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Implement streaming preview window (#2215)

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Fix #2212

    # Will start rendering after 200ms, update every 100ms
    fzf --preview 'for i in $(seq 100); do echo $i; sleep 0.01; done'

    # Should print "Loading .." message after 500ms
    fzf --preview 'sleep 1; for i in $(seq 100); do echo $i; sleep 0.01; done'

    # The first line should appear after 200ms
    fzf --preview 'date; sleep 2; date'

    # Should not render before enough lines for the scroll offset are ready
    rg --line-number --no-heading --color=always ^ |
      fzf --delimiter : --ansi --preview-window '+{2}-/2' \
          --preview 'sleep 1; bat --style=numbers --color=always --pager=never --highlight-line={2} {1}'
This commit is contained in:
Junegunn Choi 2020-10-18 17:03:33 +09:00 committed by GitHub
parent 305896fcb3
commit faf68dbc5c
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GPG Key ID: 4AEE18F83AFDEB23
8 changed files with 251 additions and 120 deletions
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7
CHANGELOG.md
View File

@ -1,6 +1,13 @@
CHANGELOG
=========
0.24.0
------
- fzf can render preview window before the command completes
```sh
fzf --preview 'sleep 1; for i in $(seq 100); do echo $i; sleep 0.01; done'
```
0.23.1
------
- Added `--preview-window` options for disabling flags

16
README.md
View File

@ -582,9 +582,9 @@ and fzf will warn you about it. To suppress the warning message, we added
### Preview window
When the `--preview` option is set, fzf automatically starts an external process
with the current line as the argument and shows the result in the split window.
Your `$SHELL` is used to execute the command with `$SHELL -c COMMAND`.
When the `--preview` option is set, fzf automatically starts an external process
with the current line as the argument and shows the result in the split window.
Your `$SHELL` is used to execute the command with `$SHELL -c COMMAND`.
The window can be scrolled using the mouse or custom key bindings.
```bash
@ -592,16 +592,8 @@ The window can be scrolled using the mouse or custom key bindings.
fzf --preview 'cat {}'
```
Since the preview window is updated only after the process is complete, it's
important that the command finishes quickly.
```bash
# Use head instead of cat so that the command doesn't take too long to finish
fzf --preview 'head -100 {}'
```
Preview window supports ANSI colors, so you can use any program that
syntax-highlights the content of a file, such as
syntax-highlights the content of a file, such as
[Bat](https://github.com/sharkdp/bat) or
[Highlight](http://www.andre-simon.de/doku/highlight/en/highlight.php):

2
src/constants.go
View File

@ -27,6 +27,8 @@ const (
initialDelayTac = 100 * time.Millisecond
spinnerDuration = 100 * time.Millisecond
previewCancelWait = 500 * time.Millisecond
previewChunkDelay = 100 * time.Millisecond
previewDelayed = 500 * time.Millisecond
maxPatternLength = 300
maxMulti = math.MaxInt32

