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|
// 11 february 2014
package ui
import (
"syscall"
"unsafe"
"runtime"
)
/*
problem: messages have to be dispatched on the same thread as system calls, and we can't mux GetMessage() with select, and PeekMessage() every iteration is wasteful (and leads to lag for me (only) with the concurrent garbage collector sweep)
solution: use PostThreadMessage() to send uimsgs out to the message loop, which runs on its own goroutine
I had come up with this first but wanted to try other things before doing it (and wasn't really sure if user-defined messages were safe, not quite understanding the system); nsf came up with it independently and explained that this was really the only right way to do it, so thanks to him
*/
var uitask chan *uimsg
type uimsg struct {
call *syscall.LazyProc
p []uintptr
ret chan uiret
}
type uiret struct {
ret uintptr
err error
}
const (
_WM_APP = 0x8000 + iota
msgRequested
msgQuit
msgSetAreaSize
)
var (
_getCurrentThreadID = kernel32.NewProc("GetCurrentThreadId")
_postThreadMessage = user32.NewProc("PostThreadMessageW")
)
func ui(main func()) error {
runtime.LockOSThread()
uitask = make(chan *uimsg)
err := doWindowsInit()
if err != nil {
return err
}
threadID, _, _ := _getCurrentThreadID.Call()
go func() {
for m := range uitask {
r1, _, err := _postThreadMessage.Call(
threadID,
msgRequested,
uintptr(0),
uintptr(unsafe.Pointer(m)))
if r1 == 0 { // failure
panic("error sending message to message loop to call function: " + err.Error())
}
}
}()
go func() {
main()
r1, _, err := _postThreadMessage.Call(
threadID,
msgQuit,
uintptr(0),
uintptr(0))
if r1 == 0 { // failure
panic("error sending quit message to message loop: " + err.Error())
}
}()
msgloop()
doWindowsQuitStuff()
return nil
}
var (
_dispatchMessage = user32.NewProc("DispatchMessageW")
_getMessage = user32.NewProc("GetMessageW")
_postQuitMessage = user32.NewProc("PostQuitMessage")
_sendMessage = user32.NewProc("SendMessageW")
_translateMessage = user32.NewProc("TranslateMessage")
)
var getMessageFail = -1 // because Go doesn't let me
func msgloop() {
var msg struct {
Hwnd _HWND
Message uint32
WParam _WPARAM
LParam _LPARAM
Time uint32
Pt _POINT
}
for {
r1, _, err := _getMessage.Call(
uintptr(unsafe.Pointer(&msg)),
uintptr(_NULL),
uintptr(0),
uintptr(0))
if r1 == uintptr(getMessageFail) { // error
panic("error getting message in message loop: " + err.Error())
}
if r1 == 0 { // WM_QUIT message
return
}
if msg.Message == msgRequested {
m := (*uimsg)(unsafe.Pointer(msg.LParam))
r1, _, err := m.call.Call(m.p...)
m.ret <- uiret{
ret: r1,
err: err,
}
continue
}
if msg.Message == msgQuit {
// does not return a value according to MSDN
_postQuitMessage.Call(0)
continue
}
_translateMessage.Call(uintptr(unsafe.Pointer(&msg)))
_dispatchMessage.Call(uintptr(unsafe.Pointer(&msg)))
}
}
|
