gio/widget/material/material.go

// SPDX-License-Identifier: Unlicense OR MIT

// Package material implements the Material design.
package material

import (
	"image"
	"image/color"

	"gioui.org/f32"
	"gioui.org/font"
	"gioui.org/layout"
	"gioui.org/op"
	"gioui.org/op/paint"
	"gioui.org/text"
	"gioui.org/unit"
)

type Theme struct {
	Shaper *text.Shaper
	Color  struct {
		Primary color.RGBA
		Text    color.RGBA
		Hint    color.RGBA
	}
	TextSize unit.Value
}

func NewTheme() *Theme {
	t := &Theme{
		Shaper: font.Default(),
	}
	t.Color.Primary = rgb(0x3f51b5)
	t.Color.Text = rgb(0x000000)
	t.Color.Hint = rgb(0xbbbbbb)
	t.TextSize = unit.Sp(16)
	return t
}

func rgb(c uint32) color.RGBA {
	return argb(0xff000000 | c)
}

func argb(c uint32) color.RGBA {
	return color.RGBA{A: uint8(c >> 24), R: uint8(c >> 16), G: uint8(c >> 8), B: uint8(c)}
}

func fill(gtx *layout.Context, col color.RGBA) {
	cs := gtx.Constraints
	d := image.Point{X: cs.Width.Max, Y: cs.Height.Max}
	dr := f32.Rectangle{
		Max: f32.Point{X: float32(d.X), Y: float32(d.Y)},
	}
	paint.ColorOp{Color: col}.Add(gtx.Ops)
	paint.PaintOp{Rect: dr}.Add(gtx.Ops)
	gtx.Dimensions = layout.Dimensions{Size: d, Baseline: d.Y}
}

// https://pomax.github.io/bezierinfo/#circles_cubic.
func rrect(ops *op.Ops, width, height, se, sw, nw, ne float32) {
	w, h := float32(width), float32(height)
	const c = 0.55228475 // 4*(sqrt(2)-1)/3
	var b paint.Path
	b.Begin(ops)
	b.Move(f32.Point{X: w, Y: h - se})
	b.Cube(f32.Point{X: 0, Y: se * c}, f32.Point{X: -se + se*c, Y: se}, f32.Point{X: -se, Y: se}) // SE
	b.Line(f32.Point{X: sw - w + se, Y: 0})
	b.Cube(f32.Point{X: -sw * c, Y: 0}, f32.Point{X: -sw, Y: -sw + sw*c}, f32.Point{X: -sw, Y: -sw}) // SW
	b.Line(f32.Point{X: 0, Y: nw - h + sw})
	b.Cube(f32.Point{X: 0, Y: -nw * c}, f32.Point{X: nw - nw*c, Y: -nw}, f32.Point{X: nw, Y: -nw}) // NW
	b.Line(f32.Point{X: w - ne - nw, Y: 0})
	b.Cube(f32.Point{X: ne * c, Y: 0}, f32.Point{X: ne, Y: ne - ne*c}, f32.Point{X: ne, Y: ne}) // NE
	b.End().Add(ops)
}