Calendar widget (#43)

README.md

@@ -57,6 +57,29 @@ Community contributed widgets.
 
 `import "fyne.io/x/fyne/widget"`
 
+### Calendar
+
+
+
+A date picker which returns a [time](https://pkg.go.dev/time) object with the selected date.
+
+<p  align="center"  class="align:center;margin:auto">
+
+<img  src="https://user-images.githubusercontent.com/45520351/179398051-a1f961fd-64be-4214-a565-0da85ce4a543.png"  style="max-width: 100%"  alt="Calendar widget"/>
+
+</p>
+
+
+
+To use create a new calendar with a given time and a callback function:
+
+```go
+
+calendar := widget.NewCalendar(time.Now(), onSelected, cellSize, padding)
+
+```
+[Demo](./cmd/hexwidget_demo/main.go) available for example usage
+
 ### Animated Gif
 
 A widget that will run animated gifs.

cmd/calendar_demo/main.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"time"
+
+	"fyne.io/fyne/v2"
+	"fyne.io/fyne/v2/app"
+	"fyne.io/fyne/v2/container"
+	"fyne.io/fyne/v2/widget"
+	xwidget "fyne.io/x/fyne/widget"
+)
+
+func main() {
+	a := app.New()
+	w := a.NewWindow("Calendar")
+
+	i := widget.NewLabel("Please Choose a Date")
+	i.Alignment = fyne.TextAlignCenter
+	l := widget.NewLabel("")
+	l.Alignment = fyne.TextAlignCenter
+	d := &date{instruction: i, dateChosen: l}
+
+	// Defines which date you would like the calendar to start
+	startingDate := time.Now()
+	calendar := xwidget.NewCalendar(startingDate, d.onSelected)
+
+	c := container.NewVBox(i, l, calendar)
+
+	w.SetContent(c)
+	w.ShowAndRun()
+}
+
+type date struct {
+	instruction *widget.Label
+	dateChosen  *widget.Label
+}
+
+func (d *date) onSelected(t time.Time) {
+	// use time object to set text on label with given format
+	d.instruction.SetText("Date Selected:")
+	d.dateChosen.SetText(t.Format("Mon 02 Jan 2006"))
+}

