Multiple viewer widget

This is an example on how to have more than one viewer in the same napari window. Additional viewers state will be synchronized with the main viewer. Switching to 3D display will only impact the main viewer.

This example also contain option to enable cross that will be moved to the current dims point (viewer.dims.point).

Tags: gui

from copy import deepcopy
from typing import Optional

import numpy as np
from packaging.version import parse as parse_version
from qtpy.QtCore import Qt
from qtpy.QtWidgets import (
    QCheckBox,
    QDoubleSpinBox,
    QPushButton,
    QSplitter,
    QTabWidget,
    QVBoxLayout,
    QWidget,
)
from superqt.utils import qthrottled

import napari
from napari.components.layerlist import Extent
from napari.components.viewer_model import ViewerModel
from napari.layers import Image, Labels, Layer, Vectors
from napari.qt import QtViewer
from napari.utils.action_manager import action_manager
from napari.utils.events.event import WarningEmitter
from napari.utils.notifications import show_info

NAPARI_GE_4_16 = parse_version(napari.__version__) > parse_version('0.4.16')


def copy_layer_le_4_16(layer: Layer, name: str = ''):
    res_layer = deepcopy(layer)
    # this deepcopy is not optimal for labels and images layers
    if isinstance(layer, (Image, Labels)):
        res_layer.data = layer.data

    res_layer.metadata['viewer_name'] = name

    res_layer.events.disconnect()
    res_layer.events.source = res_layer
    for emitter in res_layer.events.emitters.values():
        emitter.disconnect()
        emitter.source = res_layer
    return res_layer


def copy_layer(layer: Layer, name: str = ''):
    if not NAPARI_GE_4_16:
        return copy_layer_le_4_16(layer, name)

    res_layer = Layer.create(*layer.as_layer_data_tuple())
    res_layer.metadata['viewer_name'] = name
    return res_layer


def get_property_names(layer: Layer):
    klass = layer.__class__
    res = []
    for event_name, event_emitter in layer.events.emitters.items():
        if isinstance(event_emitter, WarningEmitter):
            continue
        if event_name in ('thumbnail', 'name'):
            continue
        if (
            isinstance(getattr(klass, event_name, None), property)
            and getattr(klass, event_name).fset is not None
        ):
            res.append(event_name)
    return res


def center_cross_on_mouse(
    viewer_model: napari.components.viewer_model.ViewerModel,
):
    """move the cross to the mouse position"""

    if not getattr(viewer_model, 'mouse_over_canvas', True):
        # There is no way for napari 0.4.15 to check if mouse is over sending canvas.
        show_info(
            'Mouse is not over the canvas. You may need to click on the canvas.'
        )
        return

    viewer_model.dims.current_step = tuple(
        np.round(
            [
                max(min_, min(p, max_)) / step
                for p, (min_, max_, step) in zip(
                    viewer_model.cursor.position, viewer_model.dims.range
                )
            ]
        ).astype(int)
    )


action_manager.register_action(
    name='napari:move_point',
    command=center_cross_on_mouse,
    description='Move dims point to mouse position',
    keymapprovider=ViewerModel,
)

action_manager.bind_shortcut('napari:move_point', 'C')


class own_partial:
    """
    Workaround for deepcopy not copying partial functions
    (Qt widgets are not serializable)
    """

    def __init__(self, func, *args, **kwargs) -> None:
        self.func = func
        self.args = args
        self.kwargs = kwargs

    def __call__(self, *args, **kwargs):
        return self.func(*(self.args + args), **{**self.kwargs, **kwargs})

    def __deepcopy__(self, memodict=None):
        if memodict is None:
            memodict = {}
        return own_partial(
            self.func,
            *deepcopy(self.args, memodict),
            **deepcopy(self.kwargs, memodict),
        )


class QtViewerWrap(QtViewer):
    def __init__(self, main_viewer, *args, **kwargs) -> None:
        super().__init__(*args, **kwargs)
        self.main_viewer = main_viewer

    def _qt_open(
        self,
        filenames: list,
        stack: bool,
        plugin: Optional[str] = None,
        layer_type: Optional[str] = None,
        **kwargs,
    ):
        """for drag and drop open files"""
        self.main_viewer.window._qt_viewer._qt_open(
            filenames, stack, plugin, layer_type, **kwargs
        )


class CrossWidget(QCheckBox):
    """
    Widget to control the cross layer. because of the performance reason
    the cross update is throttled
    """

    def __init__(self, viewer: napari.Viewer) -> None:
        super().__init__('Add cross layer')
        self.viewer = viewer
        self.setChecked(False)
        self.stateChanged.connect(self._update_cross_visibility)
        self.layer = None
        self.viewer.dims.events.order.connect(self.update_cross)
        self.viewer.dims.events.ndim.connect(self._update_ndim)
        self.viewer.dims.events.current_step.connect(self.update_cross)
        self._extent = None

        self._update_extent()
        self.viewer.dims.events.connect(self._update_extent)

    @qthrottled(leading=False)
    def _update_extent(self):
        """
        Calculate the extent of the data.

