Print text using []byte instead of string, calculate string width using runewidth instead of uniseg

CHANGELOG

@@ -1,6 +1,7 @@
 v1.5.1 (WIP)
 - Store TextView buffer as [][]byte instead of []string
 - Add TextView.SetBytes and TextView.GetBytes
+- Allow modification of scroll bar render text
 
 v1.5.0 (2020-10-03)
 - Add scroll bar to TextView

application.go

@@ -9,9 +9,6 @@ import (
 )
 
 const (
-	// StandardDoubleClick is the standard double click interval.
-	StandardDoubleClick = 500 * time.Millisecond
-
 	// The size of the event/update/redraw channels.
 	queueSize = 100
 
@@ -19,30 +16,6 @@ const (
 	resizeEventThrottle = 200 * time.Millisecond
 )
 
-// MouseAction indicates one of the actions the mouse is logically doing.
-type MouseAction int16
-
-// Available mouse actions.
-const (
-	MouseMove MouseAction = iota
-	MouseLeftDown
-	MouseLeftUp
-	MouseLeftClick
-	MouseLeftDoubleClick
-	MouseMiddleDown
-	MouseMiddleUp
-	MouseMiddleClick
-	MouseMiddleDoubleClick
-	MouseRightDown
-	MouseRightUp
-	MouseRightClick
-	MouseRightDoubleClick
-	MouseScrollUp
-	MouseScrollDown
-	MouseScrollLeft
-	MouseScrollRight
-)
-
 // Application represents the top node of an application.
 //
 // It is not strictly required to use this class as none of the other classes

box.go

@@ -39,7 +39,7 @@ type Box struct {
 	borderAttributes tcell.AttrMask
 
 	// The title. Only visible if there is a border, too.
-	title string
+	title []byte
 
 	// The color of the title.
 	titleColor tcell.Color
@@ -376,7 +376,7 @@ func (b *Box) SetTitle(title string) *Box {
 	b.l.Lock()
 	defer b.l.Unlock()
 
-	b.title = title
+	b.title = []byte(title)
 	return b
 }
 
@@ -385,7 +385,7 @@ func (b *Box) GetTitle() string {
 	b.l.RLock()
 	defer b.l.RUnlock()
 
-	return b.title
+	return string(b.title)
 }
 
 // SetTitleColor sets the box's title color.
@@ -474,12 +474,12 @@ func (b *Box) Draw(screen tcell.Screen) {
 		screen.SetContent(b.x+b.width-1, b.y+b.height-1, bottomRight, nil, border)
 
 		// Draw title.
-		if b.title != "" && b.width >= 4 {
+		if len(b.title) > 0 && b.width >= 4 {
 			printed, _ := Print(screen, b.title, b.x+1, b.y, b.width-2, b.titleAlign, b.titleColor)
 			if len(b.title)-printed > 0 && printed > 0 {
 				_, _, style, _ := screen.GetContent(b.x+b.width-2, b.y)
 				fg, _, _ := style.Decompose()
-				Print(screen, string(SemigraphicsHorizontalEllipsis), b.x+b.width-2, b.y, 1, AlignLeft, fg)
+				Print(screen, []byte(string(SemigraphicsHorizontalEllipsis)), b.x+b.width-2, b.y, 1, AlignLeft, fg)
 			}
 		}
 	}

button.go

@@ -11,7 +11,7 @@ type Button struct {
 	*Box
 
 	// The text to be displayed before the input area.
-	label string
+	label []byte
 
 	// The label color.
 	labelColor tcell.Color
@@ -38,7 +38,7 @@ func NewButton(label string) *Button {
 	box.SetRect(0, 0, TaggedStringWidth(label)+4, 1)
 	return &Button{
 		Box:                    box,
-		label:                  label,
+		label:                  []byte(label),
 		labelColor:             Styles.PrimaryTextColor,
 		labelColorFocused:      Styles.InverseTextColor,
 		backgroundColorFocused: Styles.PrimaryTextColor,
@@ -50,7 +50,7 @@ func (b *Button) SetLabel(label string) *Button {
 	b.Lock()
 	defer b.Unlock()
 
-	b.label = label
+	b.label = []byte(label)
 	return b
 }
 
@@ -59,7 +59,7 @@ func (b *Button) GetLabel() string {
 	b.RLock()
 	defer b.RUnlock()
 
-	return b.label
+	return string(b.label)
 }
 
 // SetLabelColor sets the color of the button text.

checkbox.go

@@ -15,10 +15,10 @@ type CheckBox struct {
 	checked bool
 
 	// The text to be displayed before the checkbox.
-	label string
+	label []byte
 
 	// The text to be displayed after the checkbox.
-	message string
+	message []byte
 
 	// The screen width of the label area. A value of 0 means use the width of
 	// the label text.
@@ -106,7 +106,7 @@ func (c *CheckBox) SetLabel(label string) *CheckBox {
 	c.Lock()
 	defer c.Unlock()
 
-	c.label = label
+	c.label = []byte(label)
 	return c
 }
 
@@ -115,7 +115,7 @@ func (c *CheckBox) GetLabel() string {
 	c.RLock()
 	defer c.RUnlock()
 
-	return c.label
+	return string(c.label)
 }
 
 // SetMessage sets the text to be displayed after the checkbox
@@ -123,7 +123,7 @@ func (c *CheckBox) SetMessage(message string) *CheckBox {
 	c.Lock()
 	defer c.Unlock()
 
-	c.message = message
+	c.message = []byte(message)
 	return c
 }
 
@@ -132,7 +132,7 @@ func (c *CheckBox) GetMessage() string {
 	c.RLock()
 	defer c.RUnlock()
 
-	return c.message
+	return string(c.message)
 }
 
 // SetLabelWidth sets the screen width of the label. A value of 0 will cause the
@@ -209,7 +209,7 @@ func (c *CheckBox) GetFieldWidth() int {
 	c.RLock()
 	defer c.RUnlock()
 
