Multiple Real-Time Curves Not Overlapping Properly

Hello,

I am trying to add two real-time plot curves to one plot object. The curves are created from captured voltages and are similar to oscilloscope curves. I need to show both curves on top of each other for reference. What is happening is each curve is only being displayed in half the width as each curve seems to be overwriting the other curve with a black rectangle, making half of it disappear during replots.

Here is an image:

Attachment 9020


Is there a way, with QWT, to draw two curves on top of each other without half of the curve disappearing?

Thanks,

-brian

Quote:

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Originally Posted by brianbat

What is happening is each curve is only being displayed in half the width as each curve seems to be overwriting the other curve with a black rectangle, making half of it disappear during replots

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No this is not happening - nobody fills rectangles when drawing a curve. It looks more like that the bounding x interval of the curves is different: check your samples.

Uwe

As the curves are being displayed I can see the full curves being displayed with half of it is flashing on and off. Like I said when I display each curve separately I see the curve fill the entire view space so the bounding X interval is fine.

No you don't see anything as the x axis is disabled.

I would guess, that you have autoscaling enabled and the x-axis changes, when you enable/disable a curve: try your application with having the x axes visible.

Uwe

Quote:

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Originally Posted by Uwe

No this is not happening - nobody fills rectangles when drawing a curve. It looks more like that the bounding x interval of the curves is different: check your samples.

Uwe

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I captured three videos showing what is happening. The first two videos show the separate single plotted curves. The third video shows the two curves together in QWT and demonstrates the issue I am having.

http://youtu.be/rLvlbs3hW5o
http://youtu.be/oZ9rz3YlzU0
http://youtu.be/4Z8EKmW3YQo

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Added after 9 minutes:

Quote:

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Originally Posted by Uwe

No you don't see anything as the x axis is disabled.

I would guess, that you have autoscaling enabled and the x-axis changes, when you enable/disable a curve: try your application with having the x axes visible.

Uwe

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Hello, yes autoscaling is on and the x-axis was disabled. I tried enabling the x-axis and the plotted curves are still alternating on one half of the plot.

Quote:

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Originally Posted by brianbat

Hello, yes autoscaling is on and the x-axis was disabled. I tried enabling the x-axis and the plotted curves are still alternating on one half of the plot.

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Of course they do, but is the axis range changing, when you enable/disable curves ?

More interesting than your videos are the bounding rectangles of your curves: I'm pretty sure the x interval is different: the x coordinates of the second curve are above the first.

Uwe

Sorry Uwe, I just understood what you meant. I set the same x values for both curves and everything is fine.

Thanks for your help and patience. :o