widget: update glyph iteration

This commit updates the textIterator and glyphIndex types to consume new flag information provided on glyphs. These changes allow widget.Label and widget.Editor to correctly compute text bounding boxes and to generate valid cursor positions at the end of text. Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>
2026-07-01 07:35:40 +00:00 · 2022-12-16 13:11:42 -05:00
parent 5b40d3cd47
commit 12da71821a
4 changed files with 316 additions and 25 deletions
@@ -73,6 +73,122 @@ func makeAccountingTestText(fontSize, lineWidth int) (txt []text.Glyph) {
 	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([]text.FontFace{{
+		Font: text.Font{Typeface: "LTR"},
+		Face: ltrFace,
+	},
+		{
+			Font: text.Font{Typeface: "RTL"},
+			Face: rtlFace,
+		},
+	})
+	params := text.Parameters{PxPerEm: fixed.I(fontSize), Alignment: align}
+	shaper.LayoutString(params, minWidth, lineWidth, english, 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(0), y: 73, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 3, lineCol: screenPos{line: 3}},
+				{x: fixed.Int26_6(570), y: 73, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 4, lineCol: screenPos{line: 3, col: 1}},
+				{x: fixed.Int26_6(1140), y: 73, ascent: fixed.Int26_6(968), descent: fixed.Int26_6(216), runes: 5, lineCol: screenPos{line: 3, col: 2}},
+				{x: fixed.Int26_6(1652), y: 73, 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
+			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) {