widget,widget/material: add selection to the editor

- Allow dragging to be on both horizontal and vertical axes at once. - Split Editor.caret.pos into caret.start and caret.stop. caret.start is the old caret.pos, and is both the position of the caret, and also the start of selected text. caret.end is the end of the selected text. Start can be after end, e.g. after after Shift-DownArrow. - Update caret.end after a mouse drag, and various shifted keys (Shift-UpArrow, Shift-DownArrow, etc). - Change Shortcut-C to copy only the selected text, not the whole editor text. - Add Shortcut-X to copy and delete selected text, and Shortcut-A to select all text. - The various Insert/Delete/etc functions now overwrite or delete the selection, as appropriate. - Change MoveCaret to accept a distance for selection end, as well. Change SetCaret to accept a selection end offset. - Add SelectionLen to get the selection length, Selection to get selection offsets, SelectedText to get the selected text, and ClearSelection to clear the selection. - Add a rudimentary selection unit test, and extend the deleteWord unit test with some text selection cases. - Add SelectionColor to material.EditorStyle, which defaults to Theme.Palette.ContrastBg. Signed-off-by: Larry Clapp <larry@theclapp.org>
2026-07-05 01:15:35 +00:00 · 2021-01-20 20:57:49 -05:00
parent e78bd15564
commit 34273940a0
5 changed files with 735 additions and 193 deletions
@@ -29,61 +29,129 @@ type Label struct {
 // not pixels): Y = line number, X = rune column.
 type screenPos image.Point

-type lineIterator struct {
+type segmentIterator struct {
 	Lines     []text.Line
 	Clip      image.Rectangle
 	Alignment text.Alignment
 	Width     int
 	Offset    image.Point
+	startSel  screenPos
+	endSel    screenPos

+	pos    screenPos   // current position
+	line   text.Line   // current line
+	layout text.Layout // current line's Layout
+
+	// pixel positions
+	off         fixed.Point26_6
 	y, prevDesc fixed.Int26_6
 }

