Ensure that textinputs can only receive their own blink messages

Closes #53.

.github/workflows/build.yml

@@ -0,0 +1,28 @@
+name: build
+on: [push, pull_request]
+jobs:
+  test:
+    strategy:
+      matrix:
+        go-version: [~1.13, ^1]
+        os: [ubuntu-latest, macos-latest, windows-latest]
+    runs-on: ${{ matrix.os }}
+    env:
+      GO111MODULE: "on"
+    steps:
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ matrix.go-version }}
+
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Download Go modules
+        run: go mod download
+
+      - name: Build
+        run: go build -v ./...
+
+      - name: Test
+        run: go test ./...

.github/workflows/coverage.yml

@@ -0,0 +1,28 @@
+name: coverage
+on: [push, pull_request]
+
+jobs:
+  coverage:
+    strategy:
+      matrix:
+        go-version: [^1]
+        os: [ubuntu-latest]
+    runs-on: ${{ matrix.os }}
+    env:
+      GO111MODULE: "on"
+    steps:
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ matrix.go-version }}
+
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Coverage
+        env:
+          COVERALLS_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          go test -race -covermode atomic -coverprofile=profile.cov ./...
+          GO111MODULE=off go get github.com/mattn/goveralls
+          $(go env GOPATH)/bin/goveralls -coverprofile=profile.cov -service=github

.github/workflows/lint.yml

@@ -0,0 +1,20 @@
+name: lint
+on: [push, pull_request]
+
+jobs:
+  golangci:
+    name: lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v2
+        with:
+          # Required: the version of golangci-lint is required and must be specified without patch version: we always use the latest patch version.
+          version: v1.30
+          # Optional: golangci-lint command line arguments.
+          args: --issues-exit-code=0
+          # Optional: working directory, useful for monorepos
+          # working-directory: somedir
+          # Optional: show only new issues if it's a pull request. The default value is `false`.
+          only-new-issues: true

.golangci.yml

@@ -0,0 +1,27 @@
+run:
+  tests: false
+
+issues:
+  max-issues-per-linter: 0
+  max-same-issues: 0
+
+linters:
+  enable:
+    - bodyclose
+    - dupl
+    - exportloopref
+    - goconst
+    - godot
+    - godox
+    - goimports
+    - golint
+    - gomnd
+    - goprintffuncname
+    - gosec
+    - misspell
+    - prealloc
+    - rowserrcheck
+    - sqlclosecheck
+    - unconvert
+    - unparam
+    - whitespace

README.md

@@ -1,9 +1,94 @@
-# Tea Party
+Bubbles
+=======
 
-Components for [Tea](https://github.com/charmbraclet/tea)
+<p>
+  <img src="https://stuff.charm.sh/bubbles/bubbles-github.png" width="233" alt="The Bubbles Logo">
+</p>
+
+[![Latest Release](https://img.shields.io/github/release/charmbracelet/bubbles.svg)](https://github.com/charmbracelet/bubbles/releases)
+[![GoDoc](https://godoc.org/github.com/golang/gddo?status.svg)](https://pkg.go.dev/github.com/charmbracelet/bubbles)
+[![Build Status](https://github.com/charmbracelet/bubbles/workflows/build/badge.svg)](https://github.com/charmbracelet/bubbles/actions)
+[![Go ReportCard](https://goreportcard.com/badge/charmbracelet/bubbles)](https://goreportcard.com/report/charmbracelet/bubbles)
+
+Some components for [Bubble Tea](https://github.com/charmbracelet/bubbletea) applications.
+
+These components are used in production in [Glow][glow] and [Charm][charm].
+
+[glow]: https://github.com/charmbracelet/glow
+[charm]: https://github.com/charmbracelet/charm
+
+
+## Spinner
+
+<img src="https://stuff.charm.sh/bubbles-examples/spinner.gif" width="400" alt="Spinner Example">
+
+A spinner, useful for indicating that some kind an operation is happening.
+There are a couple default ones, but you can also pass your own ”frames.”
+
+* [Example code](https://github.com/charmbracelet/tea/tree/master/examples/spinner/main.go)
+
+
+## Text Input
+
+<img src="https://stuff.charm.sh/bubbles-examples/textinput.gif" width="400" alt="Text Input Example">
+
+A text input field, akin to an `<input type="text">` in HTML. Supports unicode,
+pasting, in-place scrolling when the value exceeds the width of the element and
+the common, and many customization options.
+
+* [Example code, one field](https://github.com/charmbracelet/tea/tree/master/examples/textinput/main.go)
+* [Example code, many fields](https://github.com/charmbracelet/tea/tree/master/examples/textinputs/main.go)
+
+
+## Progress
+
+<img src="https://stuff.charm.sh/bubbles-examples/progress.gif" width="800" alt="Progressbar Example">
+
+A simple, customizable progress meter. Supports solid and gradient fills. The
+empty and filled runes can be set to whatever you'd like. The percentage readout
+is customizable and can also be omitted entirely.
+
+* [Example code](https://github.com/charmbracelet/bubbletea/blob/master/examples/progress/main.go)
+
+
+## Paginator
+
+<img src="https://stuff.charm.sh/bubbles-examples/pagination.gif" width="200" alt="Paginator Example">
+
+A component for handling pagination logic and optionally drawing pagination UI.
+Supports "dot-style" pagination (similar to what you might see on iOS) and
+numeric page numbering, but you could also just use this component for the
+logic and visualize pagination however you like.
+
+This component is used in [Glow][glow] to browse documents and [Charm][charm] to
+browse SSH keys.
+
+
+## Viewport
+
+<img src="https://stuff.charm.sh/bubbles-examples/viewport.gif" width="600" alt="Viewport Example">
+
+A viewport for vertically scrolling content. Optionally includes standard
+pager keybindings and mouse wheel support. A high performance mode is available
+for applications which make use of the alternate screen buffer.
+
+* [Example code](https://github.com/charmbracelet/tea/tree/master/examples/pager/main.go)
+
+This component is well complimented with [Reflow][reflow] for ANSI-aware
+indenting and text wrapping.
+
+[reflow]: https://github.com/muesli/reflow
 
-⚠️  This project is a pre-release! Check back later.
 
