WIP: Add support for vertical header

main.go

@@ -438,6 +438,12 @@ func init() {
 		return []string{"1"}, cobra.ShellCompDirectiveNoFileComp
 	})
 
+	rootCmd.PersistentFlags().IntP("vertical-header", "V", 0, "number of vertical header lines to be displayed constantly")
+	_ = viper.BindPFlag("general.VerticalHeader", rootCmd.PersistentFlags().Lookup("vertical-header"))
+	_ = rootCmd.RegisterFlagCompletionFunc("vertical-header", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
+		return []string{"1"}, cobra.ShellCompDirectiveNoFileComp
+	})
+
 	rootCmd.PersistentFlags().IntP("skip-lines", "", 0, "skip the number of lines")
 	_ = viper.BindPFlag("general.SkipLines", rootCmd.PersistentFlags().Lookup("skip-lines"))
 	_ = rootCmd.RegisterFlagCompletionFunc("skip-lines", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {

oviewer/config.go

@@ -32,6 +32,9 @@ func NewConfig() Config {
 		StyleSectionLine: OVStyle{
 			Background: "slateblue",
 		},
+		StyleVerticalHeader: OVStyle{
+			Reverse: true,
+		},
 		StyleMultiColorHighlight: []OVStyle{
 			{Foreground: "red"},
 			{Foreground: "aqua"},

oviewer/document.go

@@ -100,6 +100,9 @@ type Document struct {
 	width int
 	// height is the height of the screen.
 	height int
+	// endExclude is the number of lines to exclude from the end.
+	endExclude int
+
 	// markedPoint is the position of the marked line.
 	markedPoint int
 

oviewer/draw.go

@@ -20,11 +20,12 @@ func (root *Root) draw(ctx context.Context) {
 	root.prepareDraw(ctx)
 
 	// Body.
-	lX := m.topLX
+	lX := root.scr.verticalHeader
 	lN := m.topLN + root.scr.headerEnd
-	// If WrapMode is off, lX is always 0.
-	if !m.WrapMode {
-		lX = 0
+
+	// If WrapMode is enabled, the drawing position is adjusted.
+	if m.WrapMode {
+		lX += m.topLX
 	}
 	lX, lN = root.drawBody(lX, lN)
 	m.bottomLX = lX
@@ -77,6 +78,7 @@ func (root *Root) drawBody(lX int, lN int) (int, int) {
 		wrapNum++
 		if nextLX == 0 {
 			wrapNum = 0
+			nextLX = root.scr.verticalHeader
 		}
 
 		lX = nextLX
@@ -91,7 +93,7 @@ func (root *Root) drawHeader() {
 
 	// wrapNum is the number of wrapped lines.
 	wrapNum := 0
-	lX := 0
+	lX := root.scr.verticalHeader
 	lN := root.scr.headerLN
 	for y := 0; y < m.headerHeight && lN < root.scr.headerEnd; y++ {
 		lineC, ok := root.scr.lines[lN]
@@ -118,7 +120,7 @@ func (root *Root) drawSectionHeader() {
 	m := root.Doc
 
 	wrapNum := 0
-	lX := 0
+	lX := root.scr.verticalHeader
 	lN := root.scr.sectionHeaderLN
 	for y := m.headerHeight; y < m.headerHeight+m.sectionHeaderHeight && lN < root.scr.sectionHeaderEnd; y++ {
 		lineC, ok := root.scr.lines[lN]
@@ -142,6 +144,7 @@ func (root *Root) drawSectionHeader() {
 		wrapNum++
 		if nextLX == 0 {
 			wrapNum = 0
+			nextLX = root.scr.verticalHeader
 		}
 
 		lX = nextLX
@@ -151,11 +154,40 @@ func (root *Root) drawSectionHeader() {
 
 // drawWrapLine wraps and draws the contents and returns the next drawing position.
 func (root *Root) drawLine(y int, lX int, lN int, lineC LineC) (int, int) {
+	if root.scr.verticalHeader > 0 {
+		root.drawVerticalHeader(y, lX, lineC)
+	}
 	if root.Doc.WrapMode {
 		return root.drawWrapLine(y, lX, lN, lineC)
 	}
 
-	return root.drawNoWrapLine(y, root.Doc.x, lN, lineC)
+	return root.drawNoWrapLine(y, root.scr.verticalHeader+root.Doc.x, lN, lineC)
+}
+
+// drawVerticalHeader draws the vertical header.
+func (root *Root) drawVerticalHeader(y int, lX int, lineC LineC) {
+	numberWidth := root.scr.numberWidth
+	if numberWidth > 0 {
+		numberWidth++
+	}
+	screen := root.Screen
+	for n := 0; n < root.scr.verticalHeader; n++ {
+		x := numberWidth + n
+		if lX > root.scr.verticalHeader || n >= len(lineC.lc) {
+			// EOL
+			style := lineC.eolStyle
+			if lineC.valid {
+				style = style.Reverse(true)
+			}
+			root.clearEOL(x, y, style)
+			break
+		}
+		c := lineC.lc[n]
+		if lineC.valid {
+			c.style = applyStyle(defaultStyle, root.StyleVerticalHeader)
+		}
+		screen.SetContent(x, y, c.mainc, c.combc, c.style)
+	}
 }
 
