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widget: maintain Editor caret position
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Only call layoutCaret when the text layout changes, adjust position
for caret movement.

Signed-off-by: Elias Naur <mail@eliasnaur.com>
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@eliasnaur
eliasnaur committed Jun 20, 2020
1 parent 8f31f8d commit ef21a7a
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Showing 2 changed files with 123 additions and 78 deletions.
12 changes: 0 additions & 12 deletions widget/buffer.go
View file
Expand Up @@ -152,18 +152,6 @@ func (e *editBuffer) dump() {
}
}

func (e *editBuffer) move(runes int) {
for ; runes < 0 && e.caret > 0; runes++ {
_, s := e.runeBefore(e.caret)
e.caret -= s
}
for ; runes > 0 && e.caret < e.len(); runes-- {
_, s := e.runeAt(e.caret)
e.caret += s
}
e.dump()
}

func (e *editBuffer) runeBefore(idx int) (rune, int) {
if idx > e.gapstart {
idx += e.gapLen()
Expand Down
189 changes: 123 additions & 66 deletions widget/editor.go
View file
Expand Up @@ -55,6 +55,14 @@ type Editor struct {
// xoff is the offset to the current caret
// position when moving between lines.
xoff fixed.Int26_6

// line is the caret line position as an index into lines.
line int
// col is the caret column measured in runes.
col int
// (x, y) are the caret coordinates.
x fixed.Int26_6
y int
}

scroller gesture.Scroll
Expand Down Expand Up @@ -109,14 +117,18 @@ func (e *Editor) processEvents(gtx layout.Context) {
// Can't process events without a shaper.
return
}
e.makeValid()
e.processPointer(gtx)
e.processKey(gtx)
}

func (e *Editor) makeValid() {
if !e.valid {
e.lines, e.dims = e.layoutText(e.shaper)
line, col, x, y := e.layoutCaret()
e.caret.line = line
e.caret.col = col
e.caret.x = x
e.caret.y = y
e.valid = true
}
}
Expand Down Expand Up @@ -206,11 +218,9 @@ func (e *Editor) command(k key.Event) bool {
case key.NameDeleteForward:
e.Delete(1)
case key.NameUpArrow:
line, _, carX, _ := e.layoutCaret()
e.caret.xoff = e.moveToLine(carX+e.caret.xoff, line-1)
e.caret.xoff = e.moveToLine(e.caret.x+e.caret.xoff, e.caret.line-1)
case key.NameDownArrow:
line, _, carX, _ := e.layoutCaret()
e.caret.xoff = e.moveToLine(carX+e.caret.xoff, line+1)
e.caret.xoff = e.moveToLine(e.caret.x+e.caret.xoff, e.caret.line+1)
case key.NameLeftArrow:
e.Move(-1)
case key.NameRightArrow:
Expand Down Expand Up @@ -260,14 +270,19 @@ func (e *Editor) Layout(gtx layout.Context, sh text.Shaper, font text.Font, size
e.invalidate()
}

e.makeValid()
e.processEvents(gtx)

if viewSize := gtx.Constraints.Constrain(e.dims.Size); viewSize != e.viewSize {
e.viewSize = viewSize
e.invalidate()
}
e.makeValid()

return e.layout(gtx)
}

func (e *Editor) layout(gtx layout.Context) layout.Dimensions {
e.makeValid()

e.viewSize = gtx.Constraints.Constrain(e.dims.Size)
// Adjust scrolling for new viewport and layout.
e.scrollRel(0, 0)

Expand Down Expand Up @@ -343,12 +358,14 @@ func (e *Editor) PaintCaret(gtx layout.Context) {
if !e.caret.on {
return
}
e.makeValid()
carWidth := fixed.I(gtx.Px(unit.Dp(1)))
carLine, _, carX, carY := e.layoutCaret()
carX := e.caret.x
carY := e.caret.y

stack := op.Push(gtx.Ops)
carX -= carWidth / 2
carAsc, carDesc := -e.lines[carLine].Bounds.Min.Y, e.lines[carLine].Bounds.Max.Y
carAsc, carDesc := -e.lines[e.caret.line].Bounds.Min.Y, e.lines[e.caret.line].Bounds.Max.Y
carRect := image.Rectangle{
Min: image.Point{X: carX.Ceil(), Y: carY - carAsc.Ceil()},
Max: image.Point{X: carX.Ceil() + carWidth.Ceil(), Y: carY + carDesc.Ceil()},
Expand Down Expand Up @@ -444,7 +461,7 @@ func (e *Editor) moveCoord(pos image.Point) {
carLine++
}
x := fixed.I(pos.X + e.scrollOff.X)
e.carXOff = 0
e.caret.xoff = 0
e.moveToLine(x, carLine)
}

