Add text components 021-040 with demos and behavior tests

text/paragraph.go

@@ -0,0 +1,52 @@
+package text
+
+import (
+	"fmt"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type Align uint8
+
+const (
+	Left Align = iota
+	Center
+	Right
+)
+
+type ParagraphOptions struct {
+	// Gap is extra dots between lines.
+	Gap      int
+	Align    Align
+	MaxLines int
+	Slot     pixel.Slot
+}
+
+// Paragraph wraps s at the width it had last frame.
+func Paragraph(c *ui.Context, s string, o ParagraphOptions) *ui.Element {
+	k := pixel.K(c)
+	gap := orDef("Paragraph Gap", o.Gap, 0)
+	if o.Align > Right {
+		panic(fmt.Sprintf("text: unknown Align %d", o.Align))
+	}
+	e := ui.Box(c).FillWidth().Label(s).Role(ui.RoleText)
+	w, check := pixel.WrapWidth(c, e)
+	lines := pixel.Wrap(s, w, o.MaxLines)
+	step := pixel.LineHeight + gap
+	return e.Height(k.D(max(0, len(lines)*step-gap))).Draw(func(p *ui.Painter, r ui.Rect) {
+		check(r)
+		g := k.Canvas(p, r)
+		for i, l := range lines {
+			x := 0
+			switch o.Align {
+			case Center:
+				x = (g.W - pixel.Measure(l)) / 2
+			case Right:
+				x = g.W - pixel.Measure(l)
+			}
+			g.Text(x, i*step, l, o.Slot, 1)
+		}
+	})
+}