-	if c.message == "" {
+	if len(c.message) == 0 {
 		return 1
 	}
 
@@ -321,7 +321,7 @@ func (c *CheckBox) Draw(screen tcell.Screen) {
 	screen.SetContent(x+1, y, checkedRune, nil, fieldStyle)
 	screen.SetContent(x+2, y, ' ', nil, fieldStyle)
 
-	if c.message != "" {
+	if len(c.message) > 0 {
 		Print(screen, c.message, x+4, y, len(c.message), AlignLeft, labelColor)
 	}
 }

demos/primitive/main.go

@@ -37,7 +37,7 @@ func (r *RadioButtons) Draw(screen tcell.Screen) {
 			radioButton = "\u25c9" // Checked.
 		}
 		line := fmt.Sprintf(`%s[white]  %s`, radioButton, option)
-		cview.Print(screen, line, x, y+index, width, cview.AlignLeft, tcell.ColorYellow.TrueColor())
+		cview.Print(screen, []byte(line), x, y+index, width, cview.AlignLeft, tcell.ColorYellow.TrueColor())
 	}
 }
 

dropdown.go

@@ -5,6 +5,7 @@ import (
 	"sync"
 
 	"github.com/gdamore/tcell/v2"
+	"github.com/mattn/go-runewidth"
 )
 
 // DropDownOption is one option that can be selected in a drop-down primitive.
@@ -569,10 +570,10 @@ func (d *DropDown) Draw(screen tcell.Screen) {
 		if labelWidth > rightLimit-x {
 			labelWidth = rightLimit - x
 		}
-		Print(screen, d.label, x, y, labelWidth, AlignLeft, labelColor)
+		Print(screen, []byte(d.label), x, y, labelWidth, AlignLeft, labelColor)
 		x += labelWidth
 	} else {
-		_, drawnWidth := Print(screen, d.label, x, y, rightLimit-x, AlignLeft, labelColor)
+		_, drawnWidth := Print(screen, []byte(d.label), x, y, rightLimit-x, AlignLeft, labelColor)
 		x += drawnWidth
 	}
 
@@ -614,12 +615,12 @@ func (d *DropDown) Draw(screen tcell.Screen) {
 	if d.open && len(d.prefix) > 0 {
 		// Show the prefix.
 		currentOptionPrefixWidth := TaggedStringWidth(d.currentOptionPrefix)
-		prefixWidth := stringWidth(d.prefix)
+		prefixWidth := runewidth.StringWidth(d.prefix)
 		listItemText := d.options[d.list.GetCurrentItemIndex()].text
-		Print(screen, d.currentOptionPrefix, x, y, fieldWidth, AlignLeft, fieldTextColor)
-		Print(screen, d.prefix, x+currentOptionPrefixWidth, y, fieldWidth-currentOptionPrefixWidth, AlignLeft, d.prefixTextColor)
+		Print(screen, []byte(d.currentOptionPrefix), x, y, fieldWidth, AlignLeft, fieldTextColor)
+		Print(screen, []byte(d.prefix), x+currentOptionPrefixWidth, y, fieldWidth-currentOptionPrefixWidth, AlignLeft, d.prefixTextColor)
 		if len(d.prefix) < len(listItemText) {
-			Print(screen, listItemText[len(d.prefix):]+d.currentOptionSuffix, x+prefixWidth+currentOptionPrefixWidth, y, fieldWidth-prefixWidth-currentOptionPrefixWidth, AlignLeft, fieldTextColor)
+			Print(screen, []byte(listItemText[len(d.prefix):]+d.currentOptionSuffix), x+prefixWidth+currentOptionPrefixWidth, y, fieldWidth-prefixWidth-currentOptionPrefixWidth, AlignLeft, fieldTextColor)
 		}
 	} else {
 		color := fieldTextColor
@@ -633,7 +634,7 @@ func (d *DropDown) Draw(screen tcell.Screen) {
 		}
 
 		// Just show the current selection.
-		Print(screen, text, x, y, fieldWidth, AlignLeft, color)
+		Print(screen, []byte(text), x, y, fieldWidth, AlignLeft, color)
 	}
 
 	// Draw drop-down symbol

frame.go

@@ -137,7 +137,7 @@ func (f *Frame) Draw(screen tcell.Screen) {
 		}
 
 		// Draw text.
-		Print(screen, text.Text, x, y, width, text.Align, text.Color)
+		Print(screen, []byte(text.Text), x, y, width, text.Align, text.Color)
 	}
 
 	// Set the size of the contained primitive.

inputfield.go

@@ -8,6 +8,7 @@ import (
 	"unicode/utf8"
 
 	"github.com/gdamore/tcell/v2"
+	"github.com/mattn/go-runewidth"
 )
 
 // InputField is a one-line box (three lines if there is a title) where the
@@ -613,10 +614,10 @@ func (i *InputField) Draw(screen tcell.Screen) {
 		if labelWidth > rightLimit-x {
 			labelWidth = rightLimit - x
 		}
-		Print(screen, i.label, x, y, labelWidth, AlignLeft, labelColor)
+		Print(screen, []byte(i.label), x, y, labelWidth, AlignLeft, labelColor)
 		x += labelWidth
 	} else {
-		_, drawnWidth := Print(screen, i.label, x, y, rightLimit-x, AlignLeft, labelColor)
+		_, drawnWidth := Print(screen, []byte(i.label), x, y, rightLimit-x, AlignLeft, labelColor)
 		x += drawnWidth
 	}
 
