package tview import ( "math" "regexp" "sort" "strconv" "github.com/gdamore/tcell/v2" runewidth "github.com/mattn/go-runewidth" "github.com/rivo/uniseg" ) // Text alignment within a box. const ( AlignLeft = iota AlignCenter AlignRight ) // Common regular expressions. var ( colorPattern = regexp.MustCompile(`\[([a-zA-Z]+|#[0-9a-zA-Z]{6}|\-)?(:([a-zA-Z]+|#[0-9a-zA-Z]{6}|\-)?(:([lbidrus]+|\-)?)?)?\]`) regionPattern = regexp.MustCompile(`\["([a-zA-Z0-9_,;: \-\.]*)"\]`) escapePattern = regexp.MustCompile(`\[([a-zA-Z0-9_,;: \-\."#]+)\[(\[*)\]`) nonEscapePattern = regexp.MustCompile(`(\[[a-zA-Z0-9_,;: \-\."#]+\[*)\]`) boundaryPattern = regexp.MustCompile(`(([,\.\-:;!\?&#+]|\n)[ \t\f\r]*|([ \t\f\r]+))`) spacePattern = regexp.MustCompile(`\s+`) ) // Positions of substrings in regular expressions. const ( colorForegroundPos = 1 colorBackgroundPos = 3 colorFlagPos = 5 ) // Predefined InputField acceptance functions. var ( // InputFieldInteger accepts integers. InputFieldInteger func(text string, ch rune) bool // InputFieldFloat accepts floating-point numbers. InputFieldFloat func(text string, ch rune) bool // InputFieldMaxLength returns an input field accept handler which accepts // input strings up to a given length. Use it like this: // // inputField.SetAcceptanceFunc(InputFieldMaxLength(10)) // Accept up to 10 characters. InputFieldMaxLength func(maxLength int) func(text string, ch rune) bool ) // Package initialization. func init() { // Initialize the predefined input field handlers. InputFieldInteger = func(text string, ch rune) bool { if text == "-" { return true } _, err := strconv.Atoi(text) return err == nil } InputFieldFloat = func(text string, ch rune) bool { if text == "-" || text == "." || text == "-." { return true } _, err := strconv.ParseFloat(text, 64) return err == nil } InputFieldMaxLength = func(maxLength int) func(text string, ch rune) bool { return func(text string, ch rune) bool { return len([]rune(text)) <= maxLength } } } // styleFromTag takes the given style, defined by a foreground color (fgColor), // a background color (bgColor), and style attributes, and modifies it based on // 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] if color == "-" { fgColor = "-" } else if color != "" { fgColor = color } } if tagSubstrings[colorBackgroundPos-1] != "" { color := tagSubstrings[colorBackgroundPos] if color == "-" { bgColor = "-" } else if color != "" { bgColor = color } } if tagSubstrings[colorFlagPos-1] != "" { flags := tagSubstrings[colorFlagPos] if flags == "-" { attributes = "-" } else if flags != "" { attributes = flags } } return fgColor, bgColor, attributes } // overlayStyle calculates a new style based on "style" and applying tag-based // colors/attributes to it (see also styleFromTag()). func overlayStyle(style tcell.Style, fgColor, bgColor, attributes string) tcell.Style { _, _, defAttr := style.Decompose() if fgColor != "" && fgColor != "-" { style = style.Foreground(tcell.GetColor(fgColor)) } if bgColor != "" && bgColor != "-" { style = style.Background(tcell.GetColor(bgColor)) } if attributes == "-" { style = style.Bold(defAttr&tcell.AttrBold > 0). Italic(defAttr&tcell.AttrItalic > 0). Blink(defAttr&tcell.AttrBlink > 0). Reverse(defAttr&tcell.AttrReverse > 0). Underline(defAttr&tcell.AttrUnderline > 0). Dim(defAttr&tcell.AttrDim > 0) } else if attributes != "" { style = style.Normal() for _, flag := range attributes { switch flag { case 'l': style = style.Blink(true) case 'b': style = style.Bold(true) case 'i': style = style.Italic(true) case 'd': style = style.Dim(true) case 'r': style = style.Reverse(true) case 'u': style = style.Underline(true) case 's': style = style.StrikeThrough(true) } } } return style } // decomposeString 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 // re.FindAllStringSubmatch()), the indices of region tags and the region tags // 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) { // Shortcut for the trivial case. if !findColors && !findRegions { return nil, nil, nil, nil, nil, text, stringWidth(text) } // Get positions of any tags. if findColors { colorIndices = colorPattern.FindAllStringIndex(text, -1) colors = colorPattern.FindAllStringSubmatch(text, -1) } if findRegions { regionIndices = regionPattern.FindAllStringIndex(text, -1) regions = regionPattern.FindAllStringSubmatch(text, -1) } escapeIndices = escapePattern.FindAllStringIndex(text, -1) // Because the color pattern detects empty tags, we need to filter them out. for i := len(colorIndices) - 1; i >= 0; i-- { if colorIndices[i][1]-colorIndices[i][0] == 2 { colorIndices = append(colorIndices[:i], colorIndices[i+1:]...) colors = append(colors[:i], colors[i+1:]...) } } // Make a (sorted) list of all tags. allIndices := make([][3]int, 0, len(colorIndices)+len(regionIndices)+len(escapeIndices)) for indexType, index := range [][][]int{colorIndices, regionIndices, escapeIndices} { for _, tag := range index { allIndices = append(allIndices, [3]int{tag[0], tag[1], indexType}) } } sort.Slice(allIndices, func(i int, j int) bool { return allIndices[i][0] < allIndices[j][0] }) // Remove the tags from the original string. var from int buf := make([]byte, 0, len(text)) for _, indices := range allIndices { if indices[2] == 2 { // Escape sequences are not simply removed. buf = append(buf, []byte(text[from:indices[1]-2])...) buf = append(buf, ']') from = indices[1] } else { buf = append(buf, []byte(text[from:indices[0]])...) from = indices[1] } } buf = append(buf, text[from:]...) stripped = string(buf) // Get the width of the stripped string. width = stringWidth(stripped) return } // Print prints text onto the screen into the given box at (x,y,maxWidth,1), // not exceeding that box. "align" is one of AlignLeft, AlignCenter, or // AlignRight. The screen's background color will not be changed. // // You can change the colors and text styles mid-text by inserting a color tag. // See the package description for details. // // 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) { bytes, width, _, _ := printWithStyle(screen, text, x, y, 0, maxWidth, align, tcell.StyleDefault.Foreground(color), true) return bytes, width } // printWithStyle works like Print() but it takes a style instead of just a // foreground color. The skipWidth parameter specifies the number of cells // skipped at the beginning of the text. It also returns the start and end index // (exclusively) of the text actually printed. If maintainBackground is "true", // The existing screen background is not changed (i.e. the style's background // color is ignored). func printWithStyle(screen tcell.Screen, text string, x, y, skipWidth, maxWidth, align int, style tcell.Style, maintainBackground bool) (int, int, int, int) { totalWidth, totalHeight := screen.Size() if maxWidth <= 0 || len(text) == 0 || y < 0 || y >= totalHeight { return 0, 0, 0, 0 } // Decompose the text. colorIndices, colors, _, _, escapeIndices, strippedText, strippedWidth := decomposeString(text, true, false) // We want to reduce all alignments to AlignLeft. if align == AlignRight { if strippedWidth-skipWidth <= maxWidth { // There's enough space for the entire text. return printWithStyle(screen, text, x+maxWidth-strippedWidth+skipWidth, y, skipWidth, maxWidth, AlignLeft, style, maintainBackground) } // Trim characters off the beginning. var ( bytes, width, colorPos, escapePos, tagOffset, from, to int foregroundColor, backgroundColor, attributes string ) originalStyle := style iterateString(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]) style = overlayStyle(originalStyle, foregroundColor, backgroundColor, attributes) tagOffset += colorIndices[colorPos][1] - colorIndices[colorPos][0] colorPos++ } if escapePos < len(escapeIndices) && textPos+tagOffset >= escapeIndices[escapePos][0] && textPos+tagOffset < escapeIndices[escapePos][1] { tagOffset++ escapePos++ } if strippedWidth-screenPos <= maxWidth { // We chopped off enough. 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:] } // Print and return. bytes, width, from, to = printWithStyle(screen, text[textPos+tagOffset:], x, y, 0, maxWidth, AlignLeft, style, maintainBackground) from += textPos + tagOffset to += textPos + tagOffset return true } return false }) return bytes, width, from, to } else if align == AlignCenter { if strippedWidth-skipWidth == maxWidth { // Use the exact space. return printWithStyle(screen, text, x, y, skipWidth, maxWidth, AlignLeft, style, maintainBackground) } else if strippedWidth-skipWidth < maxWidth { // We have more space than we need. half := (maxWidth - strippedWidth + skipWidth) / 2 return printWithStyle(screen, text, x+half, y, skipWidth, maxWidth-half, AlignLeft, style, maintainBackground) } else { // Chop off runes until we have a perfect fit. var choppedLeft, choppedRight, leftIndex, rightIndex int rightIndex = len(strippedText) for rightIndex-1 > leftIndex && strippedWidth-skipWidth-choppedLeft-choppedRight > maxWidth { if skipWidth > 0 || choppedLeft < choppedRight { // Iterate on the left by one character. iterateString(strippedText[leftIndex:], func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool { if skipWidth > 0 { skipWidth -= screenWidth strippedWidth -= screenWidth } else { 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 { choppedRight += screenWidth rightIndex -= textWidth return true }) } } // Add tag offsets and determine start style. var ( colorPos, escapePos, tagOffset int foregroundColor, backgroundColor, attributes string ) originalStyle := style for index := range strippedText { // We only need the offset of the left index. if index > leftIndex { // We're done. 