Files
gio/widget/index_test.go
T
Chris Waldon 6ea4119a3c text,widget: [API] implement consistent, controllable line height
This commit ensures that any given paragraph of text shaped by Gio will use a single
internal line height. This line height is determined (by default) by the text size,
rather than the fonts involved. This is a breaking change, as previously we would
blindly use the largest line height of any font in a line for that line, leading to
lines within the same paragraph with extremely uneven spacing. This commit also
updates some test expectations in package widget.

I thought pretty hard about how to implement line spacing, and consulted a few sources:

[0] https://www.figma.com/blog/line-height-changes/
[1] https://practicaltypography.com/line-spacing.html
[2] https://developer.mozilla.org/en-US/docs/Web/CSS/line-height

There is no single, universal way to think about line spacing. Fonts internally specify
a line height as the sum of their ascent, descent, and gap, but the line height of two
fonts at the same pixel size (say 20 Sp) can vary wildy (especially across writing systems).
There are two strategies we could pursue to establish the line height of a paragraph of text:

- derive the line height from the fonts involved (our old behavior, and the behavior of
  many word processors)
- derive the line height from the requested text size provided by the user (the behavior of the
  web).

The challenge with the first option is that for a given piece of text in the UI, there can
be a silly number of fonts involved. If a label dispays user-generated content, the user can
put an emoji in it, and emoji fonts have different line heights from latin ones. This can cause
unexpected and nasty layout shift. Gio would previously do exactly this, on a line-by-line basis,
resulting in unevenly spaced lines within a paragraph depending on which fonts were used on
which lines. Choosing one of the fonts and enforcing its line height would make things consistent,
but it isn't clear how to choose that canonical font. There is no 1:1 mapping between the input
text.Font provided in the shaping parameters and a single font.Face. Instead, that mapping depends
upon the runes being shaped.

I think the only sane way to implement the first option would be to synthesize some text in the
provided system.Locale (mapping the language to a script and then generating a rune from that
script), shape that single rune, and then enforce the line height of the resulting face on the
entire paragraph. This would require doing a fair bit more work per paragraph than Gio does today,
so I've opted not to do it.

Instead, the second option allows us to choose a line height based on the size of the text that
the user wants to display. While this can potentially interact poorly with unusually tall fonts,
it means that text will always have a consistent line height.

I've provided two knobs to control line height:

- text.Parameters.LineHeight lets you set a specific height in pixels with a default value of
  text.Parameters.PxPerEm.
- text.Parameters.LineHeightScale applies a scaling factor to the LineHeight, allowing you to
  easily space out text without hard-coding a specific pixel size. The default value here
  (drawn from the recommendations of [1]) is 1.2, which looks pretty good across many fonts.

I've chosen this two-value API because many users will want to set one or the other value. I
considered instead a single value field and a "mode" that would specify how it was used, but
that felt uglier. Also, you *can* set both of these two fields and get predictable results.

I'd like to revisit using the line height of the chosen fonts in the future, but it seems a
little too complex to be worthwhile right now. An interesting option would be making the
select-a-face-using-locale strategy described above an opt-in feature, though some users
might instead want to just use the tallest line height among fonts in use. Something like
this Android API might be appropriate:

[3] https://learn.microsoft.com/en-us/dotnet/api/android.widget.textview.fallbacklinespacing?view=xamarin-android-sdk-13

I'd like to thank Dominik Honnef for some good discussion around this feature, and for pointing
me to some good sources on the subject.

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>
2023-07-17 22:33:02 +02:00

