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package main
import (
"log"
"os"
"time"
"gioui.org/app" // app contains Window handling.
"gioui.org/font/gofont" // gofont is used for loading the default font.
"gioui.org/io/key" // key is used for keyboard events.
"gioui.org/io/system" // system is used for system events (e.g. closing the window).
"gioui.org/layout" // layout is used for layouting widgets.
"gioui.org/op" // op is used for recording different operations.
"gioui.org/unit" // unit is used to define pixel-independent sizes
"gioui.org/widget" // widget contains state handling for widgets.
"gioui.org/widget/material" // material contains material design widgets.
)
func main() {
// The ui loop is separated from the application window creation
// such that it can be used for testing.
ui := NewUI()
// This creates a new application window and starts the UI.
go func() {
w := app.NewWindow(
app.Title("Timer"),
app.Size(unit.Dp(360), unit.Dp(360)),
)
if err := ui.Run(w); err != nil {
log.Println(err)
os.Exit(1)
}
os.Exit(0)
}()
// This starts Gio main.
app.Main()
}
// defaultMargin is a margin applied in multiple places to give
// widgets room to breathe.
var defaultMargin = unit.Dp(10)
// UI holds all of the application state.
type UI struct {
// Theme is used to hold the fonts used throughout the application.
Theme *material.Theme
Timer *Timer
duration widget.Float
reset widget.Clickable
}
// NewUI creates a new UI using the Go Fonts.
func NewUI() *UI {
ui := &UI{}
ui.Theme = material.NewTheme(gofont.Collection())
// start with reasonable defaults.
ui.Timer = NewTimer(5 * time.Second)
ui.duration.Value = 5
return ui
}
// Run handles window events and renders the application.
func (ui *UI) Run(w *app.Window) error {
// start the timer goroutine and ensure it's closed
// when the application closes.
closeTimer := ui.Timer.Start()
defer closeTimer()
var ops op.Ops
for {
select {
// when the timer is updated we should update the screen.
case <-ui.Timer.Updated:
w.Invalidate()
case e := <-w.Events():
// detect the type of the event.
switch e := e.(type) {
// this is sent when the application should re-render.
case system.FrameEvent:
// gtx is used to pass around rendering and event information.
gtx := layout.NewContext(&ops, e)
// render and handle UI.
ui.Layout(gtx)
// render and handle the operations from the UI.
e.Frame(gtx.Ops)
// handle a global key press.
case key.Event:
switch e.Name {
// when we click escape, let's close the window.
case key.NameEscape:
return nil
}
// this is sent when the application is closed.
case system.DestroyEvent:
return e.Err
}
}
}
return nil
}
// Layout displays the main program layout.
func (ui *UI) Layout(gtx layout.Context) layout.Dimensions {
th := ui.Theme
// check whether the reset button was clicked.
if ui.reset.Clicked() {
ui.Timer.Reset()
}
// check whether the slider value has changed.
if ui.duration.Changed() {
ui.Timer.SetDuration(secondsToDuration(float64(ui.duration.Value)))
}
// get the latest information about the timer.
info := ui.Timer.Info()
progress := float32(0)
if info.Duration == 0 {
progress = 1
} else {
progress = float32(info.Progress.Seconds() / info.Duration.Seconds())
}
// inset is used to add padding around the window border.
inset := layout.UniformInset(defaultMargin)
return inset.Layout(gtx, func(gtx layout.Context) layout.Dimensions {
return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
layout.Rigid(material.Body1(th, "Elapsed Time").Layout),
layout.Rigid(material.ProgressBar(th, progress).Layout),
layout.Rigid(material.Body1(th, info.ProgressString()).Layout),
layout.Rigid(layout.Spacer{Height: th.TextSize}.Layout),
layout.Rigid(material.Body1(th, "Duration").Layout),
layout.Rigid(material.Slider(th, &ui.duration, 0, 15).Layout),
layout.Rigid(layout.Spacer{Height: th.TextSize}.Layout),
layout.Rigid(material.Button(th, &ui.reset, "Reset").Layout),
)
})
}
func secondsToDuration(s float64) time.Duration {
return time.Duration(s * float64(time.Second))
}