Add (buggy) history support to TextInput

internal/history/history.go

@@ -0,0 +1,77 @@
+package history
+
+import "time"
+
+// History stores a stack of items, always keeping the bottom-most one. It must
+// be created using the NewHistory constructor, otherwise it will be invalid.
+type History[T any] struct {
+	max      int
+	stack    []T
+	topIndex int
+	topTime  time.Time
+}
+
+// NewHistory creates a new History. The initial item will be on the bottom, and
+// it will remain there until the History overflows and chooses the item after
+// it to be the initial item.
+func NewHistory[T any] (initial T, max int) *History[T] {
+	return &History[T] {
+		max:   max,
+		stack: []T { initial },
+	}
+}
+
+// Top returns the most recent item.
+func (this *History[T]) Top () T {
+	return this.stack[this.topIndex]
+}
+
+// Swap replaces the most recent item with another.
+func (this *History[T]) Swap (item T) {
+	this.topTime = time.Now()
+	this.stack[this.topIndex] = item
+}
+
+// Push pushes a new item onto the stack.
+func (this *History[T]) Push (item T) {
+	this.topTime = time.Now()
+	this.topIndex ++
+	this.stack = append(this.stack[:this.topIndex], item)
+}
+
+// PushWeak replaces the most recent item if it was added recently (sooner than
+// specified by minAge), and will otherwise push the item normally. If the
+// history was popped or cleared beforehand, the item will always be pushed
+// normally. This is intended to be used for things such as keystrokes.
+func (this *History[T]) PushWeak (item T, minAge time.Duration) {
+	if time.Since(this.topTime) > minAge {
+		this.Push(item)
+	} else {
+		this.Swap(item)
+	}
+}
+
+// Redo undoes an Undo operation and returns the resulting top of the stack.
+func (this *History[T]) Redo () T {
+	if this.topIndex < len(this.stack) - 1 {
+		this.topIndex ++
+	}
+	return this.Top()
+}
+
+// Undo removes the most recent item and returns what was under it. If there is
+// only one item (the initial item), it will kept and returned.
+func (this *History[T]) Undo () T {
+	this.topTime = time.Time { }
+	if this.topIndex > 0 {
+		this.topIndex --
+	}
+	return this.Top()
+}
+
+// Clear removes all items except for the initial one.
+func (this *History[T]) Clear () {
+	this.topTime = time.Time { }
+	this.stack = this.stack[:1]
+	this.topIndex = 0
+}

textinput.go

@@ -1,18 +1,28 @@
 package objects
 
+import "time"
 import "image"
 import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/tomo/text"
 import "git.tebibyte.media/tomo/tomo/input"
 import "git.tebibyte.media/tomo/tomo/event"
+import "git.tebibyte.media/tomo/objects/internal/history"
 
+const textInputHistoryMaximum = 64
+const textInputHistoryMaxAge  = time.Second / 4
 var _ tomo.ContentObject = new(TextInput)
 
+type textHistoryItem struct {
+	text string
+	dot  text.Dot
+}
+
 // TextInput is a single-line editable text box.
 type TextInput struct {
 	box       tomo.TextBox
 	text      []rune
 	multiline bool
+	history   *history.History[textHistoryItem]
 	on struct {
 		valueChange event.FuncBroadcaster
 		confirm     event.FuncBroadcaster
@@ -22,7 +32,11 @@ type TextInput struct {
 func newTextInput (text string, multiline bool) *TextInput {
 	textInput := &TextInput {
 		box:       tomo.NewTextBox(),
+		text:      []rune(text),
 		multiline: multiline,
+		history:   history.NewHistory[textHistoryItem] (
+			textHistoryItem { text: text },
+			textInputHistoryMaximum),
 	}
 	textInput.box.SetRole(tomo.R("objects", "TextInput"))
 	textInput.box.SetTag("multiline", multiline)
@@ -34,7 +48,7 @@ func newTextInput (text string, multiline bool) *TextInput {
 		textInput.box.SetAttr(tomo.AOverflow(true, false))
 		textInput.box.SetAttr(tomo.AAlign(tomo.AlignStart, tomo.AlignMiddle))
 	}
-	textInput.SetValue(text)
+	textInput.box.SetText(text)
 	textInput.box.SetFocusable(true)
 	textInput.box.SetSelectable(true)
 	textInput.box.OnKeyDown(textInput.handleKeyDown)
@@ -109,6 +123,7 @@ func (this *TextInput) OnContentBoundsChange (callback func ()) event.Cookie {
 func (this *TextInput) SetValue (text string) {
 	this.text = []rune(text)
 	this.box.SetText(text)
+	this.logLargeAction()
 }
 
