widget: optimize processGlyph

processGlyph does not modify the value, so there's no reason to
return the struct.

Signed-off-by: Egon Elbre <egonelbre@gmail.com>

widget/label.go

@@ -134,7 +134,7 @@ type textIterator struct {
 
 // processGlyph checks whether the glyph is visible within the iterator's configured
 // viewport and (if so) updates the iterator's text dimensions to include the glyph.
-func (it *textIterator) processGlyph(g text.Glyph, ok bool) (_ text.Glyph, visibleOrBefore bool) {
+func (it *textIterator) processGlyph(g text.Glyph, ok bool) (visibleOrBefore bool) {
 	if it.maxLines > 0 {
 		if g.Flags&text.FlagTruncator != 0 && g.Flags&text.FlagClusterBreak != 0 {
 			// A glyph carrying both of these flags provides the count of truncated runes.
@@ -144,7 +144,7 @@ func (it *textIterator) processGlyph(g text.Glyph, ok bool) (_ text.Glyph, visib
 			it.linesSeen++
 		}
 		if it.linesSeen == it.maxLines && g.Flags&text.FlagParagraphBreak != 0 {
-			return g, false
+			return false
 		}
 	}
 	// Compute the maximum extent to which glyphs overhang on the horizontal
@@ -191,7 +191,7 @@ func (it *textIterator) processGlyph(g text.Glyph, ok bool) (_ text.Glyph, visib
 		it.bounds.Max.X = max(it.bounds.Max.X, logicalBounds.Max.X)
 		it.bounds.Max.Y = max(it.bounds.Max.Y, logicalBounds.Max.Y)
 	}
-	return g, ok && !below
+	return ok && !below
 }
 
 func fixedToFloat(i fixed.Int26_6) float32 {
@@ -206,7 +206,7 @@ func fixedToFloat(i fixed.Int26_6) float32 {
 // This design is awkward, but prevents the line slice from escaping
 // to the heap.
 func (it *textIterator) paintGlyph(gtx layout.Context, shaper *text.Shaper, glyph text.Glyph, line []text.Glyph) ([]text.Glyph, bool) {
-	_, visibleOrBefore := it.processGlyph(glyph, true)
+	visibleOrBefore := it.processGlyph(glyph, true)
 	if it.visible {
 		if len(line) == 0 {
 			it.lineOff = f32.Point{X: fixedToFloat(glyph.X), Y: float32(glyph.Y)}.Sub(layout.FPt(it.viewport.Min))

widget/label_test.go

@@ -146,10 +146,7 @@ func TestGlyphIterator(t *testing.T) {
 			glyphs := getGlyphs(16, 0, maxWidth, text.Start, tc.str)
 			it := textIterator{viewport: tc.viewport, maxLines: tc.maxLines}
 			for i, g := range glyphs {
-				gOut, ok := it.processGlyph(g, true)
+				ok := it.processGlyph(g, true)
-				if gOut != g {
-					t.Errorf("textIterator modified glyphs[%d], original:\n%#+v, modified:\n%#+v", i, g, gOut)
-				}
 				if !ok && i != tc.stopAtGlyph {
 					t.Errorf("expected iterator to stop at glyph %d, stopped at %d", tc.stopAtGlyph, i)
 				}

widget/text.go

@@ -492,14 +492,19 @@ func (e *textView) layoutText(lt *text.Shaper) {
 	it := textIterator{viewport: image.Rectangle{Max: image.Point{X: math.MaxInt, Y: math.MaxInt}}}
 	if lt != nil {
 		lt.Layout(e.params, r)
-		for glyph, ok := it.processGlyph(lt.NextGlyph()); ok; glyph, ok = it.processGlyph(lt.NextGlyph()) {
+		for {
-			e.index.Glyph(glyph)
+			g, ok := lt.NextGlyph()
+			if !it.processGlyph(g, ok) {
+				break
+			}
+			e.index.Glyph(g)
 		}
 	} else {
 		// Make a fake glyph for every rune in the reader.
 		b := bufio.NewReader(r)
 		for _, _, err := b.ReadRune(); err != io.EOF; _, _, err = b.ReadRune() {
-			g, _ := it.processGlyph(text.Glyph{Runes: 1, Flags: text.FlagClusterBreak}, true)
+			g := text.Glyph{Runes: 1, Flags: text.FlagClusterBreak}
+			_ = it.processGlyph(g, true)
 			e.index.Glyph(g)
 		}
 	}