330
src/terminal.go
View File

@ -4,7 +4,6 @@ import (
"bufio"
"bytes"
"fmt"
"io"
"io/ioutil"
"os"
"os/signal"
@ -43,11 +42,25 @@ const (
)
type previewer struct {
text string
lines int
offset int
enabled bool
more bool
version int
lines []string
offset int
enabled bool
scrollable bool
final bool
spinner string
}
type previewed struct {
version int
numLines int
offset int
filled bool
}
type eachLine struct {
line string
err error
}
type itemLine struct {
@ -125,6 +138,7 @@ type Terminal struct {
reqBox *util.EventBox
preview previewOpts
previewer previewer
previewed previewed
previewBox *util.EventBox
eventBox *util.EventBox
mutex sync.Mutex
@ -171,6 +185,7 @@ const (
reqPreviewEnqueue
reqPreviewDisplay
reqPreviewRefresh
reqPreviewDelayed
reqQuit
)
@ -263,12 +278,15 @@ type searchRequest struct {
type previewRequest struct {
template string
pwindow tui.Window
list []*Item
}
type previewResult struct {
content string
version int
lines []string
offset int
spinner string
}
func toActions(types ...actionType) []action {
@ -353,6 +371,13 @@ func hasPreviewAction(opts *Options) bool {
return false
}
func makeSpinner(unicode bool) []string {
if unicode {
return []string{`⠋`, `⠙`, `⠹`, `⠸`, `⠼`, `⠴`, `⠦`, `⠧`, `⠇`, `⠏`}
}
return []string{`-`, `\`, `|`, `/`, `-`, `\`, `|`, `/`}
}
// NewTerminal returns new Terminal object
func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
input := trimQuery(opts.Query)
@ -416,14 +441,10 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
wordRubout = fmt.Sprintf("%s[^%s]", sep, sep)
wordNext = fmt.Sprintf("[^%s]%s|(.$)", sep, sep)
}
spinner := []string{`⠋`, `⠙`, `⠹`, `⠸`, `⠼`, `⠴`, `⠦`, `⠧`, `⠇`, `⠏`}
if !opts.Unicode {
spinner = []string{`-`, `\`, `|`, `/`, `-`, `\`, `|`, `/`}
}
t := Terminal{
initDelay: delay,
infoStyle: opts.InfoStyle,
spinner: spinner,
spinner: makeSpinner(opts.Unicode),
queryLen: [2]int{0, 0},
layout: opts.Layout,
fullscreen: fullscreen,
@ -467,7 +488,8 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
selected: make(map[int32]selectedItem),
reqBox: util.NewEventBox(),
preview: opts.Preview,
previewer: previewer{"", 0, 0, previewBox != nil && !opts.Preview.hidden, false},
previewer: previewer{0, []string{}, 0, previewBox != nil && !opts.Preview.hidden, false, true, ""},
previewed: previewed{0, 0, 0, false},
previewBox: previewBox,
eventBox: eventBox,
mutex: sync.Mutex{},
@ -682,6 +704,8 @@ func (t *Terminal) resizeWindows() {
if t.pwindow != nil {
t.pwindow.Close()
}
// Reset preview version so that full redraw occurs
t.previewed.version = 0
width := screenWidth - marginInt[1] - marginInt[3]
height := screenHeight - marginInt[0] - marginInt[2]
@ -719,12 +743,6 @@ func (t *Terminal) resizeWindows() {
pwidth -= 4
x += 2
}
// ncurses auto-wraps the line when the cursor reaches the right-end of
// the window. To prevent unintended line-wraps, we use the width one
// column larger than the desired value.
if !t.preview.wrap && t.tui.DoesAutoWrap() {
pwidth += 1
}
t.pwindow = t.tui.NewWindow(y, x, pwidth, pheight, true, noBorder)
}
verticalPad := 2
@ -824,6 +842,14 @@ func (t *Terminal) printPrompt() {
t.window.CPrint(tui.ColNormal, t.strong, string(after))
}
func (t *Terminal) trimMessage(message string, maxWidth int) string {
if len(message) <= maxWidth {
return message
}
runes, _ := t.trimRight([]rune(message), maxWidth-2)
return string(runes) + strings.Repeat(".", util.Constrain(maxWidth, 0, 2))
}
func (t *Terminal) printInfo() {
pos := 0
switch t.infoStyle {
@ -875,11 +901,7 @@ func (t *Terminal) printInfo() {
if t.failed != nil && t.count == 0 {
output = fmt.Sprintf("[Command failed: %s]", *t.failed)
}
maxWidth := t.window.Width() - pos
if len(output) > maxWidth {
outputRunes, _ := t.trimRight([]rune(output), maxWidth-2)
output = string(outputRunes) + strings.Repeat(".", util.Constrain(maxWidth, 0, 2))
}
output = t.trimMessage(output, t.window.Width()-pos)
t.window.CPrint(tui.ColInfo, 0, output)
}
@ -1130,28 +1152,47 @@ func (t *Terminal) printHighlighted(result Result, attr tui.Attr, col1 tui.Color
return displayWidth
}
func (t *Terminal) printPreview() {
if !t.hasPreviewWindow() {
return
func (t *Terminal) renderPreviewSpinner() {
numLines := len(t.previewer.lines)
spin := t.previewer.spinner
if len(spin) > 0 || t.previewer.scrollable {
maxWidth := t.pwindow.Width()
if !t.previewer.scrollable {
if maxWidth > 0 {
t.pwindow.Move(0, maxWidth-1)
