Cursor tracks select focus (#358)

* place cursor at selected choice in select/multiselect

* use RenderWithCursorOffset

* delete old width thing

* fix cursor restoration

Author: Nate Smith

core/template.go

@@ -29,7 +29,7 @@ var TemplateFuncsNoColor = map[string]interface{}{
 //for colored output. The second string does not contain escape codes
 //and can be used by the renderer for layout purposes.
 func RunTemplate(tmpl string, data interface{}) (string, string, error) {
-	tPair, err := getTemplatePair(tmpl)
+	tPair, err := GetTemplatePair(tmpl)
 	if err != nil {
 		return "", "", err
 	}
@@ -52,12 +52,12 @@ var (
 	memoMutex = &sync.RWMutex{}
 )
 
-//getTemplatePair returns a pair of compiled templates where the
+//GetTemplatePair returns a pair of compiled templates where the
 //first template is generated for user-facing output and the
 //second is generated for use by the renderer. The second
 //template does not contain any color escape codes, whereas
 //the first template may or may not depending on DisableColor.
-func getTemplatePair(tmpl string) ([2]*template.Template, error) {
+func GetTemplatePair(tmpl string) ([2]*template.Template, error) {
 	memoMutex.RLock()
 	if t, ok := memoizedGetTemplate[tmpl]; ok {
 		memoMutex.RUnlock()

multiselect.go

@@ -45,9 +45,27 @@ type MultiSelectTemplateData struct {
 	ShowHelp      bool
 	PageEntries   []core.OptionAnswer
 	Config        *PromptConfig
+
+	// These fields are used when rendering an individual option
+	CurrentOpt   core.OptionAnswer
+	CurrentIndex int
+}
+
+// IterateOption sets CurrentOpt and CurrentIndex appropriately so a multiselect option can be rendered individually
+func (m MultiSelectTemplateData) IterateOption(ix int, opt core.OptionAnswer) interface{} {
+	copy := m
+	copy.CurrentIndex = ix
+	copy.CurrentOpt = opt
+	return copy
 }
 
 var MultiSelectQuestionTemplate = `
+{{- define "option"}}
+    {{- if eq .SelectedIndex .CurrentIndex }}{{color .Config.Icons.SelectFocus.Format }}{{ .Config.Icons.SelectFocus.Text }}{{color "reset"}}{{else}} {{end}}
+    {{- if index .Checked .CurrentOpt.Index }}{{color .Config.Icons.MarkedOption.Format }} {{ .Config.Icons.MarkedOption.Text }} {{else}}{{color .Config.Icons.UnmarkedOption.Format }} {{ .Config.Icons.UnmarkedOption.Text }} {{end}}
+    {{- color "reset"}}
+    {{- " "}}{{- .CurrentOpt.Value}}
+{{end}}
 {{- if .ShowHelp }}{{- color .Config.Icons.Help.Format }}{{ .Config.Icons.Help.Text }} {{ .Help }}{{color "reset"}}{{"\n"}}{{end}}
 {{- color .Config.Icons.Question.Format }}{{ .Config.Icons.Question.Text }} {{color "reset"}}
 {{- color "default+hb"}}{{ .Message }}{{ .FilterMessage }}{{color "reset"}}
@@ -56,10 +74,7 @@ var MultiSelectQuestionTemplate = `
 	{{- "  "}}{{- color "cyan"}}[Use arrows to move, space to select, <right> to all, <left> to none, type to filter{{- if and .Help (not .ShowHelp)}}, {{ .Config.HelpInput }} for more help{{end}}]{{color "reset"}}
   {{- "\n"}}
   {{- range $ix, $option := .PageEntries}}
-    {{- if eq $ix $.SelectedIndex }}{{color $.Config.Icons.SelectFocus.Format }}{{ $.Config.Icons.SelectFocus.Text }}{{color "reset"}}{{else}} {{end}}
-    {{- if index $.Checked $option.Index }}{{color $.Config.Icons.MarkedOption.Format }} {{ $.Config.Icons.MarkedOption.Text }} {{else}}{{color $.Config.Icons.UnmarkedOption.Format }} {{ $.Config.Icons.UnmarkedOption.Text }} {{end}}
-    {{- color "reset"}}
-    {{- " "}}{{$option.Value}}{{"\n"}}
+    {{- template "option" $.IterateOption $ix $option}}
   {{- end}}
 {{- end}}`
 
