.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "_gallery/events/drag_points.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download__gallery_events_drag_points.py>`
        to download the full example code.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr__gallery_events_drag_points.py:


Drag points
===========

Example where you can drag scatter points on a line. This example also demonstrates how you can use a shared buffer
between two graphics to represent the same data using different graphics. When you update the data of one graphic the
data of the other graphic is also changed simultaneously since they use the same underlying buffer on the GPU.

.. GENERATED FROM PYTHON SOURCE LINES 10-99



.. image-sg:: /_gallery/events/images/sphx_glr_drag_points_001.webp
   :alt: drag points
   :srcset: /_gallery/events/images/sphx_glr_drag_points_001.webp
   :class: sphx-glr-single-img


.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    /home/runner/work/fastplotlib/fastplotlib/fastplotlib/graphics/features/_base.py:18: UserWarning: casting float64 array to float32
      warn(f"casting {array.dtype} array to float32")







|

.. code-block:: Python


    # test_example = false

    import numpy as np
    import fastplotlib as fpl
    import pygfx

    xs = np.linspace(0, 2 * np.pi, 10)
    ys = np.sin(xs)

    data = np.column_stack([xs, ys])

    figure = fpl.Figure(size=(700, 560))

    # add a line
    line_graphic = figure[0, 0].add_line(data)

    # add a scatter, share the line graphic buffer!
    scatter_graphic = figure[0, 0].add_scatter(data=line_graphic.data, sizes=25, colors="r")

    is_moving = False
    vertex_index = None


    @scatter_graphic.add_event_handler("pointer_down")
    def start_drag(ev: pygfx.PointerEvent):
        global is_moving
        global vertex_index

        if ev.button != 1:
            return

        is_moving = True
        vertex_index = ev.pick_info["vertex_index"]
        scatter_graphic.colors[vertex_index] = "cyan"


    @figure.renderer.add_event_handler("pointer_move")
    def move_point(ev):
        global is_moving
        global vertex_index

        # if not moving, return
        if not is_moving:
            return

        # disable controller
        figure[0, 0].controller.enabled = False

        # map x, y from screen space to world space
        pos = figure[0, 0].map_screen_to_world(ev)

        if pos is None:
            # end movement
            is_moving = False
            scatter_graphic.colors[vertex_index] = "r"  # reset color
            vertex_index = None
            return

        # change scatter data
        # since we are sharing the buffer, the line data will also change
        scatter_graphic.data[vertex_index, :-1] = pos[:-1]

        # re-enable controller
        figure[0, 0].controller.enabled = True


    @figure.renderer.add_event_handler("pointer_up")
    def end_drag(ev: pygfx.PointerEvent):
        global is_moving
        global vertex_index

        # end movement
        if is_moving:
            # reset color
            scatter_graphic.colors[vertex_index] = "r"

        is_moving = False
        vertex_index = None


    figure.show()


    # NOTE: `if __name__ == "__main__"` is NOT how to use fastplotlib interactively
    # please see our docs for using fastplotlib interactively in ipython and jupyter
    if __name__ == "__main__":
        print(__doc__)
        fpl.loop.run()


.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 0.392 seconds)


.. _sphx_glr_download__gallery_events_drag_points.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: drag_points.ipynb <drag_points.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: drag_points.py <drag_points.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: drag_points.zip <drag_points.zip>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_