improve text input handlingHEADmain

1 files changed, 237 insertions, 23 deletions

diff --git a/go/ui/textInput.go b/go/ui/textInput.go
index 3a7939c8..60f749f3 100644
--- a/go/ui/textInput.go
+++ b/go/ui/textInput.go
@@ -1,67 +1,281 @@
 package ui
 
 import (
+	"image"
+	"math"
+	"strings"
+	"unicode/utf8"
+
 	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/exp/textinput"
 	"github.com/hajimehoshi/ebiten/v2/inpututil"
+	"github.com/hajimehoshi/ebiten/v2/text/v2"
+	"github.com/hajimehoshi/ebiten/v2/vector"
 )
 
+// TextInput is a widget allowing the user to input text.
+// It is based on the ebiten examples/textinput licensed under the Apache License, Version 2.0
 type TextInput struct {
 	TextBox
-	input   string
-	label   string
-	focused bool
+	label     string
+	multiline bool
+	field     textinput.Field
 }
 
-func (ti *TextInput) InitTextInput(x, y int, width, height int, label string) {
+func (ti *TextInput) InitTextInput(x, y int, width, height int, label string, multiline bool) {
 	ti.TextBox = *(NewFixedTextBox(x, y, width, height, "").Centering(true))
-	ti.input = ""
 	ti.label = label
+	ti.multiline = multiline
 
 	ti.renderImpl = func() *ebiten.Image {
-		if ti.input == "" {
+		if ti.field.Text() == "" {
 			ti.text = ti.label
 		} else {
-			ti.text = ti.input
+			ti.text = ti.field.TextForRendering()
+		}
+
+		img := ti.render()
+
+		// Draw focus hint
+		if ti.field.IsFocused() {
+			vector.StrokeRect(img, float32(0), float32(0), float32(ti.Width), float32(ti.Height), 1, FocusHintColor, false)
 		}
 
-		return ti.render()
+		// Draw the cursor
+		selectionStart, _ := ti.field.Selection()
+		if ti.field.IsFocused() && selectionStart >= 0 {
+			_cx, _cy := ti.cursorPos()
+			cx, cy := float64(_cx), float64(_cy)
+
+			w, h := text.Measure(ti.text, ti.font, ti.font.Size*ti.lineSpacing)
+			if ti.center {
+				cx += (float64(ti.Width) - w) / 2
+			} else {
+				cx += float64(ti.XMargin)
+			}
+			cy += (float64(ti.Height) - h) / 2
+
+			fMetrics := ti.font.Metrics()
+			ch := fMetrics.HLineGap + fMetrics.HAscent + fMetrics.HDescent
+			vector.StrokeLine(img, float32(cx), float32(cy), float32(cx), float32(cy+ch), 1, ti.fg, false)
+		}
+
+		return img
 	}
 }
 
-func NewTextInput(x, y int, width, height int, label string) *TextInput {
+func NewTextInput(x, y int, width, height int, label string, multiline bool) *TextInput {
 	w := &TextInput{}
-	w.InitTextInput(x, y, width, height, label)
+	w.InitTextInput(x, y, width, height, label, multiline)
 	return w
 }
 
-func (ti *TextInput) SetInput(input string) {
-	ti.input = input
-	ti.ForceRedraw()
+func (t *TextInput) SetSelectionStartByCursorPosition(x, y int) bool {
+	idx, ok := t.textIndexByCursorPosition(x, y)
+	if !ok {
+		return false
+	}
+	t.field.SetSelection(idx, idx)
+	return true
 }
 
-func (ti *TextInput) AddInput(input []rune) {
-	ti.SetInput(ti.input + string(input))
+func (t *TextInput) textIndexByCursorPosition(x, y int) (int, bool) {
+	if !t.Contains(x, y) {
+		return 0, false
+	}
+
+	x -= t.X
+	y -= t.Y
+	px, py := t.XMargin, t.YMargin
+	x -= px
+	y -= py
+	if x < 0 {
+		x = 0
+	}
+	if y < 0 {
+		y = 0
+	}
+
+	fMetrics := t.font.Metrics()
+	lineSpacingInPixels := int(fMetrics.HLineGap + fMetrics.HAscent + fMetrics.HDescent)
+	var nlCount int
+	var lineStart int
+	var prevAdvance float64
+	txt := t.field.Text()
+	for i, r := range txt {
+		var x0, x1 int
+		currentAdvance := text.Advance(txt[lineStart:i], t.font)
+		if lineStart < i {
+			x0 = int((prevAdvance + currentAdvance) / 2)
+		}
+		if r == '\n' {
+			x1 = int(math.MaxInt32)
+		} else if i < len(txt) {
+			nextI := i + 1
+			for !utf8.ValidString(txt[i:nextI]) {
+				nextI++
+			}
+			nextAdvance := text.Advance(txt[lineStart:nextI], t.font)
+			x1 = int((currentAdvance + nextAdvance) / 2)
+		} else {
+			x1 = int(currentAdvance)
+		}
+		if x0 <= x && x < x1 && nlCount*lineSpacingInPixels <= y && y < (nlCount+1)*lineSpacingInPixels {
+			return i, true
+		}
+		prevAdvance = currentAdvance
+
+		if r == '\n' {
+			nlCount++
+			lineStart = i + 1
+			prevAdvance = 0
+		}
+	}
+
+	return len(txt), true
 }
 
