Improve mouse interactions in controls

Tasks

This section was added by @swharden

• trigger mouse enter and leave events in user controls (#1040)
• provide options for automatic axis limits to ignore axis lines and spans (#1083)
• implement an axis crosshair label feature (#1093)

Original Question

Your Environment

• ScottPlot Version: 4.1.12 beta
• Operating System: Win10 20H2
• Is it a GUI app? What platform? WinForms
• .Net: net472 and net5.0-windows was checked.

Simple Mdi Winforms app. Child form with only formsPlot1 on it. MouseLeave and MouseEnter not working, MouseMove is working.

This is critical to implement some info on MouseMove (to hide it after we leave the plot).

P.s. Related question: How to properly implement axes cursor on MouseMove with ScottPlot?

I was tring something like this:

private void formsPlot1_MouseMove(object sender, MouseEventArgs e)
{
    (double x, double y) = formsPlot1.GetMouseCoordinates();
    _HLine.Y = y;
    _HLine.IsVisible = true;
    _VLine.X = x;
    _VLine.IsVisible = true;
    formsPlot1.Render(skipIfCurrentlyRendering: true);
}

And it’s worked BUT. Because of _HLine and _VLine are plots, ScottPlot autozoom and autoaxes always trying to consider their values. And this lead to whole wrong behavior. For example:

https://user-images.githubusercontent.com/17767561/116545566-47cef280-a8f9-11eb-9c29-ee21ead7fceb.mp4

Cursors must be completely excluded from plotting logic.

Also, is it possible to display Cursor coordinates on the axes (red circles on screen above)?

[swharden]

MouseEnter and MouseLeave

MouseLeave and MouseEnter not working

These probably are worth forwarding. I’ll try to implement these in the next few days, with a demo. Hiding the crosshairs when the mouse exits the plot seems like a good demo.

Keep in mind that for extreme custom mouse interaction is probably just for the programmer to make their own control and implement the features they want. The controls aren’t very complicated, and it’s much easier to start with the source code and modify it to meet your needs than to try to adapt the standard controls to meet every use case. https://github.com/ScottPlot/ScottPlot/blob/master/src/controls/ScottPlot.WinForms/FormsPlot.cs

Option to ignore axis lines when calling AxisAuto()

The video demonstrates this problem well. Thanks for sharing it! As @StendProg pointed out this question has been raised before. I can add a public field to axis lines so they are ignored when axis limits are determined automatically, which may be a simpler solution.

Labeling crosshair coordinates on the axes

Right now this is not possible, but it should be easy to create a special plot type that does this. I’ll put this idea on the triage list (#1028). This type of behavior would be especially useful for financial charts, similar to https://www.tradingview.com/chart

[bclehmann]

I noticed in the Avalonia control that OnMouseMove is commented-out. Should this be uncommented or deleted?

It should be replaced with base.OnPointerMoved(e) and uncommented. I did that in #1040