t.pwindow.CPrint(tui.ColSpinner, t.strong, spin)
}
} else {
offsetString := fmt.Sprintf("%d/%d", t.previewer.offset+1, numLines)
if len(spin) > 0 {
spin += " "
maxWidth -= 2
}
offsetRunes, _ := t.trimRight([]rune(offsetString), maxWidth)
pos := maxWidth - t.displayWidth(offsetRunes)
t.pwindow.Move(0, pos)
if maxWidth > 0 {
t.pwindow.CPrint(tui.ColSpinner, t.strong, spin)
t.pwindow.CPrint(tui.ColInfo, tui.Reverse, string(offsetRunes))
}
}
}
t.pwindow.Erase()
}
func (t *Terminal) renderPreviewText(unchanged bool) {
maxWidth := t.pwindow.Width()
if t.tui.DoesAutoWrap() {
maxWidth -= 1
}
reader := bufio.NewReader(strings.NewReader(t.previewer.text))
lineNo := -t.previewer.offset
height := t.pwindow.Height()
t.previewer.more = t.previewer.offset > 0
if unchanged {
t.pwindow.Move(0, 0)
} else {
t.previewed.filled = false
t.pwindow.Erase()
}
var ansi *ansiState
for ; ; lineNo++ {
line, err := reader.ReadString('\n')
eof := err == io.EOF
if !eof {
line = line[:len(line)-1]
}
for _, line := range t.previewer.lines {
if lineNo >= height || t.pwindow.Y() == height-1 && t.pwindow.X() > 0 {
t.previewed.filled = true
break
} else if lineNo >= 0 {
var fillRet tui.FillReturn
@ -1170,31 +1211,55 @@ func (t *Terminal) printPreview() {
}
return fillRet == tui.FillContinue
})
t.previewer.more = t.previewer.more || t.pwindow.Y() == height-1 && t.pwindow.X() == t.pwindow.Width()
t.previewer.scrollable = t.previewer.scrollable || t.pwindow.Y() == height-1 && t.pwindow.X() == t.pwindow.Width()
if fillRet == tui.FillNextLine {
continue
} else if fillRet == tui.FillSuspend {
t.previewed.filled = true
break
}
if unchanged && lineNo == 0 {
break
}
t.pwindow.Fill("\n")
}
if eof {
break
}
lineNo++
}
t.pwindow.FinishFill()
if t.previewer.lines > height {
t.previewer.more = true
offset := fmt.Sprintf("%d/%d", t.previewer.offset+1, t.previewer.lines)
pos := t.pwindow.Width() - len(offset)
if t.tui.DoesAutoWrap() {
pos -= 1
}
t.pwindow.Move(0, pos)
t.pwindow.CPrint(tui.ColInfo, tui.Reverse, offset)
if !unchanged {
t.pwindow.FinishFill()
}
}
func (t *Terminal) printPreview() {
if !t.hasPreviewWindow() {
return
}
numLines := len(t.previewer.lines)
height := t.pwindow.Height()
unchanged := (t.previewed.filled || numLines == t.previewed.numLines) &&
t.previewer.version == t.previewed.version &&
t.previewer.offset == t.previewed.offset
t.previewer.scrollable = t.previewer.offset > 0 || numLines > height
t.renderPreviewText(unchanged)
t.renderPreviewSpinner()
t.previewed.numLines = numLines
t.previewed.version = t.previewer.version
t.previewed.offset = t.previewer.offset
}
func (t *Terminal) printPreviewDelayed() {
if !t.hasPreviewWindow() || len(t.previewer.lines) > 0 && t.previewed.version == t.previewer.version {
return
}
t.previewer.scrollable = false
t.renderPreviewText(true)
message := t.trimMessage("Loading ..", t.pwindow.Width())
pos := t.pwindow.Width() - len(message)
t.pwindow.Move(0, pos)
t.pwindow.CPrint(tui.ColInfo, tui.Reverse, message)
}
func (t *Terminal) processTabs(runes []rune, prefixWidth int) (string, int) {
var strbuf bytes.Buffer
l := prefixWidth
@ -1686,9 +1751,11 @@ func (t *Terminal) Loop() {
if t.hasPreviewer() {
go func() {
version := 0
for {
var items []*Item
var commandTemplate string
var pwindow tui.Window
t.previewBox.Wait(func(events *util.Events) {
for req, value := range *events {
switch req {
@ -1696,63 +1763,129 @@ func (t *Terminal) Loop() {
request := value.(previewRequest)
commandTemplate = request.template
items = request.list
pwindow = request.pwindow
}
}
events.Clear()
})
version++
// We don't display preview window if no match
if items[0] != nil {
command := t.replacePlaceholder(commandTemplate, false, string(t.Input()), items)
offset := 0
initialOffset := 0
cmd := util.ExecCommand(command, true)
if t.pwindow != nil {
height := t.pwindow.Height()
offset = t.evaluateScrollOffset(items, height)
if pwindow != nil {
height := pwindow.Height()
initialOffset = util.Max(0, t.evaluateScrollOffset(items, height))
env := os.Environ()
lines := fmt.Sprintf("LINES=%d", height)
columns := fmt.Sprintf("COLUMNS=%d", t.pwindow.Width())
columns := fmt.Sprintf("COLUMNS=%d", pwindow.Width())
env = append(env, lines)
env = append(env, "FZF_PREVIEW_"+lines)
env = append(env, columns)
env = append(env, "FZF_PREVIEW_"+columns)
cmd.Env = env
}
var out bytes.Buffer
cmd.Stdout = &out
cmd.Stderr = &out
err := cmd.Start()
if err != nil {