 // drawWrapLine wraps and draws the contents and returns the next drawing position.
@@ -171,7 +203,7 @@ func (root *Root) drawWrapLine(y int, lX int, lN int, lineC LineC) (int, int) {
 		if lX+n >= len(lineC.lc) {
 			// EOL
 			root.clearEOL(x, y, lineC.eolStyle)
-			lX = 0
+			lX = root.scr.verticalHeader
 			lN++
 			break
 		}
@@ -208,8 +240,7 @@ func (root *Root) drawNoWrapLine(y int, lX int, lN int, lineC LineC) (int, int)
 		screen.SetContent(x, y, c.mainc, c.combc, c.style)
 	}
 	lN++
-
-	return lX, lN
+	return 0, lN
 }
 
 // blankLineNumber should be blank for the line number.
@@ -220,7 +251,7 @@ func (root *Root) blankLineNumber(y int) {
 	if root.scr.startX <= 0 {
 		return
 	}
-	numC := StrToContents(strings.Repeat(" ", root.scr.startX-1), root.Doc.TabWidth)
+	numC := StrToContents(strings.Repeat(" ", root.scr.numberWidth), root.Doc.TabWidth)
 	root.setContentString(0, y, numC)
 }
 
@@ -248,7 +279,7 @@ func (root *Root) drawLineNumber(lN int, y int, valid bool) {
 	number = number - m.firstLine() + 1
 
 	// Line numbers start at 1 except for skip and header lines.
-	numC := StrToContents(fmt.Sprintf("%*d", root.scr.startX-1, number), m.TabWidth)
+	numC := StrToContents(fmt.Sprintf("%*d", root.scr.numberWidth, number), m.TabWidth)
 	for i := 0; i < len(numC); i++ {
 		numC[i].style = applyStyle(defaultStyle, root.StyleLineNumber)
 	}

oviewer/move_vertical.go

@@ -235,9 +235,18 @@ func (m *Document) leftMostX(lN int) []int {
 	if err != nil {
 		return nil
 	}
+	lc = excludeRange(lc, m.endExclude)
 	return leftX(m.width, lc)
 }
 
+// excludeRange returns a new slice with the elements from start to end excluded.
+func excludeRange(lc contents, end int) []content {
+	if end > len(lc) {
+		return []content{}
+	}
+	return lc[end:]
+}
+
 // leftX returns a list of left - most x positions when wrapping.
 func leftX(width int, lc contents) []int {
 	if width <= 0 {

oviewer/oviewer.go

@@ -100,6 +100,11 @@ type SCR struct {
 	// sectionHeaderEnd is the end of the section header.
 	sectionHeaderEnd int
 
+	// numWidth is the width of the number.
+	numberWidth int
+	// verticalHeader is the width of the vertical header.
+	verticalHeader int
+
 	// x1, y1, x2, y2 are the coordinates selected by the mouse.
 	x1 int
 	y1 int
@@ -147,6 +152,8 @@ type general struct {
 	TabWidth int
 	// Header is number of header lines to be fixed.
 	Header int
+	// VerticalHeader is the number of vertical header lines.
+	VerticalHeader int
 	// SkipLines is the rows to skip.
 	SkipLines int
 	// WatchInterval is the watch interval (seconds).
@@ -246,6 +253,9 @@ type Config struct {
 	StyleOverStrike OVStyle
 	// StyleOverLine is a style that applies to overstrike underlines.
 	StyleOverLine OVStyle
+	// StyleVerticalHeader is a style that applies to the vertical header.
+	StyleVerticalHeader OVStyle
+
 	// General represents the general behavior.
 	General general
 	// BeforeWriteOriginal specifies the number of lines before the current position.

oviewer/prepare_draw.go

@@ -37,16 +37,20 @@ func (root *Root) prepareScreen() {
 
 // prepareStartX prepares the start position of the x.
 func (root *Root) prepareStartX() {
-	root.scr.startX = 0
+	root.scr.verticalHeader = root.General.VerticalHeader
+	root.scr.numberWidth = 0
+	root.scr.startX = root.scr.verticalHeader
 	m := root.Doc
+	m.endExclude = root.scr.verticalHeader
 	if !m.LineNumMode {
 		return
 	}
 
 	if m.parent != nil {
 		m = m.parent
 	}
-	root.scr.startX = len(strconv.Itoa(m.BufEndNum())) + 1
+	root.scr.numberWidth = len(strconv.Itoa(m.BufEndNum()))
+	root.scr.startX = root.scr.verticalHeader + root.scr.numberWidth + 1
 }
 
 // ViewSync redraws the whole thing.
@@ -73,7 +77,6 @@ func (root *Root) prepareDraw(ctx context.Context) {
 	root.scr.headerEnd = root.Doc.firstLine()
 	// Set the header height.
 	root.Doc.headerHeight = root.Doc.getHeight(root.scr.headerLN, root.scr.headerEnd)
-
 	// Section header.
 	root.scr.sectionHeaderLN = -1
 	root.scr.sectionHeaderEnd = 0