@@ -159,18 +174,17 @@ func (m *MultiSelect) OnChange(key rune, config *PromptConfig) {
 	// and we have modified the filter then we should move the page back!
 	opts, idx := paginate(pageSize, options, m.selectedIndex)
 
+	tmplData := MultiSelectTemplateData{
+		MultiSelect:   *m,
+		SelectedIndex: idx,
+		Checked:       m.checked,
+		ShowHelp:      m.showingHelp,
+		PageEntries:   opts,
+		Config:        config,
+	}
+
 	// render the options
-	m.Render(
-		MultiSelectQuestionTemplate,
-		MultiSelectTemplateData{
-			MultiSelect:   *m,
-			SelectedIndex: idx,
-			Checked:       m.checked,
-			ShowHelp:      m.showingHelp,
-			PageEntries:   opts,
-			Config:        config,
-		},
-	)
+	m.RenderWithCursorOffset(MultiSelectQuestionTemplate, tmplData, opts, idx)
 }
 
 func (m *MultiSelect) filterOptions(config *PromptConfig) []core.OptionAnswer {
@@ -250,20 +264,21 @@ func (m *MultiSelect) Prompt(config *PromptConfig) (interface{}, error) {
 	opts, idx := paginate(pageSize, core.OptionAnswerList(m.Options), m.selectedIndex)
 
 	cursor := m.NewCursor()
-	cursor.Hide()       // hide the cursor
-	defer cursor.Show() // show the cursor when we're done
+	cursor.Save()          // for proper cursor placement during selection
+	cursor.Hide()          // hide the cursor
+	defer cursor.Show()    // show the cursor when we're done
+	defer cursor.Restore() // clear any accessibility offsetting on exit
+
+	tmplData := MultiSelectTemplateData{
+		MultiSelect:   *m,
+		SelectedIndex: idx,
+		Checked:       m.checked,
+		PageEntries:   opts,
+		Config:        config,
+	}
 
 	// ask the question
-	err := m.Render(
-		MultiSelectQuestionTemplate,
-		MultiSelectTemplateData{
-			MultiSelect:   *m,
-			SelectedIndex: idx,
-			Checked:       m.checked,
-			PageEntries:   opts,
-			Config:        config,
-		},
-	)
+	err := m.RenderWithCursorOffset(MultiSelectQuestionTemplate, tmplData, opts, idx)
 	if err != nil {
 		return "", err
 	}

renderer.go

@@ -69,6 +69,14 @@ func (r *Renderer) Error(config *PromptConfig, invalid error) error {
 	return nil
 }
 
+func (r *Renderer) OffsetCursor(offset int) {
+	cursor := r.NewCursor()
+	for offset > 0 {
+		cursor.PreviousLine(-1)
+		offset--
+	}
+}
+
 func (r *Renderer) Render(tmpl string, data interface{}) error {
 	// cleanup the currently rendered text
 	lineCount := r.countLines(r.renderedText)
@@ -91,6 +99,21 @@ func (r *Renderer) Render(tmpl string, data interface{}) error {
 	return nil
 }
 
+func (r *Renderer) RenderWithCursorOffset(tmpl string, data IterableOpts, opts []core.OptionAnswer, idx int) error {
+	cursor := r.NewCursor()
+	cursor.Restore() // clear any accessibility offsetting
+
+	if err := r.Render(tmpl, data); err != nil {
+		return err
+	}
+	cursor.Save()
+
+	offset := computeCursorOffset(MultiSelectQuestionTemplate, data, opts, idx, r.termWidthSafe())
+	r.OffsetCursor(offset)
+
+	return nil
+}
+
 // appendRenderedError appends text to the renderer's error buffer
 // which is used to track what has been printed. It is not exported
 // as errors should only be displayed via Error(config, error).
@@ -123,15 +146,20 @@ func (r *Renderer) termWidth() (int, error) {
 	return termWidth, err
 }
 
