improve cursor location information in spectral profile plot

[Andreas Janz]

Requested by @Agustin Lobo in #837.

Instead of showing mouse cursor location information …

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… snap to an actual profile data point and show real data information, e.g.

x: 1750 (band 42) y: 419.6

Could look like in good old ENVI Classic, but instead of holding down the left mouse, we update on mouse movement → no clicks required.

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[Andreas Janz]

This may become slow for bigger spectral libraries, so we may need to have a checkbox to turn it off.

[Andreas Janz]

Also note that we can set points into the plot by holding [ALT] + LeftMouseClick:

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The associated information shown is actual data. But setting those points require lots of clicking and ALT-key holding. I don’t like it very much.
Also, the points stay inside the plot after changing the current z profile.

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We would need to click those points again, to get ride of them. Even more click work.

I’m sure, there are usecases, where this behaviour is very useful, but it is not sufficient for getting quick move over information of actual profile data.

[Agustin Lobo]

+1, Nicer this way, but please save space and use eg. “Bnb” instead of “Band Number”. Also reduce the nb of decimals by default.

[Agustin Lobo]

Not sure I expressed myself clearly here. To clarify:

The spectral plot is normally displayed with Wavelength in the X-axis (this is how spectra are kept in your memory),

but often you need to know the band number of a given point. Is it complicated to always display the x valued both in wavelength and band number, regardless how the x-axis is displayed? That would save a lot of time and clicks.

[Andreas Janz]

Is it complicated to always display the x valued both in wavelength and band number, regardless how the x-axis is displayed?

No, it’s not to complicated. The enhanced version will display band numbers and center wavelength at the same time.

[Andreas Janz]

Pretty much as known from ENVI Classic: band number, wavelength and value

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