@@ -643,7 +644,7 @@ func (i *InputField) Draw(screen tcell.Screen) {
 		if i.GetFocusable().HasFocus() && i.placeholderTextColorFocused != ColorUnset {
 			placeholderTextColor = i.placeholderTextColorFocused
 		}
-		Print(screen, Escape(i.placeholder), x, y, fieldWidth, AlignLeft, placeholderTextColor)
+		Print(screen, []byte(Escape(i.placeholder)), x, y, fieldWidth, AlignLeft, placeholderTextColor)
 		i.offset = 0
 	} else {
 		// Draw entered text.
@@ -651,10 +652,10 @@ func (i *InputField) Draw(screen tcell.Screen) {
 			text = strings.Repeat(string(i.maskCharacter), utf8.RuneCountInString(i.text))
 		}
 		drawnText := ""
-		if fieldWidth >= stringWidth(text) {
+		if fieldWidth >= runewidth.StringWidth(text) {
 			// We have enough space for the full text.
 			drawnText = Escape(text)
-			Print(screen, drawnText, x, y, fieldWidth, AlignLeft, fieldTextColor)
+			Print(screen, []byte(drawnText), x, y, fieldWidth, AlignLeft, fieldTextColor)
 			i.offset = 0
 			iterateString(text, func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
 				if textPos >= i.cursorPos {
@@ -674,7 +675,7 @@ func (i *InputField) Draw(screen tcell.Screen) {
 			var shiftLeft int
 			if i.offset > i.cursorPos {
 				i.offset = i.cursorPos
-			} else if subWidth := stringWidth(text[i.offset:i.cursorPos]); subWidth > fieldWidth-1 {
+			} else if subWidth := runewidth.StringWidth(text[i.offset:i.cursorPos]); subWidth > fieldWidth-1 {
 				shiftLeft = subWidth - fieldWidth + 1
 			}
 			currentOffset := i.offset
@@ -693,17 +694,17 @@ func (i *InputField) Draw(screen tcell.Screen) {
 				return false
 			})
 			drawnText = Escape(text[i.offset:])
-			Print(screen, drawnText, x, y, fieldWidth, AlignLeft, fieldTextColor)
+			Print(screen, []byte(drawnText), x, y, fieldWidth, AlignLeft, fieldTextColor)
 		}
 		// Draw suggestion
 		if i.maskCharacter == 0 && i.autocompleteListSuggestion != "" {
-			Print(screen, i.autocompleteListSuggestion, x+stringWidth(drawnText), y, fieldWidth-stringWidth(drawnText), AlignLeft, i.autocompleteSuggestionTextColor)
+			Print(screen, []byte(i.autocompleteListSuggestion), x+runewidth.StringWidth(drawnText), y, fieldWidth-runewidth.StringWidth(drawnText), AlignLeft, i.autocompleteSuggestionTextColor)
 		}
 	}
 
 	// Draw field note
 	if i.fieldNote != "" {
-		Print(screen, i.fieldNote, x, y+1, fieldWidth, AlignLeft, i.fieldNoteTextColor)
+		Print(screen, []byte(i.fieldNote), x, y+1, fieldWidth, AlignLeft, i.fieldNoteTextColor)
 	}
 
 	// Draw autocomplete list.

list.go

@@ -1,6 +1,7 @@
 package cview
 
 import (
+	"bytes"
 	"fmt"
 	"strings"
 	"sync"
@@ -871,9 +872,9 @@ func (l *List) Draw(screen tcell.Screen) {
 		}
 
 		if item.mainText == "" && item.secondaryText == "" && item.shortcut == 0 { // Divider
-			Print(screen, string(tcell.RuneLTee), (x-5)-l.paddingLeft, y, 1, AlignLeft, l.mainTextColor)
-			Print(screen, strings.Repeat(string(tcell.RuneHLine), width+4+l.paddingLeft+l.paddingRight), (x-4)-l.paddingLeft, y, width+4+l.paddingLeft+l.paddingRight, AlignLeft, l.mainTextColor)
-			Print(screen, string(tcell.RuneRTee), (x-5)+width+5+l.paddingRight, y, 1, AlignLeft, l.mainTextColor)
+			Print(screen, []byte(string(tcell.RuneLTee)), (x-5)-l.paddingLeft, y, 1, AlignLeft, l.mainTextColor)
+			Print(screen, bytes.Repeat([]byte(string(tcell.RuneHLine)), width+4+l.paddingLeft+l.paddingRight), (x-4)-l.paddingLeft, y, width+4+l.paddingLeft+l.paddingRight, AlignLeft, l.mainTextColor)
+			Print(screen, []byte(string(tcell.RuneRTee)), (x-5)+width+5+l.paddingRight, y, 1, AlignLeft, l.mainTextColor)
 
 			RenderScrollBar(screen, l.scrollBarVisibility, scrollBarX, y, scrollBarHeight, len(l.items), scrollBarCursor, index-l.offset, l.hasFocus, l.scrollBarColor)
 			y++
@@ -881,11 +882,11 @@ func (l *List) Draw(screen tcell.Screen) {
 		} else if !item.enabled { // Disabled item
 			// Shortcuts.
 			if showShortcuts && item.shortcut != 0 {
-				Print(screen, fmt.Sprintf("(%s)", string(item.shortcut)), x-5, y, 4, AlignRight, tcell.ColorDarkSlateGray.TrueColor())
+				Print(screen, []byte(fmt.Sprintf("(%c)", item.shortcut)), x-5, y, 4, AlignRight, tcell.ColorDarkSlateGray.TrueColor())
 			}
 
 			// Main text.
-			Print(screen, item.mainText, x, y, width, AlignLeft, tcell.ColorGray.TrueColor())
+			Print(screen, []byte(item.mainText), x, y, width, AlignLeft, tcell.ColorGray.TrueColor())
 
 			RenderScrollBar(screen, l.scrollBarVisibility, scrollBarX, y, scrollBarHeight, len(l.items), scrollBarCursor, index-l.offset, l.hasFocus, l.scrollBarColor)
 			y++
@@ -894,11 +895,11 @@ func (l *List) Draw(screen tcell.Screen) {
 
