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// 11 december 2015
package ui
import (
"runtime"
"errors"
"sync"
"unsafe"
)
// #include "ui.h"
// extern void doQueued(void *);
// extern int doOnShouldQuit(void *);
// /* I forgot how dumb cgo is... ./main.go:73: cannot use _Cgo_ptr(_Cfpvar_fp_doQueued) (type unsafe.Pointer) as type *[0]byte in argument to _Cfunc_uiQueueMain */
// /* I'm pretty sure this worked before... */
// static inline void realQueueMain(void *x)
// {
// uiQueueMain(doQueued, x);
// }
// static inline int realOnShouldQuit(void)
// {
// uiOnShouldQuit(doOnShouldQuit, NULL);
// }
import "C"
// Main initializes package ui, runs f to set up the program,
// and executes the GUI main loop. f should set up the program's
// initial state: open the main window, create controls, and set up
// events. It should then return, at which point Main will
// process events until Quit is called, at which point Main will return
// nil. If package ui fails to initialize, Main returns an appropriate
// error.
func Main(f func()) error {
errchan := make(chan error)
go start(errchan, f)
return <-errchan
}
func start(errchan chan error, f func()) {
runtime.LockOSThread()
// TODO set main thread on OS X
// TODO HEAP SAFETY
opts := C.uiInitOptions{}
estr := C.uiInit(&opts)
if estr != nil {
errchan <- errors.New(C.GoString(estr))
C.uiFreeInitError(estr)
return
}
// set up OnShouldQuit()
C.realOnShouldQuit()
QueueMain(f)
C.uiMain()
errchan <- nil
}
// Quit queues an exit from the GUI thread. It does not exit the
// program. Quit must be called from the GUI thread.
func Quit() {
C.uiQuit()
}
// These prevent the passing of Go functions into C land.
// TODO make an actual sparse list instead of this monotonic map thingy
var (
qmmap = make(map[uintptr]func())
qmcurrent = uintptr(0)
qmlock sync.Mutex
)
// QueueMain queues f to be executed on the GUI thread when
// next possible. It returns immediately; that is, it does not wait
// for the function to actually be executed. QueueMain is the only
// function that can be called from other goroutines, and its
// primary purpose is to allow communication between other
// goroutines and the GUI thread. Calling QueueMain after Quit
// has been called results in undefined behavior.
func QueueMain(f func()) {
qmlock.Lock()
defer qmlock.Unlock()
n := qmcurrent
qmcurrent++
qmmap[n] = f
C.realQueueMain(unsafe.Pointer(n))
}
//export doQueued
func doQueued(nn unsafe.Pointer) {
qmlock.Lock()
n := uintptr(nn)
f := qmmap[n]
delete(qmmap, n)
// allow uiQueueMain() to be called by a queued function
// TODO explicitly allow this in libui too
qmlock.Unlock()
f()
}
// no need to lock this; this API is only safe on the main thread
var shouldQuitFunc func() bool
// OnShouldQuit schedules f to be exeucted when the OS wants
// the program to quit or when a Quit menu item has been clicked.
// Only one function may be registered at a time. If the function
// returns true, Quit will be called. If the function returns false, or
// if OnShouldQuit is never called. Quit will not be called and the
// OS will be told that the program needs to continue running.
func OnShouldQuit(f func() bool) {
shouldQuitFunc = f
}
//export doOnShouldQuit
func doOnShouldQuit(unused unsafe.Pointer) C.int {
if shouldQuitFunc == nil {
return 0
}
return frombool(shouldQuitFunc())
}
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