// loop is the primary drawing loop.
//
// After Cocoa has captured the initial OS thread for processing Cocoa
// events in runApp, it starts loop on another goroutine. It is locked
// to an OS thread for its OpenGL context.
//
// Two Cocoa threads deliver draw signals to loop. The primary source of
// draw events is the CVDisplayLink timer, which is tied to the display
// vsync. Secondary draw events come from [NSView drawRect:] when the
// window is resized.
func loop(ctx C.GLintptr) {
runtime.LockOSThread()
C.makeCurrentContext(ctx)
var worker gl.Worker
glctx, worker = gl.NewContext()
workAvailable := worker.WorkAvailable()
for {
select {
case <-workAvailable:
worker.DoWork()
case <-draw:
loop1:
for {
select {
case <-workAvailable:
worker.DoWork()
case <-theApp.publish:
C.CGLFlushDrawable(C.CGLGetCurrentContext())
theApp.publishResult <- PublishResult{}
break loop1
}
}
drawDone <- struct{}{}
}
}
}
func main(f func(App)) {
runtime.LockOSThread()
var worker gl.Worker
glctx, worker = gl.NewContext()
workAvailable := worker.WorkAvailable()
C.createWindow()
// TODO: send lifecycle events when e.g. the X11 window is iconified or moved off-screen.
theApp.sendLifecycle(lifecycle.StageFocused)
// TODO: translate X11 expose events to shiny paint events, instead of
// sending this synthetic paint event as a hack.
theApp.eventsIn <- paint.Event{}
donec := make(chan struct{})
go func() {
f(theApp)
close(donec)
}()
// TODO: can we get the actual vsync signal?
ticker := time.NewTicker(time.Second / 60)
defer ticker.Stop()
var tc <-chan time.Time
for {
select {
case <-donec:
return
case <-workAvailable:
worker.DoWork()
case <-theApp.publish:
C.swapBuffers()
tc = ticker.C
case <-tc:
tc = nil
theApp.publishResult <- PublishResult{}
}
C.processEvents()
}
}
func mainUI(vm, jniEnv, ctx uintptr) error {
var worker gl.Worker
glctx, worker = gl.NewContext()
workAvailable := worker.WorkAvailable()
donec := make(chan struct{})
go func() {
mainUserFn(theApp)
close(donec)
}()
var pixelsPerPt float32
var orientation size.Orientation
// Android can send a windowRedrawNeeded event any time, including
// in the middle of a paint cycle. The redraw event may have changed
// the size of the screen, so any partial painting is now invalidated.
// We must also not return to Android (via sending on windowRedrawDone)
// until a complete paint with the new configuration is complete.
//
// When a windowRedrawNeeded request comes in, we increment redrawGen
// (Gen is short for generation number), and do not make a paint cycle
// visible on <-endPaint unless Generation agrees. If possible,
// windowRedrawDone is signalled, allowing onNativeWindowRedrawNeeded
// to return.
//
// TODO: is this still needed?
var redrawGen uint32
for {
select {
case <-donec:
return nil
case cfg := <-windowConfigChange:
pixelsPerPt = cfg.pixelsPerPt
orientation = cfg.orientation
case w := <-windowRedrawNeeded:
if C.surface == nil {
if errStr := C.createEGLSurface(w); errStr != nil {
return fmt.Errorf("%s (%s)", C.GoString(errStr), eglGetError())
}
}
theApp.sendLifecycle(lifecycle.StageFocused)
widthPx := int(C.ANativeWindow_getWidth(w))
heightPx := int(C.ANativeWindow_getHeight(w))
theApp.eventsIn <- size.Event{
WidthPx: widthPx,
HeightPx: heightPx,
WidthPt: geom.Pt(float32(widthPx) / pixelsPerPt),
HeightPt: geom.Pt(float32(heightPx) / pixelsPerPt),
PixelsPerPt: pixelsPerPt,
Orientation: orientation,
}
redrawGen++
theApp.eventsIn <- paint.Event{redrawGen}
case <-windowDestroyed:
if C.surface != nil {
if errStr := C.destroyEGLSurface(); errStr != nil {
return fmt.Errorf("%s (%s)", C.GoString(errStr), eglGetError())
}
}
C.surface = nil
theApp.sendLifecycle(lifecycle.StageAlive)
case <-workAvailable:
worker.DoWork()
case <-theApp.publish:
// TODO: compare a generation number to redrawGen for stale paints?
if C.surface != nil {
// eglSwapBuffers blocks until vsync.
if C.eglSwapBuffers(C.display, C.surface) == C.EGL_FALSE {
log.Printf("app: failed to swap buffers (%s)", eglGetError())
}
}
select {
case windowRedrawDone <- struct{}{}:
default:
}
theApp.publishResult <- PublishResult{}
}
}
}