scales

Interfaces

Scale

Defined in: scales.ts:23

How a value is distributed across the travel of a control.

normalize and denormalize are inverses of each other: the position is 0 at min and 1 at max, and everything in between is up to the scale.

min and max are arguments rather than baked into the scale, so a scale holds no state and can be a module level constant. Passing the same object on every render therefore costs nothing.

Example

exponentialScale.denormalize(0.5, 20, 20000) // 632.45…

Properties

denormalize

denormalize: (position, min, max) => number;

Defined in: scales.ts:27

Position on the travel, 0-1, back to a value.

Parameters

Parameter	Type
position	number
min	number
max	number

Returns

number

normalize

normalize: (value, min, max) => number;

Defined in: scales.ts:25

Value to its position on the travel, 0-1.

Parameters

Parameter	Type
value	number
min	number
max	number

Returns

number

---

ValueRange

Defined in: scales.ts:246

How a value is scaled: the range it lives in, how it is rounded, and how it is distributed across the travel.

AxisOptions of @tremolo-ui/dom extends this, so a drag and a wheel / keyboard nudge run the same value pipeline.

Properties

max

max: number;

Defined in: scales.ts:248

min

min: number;

Defined in: scales.ts:247

scale?

optional scale?: Scale;

Defined in: scales.ts:258

How the value is distributed across the travel.

Default

linearScale

step?

optional step?: number;

Defined in: scales.ts:252

Rounding applied to the value. Left unrounded when omitted.

Variables

exponentialScale

const exponentialScale: Scale;

Defined in: scales.ts:103

Equal travel gives an equal ratio, so an octave — or a percentage — takes the same distance wherever it falls.

The scale for frequency (a filter cutoff over 20-20000 Hz), free running rates, and delay times.

Requires min and max to be non-zero and of the same sign, since no ratio reaches zero or crosses it. Use curveScale for a range that starts at 0.

---

linearScale

const linearScale: Scale;

Defined in: scales.ts:40

Equal travel gives an equal change in value.

The right default for anything already linear in perception: dB values, pan, percentages, MIDI note numbers, semitones.

Functions

applyDelta()

function applyDelta(
   value, 
   direction, 
   options, 
   __namedParameters, 
   modifiers?
): number;

Defined in: scales.ts:282

Move a value by an amount of input, as reported by a wheel or an arrow key.

The pipeline matches createDragValue of @tremolo-ui/dom: scale, then step, then clamp. Which key or which sign of deltaY counts as which direction is left to the caller, since it differs per component.

Parameters

Parameter	Type	Description
value	number	-
direction	number	which way, and how many times, to apply the option. The size of one step is option[1], so this is normally 1 or -1.
options	InputEventOptions	-
__namedParameters	ValueRange	-
modifiers?	ModifierState	the event, for options that name a modifier key. See selectInputEvent.

Returns

number

Examples

// ArrowDown on a slider whose keyboard option is ['raw', 1]
applyDelta(value, -1, keyboard, { min, max, step, scale })

// Shift+ArrowDown, where `keyboard` is { default: …, shift: ['raw', 0.1] }
applyDelta(value, -1, keyboard, range, event)

---

curveScale()

function curveScale(curve): Scale;

Defined in: scales.ts:151

An exponential bend that still passes exactly through min and max, so unlike exponentialScale it works on a range that starts at 0 or crosses it, and unlike skewScale its slope is neither zero nor infinite at either end.

The general purpose taper, and the same family as the curve of an envelope segment (SuperCollider's CurveWarp).

• curve > 0 gives the lower end more travel — envelope times from 0 ms, delay times, anything that wants fine control near the bottom
• curve < 0 gives the upper end more travel — a volume fader over -60..+6 dB that should be precise around 0 dB
• near 0 it is indistinguishable from linearScale, and is treated as linear to avoid dividing by zero

curveWithCenterValue gives the curve that places a chosen value at the middle of the travel.

Parameters

Parameter	Type	Description
curve	number	how hard the curve bends, and in which direction

Returns

Scale

---

curveWithCenterValue()

function curveWithCenterValue(
   centerValue, 
   min, 
   max
): number;

Defined in: scales.ts:225

The curve for curveScale that puts centerValue at the middle of the travel — the counterpart of skewWithCenterValue.

Parameters

Parameter	Type
centerValue	number
min	number
max	number

Returns

number

---

skewScale()

function skewScale(skew): Scale;

Defined in: scales.ts:61

The power law of JUCE's NormalisableRange::skew, applied to value - min.

Use it when the value has to agree with a JUCE or iPlug2 parameter — a plugin UI in a WebView, say, where the knob must sit exactly where the host's automation curve puts it. skewWithCenterValue gives the factor that places a chosen value at the middle of the travel.

skew < 1 gives the lower end more travel, skew > 1 the upper end.

For new designs prefer exponentialScale or curveScale: the slope of this curve is either zero or infinite at min, so the bottom of the range is a dead zone or jumps.

Parameters

Parameter	Type	Description
skew	number	the JUCE skew factor

Returns

Scale

---

skewWithCenterValue()

function skewWithCenterValue(
   centerValue, 
   min, 
   max
): number;

Defined in: scales.ts:82

The skew factor for skewScale that puts centerValue at the middle of the travel — JUCE's NormalisableRange::setSkewForCentre.

Parameters

Parameter	Type
centerValue	number
min	number
max	number

Returns

number

---

symmetricSkewScale()

function symmetricSkewScale(skew): Scale;

Defined in: scales.ts:193

skewScale mirrored about the middle of the range, so both halves bend the same way — JUCE's symmetricSkew.

For a bipolar control whose centre matters: detune over -100..+100 cents, or a bipolar filter envelope amount, where the fine adjustment is around 0 rather than at either end.

skew < 1 gives the middle more travel, skew > 1 the two ends.

Parameters

Parameter	Type	Description
skew	number	the JUCE skew factor

Returns

Scale