Added regions and highlights to TextView.

application.go

@@ -32,13 +32,16 @@ func NewApplication() *Application {
 // when Stop() was called.
 func (a *Application) Run() error {
 	var err error
+	a.Lock()
 
 	// Make a screen.
 	a.screen, err = tcell.NewScreen()
 	if err != nil {
+		a.Unlock()
 		return err
 	}
 	if err = a.screen.Init(); err != nil {
+		a.Unlock()
 		return err
 	}
 
@@ -57,6 +60,7 @@ func (a *Application) Run() error {
 		width, height := a.screen.Size()
 		a.root.SetRect(0, 0, width, height)
 	}
+	a.Unlock()
 	a.Draw()
 
 	// Start event loop.
@@ -86,8 +90,8 @@ func (a *Application) Run() error {
 			}
 		case *tcell.EventResize:
 			if a.rootAutoSize && a.root != nil {
-				width, height := a.screen.Size()
 				a.Lock()
+				width, height := a.screen.Size()
 				a.root.SetRect(0, 0, width, height)
 				a.Unlock()
 				a.Draw()
@@ -114,14 +118,12 @@ func (a *Application) Draw() *Application {
 	defer a.Unlock()
 
 	// Maybe we're not ready yet or not anymore.
-	if a.screen == nil {
+	if a.screen == nil || a.root == nil {
 		return a
 	}
 
 	// Draw all primitives.
-	if a.root != nil {
-		a.root.Draw(a.screen)
-	}
+	a.root.Draw(a.screen)
 
 	// Sync screen.
 	a.screen.Show()

box.go

@@ -67,7 +67,7 @@ func NewBox() *Box {
 	return b
 }
 
-// SetPadding sets the size of the borders around the box content.
+// SetBorderPadding sets the size of the borders around the box content.
 func (b *Box) SetBorderPadding(top, bottom, left, right int) *Box {
 	b.paddingTop, b.paddingBottom, b.paddingLeft, b.paddingRight = top, bottom, left, right
 	return b

demos/basic.go

@@ -2,8 +2,6 @@ package main
 
 import (
 	"fmt"
-	"io"
-	"net/http"
 
 	"github.com/gdamore/tcell"
 	"github.com/rivo/tview"
@@ -45,26 +43,19 @@ func main() {
 		})
 	form.SetTitle("Customer").SetBorder(true)
 
-	textView := tview.NewTextView().
-		SetWrap(false).
-		SetDynamicColors(false).
+	textView := tview.NewTextView()
+	textView.SetWrap(true).
+		SetDynamicColors(true).
+		SetScrollable(true).
+		SetRegions(true).
 		SetChangedFunc(func() { app.Draw() }).
-		SetDoneFunc(func(key tcell.Key) { app.SetFocus(list) })
+		SetDoneFunc(func(key tcell.Key) { textView.ScrollToHighlight(); app.SetFocus(list) })
 	textView.SetBorder(true).SetTitle("Text view")
 	go func() {
-		url := "https://www.rentafounder.com"
-		fmt.Fprintf(textView, "Reading from: %s\n\n", url)
-		resp, err := http.Get(url)
-		if err != nil {
-			fmt.Fprint(textView, err)
-			return
+		for i := 0; i < 200; i++ {
+			fmt.Fprintf(textView, "[\"%d\"]%d\n", i, i)
 		}
-		defer resp.Body.Close()
-		n, err := io.Copy(textView, resp.Body)
-		if err != nil {
-			fmt.Fprint(textView, err)
-		}
-		fmt.Fprintf(textView, "\n\n%d bytes read", n)
+		textView.Highlight("199")
 	}()
 
 	list = tview.NewList().

textview.go

@@ -1,6 +1,7 @@
 package tview
 
 import (
+	"bytes"
 	"math"
 	"regexp"
 	"sync"
@@ -19,33 +20,77 @@ var textColors = map[string]tcell.Color{
 	"green":  tcell.ColorGreen,
 }
 
-// A regular expression commonly used throughout the TextView class.
-var colorPattern = regexp.MustCompile(`\[(white|yellow|blue|green|red)\]`)
+// Regular expressions commonly used throughout the TextView class.
+var (
+	colorPattern  = regexp.MustCompile(`\[(white|yellow|blue|green|red)\]`)
+	regionPattern = regexp.MustCompile(`\["([a-zA-Z0-9_,;: \-\.]*)"\]`)
+)
 
