Drafter.Widget.Slider.Scale (drafter v0.3.1)

Value arithmetic for Drafter.Widget.Slider.

Every function takes the slider's bounds as min_value, max_value and a step that may be nil, and returns a value inside those bounds. A range whose bounds and step are all integers keeps integer values; any other range works in floats, rounded to the decimals the step implies so that repeated stepping does not accumulate float error.

A nil step means "continuous", which is still quantised: step_size/3 supplies a hundredth of the range as the working step, whole numbers for an integer range.

Summary

Functions

clamp(value, min_value, max_value)

value held inside min_value..max_value.

decimals(step)

How many decimals a step needs to be written exactly, up to 6.

fraction(value, min_value, max_value)

Where value sits in the range, as 0.0 at min_value through 1.0 at max_value.

integral?(min_value, max_value, step)

Whether the range works in integers.

nudge(value, min_value, max_value, step, count)

value moved count steps, stopping at the ends of the range.

snap(value, min_value, max_value, step)

value moved onto the nearest step from min_value and clamped into the range.

step_size(min_value, max_value, step)

The working step for a range.

value_at(fraction, min_value, max_value, step)

The value at fraction of the way through the range, snapped to the working step.

Functions

clamp(value, min_value, max_value)

@spec clamp(number(), number(), number()) :: number()

value held inside min_value..max_value.

iex> Drafter.Widget.Slider.Scale.clamp(1.5, 0.0, 1.0)
1.0

decimals(step)

@spec decimals(number()) :: non_neg_integer()

How many decimals a step needs to be written exactly, up to 6.

iex> Drafter.Widget.Slider.Scale.decimals(0.25)
2

iex> Drafter.Widget.Slider.Scale.decimals(5)
0

fraction(value, min_value, max_value)

@spec fraction(number(), number(), number()) :: float()

Where value sits in the range, as 0.0 at min_value through 1.0 at max_value.

Values outside the range come back clamped, and a range with no span reads as 0.0.

iex> Drafter.Widget.Slider.Scale.fraction(50, 0, 100)
0.5

iex> Drafter.Widget.Slider.Scale.fraction(5, 5, 5)
0.0

integral?(min_value, max_value, step)

@spec integral?(number(), number(), number() | nil) :: boolean()

Whether the range works in integers.

True when min_value, max_value and step are all integers; a nil step counts as integral when both bounds are.

iex> Drafter.Widget.Slider.Scale.integral?(0, 10, 1)
true

iex> Drafter.Widget.Slider.Scale.integral?(0.0, 1.0, nil)
false

nudge(value, min_value, max_value, step, count)

@spec nudge(number(), number(), number(), number() | nil, integer()) :: number()

value moved count steps, stopping at the ends of the range.

count is negative to move down.

iex> Drafter.Widget.Slider.Scale.nudge(0.5, 0.0, 1.0, 0.1, 1)
0.6

iex> Drafter.Widget.Slider.Scale.nudge(0.0, 0.0, 1.0, 0.1, -1)
0.0

snap(value, min_value, max_value, step)

@spec snap(number(), number(), number(), number() | nil) :: number()

value moved onto the nearest step from min_value and clamped into the range.

A nil or non-positive step clamps only.

iex> Drafter.Widget.Slider.Scale.snap(0.37, 0.0, 1.0, 0.25)
0.25

iex> Drafter.Widget.Slider.Scale.snap(2.6, 0, 10, 1)
3

step_size(min_value, max_value, step)

@spec step_size(number(), number(), number() | nil) :: number()

The working step for a range.

An explicit step is returned as given. A nil step becomes a hundredth of the range, rounded up to at least 1 when the range is integral.

iex> Drafter.Widget.Slider.Scale.step_size(0.0, 1.0, nil)
0.01

iex> Drafter.Widget.Slider.Scale.step_size(0, 3, nil)
1

iex> Drafter.Widget.Slider.Scale.step_size(0.0, 1.0, 0.25)
0.25

value_at(fraction, min_value, max_value, step)

@spec value_at(number(), number(), number(), number() | nil) :: number()

The value at fraction of the way through the range, snapped to the working step.

iex> Drafter.Widget.Slider.Scale.value_at(0.5, 0, 100, nil)
50

iex> Drafter.Widget.Slider.Scale.value_at(0.42, 0.0, 1.0, 0.25)
0.5