// SPDX-License-Identifier: Unlicense OR MIT

// Device independent units: dp, sp, and px conversions.
// Ported from gioui.org/unit.

package gio

import (
	"math"
)

// Metric converts Dp and Sp values to device-dependent pixels.
// The zero value represents a 1-to-1 scale from dp, sp to pixels.
type Metric struct {
	// PxPerDp is the device-dependent pixels per dp.
	PxPerDp float32
	// PxPerSp is the device-dependent pixels per sp.
	PxPerSp float32
}

type (
	// Dp represents device independent pixels. 1 dp will
	// have the same apparent size across platforms and
	// display resolutions.
	Dp float32
	// Sp is like Dp but for font sizes.
	Sp float32
)

// Dp converts v to pixels, rounded to the nearest integer value.
func (c Metric) Dp(v Dp) int {
	return int(math.Round(float64(nonZero(c.PxPerDp)) * float64(v)))
}

// Sp converts v to pixels, rounded to the nearest integer value.
func (c Metric) Sp(v Sp) int {
	return int(math.Round(float64(nonZero(c.PxPerSp)) * float64(v)))
}

// DpToSp converts v dp to sp.
func (c Metric) DpToSp(v Dp) Sp {
	return Sp(float32(v) * nonZero(c.PxPerDp) / nonZero(c.PxPerSp))
}

// SpToDp converts v sp to dp.
func (c Metric) SpToDp(v Sp) Dp {
	return Dp(float32(v) * nonZero(c.PxPerSp) / nonZero(c.PxPerDp))
}

// PxToSp converts v px to sp.
func (c Metric) PxToSp(v int) Sp {
	return Sp(float32(v) / nonZero(c.PxPerSp))
}

// PxToDp converts v px to dp.
func (c Metric) PxToDp(v int) Dp {
	return Dp(float32(v) / nonZero(c.PxPerDp))
}

func nonZero(v float32) float32 {
	if v == 0. {
		return 1
	}
	return v
}