Added basic text entering.

doc.go

@@ -3,77 +3,77 @@ Package tview implements rich widgets for terminal based user interfaces. The
 widgets provided with this package are useful for data exploration and data
 entry.
 
-Widgets
+# Widgets
 
 The package implements the following widgets:
 
-  - TextView: A scrollable window that display multi-colored text. Text may also
-    be highlighted.
-  - Table: A scrollable display of tabular data. Table cells, rows, or columns
+  - [TextView]: A scrollable window that display multi-colored text. Text may
+    also be highlighted.
+  - [Table]: A scrollable display of tabular data. Table cells, rows, or columns
     may also be highlighted.
-  - TreeView: A scrollable display for hierarchical data. Tree nodes can be
+  - [TreeView]: A scrollable display for hierarchical data. Tree nodes can be
     highlighted, collapsed, expanded, and more.
-  - List: A navigable text list with optional keyboard shortcuts.
-  - InputField: One-line input fields to enter text.
-  - DropDown: Drop-down selection fields.
-  - Checkbox: Selectable checkbox for boolean values.
-  - Button: Buttons which get activated when the user selects them.
+  - [List]: A navigable text list with optional keyboard shortcuts.
+  - [InputField]: One-line input fields to enter text.
+  - [DropDown]: Drop-down selection fields.
+  - [Checkbox]: Selectable checkbox for boolean values.
+  - [Button]: Buttons which get activated when the user selects them.
   - Form: Forms composed of input fields, drop down selections, checkboxes, and
     buttons.
-  - Modal: A centered window with a text message and one or more buttons.
-  - Grid: A grid based layout manager.
-  - Flex: A Flexbox based layout manager.
-  - Pages: A page based layout manager.
+  - [Modal]: A centered window with a text message and one or more buttons.
+  - [Grid]: A grid based layout manager.
+  - [Flex]: A Flexbox based layout manager.
+  - [Pages]: A page based layout manager.
 
 The package also provides Application which is used to poll the event queue and
 draw widgets on screen.
 
-Hello World
+# Hello World
 
 The following is a very basic example showing a box with the title "Hello,
 world!":
 
-  package main
+	package main
 
-  import (
-  	"github.com/rivo/tview"
-  )
+	import (
+		"github.com/rivo/tview"
+	)
 
-  func main() {
-  	box := tview.NewBox().SetBorder(true).SetTitle("Hello, world!")
-  	if err := tview.NewApplication().SetRoot(box, true).Run(); err != nil {
-  		panic(err)
-  	}
-  }
+	func main() {
+		box := tview.NewBox().SetBorder(true).SetTitle("Hello, world!")
+		if err := tview.NewApplication().SetRoot(box, true).Run(); err != nil {
+			panic(err)
+		}
+	}
 
 First, we create a box primitive with a border and a title. Then we create an
 application, set the box as its root primitive, and run the event loop. The
-application exits when the application's Stop() function is called or when
-Ctrl-C is pressed.
+application exits when the application's [Application.Stop] function is called
+or when Ctrl-C is pressed.
 
 If we have a primitive which consumes key presses, we call the application's
-SetFocus() function to redirect all key presses to that primitive. Most
-primitives then offer ways to install handlers that allow you to react to any
-actions performed on them.
+[Application.SetFocus] function to redirect all key presses to that primitive.
+Most primitives then offer ways to install handlers that allow you to react to
+any actions performed on them.
 
-More Demos
+# More Demos
 
 You will find more demos in the "demos" subdirectory. It also contains a
 presentation (written using tview) which gives an overview of the different
 widgets and how they can be used.
 
-Colors
+# Colors
 
-Throughout this package, colors are specified using the tcell.Color type.
-Functions such as tcell.GetColor(), tcell.NewHexColor(), and tcell.NewRGBColor()
+Throughout this package, colors are specified using the [tcell.Color] type.
+Functions such as [tcell.GetColor], [tcell.NewHexColor], and [tcell.NewRGBColor]
 can be used to create colors from W3C color names or RGB values.
 
 Almost all strings which are displayed can contain color tags. Color tags are
 W3C color names or six hexadecimal digits following a hash tag, wrapped in
 square brackets. Examples:
 
-  This is a [red]warning[white]!
-  The sky is [#8080ff]blue[#ffffff].
+	This is a [red]warning[white]!
+	The sky is [#8080ff]blue[#ffffff].
 
