napari selectable evented list example

napari_selectable_evented_list.py

import napari
from napari.utils.events import SelectableEventedList
from napari._qt.containers import QtListView, QtListModel
from qtpy.QtCore import Qt, QModelIndex, QSize
from qtpy.QtGui import QImage
import numpy as np


# simple object for our genes
class MyGene:
    def __init__(self, name):
        self.name = name


# Model class is an interface between our data and Qt,
# Qt uses this to see what it should render when certain 'roles'
# are requested.
# https://doc.qt.io/qt-5/model-view-programming.html#model-classes
class MyGeneModel(QtListModel):
    def __init__(self, root: SelectableEventedList[MyGene]):
        super().__init__(root)

    def data(self, index: QModelIndex, role: Qt.ItemDataRole):
        """Return data at `index` for the requested `role`.
        see https://doc.qt.io/qt-5/model-view-programming.html#item-roles
        """
        if role == Qt.DisplayRole:  # displayed text
            # this is how you access your MyGene object
            my_gene = index.data(Qt.UserRole)
            return my_gene.name
        if role == Qt.EditRole:
            return 'edit me'
        if role == Qt.DecorationRole:  # thumbnail image
            return QImage(
                np.random.random((32, 32, 4)),
                32,
                32,
                QImage.Format_RGBA8888,
            )
        if role == Qt.SizeHintRole:  # determines size of item
            return QSize(64, 34)
        return super().data(index, role)

    def setData(self, index: QModelIndex, value, role: Qt.ItemDataRole) -> bool:
        """Set data at `index` for `role` to `value`."""
        if value and role == Qt.EditRole:
            # User has double-clicked on the item name
            my_object = index.data(Qt.UserRole)
            my_object.name = value
        return super().setData(index, value, role=role)


class MyGeneListView(QtListView):
    def __init__(self, root, parent=None):
        super().__init__(root=root, parent=parent)
        self.setModel(MyGeneModel(root))

# set up napari viewer
viewer = napari.Viewer()

# list of placeholder genes as an example
gene_list = [MyGene(f'gene {i}') for i in range(3)]
selectable_evented_gene_list = SelectableEventedList(gene_list)

# example function which will fire on selection change
def on_selection_change(event=None):
    print('selection changed!')
    viewer.add_image(np.random.random((28, 28)))


selectable_evented_gene_list.selection.events.active.connect(
    on_selection_change
)

# create widget from SelectableEventedList and add to viewer
my_list_widget = MyGeneListView(selectable_evented_gene_list)
viewer.window.add_dock_widget(my_list_widget)

napari.run()