Rectangle


Martin McBride, 2020-08-18
Tags geometry rectangle
Categories generativepy generative art

The Rectangle class draws a rectangle.

There is also a rectangle function that just creates a rectangle as a new path.

Rectangle class methods

The Rectangle class inherits add, fill, stroke, fill_stroke, path, clip and other methods from Shape.

It has an additional method:

  • of_corner_size

of_corner_size

Creates a rectangle based on the position and size.

of_corner_size(corner, width, height)
Parameter Type Description
corner (number, number) A tuple of two numbers, giving the (x, y) position of the top left corner.
width number The width.
height number The height.

rectangle function

Adds a rectangle as a new path, without the need to create a Rectangle object in code.

rectangle(ctx, corner, width, height)
Parameter Type Description
ctx Context The Pycairo Context to draw to
corner (number, number) A tuple of two numbers, giving the (x, y) position of the top left corner.
width number The width.
height number The height.

Example

Here is some example code that draws rectangles using the class and the utility function. The full code can be found on github.

from generativepy.drawing import make_image, setup
from generativepy.color import Color
from generativepy.geometry import Rectangle, rectangle

'''
Create rectangles using the geometry module.
'''

def draw(ctx, width, height, frame_no, frame_count):
    setup(ctx, width, height, width=5, background=Color(0.8))

    # The rectangle function is a convenience function that adds a rectangle as a new the path.
    # You can fill or stroke it as you wish.
    rectangle(ctx, (1, 1), 1, 1.2)
    ctx.set_source_rgba(*Color(1, 0, 0))
    ctx.fill()

    # Rectangle objects can be filled, stroked, filled and stroked.
    Rectangle(ctx).of_corner_size((3, 1), 1, 1.2).fill(Color(0, .5, 0))
    Rectangle(ctx).of_corner_size((1, 3), 1.2, 1).stroke(Color(0, .5, 0), 0.1)
    Rectangle(ctx).of_corner_size((3, 3), 1.2, 1).fill_stroke(Color(0, 0, 1), Color(0), 0.2)

make_image("/tmp/geometry-rectangles.png", draw, 500, 500)
If you found this article useful, you might be interested in the book Computer Graphics in Python or other books by the same author.

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