808 lines
25 KiB
Go

package widget
import (
"bytes"
"io"
"testing"
nsareg "eliasnaur.com/font/noto/sans/arabic/regular"
"gioui.org/font"
"gioui.org/font/opentype"
"gioui.org/text"
"golang.org/x/image/font/gofont/goregular"
"golang.org/x/image/math/fixed"
)
// makePosTestText returns two bidi samples of shaped text at the given
// font size and wrapped to the given line width. The runeLimit, if nonzero,
// truncates the sample text to ensure shorter output for expensive tests.
func makePosTestText(fontSize, lineWidth int, alignOpposite bool) (source string, bidiLTR, bidiRTL []text.Glyph) {
ltrFace, _ := opentype.Parse(goregular.TTF)
rtlFace, _ := opentype.Parse(nsareg.TTF)
shaper := text.NewShaper([]font.FontFace{
{
Font: font.Font{Typeface: "LTR"},
Face: ltrFace,
},
{
Font: font.Font{Typeface: "RTL"},
Face: rtlFace,
},
})
// bidiSource is crafted to contain multiple consecutive RTL runs (by
// changing scripts within the RTL).
bidiSource := "The quick سماء שלום لا fox تمط שלום غير the lazy dog."
ltrParams := text.Parameters{
Font: font.Font{Typeface: "LTR"},
PxPerEm: fixed.I(fontSize),
MaxWidth: lineWidth,
MinWidth: lineWidth,
Locale: english,
}
rtlParams := text.Parameters{
Alignment: text.End,
Font: font.Font{Typeface: "RTL"},
PxPerEm: fixed.I(fontSize),
MaxWidth: lineWidth,
MinWidth: lineWidth,
Locale: arabic,
}
if alignOpposite {
ltrParams.Alignment = text.End
rtlParams.Alignment = text.Start
}
shaper.LayoutString(ltrParams, bidiSource)
for g, ok := shaper.NextGlyph(); ok; g, ok = shaper.NextGlyph() {
bidiLTR = append(bidiLTR, g)
}
shaper.LayoutString(rtlParams, bidiSource)
for g, ok := shaper.NextGlyph(); ok; g, ok = shaper.NextGlyph() {
bidiRTL = append(bidiRTL, g)
}
return bidiSource, bidiLTR, bidiRTL
}
// makeAccountingTestText shapes text designed to stress rune accounting
// logic within the index.
func makeAccountingTestText(str string, fontSize, lineWidth int) (txt []text.Glyph) {
ltrFace, _ := opentype.Parse(goregular.TTF)
rtlFace, _ := opentype.Parse(nsareg.TTF)
shaper := text.NewShaper([]font.FontFace{{
Font: font.Font{Typeface: "LTR"},
Face: ltrFace,
},
{
Font: font.Font{Typeface: "RTL"},
Face: rtlFace,
},
})
params := text.Parameters{
PxPerEm: fixed.I(fontSize),
MaxWidth: lineWidth,
Locale: english,
}
shaper.LayoutString(params, str)
for g, ok := shaper.NextGlyph(); ok; g, ok = shaper.NextGlyph() {
txt = append(txt, g)
}
return txt
}
// getGlyphs shapes text as english.
func getGlyphs(fontSize, minWidth, lineWidth int, align text.Alignment, str string) (txt []text.Glyph) {
ltrFace, _ := opentype.Parse(goregular.TTF)
rtlFace, _ := opentype.Parse(nsareg.TTF)
shaper := text.NewShaper([]font.FontFace{{
Font: font.Font{Typeface: "LTR"},
Face: ltrFace,
},
{
Font: font.Font{Typeface: "RTL"},
Face: rtlFace,
},
})
params := text.Parameters{
PxPerEm: fixed.I(fontSize),
Alignment: align,
MinWidth: minWidth,
MaxWidth: lineWidth,
Locale: english,
}
shaper.LayoutString(params, str)
for g, ok := shaper.NextGlyph(); ok; g, ok = shaper.NextGlyph() {
txt = append(txt, g)
}
return txt
}
// TestIndexPositionWhitespace checks that the index correctly generates cursor positions
// for empty lines and the empty string.
func TestIndexPositionWhitespace(t *testing.T) {
type testcase struct {
name string
str string
align text.Alignment
expected []combinedPos
}
for _, tc := range []testcase{
{
name: "empty string",
