example_partial_viewport.py

import argparse
import copy

import neuroglancer
import neuroglancer.cli
import numpy as np
from example import add_example_layers


def _make_viewport_adjust_command(adjustments):
    def handler(s):
        with viewer.txn() as s:
            for i, amount in adjustments:
                s.partial_viewport[i] += amount
            s.partial_viewport[:2] = np.clip(s.partial_viewport[:2], 0, 0.9)
            s.partial_viewport[2:] = np.clip(
                s.partial_viewport[2:], 0.1, 1 - s.partial_viewport[:2]
            )
            partial_viewport = np.array(s.partial_viewport)

        with viewer.config_state.txn() as s:
            s.viewer_size = [256, 256]
            s.status_messages["note"] = f"Viewport: {partial_viewport!r}"

    return handler


if __name__ == "__main__":
    ap = argparse.ArgumentParser()
    neuroglancer.cli.add_server_arguments(ap)
    args = ap.parse_args()
    neuroglancer.cli.handle_server_arguments(args)
    viewer = neuroglancer.Viewer()
    with viewer.txn() as s:
        a, b = add_example_layers(s)
    initial_state = viewer.state

    def _add_prefetch(s):
        with viewer.config_state.txn() as s:
            prefetch_state = copy.deepcopy(initial_state)
            prefetch_state.partial_viewport = [0.5, 0, 0.5, 1]
            s.prefetch = [neuroglancer.PrefetchState(state=prefetch_state, priority=0)]

    def _remove_prefetch(s):
        with viewer.config_state.txn() as s:
            del s.prefetch[:]

    viewer.actions.add(
        "viewport-translate-left", _make_viewport_adjust_command([(0, -0.1)])
    )
    viewer.actions.add(
        "viewport-translate-right", _make_viewport_adjust_command([(0, 0.1)])
    )
    viewer.actions.add(
        "viewport-translate-up", _make_viewport_adjust_command([(1, -0.1)])
    )
    viewer.actions.add(
        "viewport-translate-down", _make_viewport_adjust_command([(1, 0.1)])
    )
    viewer.actions.add(
        "viewport-shrink-width", _make_viewport_adjust_command([(2, -0.1)])
    )
    viewer.actions.add(
        "viewport-enlarge-width", _make_viewport_adjust_command([(2, 0.1)])
    )
    viewer.actions.add(
        "viewport-shrink-height", _make_viewport_adjust_command([(3, -0.1)])
    )
    viewer.actions.add(
        "viewport-enlarge-height", _make_viewport_adjust_command([(3, 0.1)])
    )
    viewer.actions.add("viewport-add-prefetch", _add_prefetch)
    viewer.actions.add("viewport-remove-prefetch", _remove_prefetch)

    with viewer.config_state.txn() as s:
        s.input_event_bindings.viewer["keyh"] = "viewport-translate-left"
        s.input_event_bindings.viewer["keyl"] = "viewport-translate-right"
        s.input_event_bindings.viewer["keyj"] = "viewport-translate-down"
        s.input_event_bindings.viewer["keyk"] = "viewport-translate-up"
        s.input_event_bindings.viewer["keyt"] = "viewport-add-prefetch"
        s.input_event_bindings.viewer["keyg"] = "viewport-remove-prefetch"
        s.input_event_bindings.viewer["shift+keyu"] = "viewport-shrink-height"
        s.input_event_bindings.viewer["shift+keyi"] = "viewport-enlarge-height"
        s.input_event_bindings.viewer["shift+keyy"] = "viewport-shrink-width"
        s.input_event_bindings.viewer["shift+keyo"] = "viewport-enlarge-width"

    print(viewer)