Add text components 021-040 with demos and behavior tests

text/rainbowtext.go

@@ -0,0 +1,30 @@
+package text
+
+import (
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+var rainbow = []pixel.Slot{pixel.Bad, pixel.Warn, pixel.Good, pixel.Info, pixel.Magic}
+
+type RainbowTextOptions struct {
+	// Band is zero for Bad, Warn, Good, Info, Magic.
+	Band  []pixel.Slot
+	Scale int
+}
+
+// RainbowText gives each character the next slot of a band.
+func RainbowText(c *ui.Context, s string, o RainbowTextOptions) *ui.Element {
+	k, sc := pixel.K(c), scale(o.Scale)
+	band := o.Band
+	if len(band) == 0 {
+		band = rainbow
+	}
+	return block(c, k, s, pixel.Measure(s)*sc, pixel.LineHeight*sc, func(g pixel.Canvas) {
+		cur := pixel.Cycle(band, g.Step(8))
+		each(s, sc, func(i int, r rune, x int) {
+			g.Text(x, 0, string(r), cur[i%len(cur)], sc)
+		})
+	})
+}