 ## License
 
 [MIT](https://github.com/charmbracelet/teaparty/raw/master/LICENSE)
+
+
+***
+
+Part of [Charm](https://charm.sh).
+
+<a href="https://charm.sh/"><img alt="The Charm logo" src="https://stuff.charm.sh/charm-badge-unrounded.jpg" width="400"></a>
+
+Charm热爱开源 • Charm loves open source

go.mod

@@ -3,8 +3,12 @@ module github.com/charmbracelet/bubbles
 go 1.13
 
 require (
-	github.com/charmbracelet/bubbletea v0.8.0
+	github.com/atotto/clipboard v0.1.2
-	github.com/muesli/termenv v0.5.3-0.20200526053627-d728968dcf83
+	github.com/charmbracelet/bubbletea v0.13.1
-	golang.org/x/crypto v0.0.0-20200604202706-70a84ac30bf9 // indirect
+	github.com/charmbracelet/lipgloss v0.1.2
-	golang.org/x/sys v0.0.0-20200602225109-6fdc65e7d980 // indirect
+	github.com/lucasb-eyer/go-colorful v1.2.0
+	github.com/mattn/go-runewidth v0.0.12
+	github.com/muesli/reflow v0.2.1-0.20210115123740-9e1d0d53df68
+	github.com/muesli/termenv v0.8.1
+	golang.org/x/crypto v0.0.0-20201016220609-9e8e0b390897 // indirect
 )

go.sum

@@ -1,26 +1,41 @@
-github.com/charmbracelet/bubbletea v0.8.0 h1:ruZFaFF+2kgCI1IwNG40KTYDW5ZvE2+hPy4odlBdUko=
+github.com/atotto/clipboard v0.1.2 h1:YZCtFu5Ie8qX2VmVTBnrqLSiU9XOWwqNRmdT3gIQzbY=
-github.com/charmbracelet/bubbletea v0.8.0/go.mod h1:DzNhKkQQJI30eb+kBcaOs1+z86zTSqcMgSHoFY+uCsg=
+github.com/atotto/clipboard v0.1.2/go.mod h1:ZY9tmq7sm5xIbd9bOK4onWV4S6X0u6GY7Vn0Yu86PYI=
-github.com/google/goterm v0.0.0-20190703233501-fc88cf888a3f h1:5CjVwnuUcp5adK4gmY6i72gpVFVnZDP2h5TmPScB6u4=
+github.com/charmbracelet/bubbletea v0.13.1 h1:huvX8mPaeMZ8DLulT50iEWRF+iitY5FNEDqDVLu69nM=
+github.com/charmbracelet/bubbletea v0.13.1/go.mod h1:tp9tr9Dadh0PLhgiwchE5zZJXm5543JYjHG9oY+5qSg=
+github.com/charmbracelet/lipgloss v0.1.2 h1:D+LUMg34W7n2pkuMrevKVxT7HXqnoRHm7IoomkX3/ZU=
+github.com/charmbracelet/lipgloss v0.1.2/go.mod h1:5D8zradw52m7QmxRF6QgwbwJi9je84g8MkWiGN07uKg=
+github.com/containerd/console v1.0.1 h1:u7SFAJyRqWcG6ogaMAx3KjSTy1e3hT9QxqX7Jco7dRc=
+github.com/containerd/console v1.0.1/go.mod h1:XUsP6YE/mKtz6bxc+I8UiKKTP04qjQL4qcS3XoQ5xkw=
 github.com/google/goterm v0.0.0-20190703233501-fc88cf888a3f/go.mod h1:nOFQdrUlIlx6M6ODdSpBj1NVA+VgLC6kmw60mkw34H4=
-github.com/lucasb-eyer/go-colorful v1.0.3 h1:QIbQXiugsb+q10B+MI+7DI1oQLdmnep86tWFlaaUAac=
 github.com/lucasb-eyer/go-colorful v1.0.3/go.mod h1:R4dSotOR9KMtayYi1e77YzuveK+i7ruzyGqttikkLy0=
+github.com/lucasb-eyer/go-colorful v1.2.0 h1:1nnpGOrhyZZuNyfu1QjKiUICQ74+3FNCN69Aj6K7nkY=
+github.com/lucasb-eyer/go-colorful v1.2.0/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 v0.5.3-0.20200526053627-d728968dcf83 h1:AfshZBlqAwhCZ27NJ1aPlMcPBihF1squ1GpaollhLQk=
+github.com/mattn/go-runewidth v0.0.9/go.mod h1:H031xJmbD/WCDINGzjvQ9THkh0rPKHF+m2gUSrubnMI=
-github.com/muesli/termenv v0.5.3-0.20200526053627-d728968dcf83/go.mod h1:O1/I6sw+6KcrgAmcs6uiUVr7Lui+DNVbHTzt9Lm/PlI=
+github.com/mattn/go-runewidth v0.0.10/go.mod h1:RAqKPSqVFrSLVXbA8x7dzmKdmGzieGRCM46jaSJTDAk=
-github.com/pkg/term v0.0.0-20200520122047-c3ffed290a03 h1:pd4YKIqCB0U7O2I4gWHgEUA2mCEOENmco0l/bM957bU=
+github.com/mattn/go-runewidth v0.0.12 h1:Y41i/hVW3Pgwr8gV+J23B9YEY0zxjptBuCWEaxmAOow=
-github.com/pkg/term v0.0.0-20200520122047-c3ffed290a03/go.mod h1:Z9+Ul5bCbBKnbCvdOWbLqTHhJiYV414CURZJba6L8qA=
+github.com/mattn/go-runewidth v0.0.12/go.mod h1:RAqKPSqVFrSLVXbA8x7dzmKdmGzieGRCM46jaSJTDAk=
+github.com/muesli/reflow v0.2.1-0.20210115123740-9e1d0d53df68 h1:y1p/ycavWjGT9FnmSjdbWUlLGvcxrY0Rw3ATltrxOhk=
+github.com/muesli/reflow v0.2.1-0.20210115123740-9e1d0d53df68/go.mod h1:Xk+z4oIWdQqJzsxyjgl3P22oYZnHdZ8FFTHAQQt5BMQ=
+github.com/muesli/termenv v0.7.2/go.mod h1:ct2L5N2lmix82RaY3bMWwVu/jUFc9Ule0KGDCiKYPh8=
+github.com/muesli/termenv v0.8.1 h1:9q230czSP3DHVpkaPDXGp0TOfAwyjyYwXlUCQxQSaBk=
+github.com/muesli/termenv v0.8.1/go.mod h1:kzt/D/4a88RoheZmwfqorY3A+tnsSMA9HJC/fQSFKo0=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/rivo/uniseg v0.1.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
+github.com/rivo/uniseg v0.2.0 h1:S1pD9weZBuJdFmowNwbpi7BJ8TNftyUImj/0WQi72jY=
+github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
 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 v0.0.0-20201012173705-84dcc777aaee/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
-golang.org/x/crypto v0.0.0-20200510223506-06a226fb4e37/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/crypto v0.0.0-20201016220609-9e8e0b390897 h1:pLI5jrR7OSLijeIDcmRxNmw2api+jEfxLoykJVice/E=
-golang.org/x/crypto v0.0.0-20200604202706-70a84ac30bf9 h1:vEg9joUBmeBcK9iSJftGNf3coIG4HqZElCPehJsfAYM=
+golang.org/x/crypto v0.0.0-20201016220609-9e8e0b390897/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
-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=
 golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200523222454-059865788121 h1:rITEj+UZHYC927n8GT97eC3zrpzXdb/voyeOuVKS46o=
+golang.org/x/sys v0.0.0-20200916030750-2334cc1a136f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200523222454-059865788121/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20201009025420-dfb3f7c4e634/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200602225109-6fdc65e7d980 h1:OjiUf46hAmXblsZdnoSXsEUSKU8r1UEzcL5RVZ4gO9Y=
+golang.org/x/sys v0.0.0-20210119212857-b64e53b001e4 h1:myAQVi0cGEoqQVR5POX+8RR2mrocKqNN1hmeMqhX27k=
-golang.org/x/sys v0.0.0-20200602225109-6fdc65e7d980/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210119212857-b64e53b001e4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