        Ignores the the cross layer itself in calculating the extent.
        """
        if NAPARI_GE_4_16:
            layers = [
                layer
                for layer in self.viewer.layers
                if layer is not self.layer
            ]
            self._extent = self.viewer.layers.get_extent(layers)
        else:
            extent_list = [
                layer.extent
                for layer in self.viewer.layers
                if layer is not self.layer
            ]
            self._extent = Extent(
                data=None,
                world=self.viewer.layers._get_extent_world(extent_list),
                step=self.viewer.layers._get_step_size(extent_list),
            )
        self.update_cross()

    def _update_ndim(self, event):
        if self.layer in self.viewer.layers:
            self.viewer.layers.remove(self.layer)
        self.layer = Vectors(name='.cross', ndim=event.value)
        self.layer.edge_width = 1.5
        self.update_cross()

    def _update_cross_visibility(self, state):
        if state:
            self.viewer.layers.append(self.layer)
        else:
            self.viewer.layers.remove(self.layer)
        self.update_cross()

    def update_cross(self):
        if self.layer not in self.viewer.layers:
            return

        point = self.viewer.dims.current_step
        vec = []
        for i, (lower, upper) in enumerate(self._extent.world.T):
            if (upper - lower) / self._extent.step[i] == 1:
                continue
            point1 = list(point)
            point1[i] = (lower + self._extent.step[i] / 2) / self._extent.step[
                i
            ]
            point2 = [0 for _ in point]
            point2[i] = (upper - lower) / self._extent.step[i]
            vec.append((point1, point2))
        if np.any(self.layer.scale != self._extent.step):
            self.layer.scale = self._extent.step
        self.layer.data = vec


class ExampleWidget(QWidget):
    """
    Dummy widget showcasing how to place additional widgets to the right
    of the additional viewers.
    """

    def __init__(self) -> None:
        super().__init__()
        self.btn = QPushButton('Perform action')
        self.spin = QDoubleSpinBox()
        layout = QVBoxLayout()
        layout.addWidget(self.spin)
        layout.addWidget(self.btn)
        layout.addStretch(1)
        self.setLayout(layout)


class MultipleViewerWidget(QSplitter):
    """The main widget of the example."""

    def __init__(self, viewer: napari.Viewer) -> None:
        super().__init__()
        self.viewer = viewer
        self.viewer_model1 = ViewerModel(title='model1')
        self.viewer_model2 = ViewerModel(title='model2')
        self._block = False
        self.qt_viewer1 = QtViewerWrap(viewer, self.viewer_model1)
        self.qt_viewer2 = QtViewerWrap(viewer, self.viewer_model2)
        self.tab_widget = QTabWidget()
        w1 = ExampleWidget()
        w2 = ExampleWidget()
        self.tab_widget.addTab(w1, 'Sample 1')
        self.tab_widget.addTab(w2, 'Sample 2')
        viewer_splitter = QSplitter()
        viewer_splitter.setOrientation(Qt.Vertical)
        viewer_splitter.addWidget(self.qt_viewer1)
        viewer_splitter.addWidget(self.qt_viewer2)
        viewer_splitter.setContentsMargins(0, 0, 0, 0)

        self.addWidget(viewer_splitter)
        self.addWidget(self.tab_widget)

        self.viewer.layers.events.inserted.connect(self._layer_added)
        self.viewer.layers.events.removed.connect(self._layer_removed)
        self.viewer.layers.events.moved.connect(self._layer_moved)
        self.viewer.layers.selection.events.active.connect(
            self._layer_selection_changed
        )
        self.viewer.dims.events.current_step.connect(self._point_update)
        self.viewer_model1.dims.events.current_step.connect(self._point_update)
        self.viewer_model2.dims.events.current_step.connect(self._point_update)
        self.viewer.dims.events.order.connect(self._order_update)
        self.viewer.events.reset_view.connect(self._reset_view)
        self.viewer_model1.events.status.connect(self._status_update)
        self.viewer_model2.events.status.connect(self._status_update)

    def _status_update(self, event):
        self.viewer.status = event.value

    def _reset_view(self):
        self.viewer_model1.reset_view()
        self.viewer_model2.reset_view()

    def _layer_selection_changed(self, event):
        """
        update of current active layer
        """
        if self._block:
            return

        if event.value is None:
            self.viewer_model1.layers.selection.active = None
            self.viewer_model2.layers.selection.active = None
            return

