From 4f42c502ed396fff9497b1f23138d2acc994b4d8 Mon Sep 17 00:00:00 2001
From: Christian Rocha <christian@rocha.is>
Date: Fri, 17 Jan 2020 15:37:04 -0500
Subject: [PATCH] Fullscreen mode via altscreen + fullscreen example

---
 examples/fullscreen/main.go | 59 +++++++++++++++++++++++++++++++++++++
 go.mod                      |  2 +-
 go.sum                      | 13 ++------
 tea.go                      | 21 +++++++++----
 4 files changed, 78 insertions(+), 17 deletions(-)
 create mode 100644 examples/fullscreen/main.go

diff --git a/examples/fullscreen/main.go b/examples/fullscreen/main.go
new file mode 100644
index 0000000..df04efa
--- /dev/null
+++ b/examples/fullscreen/main.go
@@ -0,0 +1,59 @@
+package main
+
+// A simple program that counts down from 5 and then exits.
+
+import (
+	"fmt"
+	"log"
+	"tea"
+	"time"
+)
+
+type model int
+
+type tickMsg struct{}
+
+func main() {
+	tea.Fullscreen()
+	defer tea.ExitFullscreen()
+	err := tea.NewProgram(model(5), update, view, []tea.Sub{tick}).Start()
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func update(msg tea.Msg, mdl tea.Model) (tea.Model, tea.Cmd) {
+	m, _ := mdl.(model)
+
+	switch message := msg.(type) {
+
+	case tea.KeyPressMsg:
+		switch message {
+		case "ctrl+c":
+			fallthrough
+		case "esc":
+			fallthrough
+		case "q":
+			return m, tea.Quit
+		}
+
+	case tickMsg:
+		m -= 1
+		if m <= 0 {
+			return m, tea.Quit
+		}
+
+	}
+
+	return m, nil
+}
+
+func view(mdl tea.Model) string {
+	m, _ := mdl.(model)
+	return fmt.Sprintf("\n\n     Hi. This program will exit in %d seconds...", m)
+}
+
+func tick(_ tea.Model) tea.Msg {
+	time.Sleep(time.Second)
+	return tickMsg{}
+}
diff --git a/go.mod b/go.mod
index 10ab6e6..de543ea 100644
--- a/go.mod
+++ b/go.mod
@@ -5,5 +5,5 @@ go 1.13
 require (
 	github.com/fogleman/ease v0.0.0-20170301025033-8da417bf1776
 	github.com/pkg/term v0.0.0-20190109203006-aa71e9d9e942
-	github.com/tj/go-terminput v1.0.0
+	golang.org/x/sys v0.0.0-20190626150813-e07cf5db2756 // indirect
 )
diff --git a/go.sum b/go.sum
index 8d87886..347edff 100644
--- a/go.sum
+++ b/go.sum
@@ -1,15 +1,6 @@
 github.com/fogleman/ease v0.0.0-20170301025033-8da417bf1776 h1:VRIbnDWRmAh5yBdz+J6yFMF5vso1It6vn+WmM/5l7MA=
 github.com/fogleman/ease v0.0.0-20170301025033-8da417bf1776/go.mod h1:9wvnDu3YOfxzWM9Cst40msBF1C2UdQgDv962oTxSuMs=
-github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1/go.mod h1:wJfORRmW1u3UXTncJ5qlYoELFm8eSnnEO6hX4iZ3EWY=
-github.com/jtolds/gls v4.20.0+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
 github.com/pkg/term v0.0.0-20190109203006-aa71e9d9e942 h1:A7GG7zcGjl3jqAqGPmcNjd/D9hzL95SuoOQAaFNdLU0=
 github.com/pkg/term v0.0.0-20190109203006-aa71e9d9e942/go.mod h1:eCbImbZ95eXtAUIbLAuAVnBnwf83mjf6QIVH8SHYwqQ=
-github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d/go.mod h1:OnSkiWE9lh6wB0YB77sQom3nweQdgAjqCqsofrRNTgc=
-github.com/smartystreets/goconvey v0.0.0-20190731233626-505e41936337/go.mod h1:syvi0/a8iFYH4r/RixwvyeAJjdLS9QV7WQ/tjFTllLA=
-github.com/tj/go-terminput v1.0.0 h1:X928u7ohxr7Dfzlxppvc5Zql5Lwd1bOH5VyIL2RPrFw=
-github.com/tj/go-terminput v1.0.0/go.mod h1:8zzAs+cqdjZlTxE9DbGyjKDfGNxaJjC5bvg4vkWX2V0=
-golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-golang.org/x/tools v0.0.0-20190328211700-ab21143f2384/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
+golang.org/x/sys v0.0.0-20190626150813-e07cf5db2756 h1:9nuHUbU8dRnRRfj9KjWUVrJeoexdbeMjttk6Oh1rD10=
+golang.org/x/sys v0.0.0-20190626150813-e07cf5db2756/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
diff --git a/tea.go b/tea.go
index 5e6abd3..5af309b 100644
--- a/tea.go
+++ b/tea.go
@@ -87,10 +87,9 @@ func (p *Program) Start() error {
 	hideCursor()
 	p.render(model)
 
-	// Subscribe to user input
-	// TODO: should we move this to the end-user program level or just keep this
-	// here, since it blocks nicely and user input will probably be something
-	// users typically need?
+	// Subscribe to user input. We could move this out of here and offer it
+	// as a subscription, but it blocks nicely and seems to be a common enough
+	// need that we're enabling it by default.
 	go func() {
 		for {
 			msg, _ := ReadKey(p.rw)
@@ -195,7 +194,19 @@ func clearLines(n int) {
 	}
 }
 
-// ClearScreen clears the visible portion of the terminal
+// Fullscreen switches to the altscreen and clears the terminal. The former
+// view can be restored with ExitFullscreen().
+func Fullscreen() {
+	fmt.Print(esc + "?1049h" + esc + "H")
+}
+
+// ExitFullscreen exits the altscreen and returns the former terminal view
+func ExitFullscreen() {
+	fmt.Print(esc + "?1049l")
+}
+
+// ClearScreen clears the visible portion of the terminal. Effectively, it
+// fills the terminal with blank spaces.
 func ClearScreen() {
 	fmt.Printf(esc + "2J" + esc + "3J" + esc + "1;1H")
 }