paginator/paginator.go

@@ -1,4 +1,4 @@
-// package paginator provides a Bubble Tea package for calulating pagination
+// Package paginator provides a Bubble Tea package for calulating pagination
 // and rendering pagination info. Note that this package does not render actual
 // pages: it's purely for handling keystrokes related to pagination, and
 // rendering pagination status.
@@ -13,13 +13,13 @@ import (
 // Type specifies the way we render pagination.
 type Type int
 
-// Pagination rendering options
+// Pagination rendering options.
 const (
 	Arabic Type = iota
 	Dots
 )
 
-// Model is the Tea model for this user interface.
+// Model is the Bubble Tea model for this user interface.
 type Model struct {
 	Type              Type
 	Page              int
@@ -28,6 +28,7 @@ type Model struct {
 	ActiveDot         string
 	InactiveDot       string
 	ArabicFormat      string
+	UsePgUpPgDownKeys bool
 	UseLeftRightKeys  bool
 	UseUpDownKeys     bool
 	UseHLKeys         bool
@@ -39,8 +40,8 @@ type Model struct {
 // used for other things beyond navigating sets. Note that it both returns the
 // number of total pages and alters the model.
 func (m *Model) SetTotalPages(items int) int {
-	if items == 0 {
+	if items < 1 {
-		return 0
+		return m.TotalPages
 	}
 	n := items / m.PerPage
 	if items%m.PerPage > 0 {
@@ -90,7 +91,7 @@ func (m *Model) NextPage() {
 	}
 }
 
-// LastPage returns whether or not we're on the last page.
+// OnLastPage returns whether or not we're on the last page.
 func (m Model) OnLastPage() bool {
 	return m.Page == m.TotalPages-1
 }
@@ -105,6 +106,7 @@ func NewModel() Model {
 		ActiveDot:         "•",
 		InactiveDot:       "○",
 		ArabicFormat:      "%d/%d",
+		UsePgUpPgDownKeys: true,
 		UseLeftRightKeys:  true,
 		UseUpDownKeys:     false,
 		UseHLKeys:         true,
@@ -113,9 +115,17 @@ func NewModel() Model {
 }
 
 // Update is the Tea update function which binds keystrokes to pagination.
-func Update(msg tea.Msg, m Model) (Model, tea.Cmd) {
+func (m Model) Update(msg tea.Msg) (Model, tea.Cmd) {
 	switch msg := msg.(type) {
 	case tea.KeyMsg:
+		if m.UsePgUpPgDownKeys {
+			switch msg.String() {
+			case "pgup":
+				m.PrevPage()
+			case "pgdown":
+				m.NextPage()
+			}
+		}
 		if m.UseLeftRightKeys {
 			switch msg.String() {
 			case "left":
@@ -154,20 +164,16 @@ func Update(msg tea.Msg, m Model) (Model, tea.Cmd) {
 }
 
 // View renders the pagination to a string.
-func View(model tea.Model) string {
+func (m Model) View() string {
-	m, ok := model.(Model)
-	if !ok {
-		return "could not perform assertion on model"
-	}
 	switch m.Type {
 	case Dots:
-		return dotsView(m)
+		return m.dotsView()
 	default:
-		return arabicView(m)
+		return m.arabicView()
 	}
 }
 
-func dotsView(m Model) string {
+func (m Model) dotsView() string {
 	var s string
 	for i := 0; i < m.TotalPages; i++ {
 		if i == m.Page {
@@ -179,7 +185,7 @@ func dotsView(m Model) string {
 	return s
 }
 
