3 ms·

How exactly do you that and can you interop with python?

kzrdude 5y ago
I just used this in the Jupyter notebook (toldya it was very simple, written today :). It interoperates with python by being passed data to the draw call. Usage like: c = Canvas(); c.draw(xs); xs is a numpy array of shape (N, 2), the points to draw on the canvas. It's not fancy. But it drew animations faster than matplotlib (I ran this for thousands of frames, just to watch the simulation). import IPython.display as ipydisplay import json import numpy as np class Canvas: def __init__(self, canvas_id=None, width=500, height=500): self.display_id = None self._canvas_id = canvas_id or ('canvas_' + str(np.random.randint(0, 10000))) display(ipydisplay.HTML(f""" <canvas id="{self._canvas_id}" width="{width}" height="{height}" style="border:1px solid #d3d3d3;"> Your browser does not support the HTML5 canvas tag.</canvas> """)) def draw(self, xs, world_size): xs_string = json.dumps(xs.tolist()) obj = ipydisplay.HTML(f""" <script> var c = document.getElementById("{self._canvas_id}"); var ctx = c.getContext("2d"); var xs = {xs_string}; var size = {world_size}; ctx.clearRect(0, 0, c.width, c.height); var scale = c.width / size; for (let i = 0; i < xs.length; i++) {{ ctx.fillRect(xs[i][0] * scale, c.height - xs[i][1] * scale, 2, 2) }} </script> """) if self.display_id: ipydisplay.update_display(obj, display_id=self.display_id) return self.display_id self.display_id = display(obj, display_id=True).display_id
- maverickleopard 5y ago
  That's awesome. I'm probably gonna start using this instead of matplotlib
  - kzrdude 5y ago
    Maybe just use ipycanvas instead - it's on PyPI :) It works the same way except it's not a hack. I found it after I posted. I went through: - matplotlib animations (super slow, not live) - writing an image with PIL and updating display (flickers) - custom html+canvas code - ipycanvas I call display() on the canvas and then run the draw update loop on the canvas later in the same cell. That way the canvas is first displayed and then "live" updated.
    - maverickleopard 5y ago
      Oh wow even better. Thanks for enlightening me on this

I just used this in the Jupyter notebook (toldya it was very simple, written today :). It interoperates with python by being passed data to the draw call. Usage like: c = Canvas(); c.draw(xs); xs is a numpy array of shape (N, 2), the points to draw on the canvas. It's not fancy. But it drew animations faster than matplotlib (I ran this for thousands of frames, just to watch the simulation). import IPython.display as ipydisplay import json import numpy as np class Canvas: def __init__(self, canvas_id=None, width=500, height=500): self.display_id = None self._canvas_id = canvas_id or ('canvas_' + str(np.random.randint(0, 10000))) display(ipydisplay.HTML(f""" <canvas id="{self._canvas_id}" width="{width}" height="{height}" style="border:1px solid #d3d3d3;"> Your browser does not support the HTML5 canvas tag.</canvas> """)) def draw(self, xs, world_size): xs_string = json.dumps(xs.tolist()) obj = ipydisplay.HTML(f""" <script> var c = document.getElementById("{self._canvas_id}"); var ctx = c.getContext("2d"); var xs = {xs_string}; var size = {world_size}; ctx.clearRect(0, 0, c.width, c.height); var scale = c.width / size; for (let i = 0; i < xs.length; i++) {{ ctx.fillRect(xs[i][0] * scale, c.height - xs[i][1] * scale, 2, 2) }} </script> """) if self.display_id: ipydisplay.update_display(obj, display_id=self.display_id) return self.display_id self.display_id = display(obj, display_id=True).display_id

maverickleopard 5y ago
That's awesome. I'm probably gonna start using this instead of matplotlib
- kzrdude 5y ago
  Maybe just use ipycanvas instead - it's on PyPI :) It works the same way except it's not a hack. I found it after I posted. I went through: - matplotlib animations (super slow, not live) - writing an image with PIL and updating display (flickers) - custom html+canvas code - ipycanvas I call display() on the canvas and then run the draw update loop on the canvas later in the same cell. That way the canvas is first displayed and then "live" updated.
  - maverickleopard 5y ago
    Oh wow even better. Thanks for enlightening me on this