widget,widget/material: add CheckBox

widget/checkbox.go

@@ -0,0 +1,25 @@
+package widget
+
+import (
+	"gioui.org/gesture"
+	"gioui.org/layout"
+)
+
+type CheckBox struct {
+	click   gesture.Click
+	checked bool
+}
+
+func (c *CheckBox) Checked(gtx *layout.Context) bool {
+	for _, e := range c.click.Events(gtx) {
+		switch e.Type {
+		case gesture.TypeClick:
+			c.checked = !c.checked
+		}
+	}
+	return c.checked
+}
+
+func (c *CheckBox) Layout(gtx *layout.Context) {
+	c.click.Add(gtx.Ops)
+}

widget/material/checkbox.go

@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+// Package material implements the Material design.
+package material
+
+import (
+	"gioui.org/io/pointer"
+	"gioui.org/layout"
+	"gioui.org/op/paint"
+	"gioui.org/text"
+	"gioui.org/unit"
+	"gioui.org/widget"
+	"image"
+	"image/color"
+)
+
+type CheckBox struct {
+	Text string
+	// Color is the text color.
+	Color              color.RGBA
+	Font               text.Font
+	IconColor          color.RGBA
+	Size               unit.Value
+	shaper             *text.Shaper
+	checkedStateIcon   *Icon
+	uncheckedStateIcon *Icon
+}
+
+func (t *Theme) CheckBox(txt string) CheckBox {
+	return CheckBox{
+		Text:      txt,
+		Color:     t.Color.Text,
+		IconColor: t.Color.Primary,
+		Font: text.Font{
+			Size: t.TextSize.Scale(14.0 / 16.0),
+		},
+		Size:               unit.Dp(26),
+		shaper:             t.Shaper,
+		checkedStateIcon:   t.checkedStateIcon,
+		uncheckedStateIcon: t.uncheckedStateIcon,
+	}
+}
+
+func (c CheckBox) Layout(gtx *layout.Context, checkBox *widget.CheckBox) {
+
+	textColor := c.Color
+	iconColor := c.IconColor
+
+	var icon *Icon
+	if checkBox.Checked(gtx) {
+		icon = c.checkedStateIcon
+	} else {
+		icon = c.uncheckedStateIcon
+	}
+
+	hmin := gtx.Constraints.Width.Min
+	vmin := gtx.Constraints.Height.Min
+
+	flex := layout.Flex{Alignment: layout.Middle}
+
+	ico := flex.Rigid(gtx, func() {
+		layout.Align(layout.Center).Layout(gtx, func() {
+			layout.UniformInset(unit.Dp(2)).Layout(gtx, func() {
+				size := gtx.Px(c.Size)
+				icon.Color = iconColor
+				icon.Layout(gtx, unit.Px(float32(size)))
+				gtx.Dimensions = layout.Dimensions{
+					Size: image.Point{X: size, Y: size},
+				}
+			})
+		})
+	})
+
+	lbl := flex.Rigid(gtx, func() {
+		gtx.Constraints.Width.Min = hmin
+		gtx.Constraints.Height.Min = vmin
+		layout.Align(layout.Start).Layout(gtx, func() {
+			layout.UniformInset(unit.Dp(2)).Layout(gtx, func() {
+				paint.ColorOp{Color: textColor}.Add(gtx.Ops)
+				widget.Label{}.Layout(gtx, c.shaper, c.Font, c.Text)
+			})
+		})
+	})
+
+	flex.Layout(gtx, ico, lbl)
+	pointer.RectAreaOp{Rect: image.Rectangle{Max: gtx.Dimensions.Size}}.Add(gtx.Ops)
+	checkBox.Layout(gtx)
+}