-func arabicView(m Model) string {
+func (m Model) arabicView() string {
 	return fmt.Sprintf(m.ArabicFormat, m.Page+1, m.TotalPages)
 }
 

progress/progress.go

@@ -0,0 +1,192 @@
+package progress
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/lucasb-eyer/go-colorful"
+	"github.com/muesli/reflow/ansi"
+	"github.com/muesli/termenv"
+)
+
+const defaultWidth = 40
+
+var color func(string) termenv.Color = termenv.ColorProfile().Color
+
+// Option is used to set options in NewModel. For example:
+//
+//     progress := NewModel(
+//	       WithRamp("#ff0000", "#0000ff"),
+//	       WithoutPercentage(),
+//     )
+type Option func(*Model) error
+
+// WithDefaultGradient sets a gradient fill with default colors.
+func WithDefaultGradient() Option {
+	return WithGradient("#5A56E0", "#EE6FF8")
+}
+
+// WithGradient sets a gradient fill blending between two colors.
+func WithGradient(colorA, colorB string) Option {
+	return func(m *Model) error {
+		return m.setRamp(colorA, colorB, false)
+	}
+}
+
+// WithDefaultScaledGradient sets a gradient with default colors, and scales the
+// gradient to fit the filled portion of the ramp.
+func WithDefaultScaledGradient() Option {
+	return WithScaledGradient("#5A56E0", "#EE6FF8")
+}
+
+// WithScaledGradient scales the gradient to fit the width of the filled portion of
+// the progress bar.
+func WithScaledGradient(colorA, colorB string) Option {
+	return func(m *Model) error {
+		return m.setRamp(colorA, colorB, true)
+	}
+}
+
+// WithSolidFill sets the progress to use a solid fill with the given color.
+func WithSolidFill(color string) Option {
+	return func(m *Model) error {
+		m.FullColor = color
+		m.useRamp = false
+		return nil
+	}
+}
+
+// WithoutPercentage hides the numeric percentage.
+func WithoutPercentage() Option {
+	return func(m *Model) error {
+		m.ShowPercentage = false
+		return nil
+	}
+}
+
+// WithWidth sets the initial width of the progress bar. Note that you can also
+// set the width via the Width property, which can come in handy if you're
+// waiting for a tea.WindowSizeMsg.
+func WithWidth(w int) Option {
+	return func(m *Model) error {
+		m.Width = w
+		return nil
+	}
+}
+
+// Model stores values we'll use when rendering the progress bar.
+type Model struct {
+
+	// Total width of the progress bar, including percentage, if set.
+	Width int
+
+	// "Filled" sections of the progress bar
+	Full      rune
+	FullColor string
+
+	// "Empty" sections of progress bar
+	Empty      rune
+	EmptyColor string
+
+	// Settings for rendering the numeric percentage
+	ShowPercentage  bool
+	PercentFormat   string // a fmt string for a float
+	PercentageStyle *termenv.Style
+
+	useRamp    bool
+	rampColorA colorful.Color
+	rampColorB colorful.Color
+
+	// When true, we scale the gradient to fit the width of the filled section
+	// of the progress bar. When false, the width of the gradient will be set
+	// to the full width of the progress bar.
+	scaleRamp bool
+}
+
+// NewModel returns a model with default values.
+func NewModel(opts ...Option) (*Model, error) {
+	m := &Model{
+		Width:          defaultWidth,
+		Full:           '█',
+		FullColor:      "#7571F9",
+		Empty:          '░',
+		EmptyColor:     "#606060",
+		ShowPercentage: true,
+		PercentFormat:  " %3.0f%%",
+	}
+
+	for _, opt := range opts {
+		if err := opt(m); err != nil {
+			return nil, err
+		}
+	}
+
+	return m, nil
+}
+
+// View renders the progress bar as a given percentage.
+func (m Model) View(percent float64) string {
+	b := strings.Builder{}
+	if m.ShowPercentage {
+		percentage := fmt.Sprintf(m.PercentFormat, percent*100) //nolint:gomnd
+		if m.PercentageStyle != nil {
+			percentage = m.PercentageStyle.Styled(percentage)
+		}
+		m.bar(&b, percent, ansi.PrintableRuneWidth(percentage))
+		b.WriteString(percentage)
+	} else {
+		m.bar(&b, percent, 0)
+	}
+	return b.String()
+}
+
+func (m Model) bar(b *strings.Builder, percent float64, textWidth int) {
+	var (
+		tw = m.Width - textWidth        // total width
+		fw = int(float64(tw) * percent) // filled width
+		p  float64
+	)
+
+	if m.useRamp {
+		// Gradient fill
+		for i := 0; i < fw; i++ {
+			if m.scaleRamp {
+				p = float64(i) / float64(fw)
+			} else {
+				p = float64(i) / float64(tw)
+			}
+			c := m.rampColorA.BlendLuv(m.rampColorB, p).Hex()
+			b.WriteString(termenv.
+				String(string(m.Full)).
+				Foreground(color(c)).
+				String(),
+			)
+		}
+	} else {
+		// Solid fill
+		s := termenv.String(string(m.Full)).Foreground(color(m.FullColor)).String()
+		b.WriteString(strings.Repeat(s, fw))
+	}
+
+	// Empty fill
+	e := termenv.String(string(m.Empty)).Foreground(color(m.EmptyColor)).String()
+	b.WriteString(strings.Repeat(e, tw-fw))
+}
+
+func (m *Model) setRamp(colorA, colorB string, scaled bool) error {
+	a, err := colorful.Hex(colorA)
+	if err != nil {
+		return err
+	}
+
+	b, err := colorful.Hex(colorB)
+	if err != nil {
+		return err
+	}
+
+	m.useRamp = true
+	m.scaleRamp = scaled
+	m.rampColorA = a
+	m.rampColorB = b
+	return nil
+}

spinner/spinner.go

@@ -1,118 +1,241 @@
 package spinner
 
 import (
+	"strings"
 	"time"
 
 	tea "github.com/charmbracelet/bubbletea"
-	"github.com/muesli/termenv"
+	"github.com/charmbracelet/lipgloss"
+	"github.com/muesli/reflow/ansi"
 )
 
