Yes, you will always see a performance hit when you overlap graphic elements that dynamically update. (You may even notice a slow down when placing X-Y graphs over top of large, static bitmaps.)
Someone on the LabVIEW team can probably give more insight into the underlying technical details, but I expect the delay is caused by the need to poll the state of each layer between screen updates. More work = more time, and when task scheduling and critical processes are added to the equation, a slowdown of the UI thread seems inevitable.
Ideally, you should avoid layering dynamic indicators, but the best alternative to your existing strategy will depend on your GUI objectives, or more specifically, what the users need to see in order to get the job done.
Can you provide more details about your existing application? What were you trying to achieve by layering the indicators? Is all of the information presented critical to the user's task flow, or could you offload some of the indicators to subpanels (or perhaps 'hidden' tabs) without impacting the usability?
Some other questions you should be asking: Do the users really need to see the XY graph AND the other indicators at the same time? Does the information in the graph duplicate the information presented in the other indicators, or are the displays independent? If they are independent, does the user really need to seem both displays simultaneously, or does the user's task flow imply they could be viewed sequentially or independently? And are all of the indicators under the graph absolutely essential, or are some of them merely nice extras?
Sometimes, you can rethink the way you are presenting the data visually, and actually communicate more useful information with a smaller number of indicators and much less GUI clutter. Or put another way, by improving the quality and appropriateness of the data presentation, you can often reduce the total number of indicators.
Keep in mind, every time you add another item to a panel, you effectively lower the relative significance of all the other items -- or, if the panel has a single button, it is much easier to comprehend and use than a panel with dozens of buttons and indicators. Given that human cognitive processing is generally believed to be limited to about 7 items, judicious editing of the extraneous elements is recommended anyway.
But all of this depends on usability issues and the user's task flow. Without more specific information about your application and objectives, it's difficult to recommend an alternative strategy.
Can you give us a bit more info...?
Cheers,
Dave Ritter BetterVIEW www.bettervi.com
I have an XY graph which is visible sometimes and not visible at others. It
seems important what it is covering. For example if it is covering another
graphic with a changing display the whole process is slowed down. If I
remove the covered graphic or make it not visible speed improves..
There are several indicators with changing values that are covered by my
graph. Is it better to make them invisible or make their values not change
or is there some better way Tab controls for example.
Yours Sincerely
John
John Brohan National Instruments LabVIEW expert in Montreal Traders Micro "We connect all sorts of things to computers" 317 Barberry Place DDO Montreal PQ Canada H9G 1V3 Tel (514)995-3749 [EMAIL PROTECTED] http://www.TradersMicro.com/Index.htm
