1// Package anim provides an animated spinner.
2package anim
3
4import (
5 "fmt"
6 "image/color"
7 "math/rand/v2"
8 "strings"
9 "sync/atomic"
10 "time"
11
12 "github.com/zeebo/xxh3"
13
14 tea "github.com/charmbracelet/bubbletea/v2"
15 "github.com/charmbracelet/lipgloss/v2"
16 "github.com/lucasb-eyer/go-colorful"
17
18 "github.com/charmbracelet/crush/internal/csync"
19)
20
21const (
22 fps = 20
23 initialChar = '.'
24 labelGap = " "
25 labelGapWidth = 1
26
27 // Periods of ellipsis animation speed in steps.
28 //
29 // If the FPS is 20 (50 milliseconds) this means that the ellipsis will
30 // change every 8 frames (400 milliseconds).
31 ellipsisanimSpeed = 8
32
33 // The maximum amount of time that can pass before a character appears.
34 // This is used to create a staggered entrance effect.
35 maxBirthOffset = time.Second
36
37 // Number of frames to prerender for the animation. After this number
38 // of frames, the animation will loop. This only applies when color
39 // cycling is disabled.
40 prerenderedFrames = 10
41
42 // Default number of cycling chars.
43 defaultNumCyclingChars = 10
44)
45
46// Default colors for gradient.
47var (
48 defaultGradColorA = color.RGBA{R: 0xff, G: 0, B: 0, A: 0xff}
49 defaultGradColorB = color.RGBA{R: 0, G: 0, B: 0xff, A: 0xff}
50 defaultLabelColor = color.RGBA{R: 0xcc, G: 0xcc, B: 0xcc, A: 0xff}
51)
52
53var (
54 availableRunes = []rune("0123456789abcdefABCDEF~!@#$£€%^&*()+=_")
55 ellipsisFrames = []string{".", "..", "...", ""}
56)
57
58// Internal ID management. Used during animating to ensure that frame messages
59// are received only by spinner components that sent them.
60var lastID int64
61
62func nextID() int {
63 return int(atomic.AddInt64(&lastID, 1))
64}
65
66// Cache for expensive animation calculations
67type animCache struct {
68 initialFrames [][]string
69 cyclingFrames [][]string
70 width int
71 labelWidth int
72 label []string
73 ellipsisFrames []string
74}
75
76var animCacheMap = csync.NewMap[string, *animCache]()
77
78// settingsHash creates a hash key for the settings to use for caching
79func settingsHash(opts Settings) string {
80 h := xxh3.New()
81 fmt.Fprintf(h, "%d-%s-%v-%v-%v-%t",
82 opts.Size, opts.Label, opts.LabelColor, opts.GradColorA, opts.GradColorB, opts.CycleColors)
83 return fmt.Sprintf("%x", h.Sum(nil))
84}
85
86// StepMsg is a message type used to trigger the next step in the animation.
87type StepMsg struct{ id int }
88
89// Settings defines settings for the animation.
90type Settings struct {
91 Size int
92 Label string
93 LabelColor color.Color
94 GradColorA color.Color
95 GradColorB color.Color
96 CycleColors bool
97 Static bool
98}
99
100// Spinner is a Bubble for a spinner.
101type Spinner interface {
102 Init() tea.Cmd
103 Update(tea.Msg) (Spinner, tea.Cmd)
104 View() string
105 SetLabel(string)
106}
107
108type anim struct {
109 width int
110 cyclingCharWidth int
111 label *csync.Slice[string]
112 labelWidth int
113 labelColor color.Color
114 startTime time.Time
115 birthOffsets []time.Duration
116 initialFrames [][]string // frames for the initial characters
117 initialized atomic.Bool
118 cyclingFrames [][]string // frames for the cycling characters
119 step atomic.Int64 // current main frame step
120 ellipsisStep atomic.Int64 // current ellipsis frame step
121 ellipsisFrames *csync.Slice[string] // ellipsis animation frames
122 id int
123}
124
125// New creates a new anim instance with the specified width and label.
126func New(opts Settings) Spinner {
127 // Validate settings.
128 if opts.Size < 1 {
129 opts.Size = defaultNumCyclingChars
130 }
131 if colorIsUnset(opts.GradColorA) {
132 opts.GradColorA = defaultGradColorA
133 }
134 if colorIsUnset(opts.GradColorB) {
135 opts.GradColorB = defaultGradColorB
136 }
137 if colorIsUnset(opts.LabelColor) {
138 opts.LabelColor = defaultLabelColor
139 }
140
141 if opts.Static {
142 return newStatic(opts.Label, opts.LabelColor)
143 }
144 a := &anim{}
145 a.id = nextID()
146 a.startTime = time.Now()
147 a.cyclingCharWidth = opts.Size
148 a.labelColor = opts.LabelColor
149
150 // Check cache first
151 cacheKey := settingsHash(opts)
152 cached, exists := animCacheMap.Get(cacheKey)
153
154 if exists {
155 // Use cached values
156 a.width = cached.width
157 a.labelWidth = cached.labelWidth
158 a.label = csync.NewSliceFrom(cached.label)
159 a.ellipsisFrames = csync.NewSliceFrom(cached.ellipsisFrames)
160 a.initialFrames = cached.initialFrames
161 a.cyclingFrames = cached.cyclingFrames
162 } else {
163 // Generate new values and cache them
164 a.labelWidth = lipgloss.Width(opts.Label)
165
166 // Total width of anim, in cells.