 		// Shortcuts.
 		if showShortcuts && item.shortcut != 0 {
-			Print(screen, fmt.Sprintf("(%s)", string(item.shortcut)), x-5, y, 4, AlignRight, l.shortcutColor)
+			Print(screen, []byte(fmt.Sprintf("(%c)", item.shortcut)), x-5, y, 4, AlignRight, l.shortcutColor)
 		}
 
 		// Main text.
-		Print(screen, item.mainText, x, y, width, AlignLeft, l.mainTextColor)
+		Print(screen, []byte(item.mainText), x, y, width, AlignLeft, l.mainTextColor)
 
 		// Background color of selected text.
 		if index == l.currentItem && (!l.selectedFocusOnly || hasFocus) {
@@ -930,7 +931,7 @@ func (l *List) Draw(screen tcell.Screen) {
 
 		// Secondary text.
 		if l.showSecondaryText {
-			Print(screen, item.secondaryText, x, y, width, AlignLeft, l.secondaryTextColor)
+			Print(screen, []byte(item.secondaryText), x, y, width, AlignLeft, l.secondaryTextColor)
 
 			RenderScrollBar(screen, l.scrollBarVisibility, scrollBarX, y, scrollBarHeight, len(l.items), scrollBarCursor, index-l.offset, l.hasFocus, l.scrollBarColor)
 

modal.go

@@ -201,7 +201,7 @@ func (m *Modal) Draw(screen tcell.Screen) {
 	// Calculate the width of this Modal.
 	buttonsWidth := 0
 	for _, button := range m.form.buttons {
-		buttonsWidth += TaggedStringWidth(button.label) + 4 + 2
+		buttonsWidth += TaggedTextWidth(button.label) + 4 + 2
 	}
 	buttonsWidth -= 2
 	screenWidth, screenHeight := screen.Size()
@@ -213,9 +213,9 @@ func (m *Modal) Draw(screen tcell.Screen) {
 
 	// Reset the text and find out how wide it is.
 	m.frame.Clear()
-	lines := WordWrap(m.text, width)
+	lines := WordWrap([]byte(m.text), width)
 	for _, line := range lines {
-		m.frame.AddText(line, true, AlignCenter, m.textColor)
+		m.frame.AddText(string(line), true, AlignCenter, m.textColor)
 	}
 
 	// Set the Modal's position and size.

mouse.go

@@ -0,0 +1,30 @@
+package cview
+
+import "time"
+
+// MouseAction indicates one of the actions the mouse is logically doing.
+type MouseAction int16
+
+// Available mouse actions.
+const (
+	MouseMove MouseAction = iota
+	MouseLeftDown
+	MouseLeftUp
+	MouseLeftClick
+	MouseLeftDoubleClick
+	MouseMiddleDown
+	MouseMiddleUp
+	MouseMiddleClick
+	MouseMiddleDoubleClick
+	MouseRightDown
+	MouseRightUp
+	MouseRightClick
+	MouseRightDoubleClick
+	MouseScrollUp
+	MouseScrollDown
+	MouseScrollLeft
+	MouseScrollRight
+)
+
+// StandardDoubleClick is a commonly used double click interval.
+const StandardDoubleClick = 500 * time.Millisecond

table.go

@@ -995,7 +995,7 @@ ColumnLoop:
 		}
 		for _, row := range evaluationRows {
 			if cell := getCell(row, column); cell != nil {
-				_, _, _, _, _, _, cellWidth := decomposeString(cell.Text, true, false)
+				_, _, _, _, _, _, cellWidth := decomposeText([]byte(cell.Text), true, false)
 				if cell.MaxWidth > 0 && cell.MaxWidth < cellWidth {
 					cellWidth = cell.MaxWidth
 				}
@@ -1089,10 +1089,10 @@ ColumnLoop:
 				finalWidth = width - columnX - 1
 			}
 			cell.x, cell.y, cell.width = x+columnX+1, y+rowY, finalWidth
-			_, printed := printWithStyle(screen, cell.Text, x+columnX+1, y+rowY, finalWidth, cell.Align, SetAttributes(tcell.StyleDefault.Foreground(cell.Color), cell.Attributes))
+			_, printed := printWithStyle(screen, []byte(cell.Text), x+columnX+1, y+rowY, finalWidth, cell.Align, SetAttributes(tcell.StyleDefault.Foreground(cell.Color), cell.Attributes))
 			if TaggedStringWidth(cell.Text)-printed > 0 && printed > 0 {
 				_, _, style, _ := screen.GetContent(x+columnX+finalWidth, y+rowY)
-				printWithStyle(screen, string(SemigraphicsHorizontalEllipsis), x+columnX+finalWidth, y+rowY, 1, AlignLeft, style)
+				printWithStyle(screen, []byte(string(SemigraphicsHorizontalEllipsis)), x+columnX+finalWidth, y+rowY, 1, AlignLeft, style)
 			}
 		}
 

textview.go

@@ -32,13 +32,13 @@ type textViewIndex struct {
 	ForegroundColor string // The starting foreground color ("" = don't change, "-" = reset).
 	BackgroundColor string // The starting background color ("" = don't change, "-" = reset).
 	Attributes      string // The starting attributes ("" = don't change, "-" = reset).
-	Region          string // The starting region ID.
+	Region          []byte // The starting region ID.
 }
 
 // textViewRegion contains information about a region.
 type textViewRegion struct {
 	// The region ID.
-	ID string
+	ID []byte
 
 	// The starting and end screen position of the region as determined the last
 	// time Draw() was called. A negative value indicates out-of-rect positions.
@@ -831,7 +831,7 @@ func (t *TextView) reindexBuffer(width int) {
 	}
 
 	// Initial states.
-	regionID := ""
+	var regionID []byte
 	var (
 		highlighted                                  bool
 		foregroundColor, backgroundColor, attributes string
@@ -839,12 +839,11 @@ func (t *TextView) reindexBuffer(width int) {
 
