1 files changed, 86 insertions, 0 deletions
diff --git a/mux.go b/mux.go
new file mode 100644
index 0000000..cbe3488
--- /dev/null
+++ b/mux.go
@@ -0,0 +1,86 @@
+package gui
+
+import (
+	"image"
+	"image/draw"
+	"sync"
+)
+
+type Mux struct {
+	mu        sync.Mutex
+	eventsIns []chan<- Event
+	draw      chan<- func(draw.Image) image.Rectangle
+}
+
+func NewMux(env Env) (mux *Mux, master Env) {
+	drawChan := make(chan func(draw.Image) image.Rectangle)
+	mux = &Mux{draw: drawChan}
+	master = mux.makeEnv(true)
+
+	go func() {
+		for d := range drawChan {
+			env.Draw <- d
+		}
+		close(env.Draw)
+	}()
+
+	go func() {
+		for e := range env.Events {
+			mux.mu.Lock()
+			for _, eventsIn := range mux.eventsIns {
+				eventsIn <- e
+			}
+			mux.mu.Unlock()
+		}
+		mux.mu.Lock()
+		for _, eventsIn := range mux.eventsIns {
+			close(eventsIn)
+		}
+		mux.mu.Unlock()
+	}()
+
+	return mux, master
+}
+
+func (mux *Mux) MakeEnv() Env {
+	return mux.makeEnv(false)
+}
+
+func (mux *Mux) makeEnv(master bool) Env {
+	eventsOut, eventsIn := MakeEventsChan()
+	drawChan := make(chan func(draw.Image) image.Rectangle)
+	env := Env{eventsOut, drawChan}
+
+	mux.mu.Lock()
+	mux.eventsIns = append(mux.eventsIns, eventsIn)
+	mux.mu.Unlock()
+
+	go func() {
+		for d := range drawChan {
+			mux.draw <- d
+		}
+		if master {
+			mux.mu.Lock()
+			for _, eventsIn := range mux.eventsIns {
+				close(eventsIn)
+			}
+			mux.eventsIns = nil
+			close(mux.draw)
+			mux.mu.Unlock()
+		} else {
+			mux.mu.Lock()
+			i := -1
+			for i = range mux.eventsIns {
+				if mux.eventsIns[i] == eventsIn {
+					break
+				}
+			}
+			if i != -1 {
+				mux.eventsIns = append(mux.eventsIns[:i], mux.eventsIns[i+1:]...)
+			}
+			mux.mu.Unlock()
+		}
+	}()
+
+	return env
+}