# Tick

By Martin McBride, 2022-01-18
Tags: geometry tick
Categories: generativepy generative art

The TickMarker class is a special Shape that adds a small cross line marker to a line, of the type often used in geometric diagrams to show that two lines are the same length. They look like this:

You can add 1, 2 or 3 ticks.

The TickMarker only draws the tick, it doesn't draw the line itself. This would normally be draw using a Line object, Polygon object, or similar.

## TickMarker class

TickMarker is derived from the Shape class. It adds several methods:

• of_start_end
• with_length
• with_count
• with_gap

### of_start_end

Creates a marker based on a start and end points.

of_start_end(a, b)

Parameter Type Description
a (number, number) Tuple (x, y) for start of line
b (number, number) Tuple (x, y) for end of line

This will draw an tick marker for the line formed by ab. The tick will be halfway between points a and b.

### with_length

Sets the length of the tick.

with_length(length)

Parameter Type Description
length number Length of tick in user units.

The default is 4.

### with_count

Sets the number of ticks in the marker.

with_count(count)

Parameter Type Description
count int Number of ticks

This can be used to draw a single, double, or triple tick. Permitted values are 1, 2, or 3. Default is 1.

### with_gap

Sets the gap between the ticks if count > 1.

with_gap(gap)

Parameter Type Description
gap number Gap between ticks in user units.

Sets the spacing of the ticks. This is only relevant if there is more than one tick (ie if count > 1), otherwise it is ignored. The default is 1.

## tick function

This older tick function is deprecated as of GenerativePy 3.1.

tick(ctx, a, b, count=1, length=4, gap=1)

Parameter Type Description
ctx Context The Pycairo Context to draw to
a (number, number) Tuple (x, y) for point a
b (number, number) Tuple (x, y) for point b
count int Number of ticks on the line, 1, 2 or 3.
length number length of the tick in user units.
gap number Gap between ticks in user units.

Draws an tick across the line ab. The tick is half way between points a and b.

## Example

See the example in the angle_marker article.