Kivy canvas - fast drawing - polylines
<p>Tell me please, if drawing in Kivy Canvas fast, I get very acute, 
polylines figure, but if drawing very slow, then I get smooth lines.</p>

<pre><code>    ...

    def on_touch_down(self, touch):
        if Widget.on_touch_down(self, touch):
            return True
        print(touch.x, touch.y)
        with self.canvas.before:
            Color(*get_color_from_hex('#0080FF80'))
            Line(circle=(touch.x, touch.y, 2), width=2)
            touch.ud['current_line'] = Line(points=(touch.x, touch.y), width=2)

    def on_touch_move(self, touch):                               
        if 'current_line' in touch.ud:
            touch.ud['current_line'].points += (touch.x, touch.y)
    ...
</code></pre>

<p>This is my example:</p>

<p><img src="http://i.stack.imgur.com/eAtKq.png" alt="this is my example!"></p>

<p>Who knows how could I fixed it ?
Could I drawing fast and smooth in Kivy ?</p>

<p>Actually I tested your code and couldn't produce the issue you are having. I mean it doesn't matter if I draw fast or slow in Kivy. Half of these 'e's I drew fast and half slow but no difference in output. I suggest you try <a href="https://kivy.org/docs/tutorials/firstwidget.html" rel="nofollow">https://kivy.org/docs/tutorials/firstwidget.html</a> . If this example's drawing output is acute while drawing fast, then probably there is something wrong with your environment because it works well in mine. elif it's smooth in fast drawing, then your project in hand must be having issues.</p>

<p><a href="http://i.stack.imgur.com/J5d04.png" rel="nofollow"><img src="http://i.stack.imgur.com/J5d04.png" alt=""></a></p>

android python canvas drawing kivy