PDA Picture Control Scrollbars

[rberger]

Am I missing something? Are scroll bars for the picture control not supported for LV PDA? If so, this is a definite wish list item for LV PDA V7.1.1.

Robert

[ryank]

I'm seeing the same behavior, my guess is that it is expected behavior, but it's not doccumented, so I'm filing a request to have it fixed or documented.

Regards,
Ryan K.
NI

[rberger]

Hopefully NI will have it fixed because this is a complete show-stopper for future development of my current app. I cannot think of a way to get around this limitation other than to start over and program in VB :-((

Robert

[ryank]

Are you displaying a constant image, or creating it programatically?

If you are just using the picture control to display a constant image(s), it wouldn't be particularly hard to write your own scrollbars (I could probably give you a hand if you aren't sure how to do it).

Unfortunately, if you are determining an image programatically, your only option would be to make sure that it doesn't leave the drawing area since you can't convert a picture to a pixmap on PDA.

I've added a few more notes to the bug report, my guess is that the scrollbars themselves have UI considerations, and probably won't be around any time soon, but I've requested they either include a VI to set the origin or a VI to convert a picture to a pixmap so that you could man
ipulate it programatically. With any luck, one of these should be in the next version, but since 7.1 just came out a couple months ago it will probably be a while before the next version.

Regards,
Ryan K.

[rberger]

Hi Ryan:

Hmmm, I'm actually displaying constant images with one image bigger than the picture control drawing area. My images are maps of Southern California. The first image is a high altitude view of LA County. When the user clicks zoom, I want the second image (which is bigger than the drawing area of the picture control) have the same surface area accessibility as the high altitude image. Hence, I need scrollbars. Sure I can break the zoom image into smaller sections that fit into the picture control, but this entails creating a different databases for each image which is a MAJOR pain. If you have any ideas, I would like to know.

Thanks for reading
Robert

[ryank]

Ahh, I think we may be able to do something with it if it's a constant image. Get an 8 bit pixmap for your image (you can do this by switching to LV for windows and then calling picture to pixmap and unflatten pixmap). Then get the size of your picture control (you can do this by switching back to windows as well). Create two numeric slides that will serve as your "scrollbars", and then use the values from them to determine an origin for the part of your picture you want to display. From there you should be able to use an array subset to get a piece of that pixmap and use the draw 8 bit pixmap to draw it. I haven't actually tried this, but I think it should work. If I get a chance sometime today I'll try to whip up an example,
but I'm kind of swamped, so if you get the idea you might want to go ahead and give it a try.

Regards,
Ryan K.

[ryank]

Here's the basic idea, my map is a little distorted, and the scrollbars could probably be prettied up some more.

[rberger]

Thanks. I'll check it out.

Robert

[rberger]

I built your modified app for PocketPC. Your app works great.

Now, I just have to build for the Palm OS but I have to modify my image due to the 64K subVI/Data limitations of that OS.

Thanks
Robert

[tst]

Can anybody tell me if 8.0 PDA now has scrollbars for pictures? I need to find out before I actually get it.

Also, can the origin of the picture be set or retrieved with a property node?

And the last one, if the picture origin is changed, or the scrollbar is used, which coordinates are retured from the mouse down event (can't even check that one on 7.1 at the moment)? Global screen coords, global picture coords or current (based on origin) picture coords?

Charly, Bob, Ed, anyone?