str: "",
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",
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",
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}},
{x: fixed.Int26_6(0), y: 35, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 2, lineCol: screenPos{line: 1}},
},
},
{
name: "just blank line",
str: "\n\n",
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}},
{x: fixed.Int26_6(0), y: 54, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 2, lineCol: screenPos{line: 2}},
},
},
{
name: "middle aligned blank lines",
str: "\n\n\nabc",
align: text.Middle,
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}},
{x: fixed.Int26_6(832), y: 54, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 2, lineCol: screenPos{line: 2}},
{x: fixed.Int26_6(6), y: 74, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 3, lineCol: screenPos{line: 3}},
{x: fixed.Int26_6(576), y: 74, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 4, lineCol: screenPos{line: 3, col: 1}},
{x: fixed.Int26_6(1146), y: 74, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 5, lineCol: screenPos{line: 3, col: 2}},
{x: fixed.Int26_6(1658), y: 74, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 6, lineCol: screenPos{line: 3, col: 3}},
},
},
{
name: "blank line",
str: "a\n\nb",
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}},
{x: fixed.Int26_6(0), y: 35, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 2, lineCol: screenPos{line: 1}},
{x: fixed.Int26_6(0), y: 54, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 3, lineCol: screenPos{line: 2}},
{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}},
},
},
} {
t.Run(tc.name, func(t *testing.T) {
glyphs := getGlyphs(16, 0, 200, tc.align, tc.str)
var gi glyphIndex
gi.reset()
for _, g := range glyphs {
gi.Glyph(g)
}
if len(gi.positions) != len(tc.expected) {
t.Errorf("expected %d positions, got %d", len(tc.expected), len(gi.positions))
}
for i := 0; i < min(len(gi.positions), len(tc.expected)); i++ {
actual := gi.positions[i]
expected := tc.expected[i]
if actual != expected {
t.Errorf("position %d: expected:\n%#+v, got:\n%#+v", i, expected, actual)
}
}
if t.Failed() {
printPositions(t, gi.positions)
printGlyphs(t, glyphs)
}
})
}
}
// TestIndexPositionBidi tests whether the index correct generates cursor positions for
// complex bidirectional text.
func TestIndexPositionBidi(t *testing.T) {
fontSize := 16
lineWidth := fontSize * 10
_, bidiLTRText, bidiRTLText := makePosTestText(fontSize, lineWidth, false)
type testcase struct {
name string
glyphs []text.Glyph
expectedXs []fixed.Int26_6
}
for _, tc := range []testcase{
{
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.
3953, 3185, 2417, 1649, 881, 596, 298, 0, 3953, 4238, 4523, 5093, 5605, 5890, 7905, 7599, 7007, 6156, 5890, // 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.
0, 570, 1140, 1710, 2034, // Positions on line 3.
},
},
{
name: "bidi rtl",
glyphs: bidiRTLText,
expectedXs: []fixed.Int26_6{
5368, 5994, 6564, 7134, 7419, 7989, 8559, 8812, 9324, 9836, 5368, 5102, 4299, 3707, 3409, 2988, 2722, 2108, 1494, 880, 266, 0, // Positions on line 0.
8801, 8503, 8205, 7939, 6572, 6857, 7427, 7939, 6572, 6306, 6000, 5408, 4557, 4291, 3677, 3063, 2449, 1835, 1569, 1054, 672, 266, 0, // Positions on line 1.
274, 564, 1134, 1704, 1989, 2263, 2833, 3345, 3857, 4142, 4712, 5282, 5852, 274, 0, // Positions on line 2.
