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draw565: Add a polar line drawing function.

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Polar coordinates are very convenient for implementing anything with
radial lines (such as a traditional watch face).

Signed-off-by: Daniel Thompson <daniel@redfelineninja.org.uk>
This commit is contained in:
Daniel Thompson 2020-12-27 09:07:06 +00:00
parent 8c03ddbb7a
commit 0ae31a53b3
1 changed files with 33 additions and 0 deletions
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33
wasp/draw565.py
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@ -7,6 +7,7 @@
import array
import fonts.sans24
import math
import micropython
@micropython.viper
@ -411,4 +412,36 @@ class Draw565(object):
err += dx;
y0 += sy;
def polar(self, x, y, theta, r0, r1, width=1, color=None):
"""Draw a line using polar coordinates.
The coordinate system is tuned for clock applications so it
adopts navigational conventions rather than mathematical ones.
Specifically the reference direction is drawn vertically
upwards and the angle is measures clockwise in degrees.
Example:
.. code-block:: python
draw = wasp.watch.drawable
draw.line(360 / 12, 16, 64)
:param theta: Angle, in degrees
:param r0: Radius of the start of the line
:param y0: Radius of the end of the line
:param x: X coordinate of the origin
:param y: Y coordinate of the origin
:param width: Width of the line in pixels
:param color: Colour to draw line in, defaults to the foreground colour
"""
to_radians = math.pi / 180
xdelta = math.sin(theta * to_radians)
ydelta = math.cos(theta * to_radians)
x0 = x + int(xdelta * r0)
x1 = x + int(xdelta * r1)
y0 = y - int(ydelta * r0)
y1 = y - int(ydelta * r1)
self.line(x0, y0, x1, y1, width, color)