 // Value returns the text content of the input.
@@ -128,15 +143,53 @@ func (this *TextInput) OnValueChange (callback func ()) event.Cookie {
 	return this.on.valueChange.Connect(callback)
 }
 
+// Undo undoes the last action.
+func (this *TextInput) Undo () {
+	this.recoverHistoryItem(this.history.Undo())
+}
+
+// Redo redoes the last previously undone action.
+func (this *TextInput) Redo () {
+	this.recoverHistoryItem(this.history.Redo())
+}
+
 // Type types a character at the current dot position.
 func (this *TextInput) Type (char rune) {
 	dot := this.Dot()
 	this.text, dot = text.Type(this.text, dot, rune(char))
 	this.Select(dot)
 	this.box.SetText(string(this.text))
+	this.logKeystroke()
 }
 
-// TODO: add up/down controls if this is a multiline input
+func (this *TextInput) logKeystroke () {
+	if this.Dot().Empty() {
+		this.history.PushWeak (
+			this.currentHistoryState(),
+			textInputHistoryMaxAge)
+	} else {
+		this.logLargeAction()
+	}
+}
+
+func (this *TextInput) logLargeAction () {
+	this.history.Push(this.currentHistoryState())
+}
+
+func (this *TextInput) currentHistoryState () textHistoryItem {
+	return textHistoryItem {
+		text: string(this.text),
+		dot:  this.Dot(),
+	}
+}
+
+func (this *TextInput) recoverHistoryItem (item textHistoryItem) {
+	this.box.SetText(item.text)
+	this.text = []rune(item.text)
+	this.box.Select(item.dot)
+}
+
+// TODO: add things like alt+up/down to move lines
 
 func (this *TextInput) handleKeyDown (key input.Key, numpad bool) bool {
 	dot        := this.Dot()
@@ -149,6 +202,7 @@ func (this *TextInput) handleKeyDown (key input.Key, numpad bool) bool {
 		if changed {
 			this.box.SetText(string(this.text))
 			this.on.valueChange.Broadcast()
+			this.logKeystroke()
 		}
 	} ()
 
@@ -161,6 +215,7 @@ func (this *TextInput) handleKeyDown (key input.Key, numpad bool) bool {
 		switch {
 		case key == '\n', key == '\t':
 			typ()
+			this.logKeystroke()
 			return true
 		}
 	}
@@ -180,6 +235,16 @@ func (this *TextInput) handleKeyDown (key input.Key, numpad bool) bool {
 	case key.Printable() && !modifiers.Control:
 		typ()
 		return true
+	case key == 'z' && modifiers.Control:
+		if modifiers.Shift {
+			this.Redo()
+		} else {
+			this.Undo()
+		}
+		return true
+	case key == 'y' && modifiers.Control:
+		this.Redo()
+		return true
 	default:
 		return false
 	}
@@ -204,6 +269,10 @@ func (this *TextInput) handleKeyUp (key input.Key, numpad bool) bool {
 		return true
 	case key.Printable() && !modifiers.Control:
 		return true
+	case key == 'z' && modifiers.Control:
+		return true
+	case key == 'y' && modifiers.Control:
+		return true
 	default:
 		return false
 	}