Add ProgressBar widget

CHANGELOG

@@ -1,3 +1,6 @@
+v1.4.1 (WIP)
+- Add ProgressBar widget
+
 v1.4.0 (2020-01-16)
 - Bump version to resolve issues with "go get"
 

demos/presentation/main.go

@@ -39,6 +39,7 @@ func main() {
 		Form,
 		TextView1,
 		TextView2,
+		ProgressBar,
 		Table,
 		TreeView,
 		Flex,

demos/presentation/progressbar.go

@@ -0,0 +1,52 @@
+package main
+
+import (
+	"time"
+
+	"git.sr.ht/~tslocum/cview"
+)
+
+// ProgressBar demonstrates the ProgressBar.
+func ProgressBar(nextSlide func()) (title string, content cview.Primitive) {
+	grid := cview.NewGrid().SetColumns(-1, 6, 4, 30, -1).SetRows(-1, 12, 4, 4, -1)
+
+	verticalProgressBar := cview.NewProgressBar()
+	verticalProgressBar.SetBorder(true)
+	verticalProgressBar.Vertical = true
+
+	horizontalProgressBar := cview.NewProgressBar()
+	horizontalProgressBar.SetBorder(true)
+	horizontalProgressBar.SetMax(150)
+
+	padding := cview.NewTextView()
+	grid.AddItem(padding, 0, 0, 1, 5, 0, 0, false)
+	grid.AddItem(padding, 1, 0, 1, 1, 0, 0, false)
+	grid.AddItem(verticalProgressBar, 1, 1, 2, 1, 0, 0, false)
+	grid.AddItem(padding, 1, 2, 1, 1, 0, 0, false)
+	grid.AddItem(padding, 2, 0, 1, 5, 0, 0, false)
+	grid.AddItem(horizontalProgressBar, 3, 3, 1, 1, 0, 0, false)
+	grid.AddItem(padding, 1, 4, 1, 1, 0, 0, false)
+	grid.AddItem(padding, 4, 0, 1, 5, 0, 0, false)
+
+	go func() {
+		t := time.NewTicker(100 * time.Millisecond)
+		for range t.C {
+			if verticalProgressBar.Complete() {
+				verticalProgressBar.SetProgress(0)
+			} else {
+				verticalProgressBar.AddProgress(1)
+			}
+
+			if horizontalProgressBar.Complete() {
+				horizontalProgressBar.SetProgress(0)
+			} else {
+				horizontalProgressBar.AddProgress(1)
+			}
+
+			// Queue draw
+			app.QueueUpdateDraw(func() {})
+		}
+	}()
+
+	return "ProgressBar", grid
+}

demos/progressbar/main.go

@@ -0,0 +1,56 @@
+// Demo code for the ProgressBar primitive.
+package main
+
+import (
+	"time"
+
+	"git.sr.ht/~tslocum/cview"
+)
+
+func main() {
+	app := cview.NewApplication()
+
+	grid := cview.NewGrid().SetColumns(-1, 6, 4, 30, -1).SetRows(-1, 12, 4, 4, -1)
+
+	verticalProgressBar := cview.NewProgressBar()
+	verticalProgressBar.SetBorder(true)
+	verticalProgressBar.Vertical = true
+
+	horizontalProgressBar := cview.NewProgressBar()
+	horizontalProgressBar.SetBorder(true)
+	horizontalProgressBar.SetMax(150)
+
+	padding := cview.NewTextView()
+	grid.AddItem(padding, 0, 0, 1, 5, 0, 0, false)
+	grid.AddItem(padding, 1, 0, 1, 1, 0, 0, false)
+	grid.AddItem(verticalProgressBar, 1, 1, 2, 1, 0, 0, false)
+	grid.AddItem(padding, 1, 2, 1, 1, 0, 0, false)
+	grid.AddItem(padding, 2, 0, 1, 5, 0, 0, false)
+	grid.AddItem(horizontalProgressBar, 3, 3, 1, 1, 0, 0, false)
+	grid.AddItem(padding, 1, 4, 1, 1, 0, 0, false)
+	grid.AddItem(padding, 4, 0, 1, 5, 0, 0, false)
+
+	go func() {
+		t := time.NewTicker(100 * time.Millisecond)
+		for range t.C {
+			if verticalProgressBar.Complete() {
+				verticalProgressBar.SetProgress(0)
+			} else {
+				verticalProgressBar.AddProgress(1)
+			}
+
+			if horizontalProgressBar.Complete() {
+				horizontalProgressBar.SetProgress(0)
+			} else {
+				horizontalProgressBar.AddProgress(1)
+			}
+
+			// Queue draw
+			app.QueueUpdateDraw(func() {})
+		}
+	}()
+
+	if err := app.SetRoot(grid, true).Run(); err != nil {
+		panic(err)
+	}
+}

