Windows Flicker

Targets Windows
1

I noticed something I had not known before today. I am at a trade show demonstrating a retail software completely designed in RealBasic. Before now I had always demoed with my MacBook Pro. This time, I am using a Dell Inspiron. My software sits open on the projector for hours. I started realizing that in Windows (not Apple) my application flickers periodically. Maybe 4 times a hour. I know it is only the software and not windows, as only the application screen flickers, not the applications and desktop around it.

What is Xojo/RealBasic doing different in Windows than in Apple that would cause this different?

The application contains generic controls, like canvases, list boxes, etc…

On a related note,I have a web control displaying a website inside the software. At times (and only on Windows) the control goes blank, and sometimes if I move the cursor over it, a few button images from the web page appear but the rest is still blank until I refresh the control.

Are these shortcomings of Xojo/Realbasic in a windows build? Or something else that I can remedy?

TIA

2

Windows win32 does not have double buffering. You need to take steps yourself to reduce flickering. You may not be able to remove it completely.

Hopefully, this is issue will go away when a .Net Windows version is available.

3

For Windows Set Doublebuffer to True
http://documentation.xojo.com/index.php/Canvas.DoubleBuffer

The also ensure that EraseBackground is false
http://documentation.xojo.com/index.php/Canvas.Erasebackground

A older but good blog on the topic:
http://www.realsoftwareblog.com/2011/02/flicker-free-canvas-on-windows.html

4

You may want to set HTMLViewer to WebKit. Native uses Internet Explorer in an antiquated mode that often do not do justice to modern web sites.

5

Windows flicker is a fact of life with Xojo. The best you can do is minimize it.

6

Flicker is a fact of life for Windows itself. Even .NET apps do exhibit flicker in some operations. And some things have to be avoided, like staking controls on top of each other.

What the OP describes, though, is not your Xojo run off the mill flicker :

This looks more like some refresh happening. Maybe some timer somewhere ? Windows itself does some housecleaning sometimes that may trigger a paint. 4 times an hour looks more like that, if the app itself does not have any periodic refresh.

7

Thanks for the ideas. I’ll looking implementing the ones I can and I’ll report back when I get results.

I did .Net development for years before getting into Xojo. This ‘flicker/refresh’ issue (for lack of a better term) I am seeing has never plagued my .Net Visual Studio applications.

8

[quote=165259:@Todd Fletcher]Thanks for the ideas. I’ll looking implementing the ones I can and I’ll report back when I get results.

I did .Net development for years before getting into Xojo. This ‘flicker/refresh’ issue (for lack of a better term) I am seeing has never plagued my .Net Visual Studio applications.[/quote]

I have often pleaded for Xojo to implemented .NET. With some luck, we shall be seeing it coming. It would be nice with Windows 10. But I persist : what you describe does not look like anything usual. The mere frequency of the issue suggests something else that double buffering may not address.

Heck, I have seen this kind of thing often happen with HDMI devices, and it has nothing to do with Xojo. Could simply be the hardware.

9

I’ll have to check. I keep an eye on the laptop screen as well as the projector screen to check if it is one or the other. It seems to be both. So I’ll check in as see if a timer or such could cause it. THX

I look forward to .Net compiling as well. :wink:

10

I had a similar issue recently, turned out to be a bad video cable.

11

[quote=165259:@Todd Fletcher]Thanks for the ideas. I’ll looking implementing the ones I can and I’ll report back when I get results.

I did .Net development for years before getting into Xojo. This ‘flicker/refresh’ issue (for lack of a better term) I am seeing has never plagued my .Net Visual Studio applications.[/quote]

.Net has a different drawing engine than Win32 thats more like what you get in OS X so it tends to reduce if not eliminate flicker.

12

What sort of time frame are we talking for .NET support?
I’ll try Mike’s links and see if I can improve things, my main project wasn’t to bad but the side project had serious issues, its a game so any flicker is unacceptable, which was a shame as it was proving easy to do, far easier than getting a game engine to do the same thing

Anyway thanks Mike I will give it a try :slight_smile:

13

HDMI cables are notoriously finicky.

Coming to think of it, if the periodic flick happens at regular intervals, I would be inclined to suspect some Windows maintenance schedule. But if it happens more randomly, it looks very much like a power spike. Could simply be coming from the often picturesque power cabling of the trade show, which does not please the projector and/or the Dell. If you have the MBP handy, plug it in instead. If the flicker happens, then it is the projector.

If the issue is with the Inspiron, software or hardware, it should happen when it is not plugged to the projector.

Debugging electronics is more cumbersome than software, though.

14

I’d have to say Michel is so on the mark. What is described is not Xojo windows flicker (which btw is mostly OSX devs abusing the Windows UI).