 A color tag changes the color of the characters following that color tag. This
 applies to almost everything from box titles, list text, form item labels, to
@@ -84,7 +84,7 @@ Color tags may contain not just the foreground (text) color but also the
 background color and additional flags. In fact, the full definition of a color
 tag is as follows:
 
-  [<foreground>:<background>:<flags>]
+	[<foreground>:<background>:<flags>]
 
 Each of the three fields can be left blank and trailing fields can be omitted.
 (Empty square brackets "[]", however, are not considered color tags.) Colors
@@ -94,26 +94,26 @@ means "reset to default".
 You can specify the following flags (some flags may not be supported by your
 terminal):
 
-  l: blink
-  b: bold
-  i: italic
-  d: dim
-  r: reverse (switch foreground and background color)
-  u: underline
-  s: strike-through
+	l: blink
+	b: bold
+	i: italic
+	d: dim
+	r: reverse (switch foreground and background color)
+	u: underline
+	s: strike-through
 
 Examples:
 
-  [yellow]Yellow text
-  [yellow:red]Yellow text on red background
-  [:red]Red background, text color unchanged
-  [yellow::u]Yellow text underlined
-  [::bl]Bold, blinking text
-  [::-]Colors unchanged, flags reset
-  [-]Reset foreground color
-  [-:-:-]Reset everything
-  [:]No effect
-  []Not a valid color tag, will print square brackets as they are
+	[yellow]Yellow text
+	[yellow:red]Yellow text on red background
+	[:red]Red background, text color unchanged
+	[yellow::u]Yellow text underlined
+	[::bl]Bold, blinking text
+	[::-]Colors unchanged, flags reset
+	[-]Reset foreground color
+	[-:-:-]Reset everything
+	[:]No effect
+	[]Not a valid color tag, will print square brackets as they are
 
 In the rare event that you want to display a string such as "[red]" or
 "[#00ff1a]" without applying its effect, you need to put an opening square
@@ -121,26 +121,26 @@ bracket before the closing square bracket. Note that the text inside the
 brackets will be matched less strictly than region or colors tags. I.e. any
 character that may be used in color or region tags will be recognized. Examples:
 
-  [red[]      will be output as [red]
-  ["123"[]    will be output as ["123"]
-  [#6aff00[[] will be output as [#6aff00[]
-  [a#"[[[]    will be output as [a#"[[]
-  []          will be output as [] (see color tags above)
-  [[]         will be output as [[] (not an escaped tag)
+	[red[]      will be output as [red]
+	["123"[]    will be output as ["123"]
+	[#6aff00[[] will be output as [#6aff00[]
+	[a#"[[[]    will be output as [a#"[[]
+	[]          will be output as [] (see color tags above)
+	[[]         will be output as [[] (not an escaped tag)
 
 You can use the Escape() function to insert brackets automatically where needed.
 
-Styles
+# Styles
 
 When primitives are instantiated, they are initialized with colors taken from
 the global Styles variable. You may change this variable to adapt the look and
 feel of the primitives to your preferred style.
 
-Unicode Support
+# Unicode Support
 
 This package supports unicode characters including wide characters.
 
-Concurrency
+# Concurrency
 
 Many functions in this package are not thread-safe. For many applications, this
 may not be an issue: If your code makes changes in response to key events, it
@@ -148,34 +148,32 @@ will execute in the main goroutine and thus will not cause any race conditions.
 
 If you access your primitives from other goroutines, however, you will need to
 synchronize execution. The easiest way to do this is to call
-Application.QueueUpdate() or Application.QueueUpdateDraw() (see the function
+[Application.QueueUpdate] or [Application.QueueUpdateDraw] (see the function
 documentation for details):
 
-  go func() {
-    app.QueueUpdateDraw(func() {
-      table.SetCellSimple(0, 0, "Foo bar")
-    })
-  }()
+	go func() {
+	  app.QueueUpdateDraw(func() {
+	    table.SetCellSimple(0, 0, "Foo bar")
+	  })
+	}()
 
-One exception to this is the io.Writer interface implemented by TextView. You
-can safely write to a TextView from any goroutine. See the TextView
+One exception to this is the io.Writer interface implemented by [TextView]. You
+can safely write to a [TextView] from any goroutine. See the [TextView]
 documentation for details.
 
-You can also call Application.Draw() from any goroutine without having to wrap
-it in QueueUpdate(). And, as mentioned above, key event callbacks are executed
-in the main goroutine and thus should not use QueueUpdate() as that may lead to
-deadlocks.
+You can also call [Application.Draw] from any goroutine without having to wrap
+it in [Application.QueueUpdate]. And, as mentioned above, key event callbacks
+are executed in the main goroutine and thus should not use
+[Application.QueueUpdate] as that may lead to deadlocks.
 
-Type Hierarchy
+# Type Hierarchy
 
-All widgets listed above contain the Box type. All of Box's functions are
+All widgets listed above contain the [Box] type. All of [Box]'s functions are
 therefore available for all widgets, too.
 
-All widgets also implement the Primitive interface.
+All widgets also implement the [Primitive] interface.
 
