Add image.DrawRect / DrawRects (leaving some bugs)

example/shapes/main.go

@@ -26,6 +26,7 @@ const (
 )
 
 func update(screen *ebiten.Image) error {
+	screen.DrawRect(0, 0, 100, 100, color.NRGBA{0x80, 0x80, 0xff, 0x80})
 	screen.FillRect(10, 10, 100, 100, color.NRGBA{0x80, 0x80, 0xff, 0x80})
 	screen.FillRect(20, 20, 100, 100, color.NRGBA{0x80, 0x80, 0xff, 0x80})
 	screen.DrawLine(130, 10, 140, 150, color.NRGBA{0xff, 0x80, 0x80, 0x80})

image.go

@@ -108,6 +108,14 @@ func (i *Image) DrawLines(lines Lines) (err error) {
 	return
 }
 
+func (i *Image) DrawRect(x, y, width, height int, clr color.Color) error {
+	return i.DrawLines(&rectsAsLines{&rect{x, y, width, height, clr}})
+}
+
+func (i *Image) DrawRects(rects Rects) error {
+	return i.DrawLines(&rectsAsLines{rects})
+}
+
 // FillRect draws a filled rectangle.
 func (i *Image) FillRect(x, y, width, height int, clr color.Color) error {
 	return i.FillRects(&rect{x, y, width, height, clr})

shapes.go

@@ -43,6 +43,33 @@ func (l *line) Color(i int) color.Color {
 	return l.color
 }
 
+type rectsAsLines struct {
+	Rects
+}
+
+func (r *rectsAsLines) Len() int {
+	return r.Rects.Len() * 4
+}
+
+func (r *rectsAsLines) Points(i int) (x0, y0, x1, y1 int) {
+	x, y, w, h := r.Rects.Rect(i / 4)
+	switch i % 4 {
+	case 0:
+		return x, y, x + w, y
+	case 1:
+		return x, y, x + 1, y + h
+	case 2:
+		return x, y + h, x + w, y + h
+	case 3:
+		return x + w, y, x + w, y + h
+	}
+	panic("not reach")
+}
+
+func (r *rectsAsLines) Color(i int) color.Color {
+	return r.Rects.Color(i / 4)
+}
+
 // A Rects represents the set of rectangles.
 type Rects interface {
 	Len() int