Add display components 041-065; move Icon into display; QR via rsc.io/qr

display/placeholder.go

@@ -0,0 +1,36 @@
+package display
+
+import (
+	"fmt"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type PlaceholderOptions struct {
+	// W×H is zero for 64×48 dots.
+	W, H int
+}
+
+// Placeholder is a dithered box with a cross and size.
+func Placeholder(c *ui.Context, o PlaceholderOptions) *ui.Element {
+	k := pixel.K(c)
+	w, h := orDef("Placeholder W", o.W, 64), orDef("Placeholder H", o.H, 48)
+	size := fmt.Sprintf("%d×%d", w, h)
+	return art(c, k, size, w, h, func(g pixel.Canvas) {
+		if w < 3 || h < 3 {
+			g.Dither(0, 0, w, h, pixel.Face, pixel.Shade, 4)
+			return
+		}
+		g.Frame(0, 0, w, h, pixel.Flat, pixel.Face)
+		g.Dither(1, 1, w-2, h-2, pixel.Face, pixel.Shade, 4)
+		g.Line(1, 1, w-2, h-2, pixel.Shade)
+		g.Line(w-2, 1, 1, h-2, pixel.Shade)
+		tw := pixel.Measure(size)
+		if tw+4 <= w && pixel.LineHeight <= h {
+			g.Rect((w-tw)/2-2, (h-pixel.LineHeight)/2, tw+4, pixel.LineHeight, pixel.Face)
+			g.Text((w-tw)/2, (h-pixel.LineHeight)/2, size, pixel.Faint, 1)
+		}
+	})
+}