 	// Go through each line in the buffer.
 	for bufferIndex, buf := range t.buffer {
-		str := string(buf)
-		colorTagIndices, colorTags, regionIndices, regions, escapeIndices, strippedStr, _ := decomposeString(str, t.dynamicColors, t.regions)
+		colorTagIndices, colorTags, regionIndices, regions, escapeIndices, strippedStr, _ := decomposeText(buf, t.dynamicColors, t.regions)
 
 		// Split the line if required.
 		var splitLines []string
-		str = strippedStr
+		str := string(strippedStr) // TODO
 		if t.wrap && len(str) > 0 {
 			for len(str) > 0 {
 				extract := runewidth.Truncate(str, width, "")
@@ -938,14 +937,14 @@ func (t *TextView) reindexBuffer(width int) {
 				case 1:
 					// Process region tags.
 					regionID = regions[regionPos][1]
-					_, highlighted = t.highlights[regionID]
+					_, highlighted = t.highlights[string(regionID)]
 
 					// Update highlight range.
 					if highlighted {
 						line := len(t.index)
 						if t.fromHighlight < 0 {
 							t.fromHighlight, t.toHighlight = line, line
-							t.posHighlight = stringWidth(splitLine[:strippedTagStart])
+							t.posHighlight = runewidth.StringWidth(splitLine[:strippedTagStart])
 						} else if line > t.toHighlight {
 							t.toHighlight = line
 						}
@@ -963,7 +962,7 @@ func (t *TextView) reindexBuffer(width int) {
 
 			// Append this line.
 			line.NextPos = originalPos
-			line.Width = stringWidth(splitLine)
+			line.Width = runewidth.StringWidth(splitLine)
 			t.index = append(t.index, line)
 		}
 
@@ -975,7 +974,7 @@ func (t *TextView) reindexBuffer(width int) {
 				if len(trimmed) != len(str) {
 					oldNextPos := line.NextPos
 					line.NextPos -= len(str) - len(trimmed)
-					line.Width -= stringWidth(string(t.buffer[line.Line][line.NextPos:oldNextPos]))
+					line.Width -= runewidth.StringWidth(string(t.buffer[line.Line][line.NextPos:oldNextPos]))
 				}
 			}
 		}
@@ -1106,7 +1105,7 @@ func (t *TextView) Draw(screen tcell.Screen) {
 		backgroundColor := index.BackgroundColor
 		attributes := index.Attributes
 		regionID := index.Region
-		if t.regions && regionID != "" && (len(t.regionInfos) == 0 || t.regionInfos[len(t.regionInfos)-1].ID != regionID) {
+		if t.regions && len(regionID) > 0 && (len(t.regionInfos) == 0 || !bytes.Equal(t.regionInfos[len(t.regionInfos)-1].ID, regionID)) {
 			t.regionInfos = append(t.regionInfos, &textViewRegion{
 				ID:    regionID,
 				FromX: x,
@@ -1117,7 +1116,7 @@ func (t *TextView) Draw(screen tcell.Screen) {
 		}
 
 		// Process tags.
-		colorTagIndices, colorTags, regionIndices, regions, escapeIndices, strippedText, _ := decomposeString(string(text), t.dynamicColors, t.regions)
+		colorTagIndices, colorTags, regionIndices, regions, escapeIndices, strippedText, _ := decomposeText(text, t.dynamicColors, t.regions)
 
 		// Calculate the position of the line.
 		var skip, posX int
@@ -1136,7 +1135,7 @@ func (t *TextView) Draw(screen tcell.Screen) {
 		// Print the line.
 		if y+line-t.lineOffset >= 0 {
 			var colorPos, regionPos, escapePos, tagOffset, skipped int
-			iterateString(strippedText, func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
+			iterateString(string(strippedText), func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
 				// Process tags.
 				for {
 					if colorPos < len(colorTags) && textPos+tagOffset >= colorTagIndices[colorPos][0] && textPos+tagOffset < colorTagIndices[colorPos][1] {
@@ -1146,13 +1145,13 @@ func (t *TextView) Draw(screen tcell.Screen) {
 						colorPos++
 					} else if regionPos < len(regionIndices) && textPos+tagOffset >= regionIndices[regionPos][0] && textPos+tagOffset < regionIndices[regionPos][1] {
 						// Get the region.
-						if regionID != "" && len(t.regionInfos) > 0 && t.regionInfos[len(t.regionInfos)-1].ID == regionID {
+						if len(regionID) > 0 && len(t.regionInfos) > 0 && !bytes.Equal(t.regionInfos[len(t.regionInfos)-1].ID, regionID) {
 							// End last region.
 							t.regionInfos[len(t.regionInfos)-1].ToX = x + posX
 							t.regionInfos[len(t.regionInfos)-1].ToY = y + line - t.lineOffset
 						}
 						regionID = regions[regionPos][1]
-						if regionID != "" {
+						if len(regionID) > 0 {
 							// Start new region.
 							t.regionInfos = append(t.regionInfos, &textViewRegion{
 								ID:    regionID,
@@ -1182,8 +1181,8 @@ func (t *TextView) Draw(screen tcell.Screen) {
 
 				// Do we highlight this character?
 				var highlighted bool
-				if regionID != "" {
-					if _, ok := t.highlights[regionID]; ok {
+				if len(regionID) > 0 {
+					if _, ok := t.highlights[string(regionID)]; ok {
 						highlighted = true
 					}
 				}
@@ -1313,7 +1312,7 @@ func (t *TextView) MouseHandler() func(action MouseAction, event *tcell.EventMou
 						region.ToY >= 0 && y > region.ToY {
 						continue
 					}
-					t.Highlight(region.ID)
+					t.Highlight(string(region.ID))
 					break
 				}
 			}

textview_test.go

@@ -140,6 +140,9 @@ func BenchmarkTextViewIndex(b *testing.B) {
 				b.Errorf("failed to write: expected to write %d bytes, wrote %d", randomDataSize, n)
 			}
 
+			tv.index = nil
+			tv.reindexBuffer(80)
+
 			b.ReportAllocs()
 			b.ResetTimer()
 
