Some questions regarding the Graph element

Hello

We have a few questions regarding the Graph element.

1. We had an issue earlier with the x-axis not responding to our min- and max value until you added a series to the graph. You said that it earlier required to have a two-way binding but that it would be solved in the next nightly build. The issue seems to be there still. I attach a code example that uses default binding for start and end time but when you change them the graph doesn't respond. If you change the binding mode to TwoWay in the Xaml the graph responds correctly. The sample uses the 6.0.2516.23024 build of Wpf Elements. I have excluded the dlls and license files in the zip file. So these need to be added before it can run.
2. Some lines doesn't seem to be plotted on the correct position on the Y-axis. I have attached some screenshots where you can see that a line that has value 0 is plotted a few pixels off the 0 on the y-axis.
3. We have a foreground element with a cursor that we can move to a chosen location along the x-axis. The problem is that if we have many series in our graph it becomes really really slow. It seems that when we manipulate the content of our foreground element it also continuously refreshes/updates the graph area with all the lines. Can the foreground element become more separated from the actual graph area?
4. The cursor that we have in our foreground element can be moved outside the visible graph area. Even if we check that the horizontal position of our cursor never goes beyond the foreground element's width. It seems that the cursor can somehow be hidden by the padding of the graph. What is the best way to solve this issue?
5. What is the best way to offset the content of the graph so plotted values that has the same value as the min-value of the Y-Axis aren't obscured/hidden behind the X-axis? Is there a better way than just changing the Min-Max values of the Y-Axis?

Hello Nicklas

1. I have further improved the minimum and maximum binding for the ChartAxis in the next nightly build. The reason why it did not work is the ChartAxis internally makes sure that Minimum can not be larger than Maximum. If this occurs, the Chart axis will set one of the properties to ensure this invariant. If the property only has a one way binding, then setting the property internally causes the binding to be removed and effectively overwritten with the set value. I've modified this so the Minimum and Maximum properties can not be set during the loading process. NOTE however that if you break this invariant dynamically during run time (like in your sample you can use the date editors to cause minimum to be larger than maximum), then the axis will correct it's min/max values internally and the binding will be removed. If this is something that can occur in your application, then you'd be best to go with a two way binding as this is not overwritten when manually setting a property. This is a troublesome aspect of WPF data binding that we can not do anything about.

2. The equation used to plot the points on the line is the same one used to position the tick marks. Both the chart area and axis are lined up exactly with each other. The reason why this can sometimes occur is just the way WPF works out which pixels to render the line at. You may notice that zooming the chart in and out, the line can correctly line up with the tick mark. I have tried many times to counteract this issue, but this just causes the line to occasionally appear above the tick mark instead of below it. The most I've seen the line be offset is at most 1 pixel. You can work around this by setting the line thickness to 2 which can line it up more accurately.

3. The only way I can think of this occurring is if the custom foreground element could cause the chart to be remeasured. I'd need a repro project to see if this is the case though.

4. I am not completely sure what you mean here, but I find that making the foreground element extend Canvas and then adding elements to the canvas is the best way to build a foreground element. Also, set Chart.IsChartClipped to false to prevent the main charting area from clipping the foreground elements.

5. By setting IsChartClipped to false, lines and chart symbols can be rendered over the top of the axis lines. Another option is to set the padding of the chart axis. For example, on the Y axis you can set the padding to something like 0,5,0,5 which will push the tick marks and plotted data vertically inward by 5 pixels at the top and bottom.

Let me know if you need further help with any of this.

Jason Fauchelle