Ok, I think I have a sense of what is missing. Generally, it is possible
and easy to take any of pyqtgraph's components and recombine them in novel
ways. What you are trying to do, though, is reach inside the individual
components (such as PlotItem) to change the way they look/behave. There is
definitely much less support for this kind of use, and it's one area where
I would like to see pyqtgraph grow. Some parts can indeed be
customized--for example, a lot of the functionality you listed above is
provided by ImageView, but you would need to swap out the internal ViewBox
if you wanted axes (see:
https://groups.google.com/forum/#!topic/pyqtgraph/2KSFXY30WEk). If you
found that customizing past that point was too difficult, then it may be
easier to build your own from simpler components like ViewBox, AxisItem,
ImageItem, etc.

I'll think on this some more. Whereas it's relatively easy to predict the
ways people will use the existing pyqtgraph components (and write
documentation/examples based on those), it's harder to predict all the ways
people might want to customize outside of those existing components.



On Thu, Jun 8, 2017 at 2:07 AM, <[email protected]> wrote:

>
> Again, maybe it's just me -- I can't start to write a custom from that
> documentation. I started to draw UML diagrams (as the one before) and it
> starts to make more sense to me.
>

It's definitely not you; that documentation is not really meant to cover
your use case.

One particular nasty bit is that I haven't found a good way to remove the
> triangular tick marks in the LUT/Gradient items. The best way I've come up
> with is to set the size of the tick marks to zero -- by accessing the
> internal variable, which feels kind of bad. It also introduces some errors
> when mouse-clicking wildly in the area of the display, where the tick marks
> should be.
>

That'd be a nice feature to add!


> In the end I want to add further things to the above display:
> a) fixing a crosshair-like object (using the mouse) and getting the data
> slice as side histograms in the correct size -- I don't know yet how to
> draw the histograms in the right size
>

See "examples/crosshair.py" and
https://github.com/pyqtgraph/pyqtgraph/blob/develop/pyqtgraph/graphicsItems/ROI.py#L2233
for crosshair / mouse interaction ideas.
See ViewBox.setXLink() and .setYLink() to get the histogram to line up with
the image.


> b) pick a ROI, which is then displayed in a separate, detached QDialog
>

"examples/imageAnalysis.py" and "examples/ROIExamples.py" have some
relevant material.


Luke

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