Update pager example to use high performance renderer

examples/go.mod

@@ -8,5 +8,6 @@ require (
 	github.com/charmbracelet/bubbles v0.0.0-20200526000837-87c7cd778f80
 	github.com/charmbracelet/bubbletea v0.8.1
 	github.com/fogleman/ease v0.0.0-20170301025033-8da417bf1776
+	github.com/mattn/go-runewidth v0.0.9
 	github.com/muesli/termenv v0.5.3-0.20200617154346-da5de72b61c0
 )

examples/go.sum

@@ -1,5 +1,3 @@
-github.com/charmbracelet/bubbles v0.0.0-20200526000837-87c7cd778f80 h1:cfaoL1+tHPABTLEAg831PIFG96teW69Wamz9M025r5M=
-github.com/charmbracelet/bubbles v0.0.0-20200526000837-87c7cd778f80/go.mod h1:/AeLRFlL2Uf4X7U5LjnswTII6u4maPzMm1+vZfeUJKc=
 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/google/goterm v0.0.0-20190703233501-fc88cf888a3f h1:5CjVwnuUcp5adK4gmY6i72gpVFVnZDP2h5TmPScB6u4=
@@ -8,7 +6,8 @@ github.com/lucasb-eyer/go-colorful v1.0.3 h1:QIbQXiugsb+q10B+MI+7DI1oQLdmnep86tW
 github.com/lucasb-eyer/go-colorful v1.0.3/go.mod h1:R4dSotOR9KMtayYi1e77YzuveK+i7ruzyGqttikkLy0=
 github.com/mattn/go-isatty v0.0.12 h1:wuysRhFDzyxgEmMf5xjvJ2M9dZoWAXNNr5LSBS7uHXY=
 github.com/mattn/go-isatty v0.0.12/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Kysco4FUpU=
-github.com/muesli/termenv v0.5.2/go.mod h1:O1/I6sw+6KcrgAmcs6uiUVr7Lui+DNVbHTzt9Lm/PlI=
+github.com/mattn/go-runewidth v0.0.9 h1:Lm995f3rfxdpd6TSmuVCHVb/QhupuXlYr8sCI/QdE+0=
+github.com/mattn/go-runewidth v0.0.9/go.mod h1:H031xJmbD/WCDINGzjvQ9THkh0rPKHF+m2gUSrubnMI=
 github.com/muesli/termenv v0.5.3-0.20200617122104-66d435cfe924 h1:oQHK4eixHzrl+DmUKH0x7SJgbkQBiggektj3ChSuE9I=
 github.com/muesli/termenv v0.5.3-0.20200617122104-66d435cfe924/go.mod h1:O1/I6sw+6KcrgAmcs6uiUVr7Lui+DNVbHTzt9Lm/PlI=
 github.com/muesli/termenv v0.5.3-0.20200617154346-da5de72b61c0 h1:IASsj5pQ478TEN9TLiuhP+ugUQEotZ1QdzQvcJUQ1dM=
@@ -18,6 +17,8 @@ github.com/pkg/term v0.0.0-20200520122047-c3ffed290a03/go.mod h1:Z9+Ul5bCbBKnbCv
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20200510223506-06a226fb4e37 h1:cg5LA/zNPRzIXIWSCxQW10Rvpy94aQh3LT/ShoCpkHw=
 golang.org/x/crypto v0.0.0-20200510223506-06a226fb4e37/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/crypto v0.0.0-20200604202706-70a84ac30bf9 h1:vEg9joUBmeBcK9iSJftGNf3coIG4HqZElCPehJsfAYM=
+golang.org/x/crypto v0.0.0-20200604202706-70a84ac30bf9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

examples/pager/main.go

@@ -4,14 +4,18 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"strings"
 