 // textViewIndex contains information about each line displayed in the text
 // view.
 type textViewIndex struct {
-	Line  int         // The index into the "buffer" variable.
-	Pos   int         // The index into the "buffer" string.
-	Color tcell.Color // The starting color.
+	Line   int         // The index into the "buffer" variable.
+	Pos    int         // The index into the "buffer" string.
+	Color  tcell.Color // The starting color.
+	Region string      // The starting region ID.
 }
 
-// TextView is a box which displays text. It implements the Reader interface so
-// you can stream text to it.
+// TextView is a box which displays text. It implements the io.Writer interface
+// so you can stream text to it. This does not trigger a redraw automatically
+// but if a handler is installed via SetChangedFunc(), you can cause it to be
+// redrawn.
 //
-// If the text view is scrollable (the default), text is kept in a buffer and
-// can be navigated using the arrow keys, Ctrl-F and Ctrl-B for page jumps, "g"
-// for the beginning of the text, and "G" for the end of the text.
+// Navigation
+//
+// If the text view is scrollable (the default), text is kept in a buffer which
+// may be larger than the screen and can be navigated similarly to Vim:
+//
+//   - h, left arrow: Move left.
+//   - l, right arrow: Move right.
+//   - j, down arrow: Move down.
+//   - k, up arrow: Move up.
+//   - g, home: Move to the beginning.
+//   - G, end: Move to the end.
+//   - Ctrl-F, page down: Move down by one page.
+//   - Ctrl-B, page up: Move up by one page.
 //
 // If the text is not scrollable, any text above the top line is discarded.
 //
-// If dynamic colors are enabled, text color can be changed dynamically by
-// embedding it into square brackets. For example,
+// Navigation can be intercepted by installing a callback function via
+// SetCaptureFunc() which receives all keyboard events and decides which ones
+// to forward to the default handler.
 //
-//   "This is a [red]warning[white]!"
+// Colors
+//
+// If dynamic colors are enabled via SetDynamicColors(), text color can be
+// changed dynamically by embedding color strings in square brackets. For
+// example,
+//
+//   This is a [red]warning[white]!
 //
 // will print the word "warning" in red. The following colors are currently
 // supported: white, yellow, blue, green, red.
+//
+// Regions and Highlights
+//
+// If regions are enabled via SetRegions(), you can define text regions within
+// the text and assign region IDs to them. Text regions start with region tags.
+// Region tags are square brackets that contain a region ID in double quotes,
+// for example:
+//
+//   We define a ["rg"]region[""] here.
+//
+// A text region ends with the next region tag. Tags with no region ID ([""])
+// don't start new regions. They can therefore be used to mark the end of a
+// region. Region IDs must satisfy the following regular expression:
+//
+//   [a-zA-Z0-9_,;: \-\.]+
+//
+// Regions can be highlighted by calling the Highlight() function with one or
+// more region IDs. This can be used to display search results, for example.
+//
+// The ScrollToHighlight() function can be used to jump to the currently
+// highlighted region once when the text view is drawn the next time.
 type TextView struct {
 	sync.Mutex
 	*Box
@@ -53,16 +98,24 @@ type TextView struct {
 	// The text buffer.
 	buffer []string
 
+	// The last bytes that have been received but are not part of the buffer yet.
+	recentBytes []byte
+
 	// The processed line index. This is nil if the buffer has changed and needs
 	// to be re-indexed.
 	index []*textViewIndex
 
+	// Indices into the "index" slice which correspond to the first line of the
+	// first highlight and the last line of the last highlight. This is calculated
+	// during re-indexing. Set to -1 if there is no current highlight.
+	fromHighlight, toHighlight int
+
+	// A set of region IDs that are currently highlighted.
+	highlights map[string]struct{}
+
 	// The display width for which the index is created.
 	indexWidth int
 
-	// The last bytes that have been received but are not part of the buffer yet.
-	recentBytes []byte
-
 	// The index of the first line shown in the text view.
 	lineOffset int
 
@@ -91,6 +144,17 @@ type TextView struct {
 	// strings in square brackets to the text view.
 	dynamicColors bool
 
+	// If set to true, region tags can be used to define regions.
+	regions bool
+
+	// A temporary flag which, when true, will automatically bring the current
+	// highlight(s) into the visible screen.
+	scrollToHighlights bool
+
+	// An optional function which will receive all key events sent to this text
+	// view. Returning true also invokes the default key handling.
+	capture func(*tcell.EventKey) bool
+
 	// An optional function which is called when the content of the text view has
 	// changed.
 	changed func()
@@ -104,11 +168,12 @@ type TextView struct {
 func NewTextView() *TextView {
 	return &TextView{
 		Box:           NewBox(),
+		highlights:    make(map[string]struct{}),
 		lineOffset:    -1,
 		scrollable:    true,
 		wrap:          true,
 		textColor:     tcell.ColorWhite,
-		dynamicColors: true,
+		dynamicColors: false,
 	}
 }
 
