gemini-browser

util.go (4808B)

---

 package tview
 
 import (
 	"math"
 	"os"
 	"regexp"
 
 	"github.com/gdamore/tcell/v2"
 )
 
 // Text alignment within a box. Also used to align images.
 const (
 	AlignLeft = iota
 	AlignCenter
 	AlignRight
 	AlignTop    = 0
 	AlignBottom = 2
 )
 
 var (
 	// Regular expression used to escape style/region tags.
 	escapePattern = regexp.MustCompile(`(\[[a-zA-Z0-9_,;: \-\."#]+\[*)\]`)
 
 	// Regular expression used to unescape escaped style/region tags.
 	unescapePattern = regexp.MustCompile(`(\[[a-zA-Z0-9_,;: \-\."#]+\[*)\[\]`)
 
 	// The number of colors available in the terminal.
 	availableColors = 256
 )
 
 // Package initialization.
 func init() {
 	// Determine the number of colors available in the terminal.
 	info, err := tcell.LookupTerminfo(os.Getenv("TERM"))
 	if err == nil {
 		availableColors = info.Colors
 	}
 }
 
 // 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 style tag.
 // See the package description for details.
 //
 // Returns the number of actual bytes of the text printed (including style 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) {
 	start, end, width := printWithStyle(screen, text, x, y, 0, maxWidth, align, tcell.StyleDefault.Foreground(color), true)
 	return end - start, 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 returns the start index, end index
 // (exclusively), and screen width 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) (start, end, printedWidth int) {
 	totalWidth, totalHeight := screen.Size()
 	if maxWidth <= 0 || len(text) == 0 || y < 0 || y >= totalHeight {
 		return 0, 0, 0
 	}
 
 	// If we don't overwrite the background, we use the default color.
 	if maintainBackground {
 		style = style.Background(tcell.ColorDefault)
 	}
 
 	// Skip beginning and measure width.
 	var textWidth int
 	state := &stepState{
 		unisegState: -1,
 		style:       style,
 	}
 	newState := *state
 	str := text
 	for len(str) > 0 {
 		_, str, state = step(str, state, stepOptionsStyle)
 		if skipWidth > 0 {
 			skipWidth -= state.Width()
 			text = str
 			newState = *state
 			start += state.GrossLength()
 		} else {
 			textWidth += state.Width()
 		}
 	}
 	state = &newState
 
 	// Reduce all alignments to AlignLeft.
 	if align == AlignRight {
 		// Chop off characters on the left until it fits.
 		for len(text) > 0 && textWidth > maxWidth {
 			_, text, state = step(text, state, stepOptionsStyle)
 			textWidth -= state.Width()
 			start += state.GrossLength()
 		}
 		x, maxWidth = x+maxWidth-textWidth, textWidth
 	} else if align == AlignCenter {
 		// Chop off characters on the left until it fits.
 		subtracted := (textWidth - maxWidth) / 2
 		for len(text) > 0 && subtracted > 0 {
 			_, text, state = step(text, state, stepOptionsStyle)
 			subtracted -= state.Width()
 			textWidth -= state.Width()
 			start += state.GrossLength()
 		}
 		if textWidth < maxWidth {
 			x, maxWidth = x+maxWidth/2-textWidth/2, textWidth
 		}
 	}
 
 	// Draw left-aligned text.
 	end = start
 	rightBorder := x + maxWidth
 	for len(text) > 0 && x < rightBorder && x < totalWidth {
 		var c string
 		c, text, state = step(text, state, stepOptionsStyle)
 		if c == "" {
 			break // We don't care about the style at the end.
 		}
 		width := state.Width()
 
 		if width > 0 {
 			finalStyle := state.Style()
 			if maintainBackground {
 				_, backgroundColor, _ := finalStyle.Decompose()
 				if backgroundColor == tcell.ColorDefault {
 					_, _, existingStyle, _ := screen.GetContent(x, y)
 					_, background, _ := existingStyle.Decompose()
 					finalStyle = finalStyle.Background(background)
 				}
 			}
 			for offset := width - 1; offset >= 0; offset-- {
 				// To avoid undesired effects, we populate all cells.
 				runes := []rune(c)
 				if offset == 0 {
 					screen.SetContent(x+offset, y, runes[0], runes[1:], finalStyle)
 				} else {
 					screen.SetContent(x+offset, y, ' ', nil, finalStyle)
 				}
 			}
 		}
 
 		x += width
 		end += state.GrossLength()
 		printedWidth += width
 	}
 
 	return
 }
 
 // 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)
 }