appdimens-dynamic

Physical units (`compose` + `code.units`)

What it is

Conversion of real-world measures (millimeters, centimeters, inches) using DisplayMetrics / Resources. It does not follow the “300 dp axis” scaling model; use when you need approximate physical size on the device.

Calculation used

toMm(mm, resources, context?): TypedValue.COMPLEX_UNIT_MM divided by density → dp as Float; may use DimenCache (CalcType.UNITIES).
toCm(cm, resources, context?): same pattern as toMm via mm (cm × 10) → dp Float (cached like toMm).
toInch(inches, resources, context?): TypedValue.COMPLEX_UNIT_IN divided by density → dp Float (cached like toMm).
Composable Float / Int .mm, .cm, .inch: wrap the above with LocalDensity / LocalResources / LocalContext. They return a Float in dp-equivalent units (not layout pixels). For Compose layout, use .dp on the result, e.g. 10f.mm.dp.

Pure helpers (convertMmToCm, inchToMm, …) are math-only between unit labels.

Code module (com.appdimens.dynamic.code.units.DimenPhysicalUnits):

toPxFromMm / Cm / Inch: direct applyDimension → pixels (no double conversion).
toDpFromMm / Cm / Inch: physical unit → dp.
toSpFromMm / Cm / Inch: via dp and scaledDensity.
radiusFromDiameter / radiusFromCircumference: radius in dp after normalizing the diameter/circumference: MM / CM / INCH via toDp*, DP raw, SP as value × (scaledDensity / density), PX as value / density.

How to use

Compose (import com.appdimens.dynamic.compose.mm, .cm, .inch):

import androidx.compose.ui.unit.dp
import com.appdimens.dynamic.compose.mm
import com.appdimens.dynamic.compose.cm

Modifier.width(10f.mm.dp)
Modifier.height(2.5f.cm.dp)

Composable property	Receivers	Return	Typical use
`mm`	`Float`, `Int`	`Float` (dp)	`10f.mm.dp` → `Dp` for `Modifier`
`cm`	`Float`, `Int`	`Float` (dp)	`2.5f.cm.dp`
`inch`	`Float`, `Int`	`Float` (dp)	`1f.inch.dp`

Composable instance helpers (on DimenPhysicalUnits in the same file)

API	Example
`Float.radius(type: UnitType)`	`48f.radius(UnitType.MM)` — radius in dp
`Number.radius(type: UnitType)`	`48.radius(UnitType.DP)`
`Float.measureDiameter(isCircumference: Boolean)`	Toggle diameter vs circumference display
`Number.measureDiameter(isCircumference: Boolean)`	Same

Object DimenPhysicalUnits (Compose) — non-composable helpers

API	Role	Example
`toMm(mm, resources, context?)`	mm → dp `Float`	`DimenPhysicalUnits.toMm(10f, resources)`
`toCm(cm, resources, context?)`	cm → dp `Float`	`DimenPhysicalUnits.toCm(2.5f, resources)`
`toInch(inches, resources, context?)`	inch → dp `Float`	`DimenPhysicalUnits.toInch(1f, resources)`
`convertMmToCm` / `convertMmToInch`	pure `Float`	`convertMmToCm(100f)`
`convertCmToMm` / `convertCmToInch`	pure `Float`	`convertCmToInch(2.54f)`
`convertInchToCm` / `convertInchToMm`	pure `Float`	`convertInchToMm(1f)`
`Float.mmToCm()`, `Number.mmToCm()`, …	sugar over `convert*`	`5f.mmToInch()`
`radius(diameter, type: UnitType, resources)`	half-size in dp	`radius(24f, UnitType.MM, resources)`
`displayMeasureDiameter(diameter, isCircumference)`	scale for circumference	internal + extensions
`unitSizeInDp(type, resources)`	size of 1.0 logical unit in dp (mm/cm/inch/dp/sp/px normalized to dp)	`unitSizeInDp(UnitType.MM, resources)`

Use UnitType (MM, CM, INCH, SP, DP, PX, …) with radius and unitSizeInDp.

Note: the former name unitSizePerPx was renamed to unitSizeInDp because the values are expressed in dp, not raw pixels. If DOCUMENTATION/KDOC/ estiver desatualizado, gere HTML com Dokka e execute python3 scripts/sync_kdoc_from_dokka_html.py (ver README.md nesta pasta).

Why use it

Specs from print, regulation (touch target in mm), ruler-based prototyping, or physical mockups.

When to use it

Minimum tap target in mm.
Matching a cm spec.
When stakeholders reason in inches / mm, not dp.

Advantages and trade-offs

Pros: speaks “real world”; orthogonal to scaling strategies.
Cons: real vs nominal dpi varies; not a substitute for scaled / breakpoints for layout grids.

Recommended usage strategy

Use for legal / a11y minimums and isolated measurements; build the main grid with scaled (or another strategy).

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