 // Spinner is a set of frames used in animating the spinner.
-type Spinner = int
+type Spinner struct {
-
+	Frames []string
-// Available types of spinners
+	FPS    time.Duration
-const (
-	Line Spinner = iota
-	Dot
-)
-
-const (
-	defaultFPS = 9
-)
-
-var (
-	// Spinner frames
-	spinners = map[Spinner][]string{
-		Line: {"|", "/", "-", "\\"},
-		Dot:  {"⣾ ", "⣽ ", "⣻ ", "⢿ ", "⡿ ", "⣟ ", "⣯ ", "⣷ "},
 }
 
-	color = termenv.ColorProfile().Color
+// Some spinners to choose from. You could also make your own.
+var (
+	Line = Spinner{
+		Frames: []string{"|", "/", "-", "\\"},
+		FPS:    time.Second / 10, //nolint:gomnd
+	}
+	Dot = Spinner{
+		Frames: []string{"⣾ ", "⣽ ", "⣻ ", "⢿ ", "⡿ ", "⣟ ", "⣯ ", "⣷ "},
+		FPS:    time.Second / 10, //nolint:gomnd
+	}
+	MiniDot = Spinner{
+		Frames: []string{"⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏"},
+		FPS:    time.Second / 12, //nolint:gomnd
+	}
+	Jump = Spinner{
+		Frames: []string{"⢄", "⢂", "⢁", "⡁", "⡈", "⡐", "⡠"},
+		FPS:    time.Second / 10, //nolint:gomnd
+	}
+	Pulse = Spinner{
+		Frames: []string{"█", "▓", "▒", "░"},
+		FPS:    time.Second / 8, //nolint:gomnd
+	}
+	Points = Spinner{
+		Frames: []string{"∙∙∙", "●∙∙", "∙●∙", "∙∙●"},
+		FPS:    time.Second / 7, //nolint:gomnd
+	}
+	Globe = Spinner{
+		Frames: []string{"🌍", "🌎", "🌏"},
+		FPS:    time.Second / 4, //nolint:gomnd
+	}
+	Moon = Spinner{
+		Frames: []string{"🌑", "🌒", "🌓", "🌔", "🌕", "🌖", "🌗", "🌘"},
+		FPS:    time.Second / 8, //nolint:gomnd
+	}
+	Monkey = Spinner{
+		Frames: []string{"🙈", "🙉", "🙊"},
+		FPS:    time.Second / 3, //nolint:gomnd
+	}
 )
 
 // Model contains the state for the spinner. Use NewModel to create new models
 // rather than using Model as a struct literal.
 type Model struct {
 
-	// Type is the set of frames to use. See Spinner.
+	// Spinner settings to use. See type Spinner.
-	Type Spinner
+	Spinner Spinner
 
-	// FPS is the speed at which the ticker should tick
+	// Style sets the styling for the spinner. Most of the time you'll just
-	FPS int
+	// want foreground and background coloring, and potentially some padding.
+	//
+	// For an introduction to styling with Lip Gloss see:
+	// https://github.com/charmbracelet/lipgloss
+	Style lipgloss.Style
 
-	// ForegroundColor sets the background color of the spinner. It can be a
+	// MinimumLifetime is the minimum amount of time the spinner can run. Any
-	// hex code or one of the 256 ANSI colors. If the terminal emulator can't
+	// logic around this can be implemented in view that implements this
-	// doesn't support the color specified it will automatically degrade
+	// spinner. If HideFor is set MinimumLifetime will be added on top of
-	// (per github.com/muesli/termenv).
+	// HideFor. In other words, if HideFor is 100ms and MinimumLifetime is
-	ForegroundColor string
+	// 200ms then MinimumLifetime will expire after 300ms.
+	//
+	// MinimumLifetime is optional.
+	//
+	// This is considered experimental and may not appear in future versions of
+	// this library.
+	MinimumLifetime time.Duration
 
-	// BackgroundColor sets the background color of the spinner. It can be a
+	// HideFor can be used to wait to show the spinner until a certain amount
-	// hex code or one of the 256 ANSI colors. If the terminal emulator can't
+	// of time has passed. This can be useful for preventing flicking when load
-	// doesn't support the color specified it will automatically degrade
+	// times are very fast.
-	// (per github.com/muesli/termenv).
+	// Optional.
-	BackgroundColor string
+	//
-
+	// This is considered experimental and may not appear in future versions of
-	// CustomMsgFunc can be used to a custom message on tick. This can be
+	// this library.
-	// useful when you have spinners in different parts of your application and
+	HideFor time.Duration
-	// want to differentiate between the messages for clarity and simplicity.
-	// If nil, this setting is ignored.
-	CustomMsgFunc func() tea.Msg
 
 	frame     int
+	startTime time.Time
+	tag       int
+}
+
+// Start resets resets the spinner start time. For use with MinimumLifetime and
+// MinimumStartTime. Optional.
+//
+// This function is optional and generally considered for advanced use only.
+// Most of the time your application logic will obviate the need for this
+// method.
+//
+// This is considered experimental and may not appear in future versions of
+// this library.
+func (m *Model) Start() {
+	m.startTime = time.Now()
+}
+
+// Finish sets the internal timer to a completed state so long as the spinner
+// isn't flagged to be showing. If it is showing, finish has no effect. The
+// idea here is that you call Finish if your operation has completed and, if
+// the spinner isn't showing yet (by virtue of HideFor) then Visible() doesn't
+// show the spinner at all.
+//
+// This is intended to work in conjunction with MinimumLifetime and
+// MinimumStartTime, is completely optional.
+//
+// This function is optional and generally considered for advanced use only.
+// Most of the time your application logic will obviate the need for this
+// method.
+//
+// This is considered experimental and may not appear in future versions of
+// this library.
+func (m *Model) Finish() {
+	if m.hidden() {
+		m.startTime = time.Time{}
+	}
+}
+
+// advancedMode returns whether or not the user is making use of HideFor and
+// MinimumLifetime properties.
+func (m Model) advancedMode() bool {
+	return m.HideFor > 0 && m.MinimumLifetime > 0
+}
+
+// hidden returns whether or not Model.HideFor is in effect.
+func (m Model) hidden() bool {
+	if m.startTime.IsZero() {
+		return false
+	}
+	if m.HideFor == 0 {
+		return false
+	}
+	return m.startTime.Add(m.HideFor).After(time.Now())
+}
+
+// finished returns whether the minimum lifetime of this spinner has been
+// exceeded.
+func (m Model) finished() bool {
+	if m.startTime.IsZero() || m.MinimumLifetime == 0 {
+		return true
+	}
+	return m.startTime.Add(m.HideFor).Add(m.MinimumLifetime).Before(time.Now())
+}
+
+// Visible returns whether or not the view should be rendered. Works in
+// conjunction with Model.HideFor and Model.MinimumLifetimeReached. You should
+// use this method directly to determine whether or not to render this view in
+// the parent view and whether to continue sending spin messaging in the
+// parent update function.
+//
+// This function is optional and generally considered for advanced use only.
+// Most of the time your application logic will obviate the need for this
+// method.
+//
+// This is considered experimental and may not appear in future versions of
+// this library.
+func (m Model) Visible() bool {
+	return !m.hidden() && !m.finished()
 }
 
