some platform-specific code

go.mod

@@ -1,3 +1,5 @@
 module git.brut.systems/judah/xx
 
 go 1.25.0
+
+require github.com/ebitengine/purego v0.9.1 // indirect

go.sum

@@ -0,0 +1,2 @@
+github.com/ebitengine/purego v0.9.1 h1:a/k2f2HQU3Pi399RPW1MOaZyhKJL9w/xFpKAg4q1s0A=
+github.com/ebitengine/purego v0.9.1/go.mod h1:iIjxzd6CiRiOG0UyXP+V1+jWqUXVjPKLAI0mRfJZTmQ=

osthread/osthread.go

@@ -50,6 +50,9 @@ func Go(fn func()) {
 
 // Call schedules a function to be run on the main operating system thread, blocking until it returns.
 func Call(fn func()) {
+	if onmainthread() {
+		fn()
+	} else {
 		done := make(chan any)
 		queue <- func() {
 			defer func() {
@@ -60,6 +63,7 @@ func Call(fn func()) {
 		}
 
 		<-done
+	}
 }
 
 var queue chan func()

osthread/osthread_anyone.go

@@ -0,0 +1,7 @@
+//go:build !(windows || unix || darwin)
+
+package osthread
+
+func onmainthread() bool {
+	return false
+}

osthread/osthread_darwin.go

@@ -0,0 +1,33 @@
+//go:build darwin
+
+package osthread
+
+import "github.com/ebitengine/purego/objc"
+
+func onmainthread() bool {
+	return objc.Send[bool](objc.ID(cls_nsthread), sel_isMainThread)
+}
+
+var (
+	cls_nsthread      objc.Class
+	cls_nsapplication objc.Class
+	cls_nsapp         objc.Class
+
+	sel_isMainThread      objc.SEL
+	sel_sharedApplication objc.SEL
+	sel_run               objc.SEL
+)
+
+func init() {
+	cls_nsthread = objc.GetClass("NSThread")
+	cls_nsapplication = objc.GetClass("NSApplication")
+	cls_nsapp = objc.GetClass("NSApp")
+
+	sel_isMainThread = objc.RegisterName("isMainThread")
+	sel_sharedApplication = objc.RegisterName("sharedApplication")
+	sel_run = objc.RegisterName("run")
+
+	// Just a bit of magic
+	objc.ID(cls_nsapplication).Send(sel_sharedApplication)
+	objc.ID(cls_nsapp).Send(sel_run)
+}

osthread/osthread_linux.go

@@ -0,0 +1,26 @@
+//go:build linux
+
+package osthread
+
+import (
+	"github.com/ebitengine/purego"
+)
+
+func onmainthread() bool {
+	return getpid() == gettid()
+}
+
+var (
+	getpid func() int32
+	gettid func() int32
+)
+
+func init() {
+	libc, err := purego.Dlopen("libc.so.6", purego.RTLD_GLOBAL|purego.RTLD_NOW)
+	if err != nil {
+		panic(err)
+	}
+
+	purego.RegisterLibFunc(&getpid, libc, "getpid")
+	purego.RegisterLibFunc(&gettid, libc, "gettid")
+}

osthread/osthread_windows.go

@@ -0,0 +1,24 @@
+//go:build windows
+
+package osthread
+
+import (
+	"syscall"
+
+	"github.com/ebitengine/purego"
+)
+
+func onmainthread() bool {
+	return mainThreadId == getCurrentThreadId()
+}
+
+var (
+	mainThreadId       int32
+	getCurrentThreadId func() int32
+)
+
+func init() {
+	kernel32 := syscall.NewLazyDLL("kernel.dll").Handle()
+	purego.RegisterLibFunc(&getCurrentThreadId, kernel32, "GetCurrentThreadId")
+	mainThreadId = getCurrentThreadId()
+}