 const inf = 1e6

-func (l *lineIterator) Next() (text.Layout, image.Point, bool) {
-	for len(l.Lines) > 0 {
-		line := l.Lines[0]
-		l.Lines = l.Lines[1:]
-		x := align(l.Alignment, line.Width, l.Width) + fixed.I(l.Offset.X)
-		l.y += l.prevDesc + line.Ascent
-		l.prevDesc = line.Descent
-		// Align baseline and line start to the pixel grid.
-		off := fixed.Point26_6{X: fixed.I(x.Floor()), Y: fixed.I(l.y.Ceil())}
-		l.y = off.Y
-		off.Y += fixed.I(l.Offset.Y)
-		if (off.Y + line.Bounds.Min.Y).Floor() > l.Clip.Max.Y {
-			break
-		}
-		layout := line.Layout
-		if (off.Y + line.Bounds.Max.Y).Ceil() < l.Clip.Min.Y {
-			continue
-		}
-		for len(layout.Advances) > 0 {
-			_, n := utf8.DecodeRuneInString(layout.Text)
-			adv := layout.Advances[0]
-			if (off.X + adv + line.Bounds.Max.X - line.Width).Ceil() >= l.Clip.Min.X {
+func (l *segmentIterator) Next() (text.Layout, image.Point, bool, int, image.Point, bool) {
+	for l.pos.Y < len(l.Lines) {
+		if l.pos.X == 0 {
+			l.line = l.Lines[l.pos.Y]
+
+			// Calculate X & Y pixel coordinates of left edge of line. We need y
+			// for the next line, so it's in l, but we only need x here, so it's
+			// not.
+			x := align(l.Alignment, l.line.Width, l.Width) + fixed.I(l.Offset.X)
+			l.y += l.prevDesc + l.line.Ascent
+			l.prevDesc = l.line.Descent
+			// Align baseline and line start to the pixel grid.
+			l.off = fixed.Point26_6{X: fixed.I(x.Floor()), Y: fixed.I(l.y.Ceil())}
+			l.y = l.off.Y
+			l.off.Y += fixed.I(l.Offset.Y)
+			if (l.off.Y + l.line.Bounds.Min.Y).Floor() > l.Clip.Max.Y {
 				break
 			}
-			off.X += adv
-			layout.Text = layout.Text[n:]
-			layout.Advances = layout.Advances[1:]
+
+			if (l.off.Y + l.line.Bounds.Max.Y).Ceil() < l.Clip.Min.Y {
+				// This line is outside/before the clip area; go on to the next line.
+				l.pos.Y++
+				continue
+			}
+
+			// Copy the line's Layout, since we slice it up later.
+			l.layout = l.line.Layout
+
+			// Find the left edge of the text visible in the l.Clip clipping
+			// area.
+			for len(l.layout.Advances) > 0 {
+				_, n := utf8.DecodeRuneInString(l.layout.Text)
+				adv := l.layout.Advances[0]
+				if (l.off.X + adv + l.line.Bounds.Max.X - l.line.Width).Ceil() >= l.Clip.Min.X {
+					break
+				}
+				l.off.X += adv
+				l.layout.Text = l.layout.Text[n:]
+				l.layout.Advances = l.layout.Advances[1:]
+				l.pos.X++
+			}
 		}
-		endx := off.X
+
+		selected := l.inSelection()
+		endx := l.off.X
 		rune := 0
-		for n := range layout.Text {
-			if (endx + line.Bounds.Min.X).Floor() > l.Clip.Max.X {
-				layout.Advances = layout.Advances[:rune]
-				layout.Text = layout.Text[:n]
+		nextLine := true
+		retLayout := l.layout
+		for n := range l.layout.Text {
+			selChanged := selected != l.inSelection()
+			beyondClipEdge := (endx + l.line.Bounds.Min.X).Floor() > l.Clip.Max.X
+			if selChanged || beyondClipEdge {
+				retLayout.Advances = l.layout.Advances[:rune]
+				retLayout.Text = l.layout.Text[:n]
+				if selChanged {
+					// Save the rest of the line
+					l.layout.Advances = l.layout.Advances[rune:]
+					l.layout.Text = l.layout.Text[n:]
+					nextLine = false
+				}
 				break
 			}
-			endx += layout.Advances[rune]
+			endx += l.layout.Advances[rune]
 			rune++
+			l.pos.X++
 		}
-		offf := image.Point{X: off.X.Floor(), Y: off.Y.Floor()}
-		return layout, offf, true
+		offFloor := image.Point{X: l.off.X.Floor(), Y: l.off.Y.Floor()}
+
+		// Calculate the width & height if the returned text.
+		//
+		// If there's a better way to do this, I'm all ears.
+		var d fixed.Int26_6
+		for _, adv := range retLayout.Advances {
+			d += adv
+		}
+		size := image.Point{
+			X: d.Ceil(),
+			Y: (l.line.Ascent + l.line.Descent).Ceil(),
+		}
+
+		if nextLine {
+			l.pos.Y++
+			l.pos.X = 0
+		} else {
+			l.off.X = endx
+		}
+
+		return retLayout, offFloor, selected, l.prevDesc.Ceil() - size.Y, size, true
 	}
-	return text.Layout{}, image.Point{}, false
+	return text.Layout{}, image.Point{}, false, 0, image.Point{}, false
+}
+
+func (l *segmentIterator) inSelection() bool {
+	return l.startSel.LessOrEqual(l.pos) &&
+		l.pos.Less(l.endSel)
+}
+
+func (p1 screenPos) LessOrEqual(p2 screenPos) bool {
+	return p1.Y < p2.Y || (p1.Y == p2.Y && p1.X <= p2.X)
+}
+
+func (p1 screenPos) Less(p2 screenPos) bool {
+	return p1.Y < p2.Y || (p1.Y == p2.Y && p1.X < p2.X)
 }

 func (l Label) Layout(gtx layout.Context, s text.Shaper, font text.Font, size unit.Value, txt string) layout.Dimensions {
@@ -97,14 +165,14 @@ func (l Label) Layout(gtx layout.Context, s text.Shaper, font text.Font, size un
 	dims.Size = cs.Constrain(dims.Size)
 	cl := textPadding(lines)
 	cl.Max = cl.Max.Add(dims.Size)
-	it := lineIterator{
+	it := segmentIterator{
 		Lines:     lines,
 		Clip:      cl,
 		Alignment: l.Alignment,
 		Width:     dims.Size.X,
 	}
 	for {
-		l, off, ok := it.Next()
+		l, off, _, _, _, ok := it.Next()
 		if !ok {
 			break
 		}