progressbar.go

@@ -0,0 +1,133 @@
+package cview
+
+import (
+	"math"
+	"sync"
+
+	"github.com/gdamore/tcell"
+)
+
+// ProgressBar indicates the progress of an operation.
+type ProgressBar struct {
+	*Box
+
+	// Rune to use when rendering the empty area of the progress bar.
+	EmptyRune rune
+
+	// Color of the empty area of the progress bar.
+	EmptyColor tcell.Color
+
+	// Rune to use when rendering the filled area of the progress bar.
+	FilledRune rune
+
+	// Color of the filled area of the progress bar.
+	FilledColor tcell.Color
+
+	// If set to true, instead of filling from left to right, the bar is filled
+	// from bottom to top.
+	Vertical bool
+
+	max      int
+	progress int
+	*sync.Mutex
+}
+
+// NewProgressBar returns a new progress bar.
+func NewProgressBar() *ProgressBar {
+	return &ProgressBar{
+		Box:         NewBox(),
+		EmptyRune:   ' ',
+		EmptyColor:  tcell.ColorDefault,
+		FilledRune:  tcell.RuneBlock,
+		FilledColor: tcell.ColorDefault,
+		max:         100,
+		Mutex:       new(sync.Mutex),
+	}
+}
+
+// SetMax sets the progress required to fill the bar.
+func (p *ProgressBar) SetMax(max int) {
+	p.Lock()
+	defer p.Unlock()
+
+	p.max = max
+}
+
+// GetMax returns the progress required to fill the bar.
+func (p *ProgressBar) GetMax() int {
+	p.Lock()
+	defer p.Unlock()
+
+	return p.max
+}
+
+// AddProgress adds to the current progress.
+func (p *ProgressBar) AddProgress(progress int) {
+	p.Lock()
+	defer p.Unlock()
+
+	p.progress += progress
+}
+
+// SetProgress sets the current progress.
+func (p *ProgressBar) SetProgress(progress int) {
+	p.Lock()
+	defer p.Unlock()
+
+	p.progress = progress
+}
+
+// GetProgress gets the current progress.
+func (p *ProgressBar) GetProgress() int {
+	p.Lock()
+	defer p.Unlock()
+
+	return p.progress
+}
+
+// Complete returns whether the progress bar has been filled.
+func (p *ProgressBar) Complete() bool {
+	p.Lock()
+	defer p.Unlock()
+
+	return p.progress >= p.max
+}
+
+// Draw draws this primitive onto the screen.
+func (p *ProgressBar) Draw(screen tcell.Screen) {
+	p.Lock()
+	defer p.Unlock()
+
+	p.Box.Draw(screen)
+
+	x, y, width, height := p.GetInnerRect()
+
+	barSize := height
+	maxLength := width
+	if p.Vertical {
+		barSize = width
+		maxLength = height
+	}
+
+	barLength := int(math.RoundToEven(float64(maxLength) * (float64(p.progress) / float64(p.max))))
+	if barLength > maxLength {
+		barLength = maxLength
+	}
+
+	for i := 0; i < barSize; i++ {
+		for j := 0; j < barLength; j++ {
+			if p.Vertical {
+				screen.SetContent(x+i, y+(height-1-j), p.FilledRune, nil, tcell.StyleDefault.Foreground(p.FilledColor))
+			} else {
+				screen.SetContent(x+j, y+i, p.FilledRune, nil, tcell.StyleDefault.Foreground(p.FilledColor))
+			}
+		}
+		for j := barLength; j < maxLength; j++ {
+			if p.Vertical {
+				screen.SetContent(x+i, y+(height-1-j), p.EmptyRune, nil, tcell.StyleDefault.Foreground(p.EmptyColor))
+			} else {
+				screen.SetContent(x+j, y+i, p.EmptyRune, nil, tcell.StyleDefault.Foreground(p.EmptyColor))
+			}
+		}
+	}
+}