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
	list      layout.List
}

type MenuStyle struct {
	Menu          *Menu
	Title         string
	IconColor     color.NRGBA
	TextColor     color.NRGBA
	ShortCutColor color.NRGBA
	FontSize      unit.Sp
	IconSize      unit.Dp
	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 {
		for i := 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
					}
				}
			}
		}
		m.Menu.list.Axis = layout.Vertical
		return m.Menu.list.Layout(gtx, len(items), func(gtx C, i int) D {
			defer op.Offset(image.Point{}).Push(gtx.Ops).Pop()
			var macro op.MacroOp
			item := &items[i]
			if i == m.Menu.hover-1 && !item.Disabled {
				macro = op.Record(gtx.Ops)
			}
			icon := widgetForIcon(item.IconBytes)
			iconColor := m.IconColor
			if item.Disabled {
				iconColor = mediumEmphasisTextColor
			}
			iconInset := layout.Inset{Left: unit.Dp(12), Right: unit.Dp(6)}
			textLabel := LabelStyle{Text: item.Text, FontSize: m.FontSize, Color: m.TextColor}
			if item.Disabled {
				textLabel.Color = mediumEmphasisTextColor
			}
			shortcutLabel := LabelStyle{Text: item.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 {
						p := gtx.Dp(unit.Dp(m.IconSize))
						gtx.Constraints.Min = image.Pt(p, p)
						return icon.Layout(gtx, iconColor)
					})
				}),
				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 i == m.Menu.hover-1 && !item.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 !item.Disabled {
				rect := image.Rect(0, 0, dims.Size.X, dims.Size.Y)
				area := clip.Rect(rect).Push(gtx.Ops)
				pointer.InputOp{Tag: &m.Menu.tags[i],
					Types: pointer.Press | pointer.Enter | pointer.Leave,
				}.Add(gtx.Ops)
				area.Pop()
			}
			return dims
		})
	}
	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.Sp(16),
		IconSize:      unit.Dp(16),
		HoverColor:    menuHoverColor,
	}
}