 // NewModel returns a model with default values.
 func NewModel() Model {
-	return Model{
+	return Model{Spinner: Line}
-		Type: Line,
-		FPS:  defaultFPS,
-	}
 }
 
 // TickMsg indicates that the timer has ticked and we should render a frame.
-type TickMsg struct{}
+type TickMsg struct {
+	Time time.Time
+	tag  int
+}
 
 // Update is the Tea update function. This will advance the spinner one frame
 // every time it's called, regardless the message passed, so be sure the logic
 // is setup so as not to call this Update needlessly.
-func Update(msg tea.Msg, m Model) (Model, tea.Cmd) {
+func (m Model) Update(msg tea.Msg) (Model, tea.Cmd) {
+	switch msg := msg.(type) {
+	case TickMsg:
+		// If a tag is set, and it's not the one we expect, reject the message.
+		// This prevents the spinner from receiving too many messages and
+		// thus spinning too fast.
+		if msg.tag > 0 && msg.tag != m.tag {
+			return m, nil
+		}
+
 		m.frame++
-	if m.frame >= len(spinners[m.Type]) {
+		if m.frame >= len(m.Spinner.Frames) {
 			m.frame = 0
 		}
-	if m.CustomMsgFunc != nil {
+
-		return m, Tick(m)
+		m.tag++
+		return m, m.tick(m.tag)
+	default:
+		return m, nil
 	}
-	return m, Tick(m)
 }
 
 // View renders the model's view.
-func View(model Model) string {
+func (m Model) View() string {
-	s := spinners[model.Type]
+	if m.frame >= len(m.Spinner.Frames) {
-	if model.frame >= len(s) {
+		return "(error)"
-		return "[error]"
 	}
 
-	str := s[model.frame]
+	frame := m.Spinner.Frames[m.frame]
 
-	if model.ForegroundColor != "" || model.BackgroundColor != "" {
+	// If we're using the fine-grained hide/show spinner rules and those rules
-		return termenv.
+	// deem that the spinner should be hidden, draw an empty space in place of
-			String(str).
+	// the spinner.
-			Foreground(color(model.ForegroundColor)).
+	if m.advancedMode() && !m.Visible() {
-			Background(color(model.BackgroundColor)).
+		frame = strings.Repeat(" ", ansi.PrintableRuneWidth(frame))
-			String()
 	}
 
-	return str
+	return m.Style.Render(frame)
 }
 
-// Tick is the command used to advance the spinner one frame.
+// Tick is the command used to advance the spinner one frame. Use this command
-func Tick(model Model) tea.Cmd {
+// to effectively start the spinner.
-	return func() tea.Msg {
+func Tick() tea.Msg {
-		time.Sleep(time.Second / time.Duration(model.FPS))
+	return TickMsg{Time: time.Now()}
-		if model.CustomMsgFunc != nil {
-			return model.CustomMsgFunc()
 }
-		return TickMsg{}
+
+func (m Model) tick(tag int) tea.Cmd {
+	return tea.Tick(m.Spinner.FPS, func(t time.Time) tea.Msg {
+		return TickMsg{
+			Time: t,
+			tag:  tag,
 		}
+	})
 }

viewport/viewport.go

@@ -1,147 +1,373 @@
 package viewport
 
 import (
+	"math"
 	"strings"
 
 	tea "github.com/charmbracelet/bubbletea"
 )
 
-// MODEL
+const (
+	spacebar        = " "
+	mouseWheelDelta = 3
+)
 
+// Model is the Bubble Tea model for this viewport element.
 type Model struct {
-	Err    error
 	Width  int
 	Height int
-	Y      int
+
+	// YOffset is the vertical scroll position.
+	YOffset int
+
+	// YPosition is the position of the viewport in relation to the terminal
+	// window. It's used in high performance rendering.
+	YPosition int
+
+	// HighPerformanceRendering bypasses the normal Bubble Tea renderer to
+	// provide higher performance rendering. Most of the time the normal Bubble
+	// Tea rendering methods will suffice, but if you're passing content with
+	// a lot of ANSI escape codes you may see improved rendering in certain
+	// terminals with this enabled.
+	//
+	// This should only be used in program occupying the entire terminal,
+	// which is usually via the alternate screen buffer.
+	HighPerformanceRendering bool
 
 	lines []string
 }
 
-// Scrollpercent returns the amount scrolled as a float between 0 and 1.
+// AtTop returns whether or not the viewport is in the very top position.
+func (m Model) AtTop() bool {
+	return m.YOffset <= 0
+}
+
+// AtBottom returns whether or not the viewport is at or past the very bottom
+// position.
+func (m Model) AtBottom() bool {
+	return m.YOffset >= len(m.lines)-1-m.Height
+}
+
+// PastBottom returns whether or not the viewport is scrolled beyond the last
+// line. This can happen when adjusting the viewport height.
+func (m Model) PastBottom() bool {
+	return m.YOffset > len(m.lines)-1-m.Height
+}
+
+// ScrollPercent returns the amount scrolled as a float between 0 and 1.
 func (m Model) ScrollPercent() float64 {
 	if m.Height >= len(m.lines) {
 		return 1.0
 	}
-	y := float64(m.Y)
+	y := float64(m.YOffset)
 	h := float64(m.Height)
-	t := float64(len(m.lines))
+	t := float64(len(m.lines) - 1)
-	return y / (t - h)
+	v := y / (t - h)
+	return math.Max(0.0, math.Min(1.0, v))
 }
 