},
},
} {
t.Run(tc.name, func(t *testing.T) {
var gi glyphIndex
gi.reset()
for _, g := range tc.glyphs {
gi.Glyph(g)
}
if len(gi.positions) != len(tc.expectedXs) {
t.Errorf("expected %d positions, got %d", len(tc.expectedXs), len(gi.positions))
}
lastRunes := 0
lastLine := 0
lastCol := -1
lastY := 0
for i := 0; i < min(len(gi.positions), len(tc.expectedXs)); i++ {
actualX := gi.positions[i].x
expectedX := tc.expectedXs[i]
if actualX != expectedX {
t.Errorf("position %d: expected x=%v(%d), got x=%v(%d)", i, expectedX, expectedX, actualX, actualX)
}
if r := gi.positions[i].runes; r < lastRunes {
t.Errorf("position %d: expected runes >= %d, got %d", i, lastRunes, r)
}
lastRunes = gi.positions[i].runes
if y := gi.positions[i].y; y < lastY {
t.Errorf("position %d: expected y>= %d, got %d", i, lastY, y)
}
lastY = gi.positions[i].y
if y := gi.positions[i].y; y < lastY {
t.Errorf("position %d: expected y>= %d, got %d", i, lastY, y)
}
lastY = gi.positions[i].y
if lineCol := gi.positions[i].lineCol; lineCol.line == lastLine && lineCol.col < lastCol {
t.Errorf("position %d: expected col >= %d, got %d", i, lastCol, lineCol.col)
}
lastCol = gi.positions[i].lineCol.col
if line := gi.positions[i].lineCol.line; line < lastLine {
t.Errorf("position %d: expected line >= %d, got %d", i, lastLine, line)
}
lastLine = gi.positions[i].lineCol.line
}
printPositions(t, gi.positions)
if t.Failed() {
printGlyphs(t, tc.glyphs)
}
})
}
}
func TestIndexPositionLines(t *testing.T) {
fontSize := 16
lineWidth := fontSize * 10
source1, bidiLTRText, bidiRTLText := makePosTestText(fontSize, lineWidth, false)
source2, bidiLTRTextOpp, bidiRTLTextOpp := makePosTestText(fontSize, lineWidth, true)
type testcase struct {
name string
source string
glyphs []text.Glyph
expectedLines []lineInfo
}
for _, tc := range []testcase{
{
name: "bidi ltr",
source: source1,
glyphs: bidiLTRText,
expectedLines: []lineInfo{
{
xOff: fixed.Int26_6(0),
yOff: 22,
glyphs: 15,
width: fixed.Int26_6(7133),
ascent: fixed.Int26_6(1407),
descent: fixed.Int26_6(756),
},
{
xOff: fixed.Int26_6(0),
yOff: 41,
glyphs: 15,
width: fixed.Int26_6(7905),
ascent: fixed.Int26_6(1407),
descent: fixed.Int26_6(756),
},
{
xOff: fixed.Int26_6(0),
yOff: 60,
glyphs: 18,
width: fixed.Int26_6(8813),
ascent: fixed.Int26_6(1407),
descent: fixed.Int26_6(756),
},
{
xOff: fixed.Int26_6(0),
yOff: 80,
glyphs: 4,
width: fixed.Int26_6(2034),
ascent: fixed.Int26_6(968),
descent: fixed.Int26_6(216),
},
},
},
{
name: "bidi rtl",
source: source1,
glyphs: bidiRTLText,
expectedLines: []lineInfo{
{
xOff: fixed.Int26_6(0),
yOff: 22,
glyphs: 20,
width: fixed.Int26_6(9836),
ascent: fixed.Int26_6(1407),
descent: fixed.Int26_6(756),
},
{
xOff: fixed.Int26_6(0),
yOff: 41,
glyphs: 19,
width: fixed.Int26_6(8801),
ascent: fixed.Int26_6(1407),
descent: fixed.Int26_6(756),
},
{
xOff: fixed.Int26_6(0),
yOff: 60,
glyphs: 13,
width: fixed.Int26_6(5852),
ascent: fixed.Int26_6(1407),
descent: fixed.Int26_6(756),
},
},
},
{
name: "bidi ltr opposite alignment",
source: source2,
glyphs: bidiLTRTextOpp,
expectedLines: []lineInfo{
{
xOff: fixed.Int26_6(3107),
yOff: 22,
glyphs: 15,
width: fixed.Int26_6(7133),
ascent: fixed.Int26_6(1407),
descent: fixed.Int26_6(756),
},
{
xOff: fixed.Int26_6(2335),
yOff: 41,
glyphs: 15,
width: fixed.Int26_6(7905),
ascent: fixed.Int26_6(1407),
descent: fixed.Int26_6(756),