@@ -210,13 +213,16 @@ func BenchmarkTextViewGetText(b *testing.B) {
 				b.Errorf("failed to write: expected to write %d bytes, wrote %d", randomDataSize, n)
 			}
 
+			v = tv.GetBytes(true)
+
 			b.ReportAllocs()
 			b.ResetTimer()
 
 			for i := 0; i < b.N; i++ {
 				v = tv.GetBytes(true)
-				_ = v
 			}
+
+			_ = v
 		})
 	}
 }
@@ -286,6 +292,8 @@ func BenchmarkTextViewDraw(b *testing.B) {
 				b.Errorf("failed to write: expected to write %d bytes, wrote %d", randomDataSize, n)
 			}
 
+			tv.Draw(app.screen)
+
 			b.ReportAllocs()
 			b.ResetTimer()
 

treeview.go

@@ -331,7 +331,7 @@ type TreeView struct {
 	topLevel int
 
 	// Strings drawn before the nodes, based on their level.
-	prefixes []string
+	prefixes [][]byte
 
 	// Vertical scroll offset.
 	offsetY int
@@ -452,7 +452,10 @@ func (t *TreeView) SetPrefixes(prefixes []string) *TreeView {
 	t.Lock()
 	defer t.Unlock()
 
-	t.prefixes = prefixes
+	t.prefixes = make([][]byte, len(prefixes))
+	for i := range prefixes {
+		t.prefixes[i] = []byte(prefixes[i])
+	}
 	return t
 }
 
@@ -880,7 +883,7 @@ func (t *TreeView) Draw(screen tcell.Screen) {
 					}
 					style = tcell.StyleDefault.Background(backgroundColor).Foreground(foregroundColor)
 				}
-				printWithStyle(screen, node.text, x+node.textX+prefixWidth, posY, width-node.textX-prefixWidth, AlignLeft, style)
+				printWithStyle(screen, []byte(node.text), x+node.textX+prefixWidth, posY, width-node.textX-prefixWidth, AlignLeft, style)
 			}
 		}
 

util.go

@@ -101,9 +101,9 @@ func init() {
 // the substrings (tagSubstrings) extracted by the regular expression for color
 // tags. The new colors and attributes are returned where empty strings mean
 // "don't modify" and a dash ("-") means "reset to default".
-func styleFromTag(fgColor, bgColor, attributes string, tagSubstrings []string) (newFgColor, newBgColor, newAttributes string) {
-	if tagSubstrings[colorForegroundPos] != "" {
-		color := tagSubstrings[colorForegroundPos]
+func styleFromTag(fgColor, bgColor, attributes string, tagSubstrings [][]byte) (newFgColor, newBgColor, newAttributes string) {
+	if len(tagSubstrings[colorForegroundPos]) > 0 {
+		color := string(tagSubstrings[colorForegroundPos])
 		if color == "-" {
 			fgColor = "-"
 		} else if color != "" {
@@ -111,8 +111,8 @@ func styleFromTag(fgColor, bgColor, attributes string, tagSubstrings []string) (
 		}
 	}
 
-	if tagSubstrings[colorBackgroundPos-1] != "" {
-		color := tagSubstrings[colorBackgroundPos]
+	if len(tagSubstrings[colorBackgroundPos-1]) > 0 {
+		color := string(tagSubstrings[colorBackgroundPos])
 		if color == "-" {
 			bgColor = "-"
 		} else if color != "" {
@@ -120,8 +120,8 @@ func styleFromTag(fgColor, bgColor, attributes string, tagSubstrings []string) (
 		}
 	}
 
-	if tagSubstrings[colorFlagPos-1] != "" {
-		flags := tagSubstrings[colorFlagPos]
+	if len(tagSubstrings[colorFlagPos-1]) > 0 {
+		flags := string(tagSubstrings[colorFlagPos])
 		if flags == "-" {
 			attributes = "-"
 		} else if flags != "" {
@@ -200,7 +200,7 @@ func SetAttributes(style tcell.Style, attrs tcell.AttrMask) tcell.Style {
 		Underline(attrs&tcell.AttrUnderline != 0)
 }
 
-// decomposeString returns information about a string which may contain color
+// decomposeText returns information about a string which may contain color
 // tags or region tags, depending on which ones are requested to be found. It
 // returns the indices of the color tags (as returned by
 // re.FindAllStringIndex()), the color tags themselves (as returned by
@@ -208,22 +208,22 @@ func SetAttributes(style tcell.Style, attrs tcell.AttrMask) tcell.Style {
 // themselves, the indices of an escaped tags (only if at least color tags or
 // region tags are requested), the string stripped by any tags and escaped, and
 // the screen width of the stripped string.
-func decomposeString(text string, findColors, findRegions bool) (colorIndices [][]int, colors [][]string, regionIndices [][]int, regions [][]string, escapeIndices [][]int, stripped string, width int) {
+func decomposeText(text []byte, findColors, findRegions bool) (colorIndices [][]int, colors [][][]byte, regionIndices [][]int, regions [][][]byte, escapeIndices [][]int, stripped []byte, width int) {
 	// Shortcut for the trivial case.
 	if !findColors && !findRegions {
-		return nil, nil, nil, nil, nil, text, stringWidth(text)
+		return nil, nil, nil, nil, nil, text, runewidth.StringWidth(string(text))
 	}
 
 	// Get positions of any tags.
 	if findColors {
-		colorIndices = colorPattern.FindAllStringIndex(text, -1)
-		colors = colorPattern.FindAllStringSubmatch(text, -1)
+		colorIndices = colorPattern.FindAllIndex(text, -1)
+		colors = colorPattern.FindAllSubmatch(text, -1)
 	}
 	if findRegions {
-		regionIndices = regionPattern.FindAllStringIndex(text, -1)
-		regions = regionPattern.FindAllStringSubmatch(text, -1)
+		regionIndices = regionPattern.FindAllIndex(text, -1)
+		regions = regionPattern.FindAllSubmatch(text, -1)
 	}
-	escapeIndices = escapePattern.FindAllStringIndex(text, -1)
+	escapeIndices = escapePattern.FindAllIndex(text, -1)
 
 	// Because the color pattern detects empty tags, we need to filter them out.
 	for i := len(colorIndices) - 1; i >= 0; i-- {
@@ -259,10 +259,10 @@ func decomposeString(text string, findColors, findRegions bool) (colorIndices []
 	buf = append(buf, text[from:]...)
 