167 a.width = opts.Size
168 if opts.Label != "" {
169 a.width += labelGapWidth + lipgloss.Width(opts.Label)
170 }
171
172 // Render the label
173 a.renderLabel(opts.Label)
174
175 // Pre-generate gradient.
176 var ramp []color.Color
177 numFrames := prerenderedFrames
178 if opts.CycleColors {
179 ramp = makeGradientRamp(a.width*3, opts.GradColorA, opts.GradColorB, opts.GradColorA, opts.GradColorB)
180 numFrames = a.width * 2
181 } else {
182 ramp = makeGradientRamp(a.width, opts.GradColorA, opts.GradColorB)
183 }
184
185 // Pre-render initial characters.
186 a.initialFrames = make([][]string, numFrames)
187 offset := 0
188 for i := range a.initialFrames {
189 a.initialFrames[i] = make([]string, a.width+labelGapWidth+a.labelWidth)
190 for j := range a.initialFrames[i] {
191 if j+offset >= len(ramp) {
192 continue // skip if we run out of colors
193 }
194
195 var c color.Color
196 if j <= a.cyclingCharWidth {
197 c = ramp[j+offset]
198 } else {
199 c = opts.LabelColor
200 }
201
202 // Also prerender the initial character with Lip Gloss to avoid
203 // processing in the render loop.
204 a.initialFrames[i][j] = lipgloss.NewStyle().
205 Foreground(c).
206 Render(string(initialChar))
207 }
208 if opts.CycleColors {
209 offset++
210 }
211 }
212
213 // Prerender scrambled rune frames for the animation.
214 a.cyclingFrames = make([][]string, numFrames)
215 offset = 0
216 for i := range a.cyclingFrames {
217 a.cyclingFrames[i] = make([]string, a.width)
218 for j := range a.cyclingFrames[i] {
219 if j+offset >= len(ramp) {
220 continue // skip if we run out of colors
221 }
222
223 // Also prerender the color with Lip Gloss here to avoid processing
224 // in the render loop.
225 r := availableRunes[rand.IntN(len(availableRunes))]
226 a.cyclingFrames[i][j] = lipgloss.NewStyle().
227 Foreground(ramp[j+offset]).
228 Render(string(r))
229 }
230 if opts.CycleColors {
231 offset++
232 }
233 }
234
235 // Cache the results
236 labelSlice := make([]string, a.label.Len())
237 for i, v := range a.label.Seq2() {
238 labelSlice[i] = v
239 }
240 ellipsisSlice := make([]string, a.ellipsisFrames.Len())
241 for i, v := range a.ellipsisFrames.Seq2() {
242 ellipsisSlice[i] = v
243 }
244 cached = &animCache{
245 initialFrames: a.initialFrames,
246 cyclingFrames: a.cyclingFrames,
247 width: a.width,
248 labelWidth: a.labelWidth,
249 label: labelSlice,
250 ellipsisFrames: ellipsisSlice,
251 }
252 animCacheMap.Set(cacheKey, cached)
253 }
254
255 // Random assign a birth to each character for a stagged entrance effect.
256 a.birthOffsets = make([]time.Duration, a.width)
257 for i := range a.birthOffsets {
258 a.birthOffsets[i] = time.Duration(rand.N(int64(maxBirthOffset))) * time.Nanosecond
259 }
260
261 return a
262}
263
264// SetLabel updates the label text and re-renders it.
265func (a *anim) SetLabel(newLabel string) {
266 a.labelWidth = lipgloss.Width(newLabel)
267
268 // Update total width
269 a.width = a.cyclingCharWidth
270 if newLabel != "" {
271 a.width += labelGapWidth + a.labelWidth
272 }
273
274 // Re-render the label
275 a.renderLabel(newLabel)
276}
277
278// renderLabel renders the label with the current label color.
279func (a *anim) renderLabel(label string) {
280 if a.labelWidth > 0 {
281 // Pre-render the label.
282 labelRunes := []rune(label)
283 a.label = csync.NewSlice[string]()
284 for i := range labelRunes {
285 rendered := lipgloss.NewStyle().
286 Foreground(a.labelColor).
287 Render(string(labelRunes[i]))
288 a.label.Append(rendered)
289 }
290
291 // Pre-render the ellipsis frames which come after the label.
292 a.ellipsisFrames = csync.NewSlice[string]()
293 for _, frame := range ellipsisFrames {
294 rendered := lipgloss.NewStyle().