 The tview package is based on https://github.com/gdamore/tcell. It uses types
 and constants from that package (e.g. colors and keyboard values).
-
-This package does not process mouse input (yet).
 */
 package tview

textarea.go

@@ -41,17 +41,16 @@ var (
 // text in the editor as part of a doubly-linked list.
 //
 // In most places where we reference a position in the text, we use a
-// two-element int array. The first element is the index of the referenced span
-// in the piece chain. The second element is the offset into the span's
+// three-element int array. The first element is the index of the referenced
+// span in the piece chain. The second element is the offset into the span's
 // referenced text (relative to the span's start), its value is always >= 0 and
-// < span.length. Sometimes, we may use a three-element int array which also
-// contains the corresponding text parser's state in the third position.
+// < span.length. The third elements is the corresponding text parser's state.
 //
 // A range of text is represented by a span range which is a starting position
 // (int array) and an ending position (int array). The starting position
 // references the first character of the range, the ending position references
 // the position after the last character of the range. The end of the text is
-// therefore always [2]int{1, 0}, position 0 of the ending sentinel.
+// therefore always [3]int{1, 0, 0}, position 0 of the ending sentinel.
 type textAreaSpan struct {
 	// Links to the previous and next textAreaSpan objects as indices into the
 	// TextArea.spans slice. The sentinel spans (index 0 and 1) have -1 as their
@@ -128,12 +127,12 @@ type textAreaSpan struct {
 // clipboard is not used. The Ctrl-Q key was chosen for the "copy" function
 // because the Ctrl-C key is the default key to stop the application. If your
 // application frees up the global Ctrl-C key and you want to bind it to the
-// "copy to clipboard" function, you may use SetInputCapture() to override the
-// Ctrl-Q key to implement copying to the clipboard.
+// "copy to clipboard" function, you may use [Box.SetInputCapture] to override
+// the Ctrl-Q key to implement copying to the clipboard.
 //
 // Similarly, if you want to implement your own clipboard (or make use of your
-// operating system's clipboard), you can also use SetInputCapture() to override
-// the key binds for copy, cut, and paste. The GetSelection(), ReplaceText(),
+// operating system's clipboard), you can also use [Box.SetInputCapture] to
+// override the key binds for copy, cut, and paste. The GetSelection(), ReplaceText(),
 // and SetSelection() provide all the functionality needed for your own
 // clipboard. TODO: This will need to be reviewed.
 //
@@ -334,12 +333,17 @@ func (t *TextArea) SetOffset(row, column int) *TextArea {
 
 // replace deletes a range of text and inserts the given text at that position.
 // If the resulting text would exceed the maximum length, the function does not
-// do anything. See textAreaSpan for information about text positions and span
-// ranges.
+// do anything. The function returns the new position of the deleted/inserted
+// range (with an undefined state).
+//
+// The function can hang if "deleteStart" is located after "deleteEnd".
 //
 // This function does not generate Undo events. Undo events are generated
-// elsewhere, when the user changes their type of edit.
-func (t *TextArea) replace(deleteStart, deleteEnd [2]int, insert string) {
+// elsewhere, when the user changes their type of edit. It also does not modify
+// [TextArea.lineStarts].
+func (t *TextArea) replace(deleteStart, deleteEnd [3]int, insert string) (end [3]int) {
+	end = deleteEnd
+
 	// Check max length.
 	if t.maxLength > 0 && t.length+len(insert) > t.maxLength {
 		return
@@ -367,22 +371,24 @@ func (t *TextArea) replace(deleteStart, deleteEnd [2]int, insert string) {
 		}
 	} // At this point, deleteStart[0] == deleteEnd[0].
 	if deleteEnd[1] > deleteStart[1] {
-		if deleteStart[1] == 0 {
-			// Delete a partial span at the beginning.
-			t.length -= deleteEnd[1]
-			if t.spans[deleteEnd[0]].length < 0 {
-				// Initial text span. Has negative length.
-				t.spans[deleteEnd[0]].length += deleteEnd[1]
-			} else {
-				// Edit buffer span. Has positive length.
-				t.spans[deleteEnd[0]].length -= deleteEnd[1]
-			}
-			t.spans[deleteEnd[0]].offset += deleteEnd[1]
-		} else {
+		if deleteStart[1] != 0 {
 			// Delete in the middle by splitting the span.
+			deleteEnd[1] -= deleteStart[1]
 			deleteStart[0] = t.splitSpan(deleteStart[0], deleteStart[1])
 			deleteStart[1] = 0
 		}
+		// Delete a partial span at the beginning.
+		t.length -= deleteEnd[1]
+		if t.spans[deleteEnd[0]].length < 0 {
+			// Initial text span. Has negative length.
+			t.spans[deleteEnd[0]].length += deleteEnd[1]
+		} else {
+			// Edit buffer span. Has positive length.
+			t.spans[deleteEnd[0]].length -= deleteEnd[1]
+		}
+		t.spans[deleteEnd[0]].offset += deleteEnd[1]
+		deleteEnd[1] = 0
+		end[1] = 0
 	}
 