},
{
xOff: fixed.Int26_6(1427),
yOff: 60,
glyphs: 18,
width: fixed.Int26_6(8813),
ascent: fixed.Int26_6(1407),
descent: fixed.Int26_6(756),
},
{
xOff: fixed.Int26_6(8206),
yOff: 80,
glyphs: 4,
width: fixed.Int26_6(2034),
ascent: fixed.Int26_6(968),
descent: fixed.Int26_6(216),
},
},
},
{
name: "bidi rtl opposite alignment",
source: source2,
glyphs: bidiRTLTextOpp,
expectedLines: []lineInfo{
{
xOff: fixed.Int26_6(404),
yOff: 22,
glyphs: 20,
width: fixed.Int26_6(9836),
ascent: fixed.Int26_6(1407),
descent: fixed.Int26_6(756),
},
{
xOff: fixed.Int26_6(1439),
yOff: 41,
glyphs: 19,
width: fixed.Int26_6(8801),
ascent: fixed.Int26_6(1407),
descent: fixed.Int26_6(756),
},
{
xOff: fixed.Int26_6(4388),
yOff: 60,
glyphs: 13,
width: fixed.Int26_6(5852),
ascent: fixed.Int26_6(1407),
descent: fixed.Int26_6(756),
},
},
},
} {
t.Run(tc.name, func(t *testing.T) {
var gi glyphIndex
gi.reset()
for _, g := range tc.glyphs {
gi.Glyph(g)
}
if len(gi.lines) != len(tc.expectedLines) {
t.Errorf("expected %d lines, got %d", len(tc.expectedLines), len(gi.lines))
}
for i := 0; i < min(len(gi.lines), len(tc.expectedLines)); i++ {
actual := gi.lines[i]
expected := tc.expectedLines[i]
if actual != expected {
t.Errorf("line %d: expected:\n%#+v, got:\n%#+v", i, expected, actual)
}
}
})
}
}
// TestIndexPositionRunes checks for rune accounting errors in positions
// generated by the index.
func TestIndexPositionRunes(t *testing.T) {
fontSize := 16
lineWidth := fontSize * 10
// source is crafted to contain multiple consecutive RTL runs (by
// changing scripts within the RTL).
source := "The\nquick سماء של\nום لا fox\nتمط של\nום."
testText := makeAccountingTestText(source, fontSize, lineWidth)
type testcase struct {
name string
source string
glyphs []text.Glyph
expected []combinedPos
}
for _, tc := range []testcase{
{
name: "many newlines",
source: source,
glyphs: testText,
expected: []combinedPos{
{runes: 0, lineCol: screenPos{line: 0, col: 0}, runIndex: 0, towardOrigin: false},
{runes: 1, lineCol: screenPos{line: 0, col: 1}, runIndex: 0, towardOrigin: false},
{runes: 2, lineCol: screenPos{line: 0, col: 2}, runIndex: 0, towardOrigin: false},
{runes: 3, lineCol: screenPos{line: 0, col: 3}, runIndex: 0, towardOrigin: false},
{runes: 4, lineCol: screenPos{line: 1, col: 0}, runIndex: 0, towardOrigin: false},
{runes: 5, lineCol: screenPos{line: 1, col: 1}, runIndex: 0, towardOrigin: false},
{runes: 6, lineCol: screenPos{line: 1, col: 2}, runIndex: 0, towardOrigin: false},
{runes: 7, lineCol: screenPos{line: 1, col: 3}, runIndex: 0, towardOrigin: false},
{runes: 8, lineCol: screenPos{line: 1, col: 4}, runIndex: 0, towardOrigin: false},
{runes: 9, lineCol: screenPos{line: 1, col: 5}, runIndex: 0, towardOrigin: false},
{runes: 10, lineCol: screenPos{line: 1, col: 6}, runIndex: 0, towardOrigin: false},
{runes: 10, lineCol: screenPos{line: 1, col: 6}, runIndex: 1, towardOrigin: true},
{runes: 11, lineCol: screenPos{line: 1, col: 7}, runIndex: 1, towardOrigin: true},
{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: 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: 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},
{runes: 24, lineCol: screenPos{line: 2, col: 6}, runIndex: 2, towardOrigin: false},
{runes: 25, lineCol: screenPos{line: 2, col: 7}, runIndex: 2, towardOrigin: false},
{runes: 26, lineCol: screenPos{line: 2, col: 8}, runIndex: 2, towardOrigin: false},