Expand All @@ -468,39 +485,39 @@ func (e *Editor) layoutText(s text.Shaper) ([]text.Line, layout.Dimensions) {

// CaretPos returns the line & column numbers of the caret.
func (e *Editor) CaretPos() (line, col int) {
line, col, _, _ = e.layoutCaret()
return
e.makeValid()
return e.caret.line, e.caret.col
}

// CaretCoords returns the coordinates of the caret, relative to the
// editor itself.
func (e *Editor) CaretCoords() f32.Point {
_, _, x, y := e.layoutCaret()
return f32.Pt(float32(x)/64, float32(y))
e.makeValid()
return f32.Pt(float32(e.caret.x)/64, float32(e.caret.y))
}

func (e *Editor) layoutCaret() (carLine, carCol int, x fixed.Int26_6, y int) {
func (e *Editor) layoutCaret() (line, col int, x fixed.Int26_6, y int) {
var idx int
var prevDesc fixed.Int26_6
loop:
for carLine = 0; carLine < len(e.lines); carLine++ {
l := e.lines[carLine]
for line = 0; line < len(e.lines); line++ {
l := e.lines[line]
y += (prevDesc + l.Ascent).Ceil()
prevDesc = l.Descent
if carLine == len(e.lines)-1 || idx+l.Len > e.rr.caret {
if line == len(e.lines)-1 || idx+l.Len > e.rr.caret {
for _, g := range l.Layout {
if idx == e.rr.caret {
break loop
}
x += g.Advance
idx += utf8.RuneLen(g.Rune)
carCol++
col++
}
break
}
idx += l.Len
}
x += align(e.Alignment, e.lines[carLine].Width, e.viewSize.X)
x += align(e.Alignment, e.lines[line].Width, e.viewSize.X)
return
}

Expand Down Expand Up @@ -538,8 +555,8 @@ func (e *Editor) prepend(s string) {
}

func (e *Editor) movePages(pages int) {
_, _, carX, carY := e.layoutCaret()
y := carY + pages*e.viewSize.Y
e.makeValid()
y := e.caret.y + pages*e.viewSize.Y
var (
prevDesc fixed.Int26_6
carLine2 int
Expand All @@ -558,108 +575,148 @@ func (e *Editor) movePages(pages int) {
y2 += h
carLine2++
}
e.caret.xoff = e.moveToLine(carX+e.caret.xoff, carLine2)
e.caret.xoff = e.moveToLine(e.caret.x+e.caret.xoff, carLine2)
}

func (e *Editor) moveToLine(carX fixed.Int26_6, carLine2 int) fixed.Int26_6 {
carLine, carCol, _, _ := e.layoutCaret()
if carLine2 < 0 {
carLine2 = 0
func (e *Editor) moveToLine(x fixed.Int26_6, line int) fixed.Int26_6 {
e.makeValid()
if line < 0 {
line = 0
}
if carLine2 >= len(e.lines) {
carLine2 = len(e.lines) - 1
if line >= len(e.lines) {
line = len(e.lines) - 1
}
// Move to start of line.
for i := carCol - 1; i >= 0; i-- {
for i := e.caret.col - 1; i >= 0; i-- {
_, s := e.rr.runeBefore(e.rr.caret)
e.rr.caret -= s
}
if carLine2 != carLine {
// Move to start of line2.
if carLine2 > carLine {
for i := carLine; i < carLine2; i++ {
e.rr.caret += e.lines[i].Len
e.caret.col = 0
if line != e.caret.line {
prevDesc := e.lines[line].Descent
if line > e.caret.line {
for i := e.caret.line; i < line; i++ {
l := e.lines[i]
e.rr.caret += l.Len
e.caret.y += (prevDesc + l.Ascent).Ceil()
prevDesc = l.Descent
}
} else {
for i := carLine - 1; i >= carLine2; i-- {
e.rr.caret -= e.lines[i].Len
for i := e.caret.line - 1; i >= line; i-- {
l := e.lines[i]
e.rr.caret -= l.Len
e.caret.y -= (prevDesc + l.Ascent).Ceil()
prevDesc = l.Descent
}
}
e.caret.line = line
}
l2 := e.lines[carLine2]
carX2 := align(e.Alignment, l2.Width, e.viewSize.X)
l := e.lines[line]
e.caret.x = align(e.Alignment, l.Width, e.viewSize.X)
// Only move past the end of the last line
end := 0
if carLine2 < len(e.lines)-1 {
if line < len(e.lines)-1 {
end = 1
}
// Move to rune closest to previous horizontal position.
for i := 0; i < len(l2.Layout)-end; i++ {
g := l2.Layout[i]
if carX2 >= carX {
// Move to rune closest to x.
for i := 0; i < len(l.Layout)-end; i++ {
g := l.Layout[i]
if e.caret.x >= x {
break
}
if carX2+g.Advance-carX >= carX-carX2 {
if e.caret.x+g.Advance-x >= x-e.caret.x {
break
}
carX2 += g.Advance
e.caret.x += g.Advance
_, s := e.rr.runeAt(e.rr.caret)
e.rr.caret += s
e.caret.col++
}
return carX - carX2
return x - e.caret.x
}

