Center

center.go

@@ -0,0 +1,113 @@
+package tview
+
+import (
+	"github.com/gdamore/tcell/v2"
+)
+
+// Center is a wrapper which adds space around another primitive to shot up in the middle.
+type Center struct {
+	*Box
+
+	// the contained primitive
+	primitive Primitive
+
+	width, height int
+
+	// keep a reference in case we need it when we change the primitive
+	setFocus func(p Primitive)
+}
+
+// NewCenter returns a new frame around the given primitive.
+func NewCenter(primitive Primitive, width, height int) *Center {
+	return &Center{Box: NewBox(), primitive: primitive, width: width, height: height}
+}
+
+func (c *Center) Resize(width, height int) *Center {
+	if width > 0 {
+		c.width = width
+	}
+	if height > 0 {
+		c.height = height
+	}
+	return c
+}
+
+// SetPrimitive replaces the contained primitive with the given one.
+func (c *Center) SetPrimitive(p Primitive) *Center {
+	hasFocus := c.primitive.HasFocus()
+	c.primitive = p
+	if hasFocus && c.setFocus != nil {
+		c.setFocus(p) // Restore focus.
+	}
+	return c
+}
+
+// Primitive returns the primitive contained in this frame.
+func (c *Center) Primitive() Primitive {
+	return c.primitive
+}
+
+// Draw draws this primitive onto the screen.
+func (c *Center) Draw(screen tcell.Screen) {
+	x, y, inWidth, inHeight := c.GetInnerRect()
+	width, height := c.width, c.height
+	if width < inWidth {
+		x += (inWidth - width) >> 1
+	} else if width > inWidth {
+		width = inWidth
+	}
+	if height < inHeight {
+		y += (inHeight - height) >> 1
+	} else if height > inHeight {
+		height = inHeight
+	}
+
+	c.Box.Draw(screen)
+	c.primitive.SetRect(x, y, width, height)
+	c.primitive.Draw(screen)
+}
+
+// Focus is called when this primitive receives focus.
+func (c *Center) Focus(delegate func(p Primitive)) {
+	c.setFocus = delegate
+	delegate(c.primitive)
+	c.Box.Focus(delegate)
+}
+
+// HasFocus returns whether or not this primitive has focus.
+func (c *Center) HasFocus() bool {
+	return c.primitive.HasFocus()
+}
+
+// MouseHandler returns the mouse handler for this primitive.
+func (c *Center) MouseHandler() func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
+	return c.WrapMouseHandler(func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
+		if !c.InRect(event.Position()) {
+			return false, nil
+		}
+
+		// Pass mouse events on to contained primitive.
+		consumed, capture = c.primitive.MouseHandler()(action, event, setFocus)
+		if consumed {
+			return true, capture
+		}
+
+		// Clicking on the frame parts.
+		if action == MouseLeftDown {
+			setFocus(c)
+			consumed = true
+		}
+
+		return
+	})
+}
+
+// InputHandler returns the handler for this primitive.
+func (c *Center) InputHandler() func(event *tcell.EventKey, setFocus func(p Primitive)) {
+	return c.WrapInputHandler(func(event *tcell.EventKey, setFocus func(p Primitive)) {
+		if handler := c.primitive.InputHandler(); handler != nil {
+			handler(event, setFocus)
+			return
+		}
+	})
+}

demos/center/README.md

@@ -0,0 +1 @@
+![Screenshot](screenshot.png)

demos/center/main.go

@@ -0,0 +1,29 @@
+// Demo code for the Centered Modal primitive.
+package main
+
+import (
+	"strings"
+
+	"github.com/gdamore/tcell/v2"
+	"github.com/rivo/tview"
+)
+
+func main() {
+	app := tview.NewApplication()
+
+	background := tview.NewTextView().
+		SetTextColor(tcell.ColorBlue).
+		SetText(strings.Repeat("background ", 1000))
+
+	box := tview.NewBox().
+		SetBorder(true).
+		SetTitle("Centered Box")
+
+	pages := tview.NewPages().
+		AddPage("background", background, true, true).
+		AddPage("modal", tview.NewCenter(box, 40, 10), true, true)
+
+	if err := app.SetRoot(pages, true).Run(); err != nil {
+		panic(err)
+	}
+}

demos/presentation/code.go

@@ -20,6 +20,6 @@ func Code(p tview.Primitive, width, height int, code string) tview.Primitive {
 	fmt.Fprint(codeView, code)
 
 	return tview.NewFlex().
-		AddItem(Center(width, height, p), 0, 1, true).
+		AddItem(tview.NewCenter(p, width, height), 0, 1, true).
 		AddItem(codeView, codeWidth, 1, false)
 }

demos/presentation/colors.go

@@ -29,5 +29,5 @@ func Colors(nextSlide func()) (title string, content tview.Primitive) {
 	table.SetBorderPadding(1, 1, 2, 2).
 		SetBorder(true).
 		SetTitle("A [red]c[yellow]o[green]l[darkcyan]o[blue]r[darkmagenta]f[red]u[yellow]l[white] [black:red]c[:yellow]o[:green]l[:darkcyan]o[:blue]r[:darkmagenta]f[:red]u[:yellow]l[white:] [::bu]title")
-	return "Colors", Center(78, 19, table)
+	return "Colors", tview.NewCenter(table, 78, 19)
 }

demos/presentation/end.go

@@ -14,5 +14,5 @@ func End(nextSlide func()) (title string, content tview.Primitive) {
 	})
 	url := "https://github.com/rivo/tview"
 	fmt.Fprint(textView, url)
-	return "End", Center(len(url), 1, textView)
+	return "End", tview.NewCenter(textView, len(url), 1)
 }

demos/presentation/introduction.go

@@ -10,5 +10,5 @@ func Introduction(nextSlide func()) (title string, content tview.Primitive) {
 		AddItem("Designed to be simple", `"Hello world" is 5 lines of code`, '3', nextSlide).
 		AddItem("Good for data entry", `For charts, use "termui" - for low-level views, use "gocui" - ...`, '4', nextSlide).
 		AddItem("Extensive documentation", "Everything is documented, examples in GitHub wiki, demo code for each widget", '5', nextSlide)
-	return "Introduction", Center(80, 10, list)
+	return "Introduction", tview.NewCenter(list, 80, 10)
 }