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widget: simplify and improve cursor position generation

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This commit updates the strategy of our cursor positioning index to eliminate
cursor positions *after* trailing whitespace characters on a line. Eliminating
such cursor positions enables us to collapse trailing whitespace visually without
impacting the editability of text (this will be done in a future commit).

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>
This commit is contained in:
Chris Waldon
2023-07-24 16:25:46 -04:00
committed by Elias Naur
parent 8dc03ed655
commit fdd102aaf9
3 changed files with 131 additions and 74 deletions
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widget/editor_test.go
+5 -4
View File
@@ -508,13 +508,14 @@ func TestEditorLigature(t *testing.T) {
// Ensure that all runes in the final cluster of a line are properly
// decoded when moving to the end of the line. This is a regression test.
e.text.MoveEnd(selectionClear)
// The first line was broken by line wrapping, not a newline character. As such,
// the cursor can reach the position after the final glyph (a space).
assertCaret(t, e, 0, 14, len("fflffl fflffl "))
// The first line was broken by line wrapping, not a newline character, and has a trailing
// whitespace. However, we should never be able to reach the "other side" of such a trailing
// whitespace glyph.
assertCaret(t, e, 0, 13, len("fflffl fflffl"))
e.text.MoveLines(1, selectionClear)
assertCaret(t, e, 1, 13, len("fflffl fflffl fflffl fflffl"))
e.text.MoveLines(-1, selectionClear)
assertCaret(t, e, 0, 14, len("fflffl fflffl "))
assertCaret(t, e, 0, 13, len("fflffl fflffl"))
// Absurdly narrow constraints to force each ligature onto its own line.
gtx.Constraints = layout.Exact(image.Pt(10, 10))
widget/index.go
+50 -38
View File
@@ -44,12 +44,11 @@ type glyphIndex struct {
prog text.Flags
// clusterAdvance accumulates the advances of glyphs in a glyph cluster.
clusterAdvance fixed.Int26_6
// skipPrior controls whether a text position is inserted "before" the
// next glyph. Usually this should not happen, but the boundaries of
// lines and bidi runs require it.
skipPrior bool
// truncated indicates that the text was truncated by the shaper.
truncated bool
// midCluster tracks whether the next glyph processed is not the first glyph in a
// cluster.
midCluster bool
}
// reset prepares the index for reuse.
@@ -63,8 +62,8 @@ func (g *glyphIndex) reset() {
g.pos = combinedPos{}
g.prog = 0
g.clusterAdvance = 0
g.skipPrior = false
g.truncated = false
g.midCluster = false
}
// screenPos represents a character position in text line and column numbers,
@@ -113,6 +112,20 @@ func (g *glyphIndex) incrementPosition(pos combinedPos) (next combinedPos, eof b
return candidate, true
}
func (g *glyphIndex) insertPosition(pos combinedPos) {
lastIdx := len(g.positions) - 1
if lastIdx >= 0 {
lastPos := g.positions[lastIdx]
if lastPos.runes == pos.runes && (lastPos.y != pos.y || (lastPos.x == pos.x)) {
// If we insert a consecutive position with the same logical position,
// overwrite the previous position with the new one.
g.positions[lastIdx] = pos
return
}
}
g.positions = append(g.positions, pos)
}
// Glyph indexes the provided glyph, generating text cursor positions for it.
func (g *glyphIndex) Glyph(gl text.Glyph) {
g.glyphs = append(g.glyphs, gl)
@@ -128,30 +141,32 @@ func (g *glyphIndex) Glyph(gl text.Glyph) {
if end := gl.X + gl.Advance; end > g.currentLineMax {
g.currentLineMax = end
}
if !g.skipPrior || gl.Flags&text.FlagTowardOrigin != g.prog || gl.Flags&text.FlagParagraphStart != 0 {
// Set the new text progression based on that of the first glyph.
g.prog = gl.Flags & text.FlagTowardOrigin
g.pos.towardOrigin = g.prog == text.FlagTowardOrigin
// Create the text position prior to the first glyph.