widget/calendar.go

@@ -0,0 +1,192 @@
+package widget
+
+import (
+	"math"
+	"strconv"
+	"strings"
+	"time"
+
+	"fyne.io/fyne/v2"
+	"fyne.io/fyne/v2/container"
+	"fyne.io/fyne/v2/layout"
+	"fyne.io/fyne/v2/theme"
+	"fyne.io/fyne/v2/widget"
+)
+
+// Declare conformity with Layout interface
+var _ fyne.Layout = (*calendarLayout)(nil)
+
+const daysPerWeek int = 7
+
+type calendarLayout struct {
+	cellSize float32
+}
+
+func newCalendarLayout() fyne.Layout {
+	return &calendarLayout{}
+}
+
+// Get the leading (top or left) edge of a grid cell.
+// size is the ideal cell size and the offset is which col or row its on.
+func (g *calendarLayout) getLeading(offset int) float32 {
+	ret := (g.cellSize) * float32(offset)
+
+	return float32(math.Round(float64(ret)))
+}
+
+// Get the trailing (bottom or right) edge of a grid cell.
+// size is the ideal cell size and the offset is which col or row its on.
+func (g *calendarLayout) getTrailing(offset int) float32 {
+	return g.getLeading(offset + 1)
+}
+
+// Layout is called to pack all child objects into a specified size.
+// For a GridLayout this will pack objects into a table format with the number
+// of columns specified in our constructor.
+func (g *calendarLayout) Layout(objects []fyne.CanvasObject, size fyne.Size) {
+	g.cellSize = size.Width / float32(daysPerWeek)
+	row, col := 0, 0
+	i := 0
+	for _, child := range objects {
+		if !child.Visible() {
+			continue
+		}
+
+		x1 := g.getLeading(col)
+		y1 := g.getLeading(row)
+		x2 := g.getTrailing(col)
+		y2 := g.getTrailing(row)
+
+		child.Move(fyne.NewPos(x1, y1))
+		child.Resize(fyne.NewSize(x2-x1, y2-y1))
+
+		if (i+1)%daysPerWeek == 0 {
+			row++
+			col = 0
+		} else {
+			col++
+		}
+		i++
+	}
+}
+
+//MinSize sets the minimum size for the calendar
+func (g *calendarLayout) MinSize(objects []fyne.CanvasObject) fyne.Size {
+	return fyne.NewSize(250, 250)
+}
+
+// Calendar creates a new date time picker which returns a time object
+type Calendar struct {
+	widget.BaseWidget
+	currentTime time.Time
+
+	monthPrevious *widget.Button
+	monthNext     *widget.Button
+	monthLabel    *widget.Label
+
+	dates *fyne.Container
+
+	onSelected func(time.Time)
+}
+
+func (c *Calendar) daysOfMonth() []fyne.CanvasObject {
+	start := time.Date(c.currentTime.Year(), c.currentTime.Month(), 1, 0, 0, 0, 0, c.currentTime.Location())
+	buttons := []fyne.CanvasObject{}
+
+	//account for Go time pkg starting on sunday at index 0
+	dayIndex := int(start.Weekday())
+	if dayIndex == 0 {
+		dayIndex += daysPerWeek
+	}
+
+	//add spacers if week doesn't start on Monday
+	for i := 0; i < dayIndex-1; i++ {
+		buttons = append(buttons, layout.NewSpacer())
+	}
+
+	for d := start; d.Month() == start.Month(); d = d.AddDate(0, 0, 1) {
+
+		dayNum := d.Day()
+		s := strconv.Itoa(dayNum)
+		b := widget.NewButton(s, func() {
+
+			selectedDate := c.dateForButton(dayNum)
+
+			c.onSelected(selectedDate)
+		})
+		b.Importance = widget.LowImportance
+
+		buttons = append(buttons, b)
+	}
+
+	return buttons
+}
+
+func (c *Calendar) dateForButton(dayNum int) time.Time {
+	oldName, off := c.currentTime.Zone()
+	return time.Date(c.currentTime.Year(), c.currentTime.Month(), dayNum, c.currentTime.Hour(), c.currentTime.Minute(), 0, 0, time.FixedZone(oldName, off)).In(c.currentTime.Location())
+}
+
+func (c *Calendar) monthYear() string {
+	return c.currentTime.Format("January 2006")
+}
+
+func (c *Calendar) calendarObjects() []fyne.CanvasObject {
+	columnHeadings := []fyne.CanvasObject{}
+	for i := 0; i < daysPerWeek; i++ {
+		j := i + 1
+		if j == daysPerWeek {
+			j = 0
+		}
+
+		t := widget.NewLabel(strings.ToUpper(time.Weekday(j).String()[:3]))
+		t.Alignment = fyne.TextAlignCenter
+		columnHeadings = append(columnHeadings, t)
+	}
+	columnHeadings = append(columnHeadings, c.daysOfMonth()...)
+
+	return columnHeadings
+}
+
+// CreateRenderer returns a new WidgetRenderer for this widget.
+// This should not be called by regular code, it is used internally to render a widget.
+func (c *Calendar) CreateRenderer() fyne.WidgetRenderer {
+	c.monthPrevious = widget.NewButtonWithIcon("", theme.NavigateBackIcon(), func() {
+		c.currentTime = c.currentTime.AddDate(0, -1, 0)
+		// Dates are 'normalised', forcing date to start from the start of the month ensures move from March to February
+		c.currentTime = time.Date(c.currentTime.Year(), c.currentTime.Month(), 1, 0, 0, 0, 0, c.currentTime.Location())
+		c.monthLabel.SetText(c.monthYear())
+		c.dates.Objects = c.calendarObjects()
+	})
+	c.monthPrevious.Importance = widget.LowImportance
+
+	c.monthNext = widget.NewButtonWithIcon("", theme.NavigateNextIcon(), func() {
+		c.currentTime = c.currentTime.AddDate(0, 1, 0)
+		c.monthLabel.SetText(c.monthYear())
+		c.dates.Objects = c.calendarObjects()
+	})
+	c.monthNext.Importance = widget.LowImportance
+
+	c.monthLabel = widget.NewLabel(c.monthYear())
+
+	nav := container.New(layout.NewBorderLayout(nil, nil, c.monthPrevious, c.monthNext),
+		c.monthPrevious, c.monthNext, container.NewCenter(c.monthLabel))
+
+	c.dates = container.New(newCalendarLayout(), c.calendarObjects()...)
+
+	dateContainer := container.NewVBox(nav, c.dates)
+
+	return widget.NewSimpleRenderer(dateContainer)
+}
+
+// NewCalendar creates a calendar instance
+func NewCalendar(cT time.Time, onSelected func(time.Time)) *Calendar {
+	c := &Calendar{
+		currentTime: cT,
+		onSelected:  onSelected,
+	}
+
+	c.ExtendBaseWidget(c)
+
+	return c
+}

