text: [API] remove Text and Advances from Layout

These fields are no longer needed with the new text shaper.
Advances is redundant to the glyph information, and Text
should never be used during layout, as you should
traverse the cluster list instead. This commit also removed
the now-unused string field from the path LRU cache key.

References: https://todo.sr.ht/~eliasnaur/gio/146
Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

widget/editor.go

@@ -1476,8 +1476,6 @@ func nullLayout(rr io.RuneReader) ([]text.Line, error) {
 				Runes: text.Range{
 					Count: n,
 				},
-				Text:     buf.String(),
-				Advances: make([]fixed.Int26_6, n),
 			},
 		},
 	}, rerr

widget/editor_test.go

@@ -966,8 +966,14 @@ func (q *testQueue) Events(_ event.Tag) []event.Event {
 }
 
 func printLines(e *Editor) {
-	for n, line := range e.lines {
-		text := strings.TrimSuffix(line.Layout.Text, "\n")
+	for _, line := range e.lines {
+		start := e.runeOffset(line.Layout.Runes.Offset)
+		buf := make([]byte, 0, 4*line.Layout.Runes.Count)
+		e.Seek(int64(start), 0)
+		n, _ := e.Read(buf)
+		buf = buf[:n]
+		asStr := string([]rune(string(buf))[:line.Layout.Runes.Count])
+		text := strings.TrimSuffix(asStr, "\n")
 		fmt.Printf("%d: %s\n", n, text)
 	}
 }