tega
Registered: 11/04/09
Posts: 4
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Reply with quote | #1 |
Hi, I'm placing about 10 MicroCharts on a worksheet and they depend on cells obtained from market data sources that are implemented as a DDE server and/or a COM addin.
With these charts, flickering can be observed due to unnecessary redrawing of entire sheet and a part of status bar, where zoom related controls are located.
In addition to this visual problem, it interferes with my Excel operations too. For example, when you copy a cell, the cell is marked as being copied and indicated as such, but it reverts to normal state whenever the flickering happens. That way, I can't move on to, say, a paste operation.
These artifacts aren't observed while MicroCharts design mode is on. However, it isn't a satisfying solution because I will have to use MicroCharts in design mode all the time.
I am wondering if this is how the MicroCharts is supposed to work by design or something is just wrong with my PC, my usage and so on.
Any help would be appreciated.
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AndreasFlockermann
Moderator
Registered: 12/19/06
Posts: 227
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Reply with quote | #2 |
Not quite sure how to repro you problem Maybe you can send me the sheet?
Do you make use of the OFFSET function?
Andreas
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tega
Registered: 11/04/09
Posts: 4
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Reply with quote | #3 |
Sample sheet is attached with a test DDE server application included. There's no special formula and/or functions used in the sheet, only a handful of DDE connections and a CMicroline refering to those DDE cells.
If the problem can be reproduced on your environment, you can observe it by moving the slider bars of the DDE server back and forth. Although cell redraw flicker is a bit hard to recognize (but it does happen), status bar flicker should be obvious.
Attached Files:
 ddetest.zip (138.88 KB, 1 views)
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AndreasFlockermann
Moderator
Registered: 12/19/06
Posts: 227
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Reply with quote | #4 |
What I observed is that each time you change a value in the sliders of the DDE server the chart updates and Excel flickers. Technically what we are doing is running a Excel udf and updating the cells after the sheet recalc. During the chart update we disable the screen refresh and enable the screen refresh after the chart update (otherwise you would have a flicker for each data point). When you re-enable the screen refresh Excel flickers. As this is how Excel behaves I fear we cannot do anything about this.
Regarding the copy cell problem, this is a know issue. When you calculate colored charts the Excel Undo function is disabled. This is something that we try to address with MicroCharts 4.
Andreas
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tega
Registered: 11/04/09
Posts: 4
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Reply with quote | #5 |
Thanks, my thinking was that, since MicroCharts uses fonts and Excel seems to be able to redraw text cells without a flicker, flickering like that can also be avoided somehow. If that's not technically possible, I understand.
By the way, even in design mode, charts are updated according to the cell change which is caused by a non-DDE data source implmented as a VSTO COM addin. I assume it is because "CHANGE" events are occurring in this case, instead of "CALCULATE" events.
With that in mind, do you think that the flicker can be avoided if I wrap the DDE data source with a VSTO addin so that it directly modifies the cell values and let Excel handle its redraw, instead of having MicroCharts react to recalc events? As I don't have so much experience with Excel development, I'd like to hear your opinion on this.
Thank you.
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AndreasFlockermann
Moderator
Registered: 12/19/06
Posts: 227
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Reply with quote | #6 |
If you want to achieve that you don't get a flicker each time the user changes the value in the DDE slider that wont work.
Even if you use VSTO you have to to an
Application.ScreenUpdating = false before updating and
Application.ScreenUpdating = true after updating
which causes the flicker you are seeing
Andreas
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tega
Registered: 11/04/09
Posts: 4
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Reply with quote | #7 |
Thanks for sharing your thoughts.
If that is the case, I will rather consider how to reduce the frequency of the redraw/flicker due to data update than how to avoid it completely.
Cheers,
Toshiyuki
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