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:] } break } // Update color/escape tag offset. if colorPos < len(colorIndices) && index+tagOffset >= colorIndices[colorPos][0] && index+tagOffset < colorIndices[colorPos][1] { if index <= leftIndex { foregroundColor, backgroundColor, attributes = styleFromTag(foregroundColor, backgroundColor, attributes, colors[colorPos]) style = overlayStyle(originalStyle, foregroundColor, backgroundColor, attributes) } tagOffset += colorIndices[colorPos][1] - colorIndices[colorPos][0] colorPos++ } if escapePos < len(escapeIndices) && index+tagOffset >= escapeIndices[escapePos][0] && index+tagOffset < escapeIndices[escapePos][1] { tagOffset++ escapePos++ } } bytes, width, from, to := printWithStyle(screen, text[leftIndex+tagOffset:], x, y, 0, maxWidth, AlignLeft, style, maintainBackground) from += leftIndex + tagOffset to += leftIndex + tagOffset return bytes, width, from, to } } // Draw text. var ( drawn, drawnWidth, colorPos, escapePos, tagOffset, from, to int foregroundColor, backgroundColor, attributes string ) iterateString(strippedText, func(main rune, comb []rune, textPos, length, screenPos, screenWidth int) bool { // Skip character if necessary. if skipWidth > 0 { skipWidth -= screenWidth from = textPos + length to = from return false } // Only continue if there is still space. if drawnWidth+screenWidth > maxWidth || x+drawnWidth >= totalWidth { return true } // Handle color tags. for colorPos < len(colorIndices) && textPos+tagOffset >= colorIndices[colorPos][0] && textPos+tagOffset < colorIndices[colorPos][1] { foregroundColor, backgroundColor, attributes = styleFromTag(foregroundColor, backgroundColor, attributes, colors[colorPos]) tagOffset += colorIndices[colorPos][1] - colorIndices[colorPos][0] colorPos++ } // Handle escape tags. if escapePos < len(escapeIndices) && textPos+tagOffset >= escapeIndices[escapePos][0] && textPos+tagOffset < escapeIndices[escapePos][1] { if textPos+tagOffset == escapeIndices[escapePos][1]-2 { tagOffset++ escapePos++ } } // Memorize positions. to = textPos + length // Print the rune sequence. finalX := x + drawnWidth finalStyle := style if maintainBackground { _, _, existingStyle, _ := screen.GetContent(finalX, y) _, background, _ := existingStyle.Decompose() finalStyle = finalStyle.Background(background) } finalStyle = overlayStyle(finalStyle, foregroundColor, backgroundColor, attributes) for offset := screenWidth - 1; offset >= 0; offset-- { // To avoid undesired effects, we populate all cells. if offset == 0 { screen.SetContent(finalX+offset, y, main, comb, finalStyle) } else { screen.SetContent(finalX+offset, y, ' ', nil, finalStyle) } } // Advance. drawn += length drawnWidth += screenWidth return false }) return drawn + tagOffset + len(escapeIndices), drawnWidth, from, to } // PrintSimple prints white text to the screen at the given position. func PrintSimple(screen tcell.Screen, text string, 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 // screen. The text may contain color tags which are not counted. func TaggedStringWidth(text string) int { _, _, _, _, _, _, width := decomposeString(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 } // WordWrap splits a text such that each resulting line does not exceed the // given screen width. Possible split points are after any punctuation or // whitespace. Whitespace after split points will be dropped. // // 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) // Find candidate breakpoints. breakpoints := boundaryPattern.FindAllStringSubmatchIndex(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. // Process stripped text one character at a time. var ( colorPos, escapePos, breakpointPos, tagOffset int lastBreakpoint, lastContinuation, currentLineStart int lineWidth, overflow int forceBreak bool ) unescape := func(substr string, startIndex int) string { // 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 substr } iterateString(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] { // Colour tags. tagOffset += colorTagIndices[colorPos][1] - colorTagIndices[colorPos][0] colorPos++ } else if escapePos < len(escapeIndices) && textPos+tagOffset == escapeIndices[escapePos][1]-2 { // Escape tags. tagOffset++ escapePos++ } else { break } } // Is this a breakpoint? if breakpointPos < len(breakpoints) && textPos+tagOffset == breakpoints[breakpointPos][0] { // Yes, it is. Set up breakpoint infos depending on its type. lastBreakpoint = breakpoints[breakpointPos][0] + tagOffset lastContinuation = breakpoints[breakpointPos][1] + tagOffset overflow = 0 forceBreak = main == '\n' if breakpoints[breakpointPos][6] < 0 && !forceBreak { lastBreakpoint++ // Don't skip punctuation. } breakpointPos++ } // Check if a break is warranted. if forceBreak || lineWidth > 0 && lineWidth+screenWidth > width { breakpoint := lastBreakpoint continuation := lastContinuation if forceBreak { breakpoint = textPos + tagOffset continuation = textPos + tagOffset + 1 lastBreakpoint = 0 overflow = 0 } else if lastBreakpoint <= currentLineStart { breakpoint = textPos + tagOffset continuation = textPos + tagOffset overflow = 0 } lines = append(lines, unescape(text[currentLineStart:breakpoint], currentLineStart)) currentLineStart, lineWidth, forceBreak = continuation, overflow, false } // Remember the characters since the last breakpoint. if lastBreakpoint > 0 && lastContinuation <= textPos+tagOffset { overflow += screenWidth } // Advance. lineWidth += screenWidth // But if we're still inside a breakpoint, skip next character (whitespace). if textPos+tagOffset < currentLineStart { lineWidth -= screenWidth } return false }) // Flush the rest. if currentLineStart < len(text) { lines = append(lines, unescape(text[currentLineStart:], currentLineStart)) } return } // Escape escapes the given text such that color and/or region tags are not // recognized and substituted by the print functions of this package. For // example, to include a tag-like string in a box title or in a TextView: // // box.SetTitle(tview.Escape("[squarebrackets]")) // fmt.Fprint(textView, tview.Escape(`["quoted"]`)) func Escape(text string) string { return nonEscapePattern.ReplaceAllString(text, "$1[]") } // iterateString iterates through the given string one printed character at a // time. For each such character, the callback function is called with the // Unicode code points of the character (the first rune and any combining runes // which may be nil if there aren't any), the starting position (in bytes) // within the original string, its length in bytes, the screen position of the // character, and the screen width of it. The iteration stops if the callback // returns true. This function returns true if the iteration was stopped before // the last character. func iterateString(text string, callback func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool) bool { var screenPos int gr := uniseg.NewGraphemes(text) for gr.Next() { r := gr.Runes() from, to := gr.Positions() width := stringWidth(gr.Str()) var comb []rune if len(r) > 1 { comb = r[1:] } if callback(r[0], comb, from, to-from, screenPos, width) { return true } screenPos += width } return false } // iterateStringReverse iterates through the given string in reverse, starting // from the end of the string, one printed character at a time. For each such // character, the callback function is called with the Unicode code points of // the character (the first rune and any combining runes which may be nil if // there aren't any), the starting position (in bytes) within the original // string, its length in bytes, the screen position of the character, and the // screen width of it. The iteration stops if the callback returns true. This // function returns true if the iteration was stopped before the last character. func iterateStringReverse(text string, callback func(main rune, comb []rune, textPos, textWidth, screenPos, screenWidth int) bool) bool { type cluster struct { main rune comb []rune textPos, textWidth, screenPos, screenWidth int } // Create the grapheme clusters. var clusters []cluster iterateString(text, func(main rune, comb []rune, textPos int, textWidth int, screenPos int, screenWidth int) bool { clusters = append(clusters, cluster{ main: main, comb: comb, textPos: textPos, textWidth: textWidth, screenPos: screenPos, screenWidth: screenWidth, }) return false }) // Iterate in reverse. for index := len(clusters) - 1; index >= 0; index-- { if callback( clusters[index].main, clusters[index].comb, clusters[index].textPos, clusters[index].textWidth, clusters[index].screenPos, clusters[index].screenWidth, ) { return true } } return false } // stripTags strips colour tags from the given string. (Region tags are not // stripped.) func stripTags(text string) string { stripped := colorPattern.ReplaceAllStringFunc(text, func(match string) string { if len(match) > 2 { return "" } return match }) return escapePattern.ReplaceAllString(stripped, `[$1$2]`) }