 	"github.com/charmbracelet/bubbles/viewport"
 	tea "github.com/charmbracelet/bubbletea"
+	"github.com/mattn/go-runewidth"
 )
 
 const (
-	viewportTopMargin    = 2
-	viewportBottomMargin = 2
+	useHighPerformanceRenderer = true
+
+	headerHeight = 3
+	footerHeight = 3
 )
 
 func main() {
@@ -24,7 +28,9 @@ func main() {
 	}
 
 	// Set PAGER_LOG to a path to log to a file. For example,
+	//
 	//     export PAGER_LOG=debug.log
+	//
 	if os.Getenv("PAGER_LOG") != "" {
 		p := os.Getenv("PAGER_LOG")
 		f, err := tea.LogToFile(p, "pager")
@@ -78,22 +84,24 @@ func update(msg tea.Msg, mdl tea.Model) (tea.Model, tea.Cmd) {
 		}
 
 	case tea.WindowSizeMsg:
-		viewportVerticalMargins := viewportTopMargin + viewportBottomMargin
+		verticalMargins := headerHeight + footerHeight
 
 		if !m.ready {
-			m.viewport = viewport.NewModel(msg.Width, msg.Height-viewportVerticalMargins)
-			m.viewport.YPosition = viewportTopMargin
-			m.viewport.HighPerformanceRendering = true
+			m.viewport = viewport.NewModel(msg.Width, msg.Height-verticalMargins)
+			m.viewport.YPosition = headerHeight
+			m.viewport.HighPerformanceRendering = useHighPerformanceRenderer
 			m.viewport.SetContent(m.content)
 			m.ready = true
 		} else {
 			m.viewport.Width = msg.Width
-			m.viewport.Height = msg.Height - viewportBottomMargin
+			m.viewport.Height = msg.Height - verticalMargins
 		}
 
 		// Render (or re-render) the whole viewport
+		if useHighPerformanceRenderer {
 			cmds = append(cmds, viewport.Sync(m.viewport))
 		}
+	}
 
 	// Because we're using the viewport's default update function (with pager-
 	// style navigation) it's important that the viewport's update function:
@@ -101,24 +109,39 @@ func update(msg tea.Msg, mdl tea.Model) (tea.Model, tea.Cmd) {
 	// * Recieves messages from the Bubble Tea runtime
 	// * Returns commands to the Bubble Tea runtime
 	m.viewport, cmd = viewport.Update(msg, m.viewport)
+	if useHighPerformanceRenderer {
 		cmds = append(cmds, cmd)
+	}
 
 	return m, tea.Batch(cmds...)
 }
 
 func view(mdl tea.Model) string {
-	m, ok := mdl.(model)
-	if !ok {
-		return "\n  Error: could not perform assertion on model in view."
-	}
+	m, _ := mdl.(model)
 
 	if !m.ready {
 		return "\n  Initalizing..."
 	}
 
+	headerTop := "╭───────────╮"
+	headerMid := "│ Mr. Pager ├"
+	headerBot := "╰───────────╯"
+	headerMid += strings.Repeat("─", m.viewport.Width-runewidth.StringWidth(headerMid))
+	header := fmt.Sprintf("%s\n%s\n%s", headerTop, headerMid, headerBot)
+
+	footerTop := "╭──────╮"
+	footerMid := "┤ %3.f%% │"
+	footerBot := "╰──────╯"
+	space := m.viewport.Width - runewidth.StringWidth(footerMid)
+	footerTop = strings.Repeat(" ", space) + footerTop
+	footerMid = strings.Repeat("─", space) + footerMid
+	footerBot = strings.Repeat(" ", space) + footerBot
+	footer := footerTop + "\n" + footerMid + "\n" + footerBot
+
 	return fmt.Sprintf(
-		"── Mr. Pager ──\n\n%s\n\n── %3.f%% ──",
+		"%s\n%s\n%s",
+		header,
 		viewport.View(m.viewport),
-		m.viewport.ScrollPercent()*100,
+		fmt.Sprintf(footer, m.viewport.ScrollPercent()*100),
 	)
 }