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I’m user of WPF Element 4 Chart. I’m now developing a chart application that displays voltage & current of a battery. This chart application requires a bunch of data to display on a chart at a time. And I found something wrong when displaying the whole data by using WPF Element 4 Chart Let me show you an example of wrong display of chart.
When you see the whole view of chart the down peak should reach the scale of 1980mV. (Only the third peak has correct display of data.) When I zoom in the first down-peak the lowest value is 1980mV.
But When I zoom out
then the 1980mV disappears and the lowest value becomes 2012mV. It seems it loses the lowest value. Because of the loss of data the WPF Element 4 Chart shows different chart when I draw the whole data just like the first picture. |
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Hello When there are lots of data points within the chart viewport, the chart will only render a sample of them to help improve the performance. You can however override this behaviour to get the desired effect. On a DataSeries, you can set the DataSampler property to be either a FixedSampleCountSampler, or a PixelDensitySampler. The FixedSampleCountSampler would work best for your scenario. For a FixedSampleCountSampler, you can set the MaxDataPointCount property to specify the maximum number of points you want to allow to be rendered. By default, this value is 400. If you use a higher number, then more data points can be displayed. Let us know how it goes. |
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Hi, Could you post a short sample on how to do this, maybe something based on the LargeDataSeriesPage code you have in the samples? I cannot find the properties you mention and I am using the latest build. Cheers, Jose |
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Hello Jose I have attached a sample that demonstrates how to use the DataSampler. This sample has been built with WPF Element 5.0, but the code would be the same in version 4.0 too. To run the sample, make sure to include a reference to the Mindscape.WpfElement.dll. In MainWindow.xaml I have set up a chart with an AreaSeries which is bound to a large data set. In the resource dictionary on line 9 I have defined a FixedSampleCountSampler with a maximum data point count of 700 (the default one that the chart uses has a MaxDataPointCount of 400). Then on line 15 I set the DataSampler property of the AreaSeries. (All cartesian series inherit this property, but some of the series such as Bar, Scatter and Bubble don't support data sampling). When you run the sample, you will see the chart displays more data points compared to letting it use the default sampler. By using an even larger MaxDataPointCount, you can display more and more data at once. Let me know if you have further questions. -Jason |
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Sorry for the late reply. I tried FixedSampleCountSampler but the chart display got too slow. So I modified the DataSerise source code and solved the problem in my own way. Thank you for your help. |
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