-// countLines will return the count of `\n` with the addition of any
-// lines that have wrapped due to narrow terminal width
-func (r *Renderer) countLines(buf bytes.Buffer) int {
+func (r *Renderer) termWidthSafe() int {
 	w, err := r.termWidth()
 	if err != nil || w == 0 {
 		// if we got an error due to terminal.GetSize not being supported
 		// on current platform then just assume a very wide terminal
 		w = 10000
 	}
+	return w
+}
+
+// countLines will return the count of `\n` with the addition of any
+// lines that have wrapped due to narrow terminal width
+func (r *Renderer) countLines(buf bytes.Buffer) int {
+	w := r.termWidthSafe()
 
 	bufBytes := buf.Bytes()
 

select.go

@@ -43,20 +43,35 @@ type SelectTemplateData struct {
 	ShowAnswer    bool
 	ShowHelp      bool
 	Config        *PromptConfig
+
+	// These fields are used when rendering an individual option
+	CurrentOpt   core.OptionAnswer
+	CurrentIndex int
+}
+
+// IterateOption sets CurrentOpt and CurrentIndex appropriately so a select option can be rendered individually
+func (s SelectTemplateData) IterateOption(ix int, opt core.OptionAnswer) interface{} {
+	copy := s
+	copy.CurrentIndex = ix
+	copy.CurrentOpt = opt
+	return copy
 }
 
 var SelectQuestionTemplate = `
+{{- define "option"}}
+    {{- if eq .SelectedIndex .CurrentIndex }}{{color .Config.Icons.SelectFocus.Format }}{{ .Config.Icons.SelectFocus.Text }} {{else}}{{color "default"}}  {{end}}
+    {{- .CurrentOpt.Value}}
+    {{- color "reset"}}
+{{end}}
 {{- if .ShowHelp }}{{- color .Config.Icons.Help.Format }}{{ .Config.Icons.Help.Text }} {{ .Help }}{{color "reset"}}{{"\n"}}{{end}}
 {{- color .Config.Icons.Question.Format }}{{ .Config.Icons.Question.Text }} {{color "reset"}}
 {{- color "default+hb"}}{{ .Message }}{{ .FilterMessage }}{{color "reset"}}
 {{- if .ShowAnswer}}{{color "cyan"}} {{.Answer}}{{color "reset"}}{{"\n"}}
 {{- else}}
   {{- "  "}}{{- color "cyan"}}[Use arrows to move, type to filter{{- if and .Help (not .ShowHelp)}}, {{ .Config.HelpInput }} for more help{{end}}]{{color "reset"}}
   {{- "\n"}}
-  {{- range $ix, $choice := .PageEntries}}
-    {{- if eq $ix $.SelectedIndex }}{{color $.Config.Icons.SelectFocus.Format }}{{ $.Config.Icons.SelectFocus.Text }} {{else}}{{color "default"}}  {{end}}
-    {{- $choice.Value}}
-    {{- color "reset"}}{{"\n"}}
+  {{- range $ix, $option := .PageEntries}}
+    {{- template "option" $.IterateOption $ix $option}}
   {{- end}}
 {{- end}}`
 
@@ -152,17 +167,16 @@ func (s *Select) OnChange(key rune, config *PromptConfig) bool {
 	// and we have modified the filter then we should move the page back!
 	opts, idx := paginate(pageSize, options, s.selectedIndex)
 