pos := g.pos
pos.x = gl.X
pos.y = int(gl.Y)
pos.ascent = gl.Ascent
pos.descent = gl.Descent
if pos.towardOrigin {
pos.x += gl.Advance
}
g.pos = pos
g.positions = append(g.positions, pos)
g.skipPrior = true
}
needsNewLine := gl.Flags&text.FlagLineBreak != 0
needsNewRun := gl.Flags&text.FlagRunBreak != 0
breaksParagraph := gl.Flags&text.FlagParagraphBreak != 0
breaksCluster := gl.Flags&text.FlagClusterBreak != 0
// We should insert new positions if the glyph we're processing terminates
// a glyph cluster.
insertPositionAfter := gl.Flags&text.FlagClusterBreak != 0 && !breaksParagraph && gl.Runes > 0
// a glyph cluster, has nonzero runes, and is not a hard newline.
insertPositionsWithin := breaksCluster && !breaksParagraph && gl.Runes > 0
// Get the text progression/direction right.
g.prog = gl.Flags & text.FlagTowardOrigin
g.pos.towardOrigin = g.prog == text.FlagTowardOrigin
if !g.midCluster {
// Create the text position prior to the glyph.
g.pos.x = gl.X
g.pos.y = int(gl.Y)
g.pos.ascent = gl.Ascent
g.pos.descent = gl.Descent
if g.pos.towardOrigin {
g.pos.x += gl.Advance
}
g.insertPosition(g.pos)
}
g.midCluster = !breaksCluster
if breaksParagraph {
// Paragraph breaking clusters shouldn't have positions generated for both
// sides of them. They're always zero-width, so doing so would
@@ -164,12 +179,11 @@ func (g *glyphIndex) Glyph(gl text.Glyph) {
// Always track the cumulative advance added by the glyph, even if it
// doesn't terminate a cluster itself.
g.clusterAdvance += gl.Advance
if insertPositionAfter {
// Construct the text position _after_ gl.
pos := g.pos
pos.y = int(gl.Y)
pos.ascent = gl.Ascent
pos.descent = gl.Descent
if insertPositionsWithin {
// Construct the text positions _within_ gl.
g.pos.y = int(gl.Y)
g.pos.ascent = gl.Ascent
g.pos.descent = gl.Descent
width := g.clusterAdvance
positionCount := int(gl.Runes)
runesPerPosition := 1
@@ -181,19 +195,18 @@ func (g *glyphIndex) Glyph(gl text.Glyph) {
}
perRune := width / fixed.Int26_6(positionCount)
adjust := fixed.Int26_6(0)
if pos.towardOrigin {
if g.pos.towardOrigin {
// If RTL, subtract increments from the width of the cluster
// instead of adding.
adjust = width
perRune = -perRune
}
for i := 1; i <= positionCount; i++ {
pos.x = gl.X + adjust + perRune*fixed.Int26_6(i)
pos.runes += runesPerPosition
pos.lineCol.col += runesPerPosition
g.positions = append(g.positions, pos)
g.pos.x = gl.X + adjust + perRune*fixed.Int26_6(i)
g.pos.runes += runesPerPosition
g.pos.lineCol.col += runesPerPosition
g.insertPosition(g.pos)
}
g.pos = pos
g.clusterAdvance = 0
}
if needsNewRun {
@@ -214,7 +227,6 @@ func (g *glyphIndex) Glyph(gl text.Glyph) {
g.currentLineMin = math.MaxInt32
g.currentLineMax = 0
g.currentLineGlyphs = 0
g.skipPrior = false
}
}
widget/index_test.go
+76 -32
View File
@@ -103,11 +103,12 @@ func getGlyphs(fontSize, minWidth, lineWidth int, align text.Alignment, str stri
},
}))
params := text.Parameters{
PxPerEm: fixed.I(fontSize),
Alignment: align,
MinWidth: minWidth,
MaxWidth: lineWidth,
Locale: english,
PxPerEm: fixed.I(fontSize),
Alignment: align,
MinWidth: minWidth,
MaxWidth: lineWidth,
Locale: english,
WrapPolicy: text.WrapWords,
}
shaper.LayoutString(params, str)
for g, ok := shaper.NextGlyph(); ok; g, ok = shaper.NextGlyph() {
@@ -120,30 +121,34 @@ func getGlyphs(fontSize, minWidth, lineWidth int, align text.Alignment, str stri
// for empty lines and the empty string.