// Move the caret: positive distance moves forward, negative distance moves
// backward.
func (e *Editor) Move(distance int) {
e.rr.move(distance)
e.makeValid()
for ; distance < 0 && e.rr.caret > 0; distance++ {
if e.caret.col == 0 {
// Move to end of previous line.
e.moveToLine(fixed.I(e.maxWidth), e.caret.line-1)
continue
}
l := e.lines[e.caret.line].Layout
_, s := e.rr.runeBefore(e.rr.caret)
e.rr.caret -= s
e.caret.col--
e.caret.x -= l[e.caret.col].Advance
}
for ; distance > 0 && e.rr.caret < e.rr.len(); distance-- {
l := e.lines[e.caret.line].Layout
// Only move past the end of the last line
end := 0
if e.caret.line < len(e.lines)-1 {
end = 1
}
if e.caret.col >= len(l)-end {
// Move to start of next line.
e.moveToLine(0, e.caret.line+1)
continue
}
e.caret.x += l[e.caret.col].Advance
_, s := e.rr.runeAt(e.rr.caret)
e.rr.caret += s
e.caret.col++
}
e.caret.xoff = 0
}

func (e *Editor) moveStart() {
carLine, carCol, x, _ := e.layoutCaret()
layout := e.lines[carLine].Layout
for i := carCol - 1; i >= 0; i-- {
e.makeValid()
layout := e.lines[e.caret.line].Layout
for i := e.caret.col - 1; i >= 0; i-- {
_, s := e.rr.runeBefore(e.rr.caret)
e.rr.caret -= s
x -= layout[i].Advance
e.caret.x -= layout[i].Advance
}
e.caret.xoff = -x
e.caret.col = 0
e.caret.xoff = -e.caret.x
}

func (e *Editor) moveEnd() {
carLine, carCol, x, _ := e.layoutCaret()
l := e.lines[carLine]
e.makeValid()
l := e.lines[e.caret.line]
// Only move past the end of the last line
end := 0
if carLine < len(e.lines)-1 {
if e.caret.line < len(e.lines)-1 {
end = 1
}
layout := l.Layout
for i := carCol; i < len(layout)-end; i++ {
for i := e.caret.col; i < len(layout)-end; i++ {
adv := layout[i].Advance
_, s := e.rr.runeAt(e.rr.caret)
e.rr.caret += s
x += adv
e.caret.x += adv
e.caret.col++
}
a := align(e.Alignment, l.Width, e.viewSize.X)
e.caret.xoff = l.Width + a - x
e.caret.xoff = l.Width + a - e.caret.x
}

func (e *Editor) scrollToCaret() {
carLine, _, x, y := e.layoutCaret()
l := e.lines[carLine]
e.makeValid()
l := e.lines[e.caret.line]
if e.SingleLine {
var dist int
if d := x.Floor() - e.scrollOff.X; d < 0 {
if d := e.caret.x.Floor() - e.scrollOff.X; d < 0 {
dist = d
} else if d := x.Ceil() - (e.scrollOff.X + e.viewSize.X); d > 0 {
} else if d := e.caret.x.Ceil() - (e.scrollOff.X + e.viewSize.X); d > 0 {
dist = d
}
e.scrollRel(dist, 0)
} else {
miny := y - l.Ascent.Ceil()
maxy := y + l.Descent.Ceil()
miny := e.caret.y - l.Ascent.Ceil()
maxy := e.caret.y + l.Descent.Ceil()
var dist int
if d := miny - e.scrollOff.Y; d < 0 {
dist = d
Expand Down

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