out.Write([]byte(err.Error()))
}
out, _ := cmd.StdoutPipe()
cmd.Stderr = cmd.Stdout
reader := bufio.NewReader(out)
eofChan := make(chan bool)
finishChan := make(chan bool, 1)
updateChan := make(chan bool)
go func() {
select {
case code := <-t.killChan:
if code != exitCancel {
util.KillCommand(cmd)
os.Exit(code)
} else {
select {
case <-time.After(previewCancelWait):
util.KillCommand(cmd)
updateChan <- true
case <-finishChan:
updateChan <- false
reapChan := make(chan bool)
err := cmd.Start()
reaps := 0
if err != nil {
t.reqBox.Set(reqPreviewDisplay, previewResult{version, []string{err.Error()}, 0, ""})
} else {
reaps = 2
lineChan := make(chan eachLine)
// Goroutine 1 reads process output
go func() {
for {
line, err := reader.ReadString('\n')
lineChan <- eachLine{line, err}
if err != nil {
break
}
}
case <-finishChan:
updateChan <- false
eofChan <- true
}()
// Goroutine 2 periodically requests rendering
go func(version int) {
lines := []string{}
spinner := makeSpinner(t.unicode)
spinnerIndex := -1 // Delay initial rendering by an extra tick
ticker := time.NewTicker(previewChunkDelay)
offset := initialOffset
Loop:
for {
select {
case <-ticker.C:
if len(lines) > 0 && len(lines) >= initialOffset {
if spinnerIndex >= 0 {
spin := spinner[spinnerIndex%len(spinner)]
t.reqBox.Set(reqPreviewDisplay, previewResult{version, lines, offset, spin})
offset = -1
}
spinnerIndex++
}
case eachLine := <-lineChan:
line := eachLine.line
err := eachLine.err
if len(line) > 0 {
lines = append(lines, line)
}
if err != nil {
if len(lines) > 0 {
t.reqBox.Set(reqPreviewDisplay, previewResult{version, lines, offset, ""})
}
break Loop
}
}
}
ticker.Stop()
reapChan <- true
}(version)
}
// Goroutine 3 is responsible for cancelling running preview command
go func(version int) {
timer := time.NewTimer(previewDelayed)
Loop:
for {
select {
case <-timer.C:
t.reqBox.Set(reqPreviewDelayed, version)
case code := <-t.killChan:
if code != exitCancel {
util.KillCommand(cmd)
os.Exit(code)
} else {
timer := time.NewTimer(previewCancelWait)
select {
case <-timer.C:
util.KillCommand(cmd)
case <-finishChan:
}
timer.Stop()
}
break Loop
case <-finishChan:
break Loop
}
}
}()
cmd.Wait()
timer.Stop()
reapChan <- true
}(version)
<-eofChan
cmd.Wait() // NOTE: We should not call Wait before EOF
finishChan <- true
if out.Len() > 0 || !<-updateChan {
t.reqBox.Set(reqPreviewDisplay, previewResult{out.String(), offset})
for i := 0; i < reaps; i++ {
<-reapChan
}
cleanTemporaryFiles()
} else {
t.reqBox.Set(reqPreviewDisplay, previewResult{"", 0})
t.reqBox.Set(reqPreviewDisplay, previewResult{version, nil, 0, ""})
}
}
}()
@ -1772,7 +1905,7 @@ func (t *Terminal) Loop() {
if len(command) > 0 && t.isPreviewEnabled() {
_, list := t.buildPlusList(command, false)
t.cancelPreview()
t.previewBox.Set(reqPreviewEnqueue, previewRequest{command, list})
t.previewBox.Set(reqPreviewEnqueue, previewRequest{command, t.pwindow, list})
}
}
@ -1827,12 +1960,18 @@ func (t *Terminal) Loop() {
})
case reqPreviewDisplay:
result := value.(previewResult)
t.previewer.text = result.content
t.previewer.lines = strings.Count(t.previewer.text, "\n")
t.previewer.offset = util.Constrain(result.offset, 0, t.previewer.lines-1)
t.previewer.version = result.version
t.previewer.lines = result.lines
t.previewer.spinner = result.spinner
if result.offset >= 0 {
t.previewer.offset = util.Constrain(result.offset, 0, len(t.previewer.lines)-1)
}
t.printPreview()
case reqPreviewRefresh:
t.printPreview()
case reqPreviewDelayed:
t.previewer.version = value.(int)
t.printPreviewDelayed()
case reqPrintQuery:
exit(func() int {
t.printer(string(t.input))
@ -1885,14 +2024,15 @@ func (t *Terminal) Loop() {
return false
}
scrollPreview := func(amount int) {
if !t.previewer.more {
if !t.previewer.scrollable {
return
}
newOffset := t.previewer.offset + amount
numLines := len(t.previewer.lines)
if t.preview.cycle {
newOffset = (newOffset + t.previewer.lines) % t.previewer.lines
newOffset = (newOffset + numLines) % numLines
}
newOffset = util.Constrain(newOffset, 0, t.previewer.lines-1)
newOffset = util.Constrain(newOffset, 0, numLines-1)
if t.previewer.offset != newOffset {
t.previewer.offset = newOffset
req(reqPreviewRefresh)
@ -1934,7 +2074,7 @@ func (t *Terminal) Loop() {
if valid {
t.cancelPreview()
t.previewBox.Set(reqPreviewEnqueue,
previewRequest{t.preview.command, list})
previewRequest{t.preview.command, t.pwindow, list})
}
}
}

