Add canvas, dither, sprites, clock and pixel elements

pixel/helpers_test.go

@@ -0,0 +1,60 @@
+package pixel_test
+
+import (
+	"image"
+	"testing"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+// dots reads a Dot 2 frame, dot by dot.
+type dots struct {
+	t   *testing.T
+	img *image.RGBA
+	pal *pixel.Palette
+}
+
+// at is the slot of dot x, y.
+func (d dots) at(x, y int) pixel.Slot {
+	d.t.Helper()
+	c := d.img.RGBAAt(2*x, 2*y)
+	for _, o := range [][2]int{{1, 0}, {0, 1}, {1, 1}} {
+		if d.img.RGBAAt(2*x+o[0], 2*y+o[1]) != c {
+			d.t.Fatalf("dot %d,%d is not one color", x, y)
+		}
+	}
+	for s, pc := range d.pal.Colors {
+		if pc.R == c.R && pc.G == c.G && pc.B == c.B && c.A == 255 {
+			return pixel.Slot(s)
+		}
+	}
+	d.t.Fatalf("dot %d,%d has %v, outside the palette", x, y, c)
+	return 0
+}
+
+// count is how many dots of an area hold s.
+func (d dots) count(x, y, w, h int, s pixel.Slot) int {
+	n := 0
+	for j := range h {
+		for i := range w {
+			if d.at(x+i, y+j) == s {
+				n++
+			}
+		}
+	}
+	return n
+}
+
+// canvas draws on a w×h dot box at the top-left.
+func canvas(t *testing.T, w, h int, draw func(g pixel.Canvas)) dots {
+	t.Helper()
+	pal := pixel.SummerDay
+	tt := ui.NewTester(func(c *ui.Context) {
+		pixel.Use(c, pixel.Settings{Palette: pal, Dot: 2})
+		k := pixel.K(c)
+		ui.Box(c).Size(k.D(w), k.D(h)).Draw(func(p *ui.Painter, r ui.Rect) { draw(k.Canvas(p, r)) })
+	}, 2*w, 2*h)
+	return dots{t: t, img: tt.Image(), pal: pal}
+}