From 3975c921c240692b622cde5b5aeaa7269d6af83a Mon Sep 17 00:00:00 2001
From: Pietro Gagliardi <pietro10@mac.com>
Date: Fri, 28 Feb 2014 23:01:48 -0500
Subject: [PATCH] Added the ui() for OS X.

---
 uitask_darwin.go | 115 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 115 insertions(+)
 create mode 100644 uitask_darwin.go

diff --git a/uitask_darwin.go b/uitask_darwin.go
new file mode 100644
index 0000000..8c15cf4
--- /dev/null
+++ b/uitask_darwin.go
@@ -0,0 +1,115 @@
+// 28 february 2014
+package ui
+
+import (
+	"fmt"
+	"runtime"
+	"unsafe"
+)
+
+/*
+We will create an Objective-C class goAppDelegate. It contains two methods:
+	- (void)applicationDidFinishLoading:(NSNotification *)unused
+		will signal to ui() that we are now in the Cocoa event loop; we make our goAppDelegate instance the NSApplication delegate
+	- (void)uitask:(NSValue *)functionPointer
+		the function that actually performs our UI task functions; it is called with NSObject's performSelectorOnMainThread system
+*/
+
+// #cgo LDFLAGS: -lobjc -framework Foundation -framework AppKit
+// #include "objc_darwin.h"
+// extern void appDelegate_applicationDidFinishLaunching(id, SEL, id);
+// extern void appDelegate_uitask(id, SEL, id);
+import "C"
+
+var uitask chan func()
+
+var mtret chan interface{}
+
+var (
+	_NSAutoreleasePool = objc_getClass("NSAutoreleasePool")
+	_NSValue = objc_getClass("NSValue")
+
+	_uitask = sel_getUid("uitask:")
+	_valueWithPointer = sel_getUid("valueWithPointer:")
+	_performSelectorOnMainThread =
+		sel_getUid("performSelectorOnMainThread:withObject:waitUntilDone:")
+	_pointerValue = sel_getUid("pointerValue")
+)
+
+func ui(initDone chan error) {
+	runtime.LockOSThread()
+
+	uitask = make(chan func())
+	mtret = make(chan interface{})
+	go mainThread()
+	v := <-mtret
+	if err, ok := v.(error); err {
+		initDone <- fmt.Errorf("error initializing Cocoa: %v", err)
+		return
+	}
+	appDelegate := v.(C.id)
+
+	for f := range uitask {
+		// we need to make an NSAutoreleasePool, otherwise we get leak warnings on stderr
+		pool := objc_new(_NSAutoreleasePool)
+		fp := C.objc_msgSend_ptr(_NSValue, _valueWithPointer,
+			unsafe.Pointer(&f))
+		C.objc_msgSend_sel_id_bool(
+			appDelegate,
+			_performSelectorOnMainThread,
+			_uitask,
+			fp,
+			C.BOOL(C.YES))			// wait so we can properly drain the autorelease pool; on other platforms we wind up waiting anyway (since the main thread can only handle one thing at a time) so
+		objc_release(pool)
+	}
+}
+
+const (
+	_goAppDelegate = "goAppDelegate"
+)
+
+var (
+	_NSApplication = objc_getClass("NSApplication")
+
+	_sharedApplication = sel_getUid("sharedApplication")
+	_applicationDidFinishLaunching = sel_getUid("applicationDidFinishLaunching:")
+	_run = sel_getUid("run")
+)
+
+func mainThread() {
+	runtime.LockOSThread()
+
+	_NSApp := C.objc_msgSend_noargs(_NSApplication, _sharedApplication)
+	appdelegateclass, err := makeDelegateClass(_goAppDelegate)
+	if err != nil {
+		mtret <- fmt.Errorf("error creating NSApplication delegate: %v", err)
+		return
+	}
+	err = addDelegateMethod(appdelegateclass, _applicationDidFinishLaunching,
+		C.appDelegate_applicationDidFinishLaunching)
+	if err != nil {
+		mtret <- fmt.Errorf("error adding NSApplication delegate applicationDidFinishLaunching: method (to start UI loop): %v", err)
+		return
+	}
+	err = addDelegateMethod(appdelegateclass, _uitask, C.appDelegate_uitask)
+	if err != nil {
+		mtret <- fmt.Errorf("error adding NSApplication delegate uitask: method (to do UI tasks): %v", err)
+		return
+	}
+	appDelegate := objc_new(objc_getClass(_goAppDelegate))
+	C.objc_msgSend_id(_NSApp, _setDelegate, appDelegate)
+	// and that's it, really
+	C.objc_msgSend_noargs(_NSApp, _run)
+}
+
+//export appDelegate_applicationDidFinishLaunching
+func appDelegate_applicationDidFinishLaunching(self C.id, sel C.SEL, arg C.id) {
+	mtret <- self
+}
+
+//export appDelegate_uitask
+func appDelegate_uitask(self C.id, sel C.SEL, arg C.id) {
+	p := C.objc_msgSend_noargs(arg, _pointerValue)
+	f := (*func ())(unsafe.Pointer(p))
+	(*f)()
+}