@@ -139,7 +204,7 @@ func (t *TextView) SetTextColor(color tcell.Color) *TextView {
 }
 
 // SetDynamicColors sets the flag that allows the text color to be changed
-// dynamically. See type description for details.
+// dynamically. See class description for details.
 func (t *TextView) SetDynamicColors(dynamic bool) *TextView {
 	if t.dynamicColors != dynamic {
 		t.index = nil
@@ -148,6 +213,22 @@ func (t *TextView) SetDynamicColors(dynamic bool) *TextView {
 	return t
 }
 
+// SetRegions sets the flag that allows to define regions in the text. See class
+// description for details.
+func (t *TextView) SetRegions(regions bool) *TextView {
+	t.regions = regions
+	return t
+}
+
+// SetCaptureFunc sets a handler which is called whenever a key is pressed.
+// This allows you to override the default key handling of the text view.
+// Returning true will allow the default key handling to go forward after the
+// handler returns. Returning false will disable any default key handling.
+func (t *TextView) SetCaptureFunc(handler func(event *tcell.EventKey) bool) *TextView {
+	t.capture = handler
+	return t
+}
+
 // SetChangedFunc sets a handler function which is called when the text of the
 // text view has changed. This is typically used to cause the application to
 // redraw the screen.
@@ -172,6 +253,115 @@ func (t *TextView) Clear() *TextView {
 	return t
 }
 
+// Highlight specifies which regions should be highlighted. See class
+// description for details on regions. Empty region strings are ignored.
+//
+// Text in highlighted regions will be drawn inverted, i.e. with their
+// background and foreground colors swapped.
+//
+// Calling this function will remove any previous highlights. To remove all
+// highlights, call this function without any arguments.
+func (t *TextView) Highlight(regionIDs ...string) *TextView {
+	t.highlights = make(map[string]struct{})
+	for _, id := range regionIDs {
+		if id == "" {
+			continue
+		}
+		t.highlights[id] = struct{}{}
+	}
+	return t
+}
+
+// ScrollToHighlight will cause the visible area to be scrolled so that the
+// highlighted regions appear in the visible area of the text view. This
+// repositioning happens the next time the text view is drawn. It happens only
+// once so you will need to call this function repeatedly to always keep
+// highlighted regions in view.
+//
+// Nothing happens if there are no highlighted regions or if the text view is
+// not scrollable.
+func (t *TextView) ScrollToHighlight() *TextView {
+	if len(t.highlights) == 0 || !t.scrollable || !t.regions {
+		return t
+	}
+	t.index = nil
+	t.scrollToHighlights = true
+	t.trackEnd = false
+	return t
+}
+
+// GetRegionText returns the text of the region with the given ID. If dynamic
+// colors are enabled, color tags are stripped from the text. Newlines are
+// always returned as '\n' runes.
+//
+// If the region does not exist or if regions are turned off, an empty string
+// is returned.
+func (t *TextView) GetRegionText(regionID string) string {
+	if !t.regions || regionID == "" {
+		return ""
+	}
+
+	var (
+		buffer          bytes.Buffer
+		currentRegionID string
+	)
+
+	for _, str := range t.buffer {
+		// Find all color tags in this line.
+		var colorTagIndices [][]int
+		if t.dynamicColors {
+			colorTagIndices = colorPattern.FindAllStringIndex(str, -1)
+		}
+
+		// Find all regions in this line.
+		var (
+			regionIndices [][]int
+			regions       [][]string
+		)
+		if t.regions {
+			regionIndices = regionPattern.FindAllStringIndex(str, -1)
+			regions = regionPattern.FindAllStringSubmatch(str, -1)
+		}
+
+		// Analyze this line.
+		var currentTag, currentRegion int
+		for pos, ch := range str {
+			// Skip any color tags.
+			if currentTag < len(colorTagIndices) && pos >= colorTagIndices[currentTag][0] && pos < colorTagIndices[currentTag][1] {
+				if pos == colorTagIndices[currentTag][1]-1 {
+					currentTag++
+				}
+				continue
+			}
+
+			// Skip any regions.
+			if currentRegion < len(regionIndices) && pos >= regionIndices[currentRegion][0] && pos < regionIndices[currentRegion][1] {
+				if pos == regionIndices[currentRegion][1]-1 {
+					if currentRegionID == regionID {
+						// This is the end of the requested region. We're done.
+						return buffer.String()
+					}
+					currentRegionID = regions[currentRegion][1]
+					currentRegion++
+				}
+				continue
+			}
+
+			// Add this rune.
+			if currentRegionID == regionID {
+				buffer.WriteRune(ch)
+			}
+		}
+
+		// Add newline.
+		if currentRegionID == regionID {
+			buffer.WriteRune('\n')
+		}
+	}
+
+	return buffer.String()
+}
+
 // Write lets us implement the io.Writer interface.
 func (t *TextView) Write(p []byte) (n int, err error) {
 	// Notify at the end.
@@ -231,7 +421,12 @@ func (t *TextView) reindexBuffer(width int) {
 		return // Nothing has changed. We can still use the current index.
 	}
 	t.index = nil
+	t.fromHighlight, t.toHighlight = -1, -1
 