295 Foreground(a.labelColor).
296 Render(frame)
297 a.ellipsisFrames.Append(rendered)
298 }
299 } else {
300 a.label = csync.NewSlice[string]()
301 a.ellipsisFrames = csync.NewSlice[string]()
302 }
303}
304
305// Width returns the total width of the animation.
306func (a *anim) Width() (w int) {
307 w = a.width
308 if a.labelWidth > 0 {
309 w += labelGapWidth + a.labelWidth
310
311 var widestEllipsisFrame int
312 for _, f := range ellipsisFrames {
313 fw := lipgloss.Width(f)
314 if fw > widestEllipsisFrame {
315 widestEllipsisFrame = fw
316 }
317 }
318 w += widestEllipsisFrame
319 }
320 return w
321}
322
323// Init starts the animation.
324func (a *anim) Init() tea.Cmd {
325 return a.Step()
326}
327
328// Update processes animation steps (or not).
329func (a *anim) Update(msg tea.Msg) (Spinner, tea.Cmd) {
330 switch msg := msg.(type) {
331 case StepMsg:
332 if msg.id != a.id {
333 // Reject messages that are not for this instance.
334 return a, nil
335 }
336
337 step := a.step.Add(1)
338 if int(step) >= len(a.cyclingFrames) {
339 a.step.Store(0)
340 }
341
342 if a.initialized.Load() && a.labelWidth > 0 {
343 // Manage the ellipsis animation.
344 ellipsisStep := a.ellipsisStep.Add(1)
345 if int(ellipsisStep) >= ellipsisanimSpeed*len(ellipsisFrames) {
346 a.ellipsisStep.Store(0)
347 }
348 } else if !a.initialized.Load() && time.Since(a.startTime) >= maxBirthOffset {
349 a.initialized.Store(true)
350 }
351 return a, a.Step()
352 default:
353 return a, nil
354 }
355}
356
357// View renders the current state of the animation.
358func (a *anim) View() string {
359 var b strings.Builder
360 step := int(a.step.Load())
361 for i := range a.width {
362 switch {
363 case !a.initialized.Load() && i < len(a.birthOffsets) && time.Since(a.startTime) < a.birthOffsets[i]:
364 // Birth offset not reached: render initial character.
365 b.WriteString(a.initialFrames[step][i])
366 case i < a.cyclingCharWidth:
367 // Render a cycling character.
368 b.WriteString(a.cyclingFrames[step][i])
369 case i == a.cyclingCharWidth:
370 // Render label gap.
371 b.WriteString(labelGap)
372 case i > a.cyclingCharWidth:
373 // Label.
374 if labelChar, ok := a.label.Get(i - a.cyclingCharWidth - labelGapWidth); ok {
375 b.WriteString(labelChar)
376 }
377 }
378 }
379 // Render animated ellipsis at the end of the label if all characters
380 // have been initialized.
381 if a.initialized.Load() && a.labelWidth > 0 {
382 ellipsisStep := int(a.ellipsisStep.Load())
383 if ellipsisFrame, ok := a.ellipsisFrames.Get(ellipsisStep / ellipsisanimSpeed); ok {
384 b.WriteString(ellipsisFrame)
385 }
386 }
387
388 return b.String()
389}
390
391// Step is a command that triggers the next step in the animation.
392func (a *anim) Step() tea.Cmd {
393 return tea.Tick(time.Second/time.Duration(fps), func(t time.Time) tea.Msg {
394 return StepMsg{id: a.id}
395 })
396}
397
398// makeGradientRamp() returns a slice of colors blended between the given keys.
399// Blending is done as Hcl to stay in gamut.
400func makeGradientRamp(size int, stops ...color.Color) []color.Color {
401 if len(stops) < 2 {
402 return nil
403 }
404
405 points := make([]colorful.Color, len(stops))
406 for i, k := range stops {
407 points[i], _ = colorful.MakeColor(k)
408 }
409
410 numSegments := len(stops) - 1
411 if numSegments == 0 {
412 return nil
413 }
414 blended := make([]color.Color, 0, size)
415
416 // Calculate how many colors each segment should have.
417 segmentSizes := make([]int, numSegments)
418 baseSize := size / numSegments
419 remainder := size % numSegments
420
421 // Distribute the remainder across segments.
422 for i := range numSegments {
423 segmentSizes[i] = baseSize
424 if i < remainder {
425 segmentSizes[i]++
426 }
427 }
428
429 // Generate colors for each segment.
430 for i := range numSegments {
431 c1 := points[i]
432 c2 := points[i+1]
433 segmentSize := segmentSizes[i]
434
435 for j := range segmentSize {
436 if segmentSize == 0 {
437 continue
438 }
439 t := float64(j) / float64(segmentSize)
440 c := c1.BlendHcl(c2, t)
441 blended = append(blended, c)
442 }
443 }
444
445 return blended
446}
447
448func colorIsUnset(c color.Color) bool {
449 if c == nil {
450 return true
451 }
452 _, _, _, a := c.RGBA()
453 return a == 0
454}