Add text components 021-040 with demos and behavior tests

text/sevensegment.go

@@ -0,0 +1,63 @@
+package text
+
+import (
+	"fmt"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+// segments lists a..g as rects in a 7×11 cell.
+var segments = [7][4]int{{1, 0, 5, 1}, {6, 1, 1, 4}, {6, 6, 1, 4}, {1, 10, 5, 1}, {0, 6, 1, 4}, {0, 1, 1, 4}, {1, 5, 5, 1}}
+
+// lit holds each rune's segments, bit 0 for a.
+var lit = map[rune]uint8{
+	'0': 0x3F, '1': 0x06, '2': 0x5B, '3': 0x4F, '4': 0x66, '5': 0x6D,
+	'6': 0x7D, '7': 0x07, '8': 0x7F, '9': 0x6F, '-': 0x40, ' ': 0,
+}
+
+type SevenSegmentOptions struct {
+	Scale int
+	// Slot lights segments; zero means Bad.
+	Slot pixel.Slot
+}
+
+// SevenSegment shows digits, minus and colon with ghost segments.
+func SevenSegment(c *ui.Context, s string, o SevenSegmentOptions) *ui.Element {
+	k, sc := pixel.K(c), scale(o.Scale)
+	ink := slotOr(o.Slot, pixel.Bad)
+	w := 0
+	for _, r := range s {
+		w += cellW(r) + 2
+	}
+	return block(c, k, s, max(0, w-2)*sc, 11*sc, func(g pixel.Canvas) {
+		x := 0
+		for _, r := range s {
+			if r == ':' {
+				g.Rect(x+sc, 3*sc, sc, sc, ink)
+				g.Rect(x+sc, 7*sc, sc, sc, ink)
+			} else {
+				for i, sg := range segments {
+					if lit[r]&(1<<i) != 0 {
+						g.Rect(x+sg[0]*sc, sg[1]*sc, sg[2]*sc, sg[3]*sc, ink)
+					} else {
+						g.Checker(x+sg[0]*sc, sg[1]*sc, sg[2]*sc, sg[3]*sc, pixel.Faint)
+					}
+				}
+			}
+			x += (cellW(r) + 2) * sc
+		}
+	})
+}
+
+// cellW is a rune's cell width; other runes panic.
+func cellW(r rune) int {
+	if r == ':' {
+		return 3
+	}
+	if _, ok := lit[r]; !ok {
+		panic(fmt.Sprintf("text: SevenSegment cannot show %q", r))
+	}
+	return 7
+}