-// SetContent set the pager's text content.
+// SetContent set the pager's text content. For high performance rendering the
+// Sync command should also be called.
 func (m *Model) SetContent(s string) {
 	s = strings.Replace(s, "\r\n", "\n", -1) // normalize line endings
 	m.lines = strings.Split(s, "\n")
+
+	if m.YOffset > len(m.lines)-1 {
+		m.GotoBottom()
+	}
 }
 
-// NewModel creates a new pager model. Pass the dimensions of the pager.
+// Return the lines that should currently be visible in the viewport.
-func NewModel(width, height int) Model {
+func (m Model) visibleLines() (lines []string) {
-	return Model{
+	if len(m.lines) > 0 {
-		Width:  width,
+		top := max(0, m.YOffset)
-		Height: height,
+		bottom := clamp(m.YOffset+m.Height, top, len(m.lines))
+		lines = m.lines[top:bottom]
 	}
+	return lines
 }
 
 // ViewDown moves the view down by the number of lines in the viewport.
 // Basically, "page down".
-func (m *Model) ViewDown() {
+func (m *Model) ViewDown() []string {
-	m.Y = min(len(m.lines)-m.Height, m.Y+m.Height)
+	if m.AtBottom() {
+		return nil
+	}
+
+	m.YOffset = min(
+		m.YOffset+m.Height,      // target
+		len(m.lines)-1-m.Height, // fallback
+	)
+
+	return m.visibleLines()
 }
 
 // ViewUp moves the view up by one height of the viewport. Basically, "page up".
-func (m *Model) ViewUp() {
+func (m *Model) ViewUp() []string {
-	m.Y = max(0, m.Y-m.Height)
+	if m.AtTop() {
+		return nil
 	}
 
-// HalfViewUp moves the view up by half the height of the viewport.
+	m.YOffset = max(
-func (m *Model) HalfViewUp() {
+		m.YOffset-m.Height, // target
-	m.Y = max(0, m.Y-m.Height/2)
+		0,                  // fallback
+	)
+
+	return m.visibleLines()
 }
 
 // HalfViewDown moves the view down by half the height of the viewport.
-func (m *Model) HalfViewDown() {
+func (m *Model) HalfViewDown() (lines []string) {
-	m.Y = min(len(m.lines)-m.Height, m.Y+m.Height/2)
+	if m.AtBottom() {
+		return nil
 	}
 
-// LineDown moves the view up by the given number of lines.
+	m.YOffset = min(
-func (m *Model) LineDown(n int) {
+		m.YOffset+m.Height/2,    // target
-	m.Y = min(len(m.lines)-m.Height, m.Y+n)
+		len(m.lines)-1-m.Height, // fallback
+	)
+
+	if len(m.lines) > 0 {
+		top := max(m.YOffset+m.Height/2, 0)
+		bottom := clamp(m.YOffset+m.Height, top, len(m.lines)-1)
+		lines = m.lines[top:bottom]
+	}
+
+	return lines
+}
+
+// HalfViewUp moves the view up by half the height of the viewport.
+func (m *Model) HalfViewUp() (lines []string) {
+	if m.AtTop() {
+		return nil
+	}
+
+	m.YOffset = max(
+		m.YOffset-m.Height/2, // target
+		0,                    // fallback
+	)
+
+	if len(m.lines) > 0 {
+		top := max(m.YOffset, 0)
+		bottom := clamp(m.YOffset+m.Height/2, top, len(m.lines)-1)
+		lines = m.lines[top:bottom]
+	}
+
+	return lines
 }
 
