From 40b62517bc5c2435178224783755a0ae3344480a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?M=C3=A1ximo=20Cuadros?= <mcuadros@gmail.com>
Date: Fri, 10 Mar 2017 01:53:47 +0100
Subject: [PATCH] emulator: canvas emulator based on shiny

---
 emulator/emulator.go | 128 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 128 insertions(+)
 create mode 100644 emulator/emulator.go

diff --git a/emulator/emulator.go b/emulator/emulator.go
new file mode 100644
index 0000000..4c837ac
--- /dev/null
+++ b/emulator/emulator.go
@@ -0,0 +1,128 @@
+package emulator
+
+import (
+	"image"
+	"image/color"
+	"log"
+
+	"sync"
+
+	"golang.org/x/exp/shiny/driver"
+	"golang.org/x/exp/shiny/imageutil"
+	"golang.org/x/exp/shiny/screen"
+	"golang.org/x/mobile/event/paint"
+	"golang.org/x/mobile/event/size"
+)
+
+var (
+	black = color.RGBA{0x00, 0x00, 0x00, 0xff}
+	red   = color.RGBA{0x7f, 0x00, 0x00, 0x7f}
+)
+
+var margin = 10
+
+type Emulator struct {
+	PixelPitch int
+	Gutter     int
+	Width      int
+	Height     int
+
+	leds    []color.Color
+	w       screen.Window
+	isReady bool
+
+	wg sync.WaitGroup
+}
+
+func (e *Emulator) Init() {
+	e.leds = make([]color.Color, 2048)
+
+	e.wg.Add(1)
+	go e.init()
+	e.wg.Wait()
+}
+
+func (e *Emulator) init() {
+	driver.Main(func(s screen.Screen) {
+		var err error
+		e.w, err = s.NewWindow(&screen.NewWindowOptions{
+			Title: "Basic Shiny Example",
+		})
+
+		if err != nil {
+			panic(err)
+		}
+
+		defer e.w.Release()
+
+		var sz size.Event
+		for {
+			evn := e.w.NextEvent()
+			switch evn := evn.(type) {
+			case paint.Event:
+				for _, r := range imageutil.Border(sz.Bounds(), margin) {
+					e.w.Fill(r, red, screen.Src)
+				}
+
+				e.w.Fill(sz.Bounds().Inset(margin), black, screen.Src)
+				e.w.Publish()
+				if e.isReady {
+					continue
+				}
+
+				e.Apply(make([]color.Color, 2048))
+				e.wg.Done()
+				e.isReady = true
+			case size.Event:
+				sz = evn
+
+			case error:
+				log.Print(e)
+			}
+		}
+	})
+}
+
+func (e *Emulator) Geometry() (width, height int) {
+	return e.Width, e.Height
+}
+
+func (e *Emulator) Apply(leds []color.Color) error {
+	defer func() { e.leds = make([]color.Color, 2048) }()
+
+	for col := 0; col < e.Width; col++ {
+		for row := 0; row < e.Height; row++ {
+			x := col * (e.PixelPitch + e.Gutter)
+			y := row * (e.PixelPitch + e.Gutter)
+
+			x += margin * 2
+			y += margin * 2
+
+			c := e.At(col + (row * e.Width))
+			e.w.Fill(image.Rect(x, y, x+e.PixelPitch, y+e.PixelPitch), c, screen.Over)
+		}
+	}
+
+	e.w.Publish()
+	return nil
+}
+
+func (e *Emulator) Render() error {
+	return e.Apply(e.leds)
+}
+
+func (e *Emulator) At(position int) color.Color {
+	if e.leds[position] == nil {
+		return color.Black
+	}
+
+	return e.leds[position]
+}
+
+func (e *Emulator) Set(position int, c color.Color) {
+	e.leds[position] = color.RGBAModel.Convert(c)
+}
+
+func (e *Emulator) Close() error {
+	return nil
+}