 	// Escape string.
-	stripped = string(escapePattern.ReplaceAll(buf, []byte("[$1$2]")))
+	stripped = escapePattern.ReplaceAll(buf, []byte("[$1$2]"))
 
 	// Get the width of the stripped string.
-	width = stringWidth(stripped)
+	width = runewidth.StringWidth(string(stripped))
 
 	return
 }
@@ -276,19 +276,19 @@ func decomposeString(text string, findColors, findRegions bool) (colorIndices []
 //
 // Returns the number of actual bytes of the text printed (including color tags)
 // and the actual width used for the printed runes.
-func Print(screen tcell.Screen, text string, x, y, maxWidth, align int, color tcell.Color) (int, int) {
+func Print(screen tcell.Screen, text []byte, x, y, maxWidth, align int, color tcell.Color) (int, int) {
 	return printWithStyle(screen, text, x, y, maxWidth, align, tcell.StyleDefault.Foreground(color))
 }
 
 // printWithStyle works like Print() but it takes a style instead of just a
 // foreground color.
-func printWithStyle(screen tcell.Screen, text string, x, y, maxWidth, align int, style tcell.Style) (int, int) {
+func printWithStyle(screen tcell.Screen, text []byte, x, y, maxWidth, align int, style tcell.Style) (int, int) {
 	if maxWidth <= 0 || len(text) == 0 {
 		return 0, 0
 	}
 
 	// Decompose the text.
-	colorIndices, colors, _, _, escapeIndices, strippedText, strippedWidth := decomposeString(text, true, false)
+	colorIndices, colors, _, _, escapeIndices, strippedText, strippedWidth := decomposeText(text, true, false)
 
 	// We want to reduce all alignments to AlignLeft.
 	if align == AlignRight {
@@ -302,7 +302,7 @@ func printWithStyle(screen tcell.Screen, text string, x, y, maxWidth, align int,
 			foregroundColor, backgroundColor, attributes string
 		)
 		_, originalBackground, _ := style.Decompose()
-		iterateString(strippedText, func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
+		iterateString(string(strippedText), func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
 			// Update color/escape tag offset and style.
 			if colorPos < len(colorIndices) && textPos+tagOffset >= colorIndices[colorPos][0] && textPos+tagOffset < colorIndices[colorPos][1] {
 				foregroundColor, backgroundColor, attributes = styleFromTag(foregroundColor, backgroundColor, attributes, colors[colorPos])
@@ -319,7 +319,7 @@ func printWithStyle(screen tcell.Screen, text string, x, y, maxWidth, align int,
 				if escapePos > 0 && textPos+tagOffset-1 >= escapeIndices[escapePos-1][0] && textPos+tagOffset-1 < escapeIndices[escapePos-1][1] {
 					// Unescape open escape sequences.
 					escapeCharPos := escapeIndices[escapePos-1][1] - 2
-					text = text[:escapeCharPos] + text[escapeCharPos+1:]
+					text = append(text[:escapeCharPos], text[escapeCharPos+1:]...)
 				}
 				// Print and return.
 				bytes, width = printWithStyle(screen, text[textPos+tagOffset:], x, y, maxWidth, AlignLeft, style)
@@ -343,14 +343,14 @@ func printWithStyle(screen tcell.Screen, text string, x, y, maxWidth, align int,
 			for rightIndex-1 > leftIndex && strippedWidth-choppedLeft-choppedRight > maxWidth {
 				if choppedLeft < choppedRight {
 					// Iterate on the left by one character.
-					iterateString(strippedText[leftIndex:], func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
+					iterateString(string(strippedText[leftIndex:]), func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
 						choppedLeft += screenWidth
 						leftIndex += textWidth
 						return true
 					})
 				} else {
 					// Iterate on the right by one character.
-					iterateStringReverse(strippedText[leftIndex:rightIndex], func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
+					iterateStringReverse(string(strippedText[leftIndex:rightIndex]), func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
 						choppedRight += screenWidth
 						rightIndex -= textWidth
 						return true
@@ -371,7 +371,7 @@ func printWithStyle(screen tcell.Screen, text string, x, y, maxWidth, align int,
 					if escapePos > 0 && leftIndex+tagOffset-1 >= escapeIndices[escapePos-1][0] && leftIndex+tagOffset-1 < escapeIndices[escapePos-1][1] {
 						// Unescape open escape sequences.
 						escapeCharPos := escapeIndices[escapePos-1][1] - 2
-						text = text[:escapeCharPos] + text[escapeCharPos+1:]
+						text = append(text[:escapeCharPos], text[escapeCharPos+1:]...)
 					}
 					break
 				}
@@ -399,7 +399,7 @@ func printWithStyle(screen tcell.Screen, text string, x, y, maxWidth, align int,
 		drawn, drawnWidth, colorPos, escapePos, tagOffset int
 		foregroundColor, backgroundColor, attributes      string
 	)
-	iterateString(strippedText, func(main rune, comb []rune, textPos, length, screenPos, screenWidth int) bool {
+	iterateString(string(strippedText), func(main rune, comb []rune, textPos, length, screenPos, screenWidth int) bool {
 		// Only continue if there is still space.
 		if drawnWidth+screenWidth > maxWidth {
 			return true
@@ -445,33 +445,21 @@ func printWithStyle(screen tcell.Screen, text string, x, y, maxWidth, align int,
 }
 
