Adding showchars option and removing @ for wide rune in bufwindow

Author: Neko-Box-Coder

internal/config/settings.go

@@ -70,7 +70,7 @@ var defaultCommonSettings = map[string]interface{}{
 	"hltrailingws":    false,
 	"ignorecase":      true,
 	"incsearch":       true,
-	"indentchar":      " ",
+	"indentchar":      " ", // Deprecated
 	"keepautoindent":  false,
 	"matchbrace":      true,
 	"matchbraceleft":  true,
@@ -88,6 +88,7 @@ var defaultCommonSettings = map[string]interface{}{
 	"scrollbar":       false,
 	"scrollmargin":    float64(3),
 	"scrollspeed":     float64(2),
+	"showchars":       "",
 	"smartpaste":      true,
 	"softwrap":        false,
 	"splitbottom":     true,
@@ -210,6 +211,7 @@ func validateParsedSettings() error {
 			}
 			continue
 		}
+
 		if _, ok := defaults[k]; ok {
 			if e := verifySetting(k, v, defaults[k]); e != nil {
 				err = e

internal/display/bufwindow.go

@@ -2,6 +2,7 @@ package display
 
 import (
 	"strconv"
+	"strings"
 
 	runewidth "github.com/mattn/go-runewidth"
 	"github.com/micro-editor/tcell/v2"
@@ -450,6 +451,30 @@ func (w *BufWindow) displayBuffer() {
 	cursors := b.GetCursors()
 
 	curStyle := config.DefStyle
+
+	// Parse showchars which is in the format of option1=val1,option2=val2,...
+	spacechars := " "
+	tabchars := b.Settings["indentchar"].(string)
+	indentspacechars := " "
+	indenttabchars := b.Settings["indentchar"].(string)
+	for _, entry := range strings.Split(b.Settings["showchars"].(string), ",") {
+		split := strings.SplitN(entry, "=", 2)
+		if len(split) < 2 {
+			continue
+		}
+		key, val := split[0], split[1]
+		switch key {
+		case "space":
+			spacechars = val
+		case "tab":
+			tabchars = val
+		case "ispace":
+			indentspacechars = val
+		case "itab":
+			indenttabchars = val
+		}
+	}
+
 	for ; vloc.Y < w.bufHeight; vloc.Y++ {
 		vloc.X = 0
 
@@ -494,7 +519,82 @@ func (w *BufWindow) displayBuffer() {
 		}
 		bloc.X = bslice
 
