Add text components 021-040 with demos and behavior tests

text/highlight.go

@@ -0,0 +1,54 @@
+package text
+
+import (
+	"unicode"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type HighlightOptions struct {
+	Slot pixel.Slot
+	// Mark is the marker slot; zero means Warn.
+	Mark pixel.Slot
+}
+
+// Highlight marks each match of query in s, ignoring case.
+func Highlight(c *ui.Context, s, query string, o HighlightOptions) *ui.Element {
+	k := pixel.K(c)
+	mark := slotOr(o.Mark, pixel.Warn)
+	rs := []rune(s)
+	spans := matches(rs, []rune(query))
+	return block(c, k, s, pixel.Measure(s), pixel.LineHeight, func(g pixel.Canvas) {
+		for _, sp := range spans {
+			x0, x1 := pixel.Measure(string(rs[:sp[0]])), pixel.Measure(string(rs[:sp[1]]))
+			g.Veil(x0, 2, x1-x0, pixel.LineHeight-4, mark, 10)
+		}
+		g.Text(0, 0, s, o.Slot, 1)
+	})
+}
+
+// matches are the rune spans of q in s.
+func matches(s, q []rune) [][2]int {
+	var out [][2]int
+	if len(q) == 0 {
+		return nil
+	}
+	for i := 0; i+len(q) <= len(s); {
+		same := true
+		for j := range q {
+			if unicode.ToLower(s[i+j]) != unicode.ToLower(q[j]) {
+				same = false
+				break
+			}
+		}
+		if same {
+			out = append(out, [2]int{i, i + len(q)})
+			i += len(q)
+		} else {
+			i++
+		}
+	}
+	return out
+}