Add canvas, dither, sprites, clock and pixel elements

pixel/element.go

@@ -0,0 +1,147 @@
+package pixel
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/egoist/mygo/ui"
+)
+
+type TextOptions struct {
+	Slot Slot
+	// Scale is 1–4; zero means 1.
+	Scale int
+	// Wrap breaks lines at the width the layout gives.
+	Wrap     bool
+	MaxLines int
+}
+
+// Text is a pixel-font label that screen readers read.
+func Text(c *ui.Context, s string, o TextOptions) *ui.Element {
+	k := K(c)
+	scale := scaleOr1(o.Scale)
+	e := ui.Box(c).Label(s).Role(ui.RoleText)
+	width, check := 0, func(ui.Rect) {}
+	if o.Wrap {
+		width, check = WrapWidth(c, e)
+	}
+	lines := textLines(s, width/scale, o.MaxLines)
+	if o.Wrap {
+		e.Height(k.D(len(lines) * LineHeight * scale))
+	} else {
+		w := 0
+		for _, l := range lines {
+			w = max(w, Measure(l))
+		}
+		e.Size(k.D(w*scale), k.D(len(lines)*LineHeight*scale))
+	}
+	return e.Draw(func(p *ui.Painter, r ui.Rect) {
+		check(r)
+		g := k.Canvas(p, r)
+		for i, l := range lines {
+			g.Text(0, i*LineHeight*scale, l, o.Slot, scale)
+		}
+	})
+}
+
+// textLines wraps s, cutting to maxLines with an ellipsis.
+func textLines(s string, width, maxLines int) []string {
+	if maxLines < 0 {
+		panic(fmt.Sprintf("pixel: MaxLines %d", maxLines))
+	}
+	lines := Lines(s, width)
+	if maxLines == 0 || len(lines) <= maxLines {
+		return lines
+	}
+	lines = lines[:maxLines]
+	last := []rune(strings.TrimRight(lines[maxLines-1], " "))
+	for width > 0 && len(last) > 0 && Measure(string(last)+"…") > width {
+		last = last[:len(last)-1]
+	}
+	lines[maxLines-1] = string(last) + "…"
+	return lines
+}
+
+type wrapKey struct{}
+
+// WrapWidth is e's last painted width; Draw must call check.
+func WrapWidth(c *ui.Context, e *ui.Element) (int, func(r ui.Rect)) {
+	dot := K(c).dot
+	w := ui.Local(e, wrapKey{}, func() int { return 0 })
+	used := *w
+	return used, func(r ui.Rect) {
+		if now := int(r.W / dot); now != *w {
+			*w = now
+			c.Invalidate()
+		}
+	}
+}
+
+type IconOptions struct {
+	Slot  Slot
+	Scale int
+	// Label names the icon; empty hides it from assistive technology.
+	Label string
+}
+
+func Icon(c *ui.Context, sp *Sprite, o IconOptions) *ui.Element {
+	k := K(c)
+	scale := scaleOr1(o.Scale)
+	e := ui.Box(c).Size(k.D(sp.W*scale), k.D(sp.H*scale))
+	if o.Label != "" {
+		e.Label(o.Label).Role(ui.RoleImage)
+	} else {
+		e.Role(ui.RoleNone)
+	}
+	return e.Draw(func(p *ui.Painter, r ui.Rect) {
+		k.Canvas(p, r).Sprite(0, 0, sp, 0, o.Slot, scale)
+	})
+}
+
+func scaleOr1(s int) int {
+	if s == 0 {
+		return 1
+	}
+	checkScale(s)
+	return s
+}
+
+// State is how a control looks this frame.
+type State struct{ Hover, Press, Focus, Disabled bool }
+
+// Shell wraps base in an enabled box that paints.
+func Shell(c *ui.Context, base func() *ui.Element) (shell, b *ui.Element, st State) {
+	shell = ui.Box(c)
+	shell.Children(func() { b = base().Fill().FocusRing(false) })
+	st = State{Hover: b.Hovered(), Press: b.Pressed(), Focus: b.FocusVisible(), Disabled: b.IsDisabled()}
+	return shell, b, st
+}
+
+var hand = MustSprite(`
+	.eee......
+	elllleeee.
+	elllllllle
+	elllleeee.
+	elllle....
+	.eeee.....
+`)
+
+// FocusMark rings a box with dots and points a hand.
+func (g Canvas) FocusMark(x, y, w, h int) {
+	rx, ry, rw, rh := x-2, y-2, w+4, h+4
+	for i := range rw {
+		g.ant(rx+i, ry)
+		g.ant(rx+i, ry+rh-1)
+	}
+	for j := 1; j < rh-1; j++ {
+		g.ant(rx, ry+j)
+		g.ant(rx+rw-1, ry+j)
+	}
+	g.Sprite(rx-hand.W-1+g.Step(4)%2, y+(h-hand.H)/2, hand, 0, Edge, 1)
+}
+
+func (g Canvas) ant(x, y int) {
+	if (g.gx+x+g.gy+y)&1 == 0 {
+		g.Dot(x, y, Accent)
+	}
+}