sointu/tracker/gioui/menu.go

package gioui

import (
	"image"
	"image/color"

	"gioui.org/io/pointer"
	"gioui.org/layout"
	"gioui.org/op"
	"gioui.org/op/clip"
	"gioui.org/op/paint"
	"gioui.org/unit"
	"gioui.org/widget"
	"gioui.org/widget/material"
)

type Menu struct {
	Visible   bool
	clickable widget.Clickable
	tags      []bool
	clicks    []int
	hover     int
}

type MenuStyle struct {
	Menu          *Menu
	Title         string
	IconColor     color.NRGBA
	TextColor     color.NRGBA
	ShortCutColor color.NRGBA
	FontSize      unit.Value
	IconSize      unit.Value
	HoverColor    color.NRGBA
}

type MenuItem struct {
	IconBytes    []byte
	Text         string
	ShortcutText string
	Disabled     bool
}

func (m *Menu) Clicked() (int, bool) {
	if len(m.clicks) == 0 {
		return 0, false
	}
	first := m.clicks[0]
	for i := 1; i < len(m.clicks); i++ {
		m.clicks[i-1] = m.clicks[i]
	}
	m.clicks = m.clicks[:len(m.clicks)-1]
	return first, true
}

func (m *MenuStyle) Layout(gtx C, items ...MenuItem) D {
	contents := func(gtx C) D {
		flexChildren := make([]layout.FlexChild, len(items))
		for i, item := range items {
			// make sure we have a tag for every item
			for len(m.Menu.tags) <= i {
				m.Menu.tags = append(m.Menu.tags, false)
			}
			// handle pointer events for this item
			for _, ev := range gtx.Events(&m.Menu.tags[i]) {
				e, ok := ev.(pointer.Event)
				if !ok {
					continue
				}
				switch e.Type {
				case pointer.Press:
					m.Menu.clicks = append(m.Menu.clicks, i)
					m.Menu.Visible = false
				case pointer.Enter:
					m.Menu.hover = i + 1
				case pointer.Leave:
					if m.Menu.hover == i+1 {
						m.Menu.hover = 0
					}
				}
			}
			// layout contents for this item
			i2 := i // avoid loop variable getting updated in closure
			item2 := item
			flexChildren[i] = layout.Rigid(func(gtx C) D {
				defer op.Save(gtx.Ops).Load()
				var macro op.MacroOp
				if i2 == m.Menu.hover-1 && !item2.Disabled {
					macro = op.Record(gtx.Ops)
				}
				icon := widgetForIcon(item2.IconBytes)
				if !item2.Disabled {
					icon.Color = m.IconColor
				} else {
					icon.Color = mediumEmphasisTextColor
				}
				iconInset := layout.Inset{Left: unit.Dp(12), Right: unit.Dp(6)}
				textLabel := LabelStyle{Text: item2.Text, FontSize: m.FontSize, Color: m.TextColor}
				if item2.Disabled {
					textLabel.Color = mediumEmphasisTextColor
				}
				shortcutLabel := LabelStyle{Text: item2.ShortcutText, FontSize: m.FontSize, Color: m.ShortCutColor}
				shortcutInset := layout.Inset{Left: unit.Dp(12), Right: unit.Dp(12), Bottom: unit.Dp(2), Top: unit.Dp(2)}
				dims := layout.Flex{Axis: layout.Horizontal, Alignment: layout.Middle}.Layout(gtx,
					layout.Rigid(func(gtx C) D {
						return iconInset.Layout(gtx, func(gtx C) D {
							return icon.Layout(gtx, m.IconSize)
						})
					}),
					layout.Rigid(textLabel.Layout),
					layout.Flexed(1, func(gtx C) D { return D{Size: image.Pt(gtx.Constraints.Max.X, 1)} }),
					layout.Rigid(func(gtx C) D {
						return shortcutInset.Layout(gtx, shortcutLabel.Layout)
					}),
				)
				if i2 == m.Menu.hover-1 && !item2.Disabled {
					recording := macro.Stop()
					paint.FillShape(gtx.Ops, m.HoverColor, clip.Rect{
						Max: image.Pt(dims.Size.X, dims.Size.Y),
					}.Op())
					recording.Add(gtx.Ops)
				}
				if !item2.Disabled {
					rect := image.Rect(0, 0, dims.Size.X, dims.Size.Y)
					pointer.Rect(rect).Add(gtx.Ops)
					pointer.InputOp{Tag: &m.Menu.tags[i2],
						Types: pointer.Press | pointer.Enter | pointer.Leave,
					}.Add(gtx.Ops)
				}
				return dims
			})
		}
		return layout.Flex{Axis: layout.Vertical}.Layout(gtx, flexChildren...)
	}
	popup := Popup(&m.Menu.Visible)
	popup.NE = unit.Dp(0)
	popup.ShadowN = unit.Dp(0)
	popup.NW = unit.Dp(0)
	return popup.Layout(gtx, contents)
}

func PopupMenu(th *material.Theme, menu *Menu) MenuStyle {
	return MenuStyle{
		Menu:          menu,
		IconColor:     white,
		TextColor:     white,
		ShortCutColor: mediumEmphasisTextColor,
		FontSize:      unit.Dp(16),
		IconSize:      unit.Dp(16),
		HoverColor:    menuHoverColor,
	}
}