{runes: 27, lineCol: screenPos{line: 2, col: 9}, runIndex: 2, towardOrigin: false},
{runes: 28, lineCol: screenPos{line: 3, col: 0}, runIndex: 0, towardOrigin: true},
{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: 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},
{runes: 36, lineCol: screenPos{line: 4, col: 1}, runIndex: 0, towardOrigin: true},
{runes: 37, lineCol: screenPos{line: 4, col: 2}, runIndex: 0, towardOrigin: true},
{runes: 38, lineCol: screenPos{line: 4, col: 3}, runIndex: 0, towardOrigin: true},
},
},
} {
t.Run(tc.name, func(t *testing.T) {
var gi glyphIndex
gi.reset()
for _, g := range tc.glyphs {
gi.Glyph(g)
}
if len(gi.positions) != len(tc.expected) {
t.Errorf("expected %d positions, got %d", len(tc.expected), len(gi.positions))
}
for i := 0; i < min(len(gi.positions), len(tc.expected)); i++ {
actual := gi.positions[i]
expected := tc.expected[i]
if expected.runes != actual.runes {
t.Errorf("position %d: expected runes=%d, got %d", i, expected.runes, actual.runes)
}
if expected.lineCol != actual.lineCol {
t.Errorf("position %d: expected lineCol=%v, got %v", i, expected.lineCol, actual.lineCol)
}
if expected.runIndex != actual.runIndex {
t.Errorf("position %d: expected runIndex=%d, got %d", i, expected.runIndex, actual.runIndex)
}
if expected.towardOrigin != actual.towardOrigin {
t.Errorf("position %d: expected towardOrigin=%v, got %v", i, expected.towardOrigin, actual.towardOrigin)
}
}
printPositions(t, gi.positions)
if t.Failed() {
printGlyphs(t, tc.glyphs)
}
})
}
}
func printPositions(t *testing.T, positions []combinedPos) {
t.Helper()
for i, p := range positions {
t.Logf("positions[%2d] = {runes: %2d, line: %2d, col: %2d, x: %5d, y: %3d}", i, p.runes, p.lineCol.line, p.lineCol.col, p.x, p.y)
}
}
func printGlyphs(t *testing.T, glyphs []text.Glyph) {
t.Helper()
for i, g := range glyphs {
t.Logf("glyphs[%2d] = {ID: 0x%013x, Flags: %4s, Advance: %4d(%6v), Runes: %d, Y: %3d, X: %4d(%6v)} ", i, g.ID, g.Flags, g.Advance, g.Advance, g.Runes, g.Y, g.X, g.X)
}
}
func TestGraphemeReaderNext(t *testing.T) {
latinDoc := bytes.NewReader([]byte(latinDocument))
arabicDoc := bytes.NewReader([]byte(arabicDocument))
emojiDoc := bytes.NewReader([]byte(emojiDocument))
complexDoc := bytes.NewReader([]byte(complexDocument))
type testcase struct {
name string
input *bytes.Reader
read func() ([]rune, bool)
}
var pr graphemeReader
for _, tc := range []testcase{
{
name: "latin",
input: latinDoc,
read: pr.next,
},
{
name: "arabic",
input: arabicDoc,
read: pr.next,
},
{
name: "emoji",
input: emojiDoc,
read: pr.next,
},
{
name: "complex",
input: complexDoc,
read: pr.next,
},
} {
t.Run(tc.name, func(t *testing.T) {
pr.SetSource(tc.input)
runes := []rune{}
var paragraph []rune
ok := true
for ok {
paragraph, ok = tc.read()
if ok && len(paragraph) > 0 && paragraph[len(paragraph)-1] != '\n' {
}
for i, r := range paragraph {
if i == len(paragraph)-1 {
if r != '\n' && ok {
t.Error("non-final paragraph does not end with newline")
}
} else if r == '\n' {
t.Errorf("paragraph[%d] contains newline", i)
}
}
runes = append(runes, paragraph...)
}
tc.input.Seek(0, 0)
b, _ := io.ReadAll(tc.input)
asRunes := []rune(string(b))
if len(asRunes) != len(runes) {
t.Errorf("expected %d runes, got %d", len(asRunes), len(runes))
}
for i := 0; i < max(len(asRunes), len(runes)); i++ {
if i < min(len(asRunes), len(runes)) {