-		draw := func(r rune, combc []rune, style tcell.Style, highlight bool, showcursor bool) {
+		getRuneStyle := func(r rune, style tcell.Style, showoffset int, isplaceholder bool) (rune, tcell.Style, bool) {
+			bgoverridable := true
+			if nColsBeforeStart > 0 || vloc.Y < 0 {
+				return r, style, bgoverridable
+			}
+
+			if isplaceholder || (r != '\t' && r != ' ') {
+				return r, style, bgoverridable
+			}
+
+			var indentrunes []rune
+			switch r {
+			case '\t':
+				if bloc.X < leadingwsEnd && !b.Settings["tabstospaces"].(bool) {
+					indentrunes = []rune(indenttabchars)
+				} else {
+					indentrunes = []rune(tabchars)
+				}
+			case ' ':
+				if bloc.X%tabsize == 0 && bloc.X < leadingwsEnd && b.Settings["tabstospaces"].(bool) {
+					indentrunes = []rune(indentspacechars)
+				} else {
+					indentrunes = []rune(spacechars)
+				}
+			}
+
+			var returnrune rune
+			if showoffset < len(indentrunes) {
+				returnrune = indentrunes[showoffset]
+			} else {
+				// use space if no showchars or after we showed showchars
+				returnrune = ' '
+			}
+
+			if s, ok := config.Colorscheme["indent-char"]; ok {
+				fg, _, _ := s.Decompose()
+				style = style.Foreground(fg)
+			}
+
+			if b.Settings["hltaberrors"].(bool) && bloc.X < leadingwsEnd && !isplaceholder {
+				if s, ok := config.Colorscheme["tab-error"]; ok {
+					if b.Settings["tabstospaces"].(bool) && r == '\t' {
+						fg, _, _ := s.Decompose()
+						style = style.Background(fg)
+						bgoverridable = false
+					} else if !b.Settings["tabstospaces"].(bool) && r == ' ' {
+						fg, _, _ := s.Decompose()
+						style = style.Background(fg)
+						bgoverridable = false
+					}
+				}
+			}
+
+			if b.Settings["hltrailingws"].(bool) {
+				if s, ok := config.Colorscheme["trailingws"]; ok {
+					if bloc.X >= trailingwsStart && bloc.X < blineLen {
+						hl := true
+						for _, c := range cursors {
+							if c.NewTrailingWsY == bloc.Y {
+								hl = false
+								break
+							}
+						}
+						if hl {
+							fg, _, _ := s.Decompose()
+							style = style.Background(fg)
+							bgoverridable = false
+						}
+					}
+				}
+			}
+
+			return returnrune, style, bgoverridable
+		}
+
+		draw := func(r rune, combc []rune, style tcell.Style, highlight bool, showcursor bool, bgoverridable bool) {
 			if nColsBeforeStart <= 0 && vloc.Y >= 0 {
 				if highlight {
 					if w.Buf.HighlightSearch && w.Buf.SearchMatch(bloc) {
@@ -510,36 +610,8 @@ func (w *BufWindow) displayBuffer() {
 					// syntax or hlsearch highlighting with non-default background takes precedence
 					// over cursor-line and color-column
 					dontOverrideBackground := origBg != defBg
-
-					if b.Settings["hltaberrors"].(bool) {
-						if s, ok := config.Colorscheme["tab-error"]; ok {
-							isTab := (r == '\t') || (r == ' ' && !showcursor)
-							if (b.Settings["tabstospaces"].(bool) && isTab) ||
-								(!b.Settings["tabstospaces"].(bool) && bloc.X < leadingwsEnd && r == ' ' && !isTab) {
-								fg, _, _ := s.Decompose()
-								style = style.Background(fg)
-								dontOverrideBackground = true
-							}
-						}
-					}
-
-					if b.Settings["hltrailingws"].(bool) {
-						if s, ok := config.Colorscheme["trailingws"]; ok {
-							if bloc.X >= trailingwsStart && bloc.X < blineLen {
-								hl := true
-								for _, c := range cursors {
-									if c.NewTrailingWsY == bloc.Y {
-										hl = false
-										break
-									}
-								}
-								if hl {
-									fg, _, _ := s.Decompose()
-									style = style.Background(fg)
-									dontOverrideBackground = true
-								}
-							}
-						}
+					if !bgoverridable {
+						dontOverrideBackground = true
 					}
 
 					for _, c := range cursors {
@@ -571,20 +643,6 @@ func (w *BufWindow) displayBuffer() {
 						}
 					}
 
-					if r == '\t' {
-						indentrunes := []rune(b.Settings["indentchar"].(string))
-						// if empty indentchar settings, use space
-						if len(indentrunes) == 0 {
-							indentrunes = []rune{' '}
-						}
-
-						r = indentrunes[0]
-						if s, ok := config.Colorscheme["indent-char"]; ok && r != ' ' {
-							fg, _, _ := s.Decompose()
-							style = style.Foreground(fg)
-						}
-					}
-
 					if s, ok := config.Colorscheme["color-column"]; ok {
 						if colorcolumn != 0 && vloc.X-w.gutterOffset+w.StartCol == colorcolumn && !dontOverrideBackground {
 							fg, _, _ := s.Decompose()
@@ -692,7 +750,7 @@ func (w *BufWindow) displayBuffer() {
 			// If a word (or just a wide rune) does not fit in the window
 			if vloc.X+wordwidth > maxWidth && vloc.X > w.gutterOffset {
 				for vloc.X < maxWidth {
-					draw(' ', nil, config.DefStyle, false, false)
+					draw(' ', nil, config.DefStyle, false, false, true)
 				}
 
