is there some other list or table component that can be "virtual" that you've had success with? I'm starting to get the feeling that, while the Virtual TreeView component might be great, it's probably a little overkill for what I need. I just need a simple listview or stringgrid component that has some sort of "ondata" event it uses to retrieve the data.

Any help would be greatly appreciated.

-Seth Grover

Christian

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RE: Virtual TreeView paint issues (both Win and Lin)
« Reply #1 on: November 04, 2006, 03:00:17 pm »
Quote
And the list goes on and on.

What you described is one error with horizontal scrolling.
Sorry but ive dont found it at time. Anyway, you can try it you have the source.