7
src/tui/dummy.go
View File

@ -32,10 +32,9 @@ func (r *FullscreenRenderer) Clear() {}
func (r *FullscreenRenderer) Refresh() {}
func (r *FullscreenRenderer) Close() {}
func (r *FullscreenRenderer) DoesAutoWrap() bool { return false }
func (r *FullscreenRenderer) GetChar() Event { return Event{} }
func (r *FullscreenRenderer) MaxX() int { return 0 }
func (r *FullscreenRenderer) MaxY() int { return 0 }
func (r *FullscreenRenderer) GetChar() Event { return Event{} }
func (r *FullscreenRenderer) MaxX() int { return 0 }
func (r *FullscreenRenderer) MaxY() int { return 0 }
func (r *FullscreenRenderer) RefreshWindows(windows []Window) {}

4
src/tui/light.go
View File

@ -624,10 +624,6 @@ func (r *LightRenderer) MaxY() int {
return r.height
}
func (r *LightRenderer) DoesAutoWrap() bool {
return false
}
func (r *LightRenderer) NewWindow(top int, left int, width int, height int, preview bool, borderStyle BorderStyle) Window {
w := &LightWindow{
renderer: r,

4
src/tui/tcell.go
View File

@ -166,10 +166,6 @@ func (w *TcellWindow) Y() int {
return w.lastY
}
func (r *FullscreenRenderer) DoesAutoWrap() bool {
return false
}
func (r *FullscreenRenderer) Clear() {
_screen.Sync()
_screen.Clear()

1
src/tui/tui.go
View File

@ -286,7 +286,6 @@ type Renderer interface {
MaxX() int
MaxY() int
DoesAutoWrap() bool
NewWindow(top int, left int, width int, height int, preview bool, borderStyle BorderStyle) Window
}