if runes[i] != asRunes[i] {
t.Errorf("expected runes[%d]=%d, got %d", i, asRunes[i], runes[i])
}
} else if i < len(asRunes) {
t.Errorf("expected runes[%d]=%d, got nothing", i, asRunes[i])
} else if i < len(runes) {
t.Errorf("expected runes[%d]=nothing, got %d", i, runes[i])
}
}
})
}
}
func TestGraphemeReaderGraphemes(t *testing.T) {
latinDoc := bytes.NewReader([]byte(latinDocument))
arabicDoc := bytes.NewReader([]byte(arabicDocument))
emojiDoc := bytes.NewReader([]byte(emojiDocument))
complexDoc := bytes.NewReader([]byte(complexDocument))
type testcase struct {
name string
input *bytes.Reader
read func() []int
}
var pr graphemeReader
for _, tc := range []testcase{
{
name: "latin",
input: latinDoc,
read: pr.Graphemes,
},
{
name: "arabic",
input: arabicDoc,
read: pr.Graphemes,
},
{
name: "emoji",
input: emojiDoc,
read: pr.Graphemes,
},
{
name: "complex",
input: complexDoc,
read: pr.Graphemes,
},
} {
t.Run(tc.name, func(t *testing.T) {
pr.SetSource(tc.input)
graphemes := []int{}
for g := tc.read(); len(g) > 0; g = tc.read() {
if len(graphemes) > 0 && g[0] != graphemes[len(graphemes)-1] {
t.Errorf("expected first boundary in new paragraph %d to match final boundary in previous %d", g[0], graphemes[len(graphemes)-1])
}
if len(graphemes) > 0 {
// Drop duplicated boundary.
g = g[1:]
}
graphemes = append(graphemes, g...)
}
tc.input.Seek(0, 0)
b, _ := io.ReadAll(tc.input)
asRunes := []rune(string(b))
if len(asRunes)+1 < len(graphemes) {
t.Errorf("expected <= %d graphemes, got %d", len(asRunes)+1, len(graphemes))
}
for i := 0; i < len(graphemes)-1; i++ {
if graphemes[i] >= graphemes[i+1] {
t.Errorf("graphemes[%d](%d) >= graphemes[%d](%d)", i, graphemes[i], i+1, graphemes[i+1])
}
}
})
}
}
func BenchmarkGraphemeReaderNext(b *testing.B) {
latinDoc := bytes.NewReader([]byte(latinDocument))
arabicDoc := bytes.NewReader([]byte(arabicDocument))
emojiDoc := bytes.NewReader([]byte(emojiDocument))
complexDoc := bytes.NewReader([]byte(complexDocument))
type testcase struct {
name string
input *bytes.Reader
read func() ([]rune, bool)
}
pr := &graphemeReader{}
for _, tc := range []testcase{
{
name: "latin",
input: latinDoc,
read: pr.next,
},
{
name: "arabic",
input: arabicDoc,
read: pr.next,
},
{
name: "emoji",
input: emojiDoc,
read: pr.next,
},
{
name: "complex",
input: complexDoc,
read: pr.next,
},
} {
var paragraph []rune = make([]rune, 4096)
b.Run(tc.name, func(b *testing.B) {
b.ResetTimer()
for i := 0; i < b.N; i++ {
pr.SetSource(tc.input)
ok := true
for ok {
paragraph, ok = tc.read()
_ = paragraph
}
_ = paragraph
}
})
}
}
func BenchmarkGraphemeReaderGraphemes(b *testing.B) {
latinDoc := bytes.NewReader([]byte(latinDocument))
arabicDoc := bytes.NewReader([]byte(arabicDocument))
emojiDoc := bytes.NewReader([]byte(emojiDocument))
complexDoc := bytes.NewReader([]byte(complexDocument))
type testcase struct {
name string
input *bytes.Reader
read func() []int
}
pr := &graphemeReader{}
for _, tc := range []testcase{
{
name: "latin",
input: latinDoc,
read: pr.Graphemes,
},
{
name: "arabic",
input: arabicDoc,
read: pr.Graphemes,
},
{
name: "emoji",
input: emojiDoc,
read: pr.Graphemes,
},
{
name: "complex",
input: complexDoc,
read: pr.Graphemes,
},
} {
b.Run(tc.name, func(b *testing.B) {
b.ResetTimer()
for i := 0; i < b.N; i++ {
pr.SetSource(tc.input)
for g := tc.read(); len(g) > 0; g = tc.read() {
_ = g
}
}
})
}
}