 	// Insert.
@@ -395,7 +401,7 @@ func (t *TextArea) replace(deleteStart, deleteEnd [2]int, insert string) {
 			if previousSpan.length > 0 && previousSpan.offset+previousSpan.length == t.editText.Len() {
 				// We can simply append to the edit buffer.
 				length, _ := t.editText.WriteString(insert)
-				previousSpan.length += length
+				t.spans[span.previous].length += length
 				t.length += length
 			} else {
 				// Insert a new span.
@@ -405,15 +411,18 @@ func (t *TextArea) replace(deleteStart, deleteEnd [2]int, insert string) {
 			// Split and insert.
 			spanIndex = t.splitSpan(spanIndex, offset)
 			t.insertSpan(insert, spanIndex)
+			end = [3]int{spanIndex, 0, 0}
 		}
 	}
+
+	return
 }
 
 // deleteSpan removes the span with the given index from the piece chain. It
 // returns the index of the span after the deleted span (or the provided index
 // if no span was deleted due to an invalid span index).
 //
-// This function also adjusts TextArea.length.
+// This function also adjusts [TextArea.length].
 func (t *TextArea) deleteSpan(index int) int {
 	if index < 2 || index >= len(t.spans) {
 		return index
@@ -440,7 +449,9 @@ func (t *TextArea) deleteSpan(index int) int {
 // index if no span was split due to an invalid span index or an invalid
 // offset.
 func (t *TextArea) splitSpan(index, offset int) int {
-	if index < 2 || index >= len(t.spans) || offset <= 0 || offset >= t.spans[index].length {
+	if index < 2 || index >= len(t.spans) || offset <= 0 ||
+		(t.spans[index].length < 0 && offset >= -t.spans[index].length) ||
+		(t.spans[index].length >= 0 && offset >= t.spans[index].length) {
 		return index
 	}
 
@@ -456,18 +467,18 @@ func (t *TextArea) splitSpan(index, offset int) int {
 	if span.length < 0 {
 		// Initial text span. Has negative length.
 		newSpan.length = span.length + offset
-		span.length = -offset
+		t.spans[index].length = -offset
 	} else {
 		// Edit buffer span. Has positive length.
 		newSpan.length = span.length - offset
-		span.length = offset
+		t.spans[index].length = offset
 	}
 
-	// Insert it.
+	// Insert the modified and new spans.
 	newIndex := len(t.spans)
 	t.spans = append(t.spans, newSpan)
 	t.spans[span.next].previous = newIndex
-	span.next = newIndex
+	t.spans[index].next = newIndex
 
 	return newIndex
 }
@@ -493,7 +504,7 @@ func (t *TextArea) insertSpan(text string, index int) int {
 	// Insert into piece chain.
 	newIndex := len(t.spans)
 	t.spans[nextSpan.previous].next = newIndex
-	nextSpan.previous = newIndex
+	t.spans[index].previous = newIndex
 	t.spans = append(t.spans, span)
 
 	// Adjust text area length.
@@ -1153,6 +1164,15 @@ func (t *TextArea) InputHandler() func(event *tcell.EventKey, setFocus func(p Pr
 			t.moveCursor(t.cursor.row+t.lastHeight, t.cursor.column)
 		case tcell.KeyPgUp, tcell.KeyCtrlB: // Move one page up.
 			t.moveCursor(t.cursor.row-t.lastHeight, t.cursor.column)
+		case tcell.KeyEnter: // Insert a newline.
+			t.cursor.pos = t.replace(t.cursor.pos, t.cursor.pos, NewLine)
+			row := t.cursor.row
+			t.cursor.row++
+			t.cursor.column, t.cursor.actualColumn = 0, 0
+			if row < len(t.lineStarts)-1 {
+				t.lineStarts = t.lineStarts[:row]
+			}
+			t.clampToCursor(row)
 		case tcell.KeyRune:
 			if event.Modifiers()&tcell.ModAlt > 0 {
 				// We accept some Alt- key combinations.
@@ -1164,6 +1184,13 @@ func (t *TextArea) InputHandler() func(event *tcell.EventKey, setFocus func(p Pr
 				}
 			} else {
 				// Other keys are simply accepted as regular characters.
+				t.cursor.pos = t.replace(t.cursor.pos, t.cursor.pos, string(event.Rune()))
+				row := t.cursor.row
+				t.cursor.row = -1
+				if row < len(t.lineStarts)-1 {
+					t.lineStarts = t.lineStarts[:row]
+				}
+				t.clampToCursor(row)
 			}
 		}
 	})