 // PrintSimple prints white text to the screen at the given position.
-func PrintSimple(screen tcell.Screen, text string, x, y int) {
+func PrintSimple(screen tcell.Screen, text []byte, x, y int) {
 	Print(screen, text, x, y, math.MaxInt32, AlignLeft, Styles.PrimaryTextColor)
 }
 
-// TaggedStringWidth returns the width of the given string needed to print it on
+// TaggedTextWidth returns the width of the given string needed to print it on
 // screen. The text may contain color tags which are not counted.
-func TaggedStringWidth(text string) int {
-	_, _, _, _, _, _, width := decomposeString(text, true, false)
+func TaggedTextWidth(text []byte) int {
+	_, _, _, _, _, _, width := decomposeText(text, true, false)
 	return width
 }
 
-// stringWidth returns the number of horizontal cells needed to print the given
-// text. It splits the text into its grapheme clusters, calculates each
-// cluster's width, and adds them up to a total.
-func stringWidth(text string) (width int) {
-	g := uniseg.NewGraphemes(text)
-	for g.Next() {
-		var chWidth int
-		for _, r := range g.Runes() {
-			chWidth = runewidth.RuneWidth(r)
-			if chWidth > 0 {
-				break // Our best guess at this point is to use the width of the first non-zero-width rune.
-			}
-		}
-		width += chWidth
-	}
-	return
+// TaggedStringWidth returns the width of the given string needed to print it on
+// screen. The text may contain color tags which are not counted.
+func TaggedStringWidth(text string) int {
+	return TaggedTextWidth([]byte(text))
 }
 
 // WordWrap splits a text such that each resulting line does not exceed the
@@ -481,11 +469,11 @@ func stringWidth(text string) (width int) {
 // This function considers color tags to have no width.
 //
 // Text is always split at newline characters ('\n').
-func WordWrap(text string, width int) (lines []string) {
-	colorTagIndices, _, _, _, escapeIndices, strippedText, _ := decomposeString(text, true, false)
+func WordWrap(text []byte, width int) (lines [][]byte) {
+	colorTagIndices, _, _, _, escapeIndices, strippedText, _ := decomposeText(text, true, false)
 
 	// Find candidate breakpoints.
-	breakpoints := boundaryPattern.FindAllStringSubmatchIndex(strippedText, -1)
+	breakpoints := boundaryPattern.FindAllSubmatchIndex(strippedText, -1)
 	// Results in one entry for each candidate. Each entry is an array a of
 	// indices into strippedText where a[6] < 0 for newline/punctuation matches
 	// and a[4] < 0 for whitespace matches.
@@ -497,17 +485,17 @@ func WordWrap(text string, width int) (lines []string) {
 		lineWidth, overflow                                int
 		forceBreak                                         bool
 	)
-	unescape := func(substr string, startIndex int) string {
+	unescape := func(substr []byte, startIndex int) []byte {
 		// A helper function to unescape escaped tags.
 		for index := escapePos; index >= 0; index-- {
 			if index < len(escapeIndices) && startIndex > escapeIndices[index][0] && startIndex < escapeIndices[index][1]-1 {
 				pos := escapeIndices[index][1] - 2 - startIndex
-				return substr[:pos] + substr[pos+1:]
+				return append(substr[:pos], substr[pos+1:]...)
 			}
 		}
 		return substr
 	}
-	iterateString(strippedText, func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
+	iterateString(string(strippedText), func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool {
 		// Handle tags.
 		for {
 			if colorPos < len(colorTagIndices) && textPos+tagOffset >= colorTagIndices[colorPos][0] && textPos+tagOffset < colorTagIndices[colorPos][1] {
@@ -603,7 +591,7 @@ func iterateString(text string, callback func(main rune, comb []rune, textPos, t
 	for gr.Next() {
 		r := gr.Runes()
 		from, to := gr.Positions()
-		width := stringWidth(gr.Str())
+		width := runewidth.StringWidth(gr.Str())
 		var comb []rune
 		if len(r) > 1 {
 			comb = r[1:]
@@ -679,7 +667,15 @@ const (
 	ScrollBarAlways
 )
 
-// RenderScrollBar renders a scroll bar character at the specified position.
+// Scroll bar render text (must be one cell wide)
+var (
+	ScrollBarArea          = []byte("[-:-:-]░")
+	ScrollBarAreaFocused   = []byte("[-:-:-]▒")
+	ScrollBarHandle        = []byte("[-:-:-]▓")
+	ScrollBarHandleFocused = []byte("[::r] [-:-:-]")
+)
+
+// RenderScrollBar renders a scroll bar at the specified position.
 func RenderScrollBar(screen tcell.Screen, visibility ScrollBarVisibility, x int, y int, height int, items int, cursor int, printed int, focused bool, color tcell.Color) {
 	if visibility == ScrollBarNever || (visibility == ScrollBarAuto && items <= height) {
 		return
@@ -698,20 +694,20 @@ func RenderScrollBar(screen tcell.Screen, visibility ScrollBarVisibility, x int,
 	// Calculate handle position.
 	handlePosition := int(float64(height-1) * (float64(cursor) / float64(items-1)))
 
-	// Print character.
-	var scrollBar string
+	// Print scroll bar.
+	var text []byte
 	if printed == handlePosition {
 		if focused {
-			scrollBar = "[::r] [-:-:-]"
+			text = ScrollBarHandleFocused
 		} else {
-			scrollBar = "[-:-:-]▓"
+			text = ScrollBarHandle
 		}
 	} else {
 		if focused {
-			scrollBar = "[-:-:-]▒"
+			text = ScrollBarAreaFocused
 		} else {
-			scrollBar = "[-:-:-]░"
+			text = ScrollBarArea
 		}
 	}
-	Print(screen, scrollBar, x, y, 1, AlignLeft, color)
+	Print(screen, text, x, y, 1, AlignLeft, color)
 }