-func (ti *TextInput) HandleKey() {
-	if inpututil.IsKeyJustPressed(ebiten.KeyBackspace) {
-		if len(ti.input) > 0 {
-			ti.input = ti.input[:len(ti.input)-1]
-			ti.ForceRedraw()
+func (t *TextInput) cursorPos() (int, int) {
+	var nlCount int
+	lastNLPos := -1
+	txt := t.field.TextForRendering()
+	selectionStart, _ := t.field.Selection()
+	if s, _, ok := t.field.CompositionSelection(); ok {
+		selectionStart += s
+	}
+	txt = txt[:selectionStart]
+	for i, r := range txt {
+		if r == '\n' {
+			nlCount++
+			lastNLPos = i
 		}
 	}
+
+	txt = txt[lastNLPos+1:]
+	x := int(text.Advance(txt, t.font))
+	fMetrics := t.font.Metrics()
+	y := nlCount * int((fMetrics.HLineGap+fMetrics.HAscent+fMetrics.HDescent)*t.lineSpacing)
+	return x, y
+}
+
+// SetTextAndSelection sets the text and selection of the underlying TextInput field and redraws the widget.
+func (t *TextInput) SetTextAndSelection(text string, selectionStartInBytes, selectionEndInBytes int) {
+	t.field.SetTextAndSelection(text, selectionStartInBytes, selectionEndInBytes)
+	t.ForceRedraw()
+}
+
+// SetInput replaces the text and sets the selection to the end.
+func (t *TextInput) SetInput(input string) {
+	t.SetTextAndSelection(input, len(input), len(input))
+}
+
+// AddInput adds input at the current selection and move the the selection.
+func (t *TextInput) AddInput(input []rune) {
+	text := t.field.Text()
+	selStart, selEnd := t.field.Selection()
+	text = text[:selStart] + string(input) + text[selEnd:]
+	t.SetTextAndSelection(text, selStart+len(input), selEnd+len(input))
 }
 
 func (ti *TextInput) Text() string {
-	return ti.input
+	return ti.field.Text()
 }
 
 // return the text or use label as fallback
 func (ti *TextInput) TextOrLabel() string {
-	if ti.input != "" {
-		return ti.input
+	if input := ti.field.Text(); input != "" {
+		return input
 	}
 	return ti.label
 }
 
 func (*TextInput) IsFocusable() bool { return true }
+
+func (ti *TextInput) Focus(focus bool) {
+	if focus {
+		ti.field.Focus()
+	} else {
+		ti.field.Blur()
+	}
+	ti.ForceRedraw()
+}
+
+func (*TextInput) IsUpdatable() bool { return true }
+func (t *TextInput) Update() error {
+	if !t.field.IsFocused() {
+		return nil
+	}
+
+	x, y := t.X, t.Y
+	cx, cy := t.cursorPos()
+	px, py := t.XMargin, t.YMargin
+	x0 := x + cx + px
+	x1 := x0 + 1
+	y0 := y + cy + py
+	fMetrics := t.font.Metrics()
+	y1 := y0 + int(fMetrics.HLineGap+fMetrics.HAscent+fMetrics.HDescent)
+	handled, err := t.field.HandleInputWithBounds(image.Rect(x0, y0, x1, y1))
+	if err != nil {
+		return err
+	}
+	if handled {
+		t.ForceRedraw()
+		return nil
+	}
+
+	switch {
+	case inpututil.IsKeyJustPressed(ebiten.KeyEnter):
+		if t.multiline {
+			text := t.field.Text()
+			selectionStart, selectionEnd := t.field.Selection()
+			text = text[:selectionStart] + "\n" + text[selectionEnd:]
+			selectionStart += len("\n")
+			selectionEnd = selectionStart
+			t.SetTextAndSelection(text, selectionStart, selectionEnd)
+		}
+	case inpututil.IsKeyJustPressed(ebiten.KeyBackspace):
+		text := t.field.Text()
+		selectionStart, selectionEnd := t.field.Selection()
+		if selectionStart != selectionEnd {
+			text = text[:selectionStart] + text[selectionEnd:]
+		} else if selectionStart > 0 {
+			// TODO: Remove a grapheme instead of a code point.
+			_, l := utf8.DecodeLastRuneInString(text[:selectionStart])
+			text = text[:selectionStart-l] + text[selectionEnd:]
+			selectionStart -= l
+		}
+		selectionEnd = selectionStart
+		t.SetTextAndSelection(text, selectionStart, selectionEnd)
+	case inpututil.IsKeyJustPressed(ebiten.KeyLeft):
+		text := t.field.Text()
+		selectionStart, _ := t.field.Selection()
+		if selectionStart > 0 {
+			// TODO: Remove a grapheme instead of a code point.
+			_, l := utf8.DecodeLastRuneInString(text[:selectionStart])
+			selectionStart -= l
+		}
+		t.SetTextAndSelection(text, selectionStart, selectionStart)
+	case inpututil.IsKeyJustPressed(ebiten.KeyRight):
+		text := t.field.Text()
+		_, selectionEnd := t.field.Selection()
+		if selectionEnd < len(text) {
+			// TODO: Remove a grapheme instead of a code point.
+			_, l := utf8.DecodeRuneInString(text[selectionEnd:])
+			selectionEnd += l
+		}
+		t.SetTextAndSelection(text, selectionEnd, selectionEnd)
+	}
+
+	if !t.multiline {
+		orig := t.field.Text()
+		new := strings.ReplaceAll(orig, "\n", "")
+		if new != orig {
+			selectionStart, selectionEnd := t.field.Selection()
+			selectionStart -= strings.Count(orig[:selectionStart], "\n")
+			selectionEnd -= strings.Count(orig[:selectionEnd], "\n")
+			t.field.SetSelection(selectionStart, selectionEnd)
+		}
+	}
+
+	return nil
+}