nicegui/nicegui/elements/interactive_image.py

from __future__ import annotations

from typing import Callable, Dict, List, Optional

from ..dependencies import register_component
from ..events import MouseEventArguments, handle_event
from .mixins.content_element import ContentElement
from .mixins.source_element import SourceElement

register_component('interactive_image', __file__, 'interactive_image.js')


class InteractiveImage(SourceElement, ContentElement):
    CONTENT_PROP = 'content'

    def __init__(self, source: str = '', *,
                 content: str = '',
                 on_mouse: Optional[Callable] = None, events: List[str] = ['click'], cross: bool = False) -> None:
        """Interactive Image

        Create an image with an SVG overlay that handles mouse events and yields image coordinates.
        It is also the best choice for non-flickering image updates.
        If the source URL changes faster than images can be loaded by the browser, some images are simply skipped.
        Thereby repeatedly updating the image source will automatically adapt to the available bandwidth.
        See `OpenCV Webcam <https://github.com/zauberzeug/nicegui/tree/main/examples/opencv_webcam/main.py>`_ for an example.

        :param source: the source of the image; can be an URL or a base64 string
        :param content: SVG content which should be overlayed; viewport has the same dimensions as the image
        :param on_mouse: callback for mouse events (yields `type`, `image_x` and `image_y`)
        :param events: list of JavaScript events to subscribe to (default: `['click']`)
        :param cross: whether to show crosshairs (default: `False`)
        """
        super().__init__(tag='interactive_image', source=source, content=content)
        self._props['events'] = events
        self._props['cross'] = cross

        def handle_mouse(msg: Dict) -> None:
            if on_mouse is None:
                return
            arguments = MouseEventArguments(
                sender=self,
                client=self.client,
                type=msg['args'].get('mouse_event_type'),
                image_x=msg['args'].get('image_x'),
                image_y=msg['args'].get('image_y'),
                button=msg['args'].get('button', 0),
                buttons=msg['args'].get('buttons', 0),
                alt=msg['args'].get('alt', False),
                ctrl=msg['args'].get('ctrl', False),
                meta=msg['args'].get('meta', False),
                shift=msg['args'].get('shift', False),
            )
            return handle_event(on_mouse, arguments)
        self.on('mouse', handle_mouse)