Add text components 021-040 with demos and behavior tests

text/gradienttext.go

@@ -0,0 +1,22 @@
+package text
+
+import (
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type GradientTextOptions struct {
+	// Top is zero for AccentLit; Bottom is zero for Accent.
+	Top, Bottom pixel.Slot
+	Scale       int
+}
+
+// GradientText dithers glyph dots from Top down to Bottom.
+func GradientText(c *ui.Context, s string, o GradientTextOptions) *ui.Element {
+	k, sc := pixel.K(c), scale(o.Scale)
+	top, bottom := slotOr(o.Top, pixel.AccentLit), slotOr(o.Bottom, pixel.Accent)
+	return block(c, k, s, pixel.Measure(s)*sc, pixel.LineHeight*sc, func(g pixel.Canvas) {
+		g.TextBlend(0, 0, s, top, bottom, sc)
+	})
+}