 // LineDown moves the view down by the given number of lines.
-func (m *Model) LineUp(n int) {
+func (m *Model) LineDown(n int) (lines []string) {
-	m.Y = max(0, m.Y-n)
+	if m.AtBottom() || n == 0 {
+		return nil
+	}
+
+	// Make sure the number of lines by which we're going to scroll isn't
+	// greater than the number of lines we actually have left before we reach
+	// the bottom.
+	maxDelta := (len(m.lines) - 1) - (m.YOffset + m.Height) // number of lines - viewport bottom edge
+	n = min(n, maxDelta)
+
+	m.YOffset = min(
+		m.YOffset+n,             // target
+		len(m.lines)-1-m.Height, // fallback
+	)
+
+	if len(m.lines) > 0 {
+		top := max(m.YOffset+m.Height-n, 0)
+		bottom := clamp(m.YOffset+m.Height, top, len(m.lines)-1)
+		lines = m.lines[top:bottom]
+	}
+
+	return lines
+}
+
+// LineUp moves the view down by the given number of lines. Returns the new
+// lines to show.
+func (m *Model) LineUp(n int) (lines []string) {
+	if m.AtTop() || n == 0 {
+		return nil
+	}
+
+	// Make sure the number of lines by which we're going to scroll isn't
+	// greater than the number of lines we are from the top.
+	n = min(n, m.YOffset)
+
+	m.YOffset = max(m.YOffset-n, 0)
+
+	if len(m.lines) > 0 {
+		top := max(0, m.YOffset)
+		bottom := clamp(m.YOffset+n, top, len(m.lines)-1)
+		lines = m.lines[top:bottom]
+	}
+
+	return lines
+}
+
+// GotoTop sets the viewport to the top position.
+func (m *Model) GotoTop() (lines []string) {
+	if m.AtTop() {
+		return nil
+	}
+
+	m.YOffset = 0
+
+	if len(m.lines) > 0 {
+		top := m.YOffset
+		bottom := clamp(m.YOffset+m.Height, top, len(m.lines)-1)
+		lines = m.lines[top:bottom]
+	}
+
+	return lines
+}
+
+// GotoBottom sets the viewport to the bottom position.
+func (m *Model) GotoBottom() (lines []string) {
+	m.YOffset = max(len(m.lines)-1-m.Height, 0)
+
+	if len(m.lines) > 0 {
+		top := m.YOffset
+		bottom := max(len(m.lines)-1, 0)
+		lines = m.lines[top:bottom]
+	}
+
+	return lines
+}
+
+// COMMANDS
+
+// Sync tells the renderer where the viewport will be located and requests
+// a render of the current state of the viewport. It should be called for the
+// first render and after a window resize.
+//
+// For high performance rendering only.
+func Sync(m Model) tea.Cmd {
+	if len(m.lines) == 0 {
+		return nil
+	}
+
+	// TODO: we should probably use m.visibleLines() rather than these two
+	// expressions.
+	top := max(m.YOffset, 0)
+	bottom := clamp(m.YOffset+m.Height, 0, len(m.lines)-1)
+
+	return tea.SyncScrollArea(
+		m.lines[top:bottom],
+		m.YPosition,
+		m.YPosition+m.Height,
+	)
+}
+
+// ViewDown is a high performance command that moves the viewport up by a given
+// numer of lines. Use Model.ViewDown to get the lines that should be rendered.
+// For example:
+//
+//     lines := model.ViewDown(1)
+//     cmd := ViewDown(m, lines)
+//
+func ViewDown(m Model, lines []string) tea.Cmd {
+	if len(lines) == 0 {
+		return nil
+	}
+	return tea.ScrollDown(lines, m.YPosition, m.YPosition+m.Height)
+}
+
+// ViewUp is a high performance command the moves the viewport down by a given
+// number of lines height. Use Model.ViewUp to get the lines that should be
+// rendered.
+func ViewUp(m Model, lines []string) tea.Cmd {
+	if len(lines) == 0 {
+		return nil
+	}
+	return tea.ScrollUp(lines, m.YPosition, m.YPosition+m.Height)
 }
 
 // UPDATE
 
-// Update runs the update loop with default keybindings. To define your own
+// Update runs the update loop with default keybindings similar to popular
-// keybindings use the methods on Model.
+// pagers. To define your own keybindings use the methods on Model (i.e.
-func Update(msg tea.Msg, m Model) (Model, tea.Cmd) {
+// Model.LineDown()) and define your own update function.
-	switch msg := msg.(type) {
+func (m Model) Update(msg tea.Msg) (Model, tea.Cmd) {
+	var cmd tea.Cmd
 
+	switch msg := msg.(type) {
 	case tea.KeyMsg:
 		switch msg.String() {
 		// Down one page
-		case "pgdown":
+		case "pgdown", spacebar, "f":
-			fallthrough
+			lines := m.ViewDown()
-		case " ": // spacebar
+			if m.HighPerformanceRendering {
-			fallthrough
+				cmd = ViewDown(m, lines)
-		case "f":
+			}
-			m.ViewDown()
-			return m, nil
 
 		// Up one page
-		case "pgup":
+		case "pgup", "b":
-			fallthrough
+			lines := m.ViewUp()
-		case "b":
+			if m.HighPerformanceRendering {
-			m.ViewUp()
+				cmd = ViewUp(m, lines)
-			return m, nil
+			}
 
 		// Down half page
-		case "d":
+		case "d", "ctrl+d":
-			m.HalfViewDown()
+			lines := m.HalfViewDown()
-			return m, nil
+			if m.HighPerformanceRendering {
+				cmd = ViewDown(m, lines)
+			}
 
 		// Up half page
-		case "u":
+		case "u", "ctrl+u":
-			m.HalfViewUp()
+			lines := m.HalfViewUp()
-			return m, nil
+			if m.HighPerformanceRendering {
+				cmd = ViewUp(m, lines)
+			}
 
 		// Down one line
-		case "down":
+		case "down", "j":
-			fallthrough
+			lines := m.LineDown(1)
-		case "j":
+			if m.HighPerformanceRendering {
-			m.LineDown(1)
+				cmd = ViewDown(m, lines)
-			return m, nil
+			}
 
 		// Up one line
-		case "up":
+		case "up", "k":
-			fallthrough
+			lines := m.LineUp(1)
-		case "k":
+			if m.HighPerformanceRendering {
-			m.LineUp(1)
+				cmd = ViewUp(m, lines)
-			return m, nil
 			}
 		}
 
-	return m, nil
+	case tea.MouseMsg:
+		switch msg.Type {
+		case tea.MouseWheelUp:
+			lines := m.LineUp(mouseWheelDelta)
+			if m.HighPerformanceRendering {
+				cmd = ViewUp(m, lines)
+			}
+
+		case tea.MouseWheelDown:
+			lines := m.LineDown(mouseWheelDelta)
+			if m.HighPerformanceRendering {
+				cmd = ViewDown(m, lines)
+			}
+		}
+	}
+
+	return m, cmd
 }
 
 // VIEW
 
 // View renders the viewport into a string.
-func View(m Model) string {
+func (m Model) View() string {
-	if m.Err != nil {
+	if m.HighPerformanceRendering {
-		return m.Err.Error()
+		// Just send newlines since we're doing to be rendering the actual
+		// content seprately. We still need send something that equals the
+		// height of this view so that the Bubble Tea standard renderer can
+		// position anything below this view properly.
+		return strings.Repeat("\n", m.Height-1)
 	}
 
-	var lines []string
+	lines := m.visibleLines()
-
-	if len(m.lines) > 0 {
-		top := max(0, m.Y)
-		bottom := min(len(m.lines), m.Y+m.Height)
-		lines = m.lines[top:bottom]
-	}
 
 	// Fill empty space with newlines
 	extraLines := ""
@@ -154,6 +380,10 @@ func View(m Model) string {
 
 // ETC
 
+func clamp(v, low, high int) int {
+	return min(high, max(low, v))
+}
+
 func min(a, b int) int {
 	if a < b {
 		return a