func TestIndexPositionWhitespace(t *testing.T) {
type testcase struct {
name string
str string
align text.Alignment
expected []combinedPos
name string
str string
lineWidth int
align text.Alignment
expected []combinedPos
}
for _, tc := range []testcase{
{
name: "empty string",
str: "",
name: "empty string",
str: "",
lineWidth: 200,
expected: []combinedPos{
{x: fixed.Int26_6(0), y: 16, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216)},
},
},
{
name: "just hard newline",
str: "\n",
name: "just hard newline",
str: "\n",
lineWidth: 200,
expected: []combinedPos{
{x: fixed.Int26_6(0), y: 16, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216)},
{x: fixed.Int26_6(0), y: 35, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 1, lineCol: screenPos{line: 1}},
},
},
{
name: "trailing newline",
str: "a\n",
name: "trailing newline",
str: "a\n",
lineWidth: 200,
expected: []combinedPos{
{x: fixed.Int26_6(0), y: 16, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216)},
{x: fixed.Int26_6(570), y: 16, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 1, lineCol: screenPos{col: 1}},
@@ -151,8 +156,9 @@ func TestIndexPositionWhitespace(t *testing.T) {
},
},
{
name: "just blank line",
str: "\n\n",
name: "just blank line",
str: "\n\n",
lineWidth: 200,
expected: []combinedPos{
{x: fixed.Int26_6(0), y: 16, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216)},
{x: fixed.Int26_6(0), y: 35, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 1, lineCol: screenPos{line: 1}},
@@ -160,9 +166,10 @@ func TestIndexPositionWhitespace(t *testing.T) {
},
},
{
name: "middle aligned blank lines",
str: "\n\n\nabc",
align: text.Middle,
name: "middle aligned blank lines",
str: "\n\n\nabc",
align: text.Middle,
lineWidth: 200,
expected: []combinedPos{
{x: fixed.Int26_6(832), y: 16, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216)},
{x: fixed.Int26_6(832), y: 35, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 1, lineCol: screenPos{line: 1}},
@@ -174,8 +181,9 @@ func TestIndexPositionWhitespace(t *testing.T) {
},
},
{
name: "blank line",
str: "a\n\nb",
name: "blank line",
str: "a\n\nb",
lineWidth: 200,
expected: []combinedPos{
{x: fixed.Int26_6(0), y: 16, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216)},
{x: fixed.Int26_6(570), y: 16, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 1, lineCol: screenPos{col: 1}},
@@ -184,9 +192,45 @@ func TestIndexPositionWhitespace(t *testing.T) {
{x: fixed.Int26_6(570), y: 54, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 4, lineCol: screenPos{line: 2, col: 1}},
},
},
{
name: "soft wrap",
str: "abc def",
lineWidth: 30,
expected: []combinedPos{
{runes: 0, lineCol: screenPos{line: 0, col: 0}, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), x: 0, y: 16},
{runes: 1, lineCol: screenPos{line: 0, col: 1}, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), x: 570, y: 16},
{runes: 2, lineCol: screenPos{line: 0, col: 2}, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), x: 1140, y: 16},
{runes: 3, lineCol: screenPos{line: 0, col: 3}, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), x: 1652, y: 16},
{runes: 4, lineCol: screenPos{line: 1, col: 0}, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), x: 0, y: 35},
{runes: 5, lineCol: screenPos{line: 1, col: 1}, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), x: 570, y: 35},
