One ImageItem movable relative to another ImageItem

[David MacKenzie]

Hello, all.

My use case is to be able to place one image over another, and give the user the ability to move the top image around relative to the bottom image, place it where they like, and then "commit" the combined image to a file such as they see it on the screen.

I have wide latitude to use any widgets I like, but so far I'm been working with ImageItems placed into a ViewBox in a GraphicsWindow.

I have the images combined as shown in the code below, but they move *in tandem.*  I'm looking for suggestions as to how to make the second one I've added movable *relative* to the first.

I've run all the examples, and the ROI example seems closest to what I need.  If it's necessary to sub-class one of the ROI objects such that it displays my image, that's fine.

Thank you for any suggestions.


        self.combo_win = pyqtgraph.GraphicsWindow()
        self.combo_view = self.combo_win.addViewBox()

        data = fits.getdata(self.combo_location +
                            self.file_selection_list.currentItem().text())
        data = data[4, :, :]
        photosphere_image_item = pyqtgraph.ImageItem(data)

        data_AR = fits.getdata('arInput/ar_1.fits')
        data_AR = data_AR[0, :, :]
        ar_image_item = pyqtgraph.ImageItem(data_AR)

        self.combo_view.addItem(photosphere_image_item)
        self.combo_view.addItem(ar_image_item)