From f20896ef3b147ac07769eb36c67ba436c6d2ed22 Mon Sep 17 00:00:00 2001
From: Martin Ashby <martin@martin-laptop.lan>
Date: Mon, 28 May 2018 16:29:18 +0100
Subject: New unicorns for displaing animated gifs! Tests pass on both old &
 new for fakes

---
 unicorn/Unicorn2.go | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

(limited to 'unicorn/Unicorn2.go')

diff --git a/unicorn/Unicorn2.go b/unicorn/Unicorn2.go
index 716fe4d..04722f7 100644
--- a/unicorn/Unicorn2.go
+++ b/unicorn/Unicorn2.go
@@ -4,21 +4,32 @@
 package unicorn
 
 import (
+	"image"
 	"image/gif"
+	"time"
 )
 
 // Unicorn2 ...
 // Interface for interacting with the Unicorn HAT HD
 // Implemented by both real & fake unicorns.
 type Unicorn2 interface {
+	// Change the image
 	GetGif() *gif.GIF
 	SetGif(*gif.GIF)
 
+	// Starts the rendering goroutine
 	StartRender()
+
+	// Must be implemented to actually render the image to device
+	renderImage(image.Image)
+
 	// Required for os to not think we're stuck
 	MainLoop()
 }
 
+// BaseUnicorn2 ...
+// Common to both real & fake unicorns!
+// timing code for rendering & stopping rendering
 type BaseUnicorn2 struct {
 	g *gif.GIF
 }
@@ -30,3 +41,32 @@ func (u *BaseUnicorn2) GetGif() *gif.GIF {
 func (u *BaseUnicorn2) SetGif(g *gif.GIF) {
 	u.g = g
 }
+
+// StartRender ...
+// Starts rendering the image. If it's an animated image,
+// renders animation frames. Return a channel to stop the
+// image rendering.
+func (u *FakeUnicorn2) StartRender() chan bool {
+	stopChan := make(chan bool)
+	go func() {
+		timer := time.NewTimer(0)
+		imageIndex := 0
+		running := true
+		for running {
+			select {
+			case <-stopChan:
+				timer.Stop()
+				running = false
+			case <-timer.C:
+				gf := u.GetGif()
+				im := gf.Image[imageIndex]
+				delay := gf.Delay[imageIndex] //100ths of a second, 10^-2
+				u.renderImage(im)
+				
+				timer.Reset(time.Duration(delay * 10000000)) // nanoseconds 10^-9 sec
+				imageIndex = (imageIndex + 1) % len(gf.Image)
+			}
+		}
+	}()
+	return stopChan
+}
\ No newline at end of file
-- 
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