{runes: 6, lineCol: screenPos{line: 1, col: 2}, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), x: 1140, y: 35},
{runes: 7, lineCol: screenPos{line: 1, col: 3}, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), x: 1425, y: 35},
},
},
{
name: "soft wrap arabic",
str: "ثنائي الاتجاه",
lineWidth: 30,
expected: []combinedPos{
{runes: 0, lineCol: screenPos{line: 0, col: 0}, ascent: 1407, descent: 756, x: 2250, y: 22, towardOrigin: true},
{runes: 1, lineCol: screenPos{line: 0, col: 1}, ascent: 1407, descent: 756, x: 1944, y: 22, towardOrigin: true},
{runes: 2, lineCol: screenPos{line: 0, col: 2}, ascent: 1407, descent: 756, x: 1593, y: 22, towardOrigin: true},
{runes: 3, lineCol: screenPos{line: 0, col: 3}, ascent: 1407, descent: 756, x: 1295, y: 22, towardOrigin: true},
{runes: 4, lineCol: screenPos{line: 0, col: 4}, ascent: 1407, descent: 756, x: 1020, y: 22, towardOrigin: true},
{runes: 5, lineCol: screenPos{line: 0, col: 5}, ascent: 1407, descent: 756, x: 266, y: 22, towardOrigin: true},
{runes: 6, lineCol: screenPos{line: 1, col: 0}, ascent: 1407, descent: 756, x: 2511, y: 41, towardOrigin: true},
{runes: 7, lineCol: screenPos{line: 1, col: 1}, ascent: 1407, descent: 756, x: 2267, y: 41, towardOrigin: true},
{runes: 8, lineCol: screenPos{line: 1, col: 2}, ascent: 1407, descent: 756, x: 1969, y: 41, towardOrigin: true},
{runes: 9, lineCol: screenPos{line: 1, col: 3}, ascent: 1407, descent: 756, x: 1671, y: 41, towardOrigin: true},
{runes: 10, lineCol: screenPos{line: 1, col: 4}, ascent: 1407, descent: 756, x: 1365, y: 41, towardOrigin: true},
{runes: 11, lineCol: screenPos{line: 1, col: 5}, ascent: 1407, descent: 756, x: 713, y: 41, towardOrigin: true},
{runes: 12, lineCol: screenPos{line: 1, col: 6}, ascent: 1407, descent: 756, x: 415, y: 41, towardOrigin: true},
{runes: 13, lineCol: screenPos{line: 1, col: 7}, ascent: 1407, descent: 756, x: 0, y: 41, towardOrigin: true},
},
},
} {
t.Run(tc.name, func(t *testing.T) {
glyphs := getGlyphs(16, 0, 200, tc.align, tc.str)
glyphs := getGlyphs(16, 0, tc.lineWidth, tc.align, tc.str)
var gi glyphIndex
gi.reset()
for _, g := range glyphs {
@@ -227,11 +271,11 @@ func TestIndexPositionBidi(t *testing.T) {
name: "bidi ltr",
glyphs: bidiLTRText,
expectedXs: []fixed.Int26_6{
0, 626, 1196, 1766, 2051, 2621, 3191, 3444, 3956, 4468, 4753, 7133, 6330, 5738, 5440, 5019, 4753, // Positions on line 0.
0, 626, 1196, 1766, 2051, 2621, 3191, 3444, 3956, 4468, 4753, 7133, 6330, 5738, 5440, 5019, // Positions on line 0.
3953, 3185, 2417, 1649, 881, 596, 298, 0, 3953, 4238, 4523, 5093, 5605, 5890, 7905, 7599, 7007, 6156, 5890, // Positions on line 1.
3953, 3185, 2417, 1649, 881, 596, 298, 0, 3953, 4238, 4523, 5093, 5605, 5890, 7905, 7599, 7007, 6156, // Positions on line 1.
4660, 3892, 3124, 2356, 1588, 1303, 788, 406, 0, 4660, 4945, 5235, 5805, 6375, 6660, 6934, 7504, 8016, 8528, 8813, // Positions on line 2.
4660, 3892, 3124, 2356, 1588, 1303, 788, 406, 0, 4660, 4945, 5235, 5805, 6375, 6660, 6934, 7504, 8016, 8528, // Positions on line 2.
0, 570, 1140, 1710, 2034, // Positions on line 3.
},
@@ -240,11 +284,11 @@ func TestIndexPositionBidi(t *testing.T) {
name: "bidi rtl",
glyphs: bidiRTLText,
expectedXs: []fixed.Int26_6{
2665, 3291, 3861, 4431, 4716, 5286, 5856, 6109, 6621, 7133, 2665, 2380, 1577, 985, 687, 266, 0, // Positions on line 0.