+	tmplData := SelectTemplateData{
+		Select:        *s,
+		SelectedIndex: idx,
+		ShowHelp:      s.showingHelp,
+		PageEntries:   opts,
+		Config:        config,
+	}
+
 	// render the options
-	s.Render(
-		SelectQuestionTemplate,
-		SelectTemplateData{
-			Select:        *s,
-			SelectedIndex: idx,
-			ShowHelp:      s.showingHelp,
-			PageEntries:   opts,
-			Config:        config,
-		},
-	)
+	s.RenderWithCursorOffset(SelectQuestionTemplate, tmplData, opts, idx)
 
 	// keep prompting
 	return false
@@ -234,16 +248,22 @@ func (s *Select) Prompt(config *PromptConfig) (interface{}, error) {
 	// figure out the options and index to render
 	opts, idx := paginate(pageSize, core.OptionAnswerList(s.Options), sel)
 
+	cursor := s.NewCursor()
+	cursor.Save()          // for proper cursor placement during selection
+	cursor.Hide()          // hide the cursor
+	defer cursor.Show()    // show the cursor when we're done
+	defer cursor.Restore() // clear any accessibility offsetting on exit
+
+	tmplData := SelectTemplateData{
+		Select:        *s,
+		SelectedIndex: idx,
+		ShowHelp:      s.showingHelp,
+		PageEntries:   opts,
+		Config:        config,
+	}
+
 	// ask the question
-	err := s.Render(
-		SelectQuestionTemplate,
-		SelectTemplateData{
-			Select:        *s,
-			PageEntries:   opts,
-			SelectedIndex: idx,
-			Config:        config,
-		},
-	)
+	err := s.RenderWithCursorOffset(SelectQuestionTemplate, tmplData, opts, idx)
 	if err != nil {
 		return "", err
 	}
@@ -255,10 +275,6 @@ func (s *Select) Prompt(config *PromptConfig) (interface{}, error) {
 	rr.SetTermMode()
 	defer rr.RestoreTermMode()
 
-	cursor := s.NewCursor()
-	cursor.Hide()       // hide the cursor
-	defer cursor.Show() // show the cursor when we're done
-
 	// start waiting for input
 	for {
 		r, _, err := rr.ReadRune()
@@ -317,6 +333,8 @@ func (s *Select) Prompt(config *PromptConfig) (interface{}, error) {
 }
 
 func (s *Select) Cleanup(config *PromptConfig, val interface{}) error {
+	cursor := s.NewCursor()
+	cursor.Restore()
 	return s.Render(
 		SelectQuestionTemplate,
 		SelectTemplateData{

survey.go

@@ -1,10 +1,12 @@
 package survey
 
 import (
+	"bytes"
 	"errors"
 	"io"
 	"os"
 	"strings"
+	"unicode/utf8"
 
 	"github.com/AlecAivazis/survey/v2/core"
 	"github.com/AlecAivazis/survey/v2/terminal"
@@ -411,3 +413,42 @@ func paginate(pageSize int, choices []core.OptionAnswer, sel int) ([]core.Option
 	// return the subset we care about and the index
 	return choices[start:end], cursor
 }
+
+type IterableOpts interface {
+	IterateOption(int, core.OptionAnswer) interface{}
+}
+
+func computeCursorOffset(tmpl string, data IterableOpts, opts []core.OptionAnswer, idx, tWidth int) int {
+	tmpls, err := core.GetTemplatePair(tmpl)
+
+	if err != nil {
+		return 0
+	}
+
+	t := tmpls[0]
+
+	renderOpt := func(ix int, opt core.OptionAnswer) string {
+		buf := bytes.NewBufferString("")
+		t.ExecuteTemplate(buf, "option", data.IterateOption(ix, opt))
+		return buf.String()
+	}
+
+	offset := len(opts) - idx
+
+	for i, o := range opts {
+		if i < idx {
+			continue
+		}
+		renderedOpt := renderOpt(i, o)
+		valWidth := utf8.RuneCount([]byte(renderedOpt))
+		if valWidth > tWidth {
+			splitCount := valWidth / tWidth
+			if valWidth%tWidth == 0 {
+				splitCount -= 1
+			}
+			offset += splitCount
+		}
+	}
+
+	return offset
+}