widget/calendar_test.go

@@ -0,0 +1,71 @@
+package widget
+
+import (
+	"strconv"
+	"testing"
+	"time"
+
+	"fyne.io/fyne/v2"
+	"fyne.io/fyne/v2/test"
+	"fyne.io/fyne/v2/widget"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewCalendar(t *testing.T) {
+	now := time.Now()
+	c := NewCalendar(now, func(time.Time) {})
+	assert.Equal(t, now.Day(), c.currentTime.Day())
+	assert.Equal(t, int(now.Month()), int(c.currentTime.Month()))
+	assert.Equal(t, now.Year(), c.currentTime.Year())
+
+	_ = test.WidgetRenderer(c) // and render
+	assert.Equal(t, now.Format("January 2006"), c.monthLabel.Text)
+}
+
+func TestNewCalendar_ButtonDate(t *testing.T) {
+	date := time.Now()
+	c := NewCalendar(date, func(time.Time) {})
+	_ = test.WidgetRenderer(c) // and render
+
+	endNextMonth := date.AddDate(0, 1, 0).AddDate(0, 0, -(date.Day() - 1))
+	last := endNextMonth.AddDate(0, 0, -1)
+
+	firstDate := firstDateButton(c.dates)
+	assert.Equal(t, "1", firstDate.Text)
+	lastDate := c.dates.Objects[len(c.dates.Objects)-1].(*widget.Button)
+	assert.Equal(t, strconv.Itoa(last.Day()), lastDate.Text)
+}
+
+func TestNewCalendar_Next(t *testing.T) {
+	date := time.Now()
+	c := NewCalendar(date, func(time.Time) {})
+	_ = test.WidgetRenderer(c) // and render
+
+	assert.Equal(t, date.Format("January 2006"), c.monthLabel.Text)
+
+	test.Tap(c.monthNext)
+	date = date.AddDate(0, 1, 0)
+	assert.Equal(t, date.Format("January 2006"), c.monthLabel.Text)
+}
+
+func TestNewCalendar_Previous(t *testing.T) {
+	date := time.Now()
+	c := NewCalendar(date, func(time.Time) {})
+	_ = test.WidgetRenderer(c) // and render
+
+	assert.Equal(t, date.Format("January 2006"), c.monthLabel.Text)
+
+	test.Tap(c.monthPrevious)
+	date = date.AddDate(0, -1, 0)
+	assert.Equal(t, date.Format("January 2006"), c.monthLabel.Text)
+}
+
+func firstDateButton(c *fyne.Container) *widget.Button {
+	for _, b := range c.Objects {
+		if nonBlank, ok := b.(*widget.Button); ok {
+			return nonBlank
+		}
+	}
+
+	return nil
+}