+	var (
+		regionID    string
+		highlighted bool
+	)
 	color := t.textColor
 	if !t.wrap {
 		width = math.MaxInt64
@@ -247,28 +442,63 @@ func (t *TextView) reindexBuffer(width int) {
 			colorTags = colorPattern.FindAllStringSubmatch(str, -1)
 		}
 
+		// Find all regions in this line.
+		var (
+			regionIndices [][]int
+			regions       [][]string
+		)
+		if t.regions {
+			regionIndices = regionPattern.FindAllStringIndex(str, -1)
+			regions = regionPattern.FindAllStringSubmatch(str, -1)
+		}
+
 		// Break down the line.
-		var currentTag, currentWidth int
+		var currentTag, currentRegion, currentWidth int
 		for pos := range str {
 			// Skip any color tags.
-			if currentTag < len(colorTags) {
-				if pos >= colorTagIndices[currentTag][0] && pos < colorTagIndices[currentTag][1] {
+			if currentTag < len(colorTags) && pos >= colorTagIndices[currentTag][0] && pos < colorTagIndices[currentTag][1] {
+				if pos == colorTagIndices[currentTag][1]-1 {
 					color = textColors[colorTags[currentTag][1]]
-					continue
-				} else if pos >= colorTagIndices[currentTag][1] {
 					currentTag++
 				}
+				continue
+			}
+
+			// Check regions.
+			if currentRegion < len(regionIndices) && pos >= regionIndices[currentRegion][0] && pos < regionIndices[currentRegion][1] {
+				if pos == regionIndices[currentRegion][1]-1 {
+					// We're done with this region.
+					regionID = regions[currentRegion][1]
+
+					// Is this region highlighted?
+					_, highlighted = t.highlights[regionID]
+
+					currentRegion++
+				}
+				continue
 			}
 
 			// Add this line.
 			if currentWidth == 0 {
 				t.index = append(t.index, &textViewIndex{
-					Line:  index,
-					Pos:   pos,
-					Color: color,
+					Line:   index,
+					Pos:    pos,
+					Color:  color,
+					Region: regionID,
 				})
 			}
 
+			// Update highlight range.
+			if highlighted {
+				line := len(t.index) - 1
+				if t.fromHighlight < 0 {
+					t.fromHighlight, t.toHighlight = line, line
+				} else if line > t.toHighlight {
+					t.toHighlight = line
+				}
+			}
+
+			// Proceed.
 			currentWidth++
 
 			// Have we crossed the width?
@@ -294,6 +524,19 @@ func (t *TextView) Draw(screen tcell.Screen) {
 	// Re-index.
 	t.reindexBuffer(width)
 
+	// Move to highlighted regions.
+	if t.regions && t.scrollToHighlights && t.fromHighlight >= 0 {
+		// Do we fit the entire height?
+		if t.toHighlight-t.fromHighlight+1 < height {
+			// Yes, let's center the highlights.
+			t.lineOffset = (t.fromHighlight + t.toHighlight - height) / 2
+		} else {
+			// No, let's move to the start of the highlights.
+			t.lineOffset = t.fromHighlight
+		}
+	}
+	t.scrollToHighlights = false
+
 	// Adjust line offset.
 	if t.lineOffset+height > len(t.index) {
 		t.trackEnd = true
@@ -306,7 +549,6 @@ func (t *TextView) Draw(screen tcell.Screen) {
 	}
 