2665, 3291, 3861, 4431, 4716, 5286, 5856, 6109, 6621, 7133, 2665, 2380, 1577, 985, 687, 266, // Positions on line 0.
7886, 7118, 6350, 5582, 4814, 4529, 4231, 3933, 3667, 2300, 2585, 3155, 3667, 2300, 2015, 1709, 1117, 266, 0, // Positions on line 1.
7886, 7118, 6350, 5582, 4814, 4529, 4231, 3933, 3667, 2300, 2585, 3155, 3667, 2300, 2015, 1709, 1117, 266, // Positions on line 1.
8794, 8026, 7258, 6490, 5722, 5437, 4922, 4540, 4134, 3868, 0, 290, 860, 1430, 1715, 1989, 2559, 3071, 3583, 3868, // Positions on line 2.
8794, 8026, 7258, 6490, 5722, 5437, 4922, 4540, 4134, 3868, 0, 290, 860, 1430, 1715, 1989, 2559, 3071, 3583, // Positions on line 2.
324, 894, 1464, 2034, 324, 0, // Positions on line 3.
},
@@ -524,13 +568,13 @@ func TestIndexPositionRunes(t *testing.T) {
{runes: 12, lineCol: screenPos{line: 1, col: 8}, runIndex: 1, towardOrigin: true},
{runes: 13, lineCol: screenPos{line: 1, col: 9}, runIndex: 1, towardOrigin: true},
{runes: 14, lineCol: screenPos{line: 1, col: 10}, runIndex: 1, towardOrigin: true},
{runes: 15, lineCol: screenPos{line: 1, col: 11}, runIndex: 1, towardOrigin: true},
{runes: 15, lineCol: screenPos{line: 1, col: 11}, runIndex: 2, towardOrigin: true},
{runes: 16, lineCol: screenPos{line: 1, col: 12}, runIndex: 2, towardOrigin: true},
{runes: 17, lineCol: screenPos{line: 1, col: 13}, runIndex: 2, towardOrigin: true},
{runes: 18, lineCol: screenPos{line: 2, col: 0}, runIndex: 0, towardOrigin: true},
{runes: 19, lineCol: screenPos{line: 2, col: 1}, runIndex: 0, towardOrigin: true},
{runes: 20, lineCol: screenPos{line: 2, col: 2}, runIndex: 0, towardOrigin: true},
{runes: 21, lineCol: screenPos{line: 2, col: 3}, runIndex: 0, towardOrigin: true},
{runes: 21, lineCol: screenPos{line: 2, col: 3}, runIndex: 1, towardOrigin: true},
{runes: 22, lineCol: screenPos{line: 2, col: 4}, runIndex: 1, towardOrigin: true},
{runes: 23, lineCol: screenPos{line: 2, col: 5}, runIndex: 1, towardOrigin: true},
{runes: 24, lineCol: screenPos{line: 2, col: 6}, runIndex: 1, towardOrigin: true},
@@ -542,7 +586,7 @@ func TestIndexPositionRunes(t *testing.T) {
{runes: 29, lineCol: screenPos{line: 3, col: 1}, runIndex: 0, towardOrigin: true},
{runes: 30, lineCol: screenPos{line: 3, col: 2}, runIndex: 0, towardOrigin: true},
{runes: 31, lineCol: screenPos{line: 3, col: 3}, runIndex: 0, towardOrigin: true},
{runes: 32, lineCol: screenPos{line: 3, col: 4}, runIndex: 0, towardOrigin: true},
{runes: 32, lineCol: screenPos{line: 3, col: 4}, runIndex: 1, towardOrigin: true},
{runes: 33, lineCol: screenPos{line: 3, col: 5}, runIndex: 1, towardOrigin: true},
{runes: 34, lineCol: screenPos{line: 3, col: 6}, runIndex: 1, towardOrigin: true},
{runes: 35, lineCol: screenPos{line: 4, col: 0}, runIndex: 0, towardOrigin: true},