 				// We either stop or we wrap to draw the word in the next line
@@ -708,18 +766,17 @@ func (w *BufWindow) displayBuffer() {
 			}
 
 			for _, r := range word {
-				draw(r.r, r.combc, r.style, true, true)
-
-				// Draw any extra characters either spaces for tabs or @ for incomplete wide runes
-				if r.width > 1 {
-					char := ' '
-					if r.r != '\t' {
-						char = '@'
-					}
-
-					for i := 1; i < r.width; i++ {
-						draw(char, nil, r.style, true, false)
+				drawrune, drawstyle, bgoverridable := getRuneStyle(r.r, r.style, 0, false)
+				draw(drawrune, r.combc, drawstyle, true, true, bgoverridable)
+
+				// Draw extra characters for tabs or wide runes
+				for i := 1; i < r.width; i++ {
+					if r.r == '\t' {
+						drawrune, drawstyle, bgoverridable = getRuneStyle('\t', r.style, i, false)
+					} else {
+						drawrune, drawstyle, bgoverridable = getRuneStyle(' ', r.style, i, true)
 					}
+					draw(drawrune, nil, drawstyle, true, false, bgoverridable)
 				}
 				bloc.X++
 			}
@@ -764,7 +821,8 @@ func (w *BufWindow) displayBuffer() {
 
 		if vloc.X != maxWidth {
 			// Display newline within a selection
-			draw(' ', nil, config.DefStyle, true, true)
+			drawrune, drawstyle, bgoverridable := getRuneStyle(' ', config.DefStyle, 0, true)
+			draw(drawrune, nil, drawstyle, true, true, bgoverridable)
 		}
 
 		bloc.X = w.StartCol

runtime/help/options.md

@@ -203,12 +203,8 @@ Here are the available options:
 
     default value: `true`
 
-* `indentchar`: sets the indentation character. This will not be inserted into
-   files; it is only a visual indicator that whitespace is present. If set to a
-   printing character, it functions as a subset of the "show invisibles"
-   setting available in many other text editors. The color of this character is
-   determined by the `indent-char` field in the current theme rather than the
-   default text color.
+* `indentchar`: sets the character to be shown to display tab characters.
+   This option is **deprecated**, use the `showchars` option instead.
 
     default value: ` ` (space)
 
@@ -386,6 +382,22 @@ Here are the available options:
 
     default value: `2`
 
+* `showchars`: sets what characters to be shown to display various inivisible
+   characters in the file. The characters shown will not be inserted into files.
+   (This option overrides the `indentchar` option if that exists)
+   This option is specified in the form of `key1=value1,key2=value2,...`.
+   Here are the list of keys:
+   The color of the shown character is determined by the `indent-char`
+   field in the current theme rather than the default text color.
+   - `ispace`: indent space characters, for space at indent position before
+               the first visible character
+   - `itab`: indent tab characters, for tab before the first visible character
+   - `space`: space characters, for space that is not displayed by `ispace`
+   - `tab`: tab characters, for tab that is not displayed by `itab`
+   An example of this option value could be `tab=>,space=.,itab=|>,ispace=|`
+
+    default value: ``
+
 * `smartpaste`: add leading whitespace when pasting multiple lines.
    This will attempt to preserve the current indentation level when pasting an
    unindented block.
@@ -577,6 +589,7 @@ so that you can see what the formatting should look like.
     "scrollbarchar": "|",
     "scrollmargin": 3,
     "scrollspeed": 2,
+    "showchars": "",
     "smartpaste": true,
     "softwrap": false,
     "splitbottom": true,