 	// Draw the buffer.
-	style := tcell.StyleDefault.Background(t.backgroundColor)
 	for line := t.lineOffset; line < len(t.index); line++ {
 		// Are we done?
 		if line-t.lineOffset >= height {
@@ -316,7 +558,8 @@ func (t *TextView) Draw(screen tcell.Screen) {
 		// Get the text for this line.
 		index := t.index[line]
 		text := t.buffer[index.Line][index.Pos:]
-		style = style.Foreground(index.Color)
+		color := index.Color
+		regionID := index.Region
 
 		// Get color tags.
 		var (
@@ -328,16 +571,35 @@ func (t *TextView) Draw(screen tcell.Screen) {
 			colorTags = colorPattern.FindAllStringSubmatch(text, -1)
 		}
 
+		// Get regions.
+		var (
+			regionIndices [][]int
+			regions       [][]string
+		)
+		if t.regions {
+			regionIndices = regionPattern.FindAllStringIndex(text, -1)
+			regions = regionPattern.FindAllStringSubmatch(text, -1)
+		}
+
 		// Print one line.
-		var currentTag, skip, posX int
+		var currentTag, currentRegion, skip, posX int
 		for pos, ch := range text {
-			if currentTag < len(colorTags) {
-				if pos >= colorTagIndices[currentTag][0] && pos < colorTagIndices[currentTag][1] {
-					style = style.Foreground(textColors[colorTags[currentTag][1]])
-					continue
-				} else if pos >= colorTagIndices[currentTag][1] {
+			// Get the color.
+			if currentTag < len(colorTags) && pos >= colorTagIndices[currentTag][0] && pos < colorTagIndices[currentTag][1] {
+				if pos == colorTagIndices[currentTag][1]-1 {
+					color = textColors[colorTags[currentTag][1]]
 					currentTag++
 				}
+				continue
+			}
+
+			// Get the region.
+			if currentRegion < len(regionIndices) && pos >= regionIndices[currentRegion][0] && pos < regionIndices[currentRegion][1] {
+				if pos == regionIndices[currentRegion][1]-1 {
+					regionID = regions[currentRegion][1]
+					currentRegion++
+				}
+				continue
 			}
 
 			// Skip to the right.
@@ -351,17 +613,54 @@ func (t *TextView) Draw(screen tcell.Screen) {
 				break
 			}
 
+			// Do we highlight this character?
+			style := tcell.StyleDefault.Background(t.backgroundColor).Foreground(color)
+			if len(regionID) > 0 {
+				if _, ok := t.highlights[regionID]; ok {
+					style = tcell.StyleDefault.Background(color).Foreground(t.backgroundColor)
+				}
+			}
+
+			// Draw the character.
 			screen.SetContent(x+posX, y+line-t.lineOffset, ch, nil, style)
 
+			// Advance.
 			posX++
 		}
 	}
+
+	// If this view is not scrollable, we'll purge the buffer of lines that have
+	// scrolled out of view.
+	if !t.scrollable && t.lineOffset > 0 {
+		t.buffer = t.buffer[t.index[t.lineOffset].Line:]
+		t.index = nil
+	}
 }
 
 // InputHandler returns the handler for this primitive.
 func (t *TextView) InputHandler() func(event *tcell.EventKey, setFocus func(p Primitive)) {
 	return func(event *tcell.EventKey, setFocus func(p Primitive)) {
-		switch key := event.Key(); key {
+		// Do we pass this event on?
+		if t.capture != nil {
+			if !t.capture(event) {
+				return
+			}
+		}
+
+		key := event.Key()
+
+		if key == tcell.KeyEscape || key == tcell.KeyEnter || key == tcell.KeyTab || key == tcell.KeyBacktab {
+			if t.done != nil {
+				t.done(key)
+			}
+			return
+		}
+
+		if !t.scrollable {
+			return
+		}
+
+		switch key {
 		case tcell.KeyRune:
 			switch event.Rune() {
 			case 'g': // Home.
@@ -408,10 +707,6 @@ func (t *TextView) InputHandler() func(event *tcell.EventKey, setFocus func(p Pr
 		case tcell.KeyPgUp, tcell.KeyCtrlB:
 			t.trackEnd = false
 			t.lineOffset -= t.pageSize
-		case tcell.KeyEscape, tcell.KeyEnter, tcell.KeyTab, tcell.KeyBacktab:
-			if t.done != nil {
-				t.done(key)
-			}
 		}
 	}
 }