        self.viewer_model1.layers.selection.active = self.viewer_model1.layers[
            event.value.name
        ]
        self.viewer_model2.layers.selection.active = self.viewer_model2.layers[
            event.value.name
        ]

    def _point_update(self, event):
        for model in [self.viewer, self.viewer_model1, self.viewer_model2]:
            if model.dims is event.source:
                continue
            if len(self.viewer.layers) != len(model.layers):
                continue
            model.dims.current_step = event.value

    def _order_update(self):
        order = list(self.viewer.dims.order)
        if len(order) <= 2:
            self.viewer_model1.dims.order = order
            self.viewer_model2.dims.order = order
            return

        order[-3:] = order[-2], order[-3], order[-1]
        self.viewer_model1.dims.order = order
        order = list(self.viewer.dims.order)
        order[-3:] = order[-1], order[-2], order[-3]
        self.viewer_model2.dims.order = order

    def _layer_added(self, event):
        """add layer to additional viewers and connect all required events"""
        self.viewer_model1.layers.insert(
            event.index, copy_layer(event.value, 'model1')
        )
        self.viewer_model2.layers.insert(
            event.index, copy_layer(event.value, 'model2')
        )
        for name in get_property_names(event.value):
            getattr(event.value.events, name).connect(
                own_partial(self._property_sync, name)
            )

        if isinstance(event.value, Labels):
            event.value.events.set_data.connect(self._set_data_refresh)
            event.value.events.labels_update.connect(self._set_data_refresh)
            self.viewer_model1.layers[
                event.value.name
            ].events.set_data.connect(self._set_data_refresh)
            self.viewer_model2.layers[
                event.value.name
            ].events.set_data.connect(self._set_data_refresh)
            event.value.events.labels_update.connect(self._set_data_refresh)
            self.viewer_model1.layers[
                event.value.name
            ].events.labels_update.connect(self._set_data_refresh)
            self.viewer_model2.layers[
                event.value.name
            ].events.labels_update.connect(self._set_data_refresh)
        if event.value.name != '.cross':
            self.viewer_model1.layers[event.value.name].events.data.connect(
                self._sync_data
            )
            self.viewer_model2.layers[event.value.name].events.data.connect(
                self._sync_data
            )

        event.value.events.name.connect(self._sync_name)

        self._order_update()

    def _sync_name(self, event):
        """sync name of layers"""
        index = self.viewer.layers.index(event.source)
        self.viewer_model1.layers[index].name = event.source.name
        self.viewer_model2.layers[index].name = event.source.name

    def _sync_data(self, event):
        """sync data modification from additional viewers"""
        if self._block:
            return
        for model in [self.viewer, self.viewer_model1, self.viewer_model2]:
            layer = model.layers[event.source.name]
            if layer is event.source:
                continue
            try:
                self._block = True
                layer.data = event.source.data
            finally:
                self._block = False

    def _set_data_refresh(self, event):
        """
        synchronize data refresh between layers
        """
        if self._block:
            return
        for model in [self.viewer, self.viewer_model1, self.viewer_model2]:
            layer = model.layers[event.source.name]
            if layer is event.source:
                continue
            try:
                self._block = True
                layer.refresh()
            finally:
                self._block = False

    def _layer_removed(self, event):
        """remove layer in all viewers"""
        self.viewer_model1.layers.pop(event.index)
        self.viewer_model2.layers.pop(event.index)

    def _layer_moved(self, event):
        """update order of layers"""
        dest_index = (
            event.new_index
            if event.new_index < event.index
            else event.new_index + 1
        )
        self.viewer_model1.layers.move(event.index, dest_index)
        self.viewer_model2.layers.move(event.index, dest_index)

    def _property_sync(self, name, event):
        """Sync layers properties (except the name)"""
        if event.source not in self.viewer.layers:
            return
        try:
            self._block = True
            setattr(
                self.viewer_model1.layers[event.source.name],
                name,
                getattr(event.source, name),
            )
            setattr(
                self.viewer_model2.layers[event.source.name],
                name,
                getattr(event.source, name),
            )
        finally:
            self._block = False


if __name__ == '__main__':
    from qtpy import QtCore, QtWidgets
    QtWidgets.QApplication.setAttribute(QtCore.Qt.AA_ShareOpenGLContexts)
    # above two lines are needed to allow to undock the widget with
    # additional viewers
    view = napari.Viewer()
    dock_widget = MultipleViewerWidget(view)
    cross = CrossWidget(view)

    view.window.add_dock_widget(dock_widget, name='Sample')
    view.window.add_dock_widget(cross, name='Cross', area='left')

    view.open_sample('napari', 'cells3d')

    napari.run()