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// SPDX-License-Identifier: Unlicense OR MIT
package app
/*
#include <Foundation/Foundation.h>
__attribute__ ((visibility ("hidden"))) void gio_wakeupMainThread(void);
__attribute__ ((visibility ("hidden"))) CFTypeRef gio_createDisplayLink(void);
__attribute__ ((visibility ("hidden"))) void gio_releaseDisplayLink(CFTypeRef dl);
__attribute__ ((visibility ("hidden"))) int gio_startDisplayLink(CFTypeRef dl);
__attribute__ ((visibility ("hidden"))) int gio_stopDisplayLink(CFTypeRef dl);
__attribute__ ((visibility ("hidden"))) void gio_setDisplayLinkDisplay(CFTypeRef dl, uint64_t did);
__attribute__ ((visibility ("hidden"))) void gio_hideCursor();
__attribute__ ((visibility ("hidden"))) void gio_showCursor();
__attribute__ ((visibility ("hidden"))) void gio_setCursor(NSUInteger curID);
static bool isMainThread() {
return [NSThread isMainThread];
}
static NSUInteger nsstringLength(CFTypeRef cstr) {
NSString *str = (__bridge NSString *)cstr;
return [str length];
}
static void nsstringGetCharacters(CFTypeRef cstr, unichar *chars, NSUInteger loc, NSUInteger length) {
NSString *str = (__bridge NSString *)cstr;
[str getCharacters:chars range:NSMakeRange(loc, length)];
}
*/
import "C"
import (
"errors"
"sync"
"sync/atomic"
"time"
"unicode/utf16"
"unsafe"
"gioui.org/io/pointer"
)
// displayLink is the state for a display link (CVDisplayLinkRef on macOS,
// CADisplayLink on iOS). It runs a state-machine goroutine that keeps the
// display link running for a while after being stopped to avoid the thread
// start/stop overhead and because the CVDisplayLink sometimes fails to
// start, stop and start again within a short duration.
type displayLink struct {
callback func()
// states is for starting or stopping the display link.
states chan bool
// done is closed when the display link is destroyed.
done chan struct{}
// dids receives the display id when the callback owner is moved
// to a different screen.
dids chan uint64
// running tracks the desired state of the link. running is accessed
// with atomic.
running uint32
}
// displayLinks maps CFTypeRefs to *displayLinks.
var displayLinks sync.Map
var mainFuncs = make(chan func(), 1)
// runOnMain runs the function on the main thread.
func runOnMain(f func()) {
if C.isMainThread() {
f()
return
}
go func() {
mainFuncs <- f
C.gio_wakeupMainThread()
}()
}
//export gio_dispatchMainFuncs
func gio_dispatchMainFuncs() {
for {
select {
case f := <-mainFuncs:
f()
default:
return
}
}
}
// nsstringToString converts a NSString to a Go string, and
// releases the original string.
func nsstringToString(str C.CFTypeRef) string {
if str == 0 {
return ""
}
defer C.CFRelease(str)
n := C.nsstringLength(str)
if n == 0 {
return ""
}
chars := make([]uint16, n)
C.nsstringGetCharacters(str, (*C.unichar)(unsafe.Pointer(&chars[0])), 0, n)
utf8 := utf16.Decode(chars)
return string(utf8)
}
func NewDisplayLink(callback func()) (*displayLink, error) {
d := &displayLink{
callback: callback,
done: make(chan struct{}),
states: make(chan bool),
dids: make(chan uint64),
}
dl := C.gio_createDisplayLink()
if dl == 0 {
return nil, errors.New("app: failed to create display link")
}
go d.run(dl)
return d, nil
}
func (d *displayLink) run(dl C.CFTypeRef) {
defer C.gio_releaseDisplayLink(dl)
displayLinks.Store(dl, d)
defer displayLinks.Delete(dl)
var stopTimer *time.Timer
var tchan <-chan time.Time
started := false
for {
select {
case <-tchan:
tchan = nil
started = false
C.gio_stopDisplayLink(dl)
case start := <-d.states:
switch {
case !start && tchan == nil:
// stopTimeout is the delay before stopping the display link to
// avoid the overhead of frequently starting and stopping the
// link thread.
const stopTimeout = 500 * time.Millisecond
if stopTimer == nil {
stopTimer = time.NewTimer(stopTimeout)
} else {
// stopTimer is always drained when tchan == nil.
stopTimer.Reset(stopTimeout)
}
tchan = stopTimer.C
atomic.StoreUint32(&d.running, 0)
case start:
if tchan != nil && !stopTimer.Stop() {
<-tchan
}
tchan = nil
atomic.StoreUint32(&d.running, 1)
if !started {
started = true
C.gio_startDisplayLink(dl)
}
}
case did := <-d.dids:
C.gio_setDisplayLinkDisplay(dl, C.uint64_t(did))
case <-d.done:
return
}
}
}
func (d *displayLink) Start() {
d.states <- true
}
func (d *displayLink) Stop() {
d.states <- false
}
func (d *displayLink) Close() {
close(d.done)
}
func (d *displayLink) SetDisplayID(did uint64) {
d.dids <- did
}
//export gio_onFrameCallback
func gio_onFrameCallback(dl C.CFTypeRef) {
if d, exists := displayLinks.Load(dl); exists {
d := d.(*displayLink)
if atomic.LoadUint32(&d.running) != 0 {
d.callback()
}
}
}
// windowSetCursor updates the cursor from the current one to a new one
// and returns the new one.
func windowSetCursor(from, to pointer.CursorName) pointer.CursorName {
if from == to {
return to
}
var curID int
switch to {
default:
to = pointer.CursorDefault
fallthrough
case pointer.CursorDefault:
curID = 1
case pointer.CursorText:
curID = 2
case pointer.CursorPointer:
curID = 3
case pointer.CursorCrossHair:
curID = 4
case pointer.CursorColResize:
curID = 5
case pointer.CursorRowResize:
curID = 6
case pointer.CursorGrab:
curID = 7
case pointer.CursorNone:
C.gio_hideCursor()
return to
}
if from == pointer.CursorNone {
C.gio_showCursor()
}
C.gio_setCursor(C.NSUInteger(curID))
return to
}
func (w *window) Wakeup() {
runOnMain(func() {
w.w.Event(wakeupEvent{})
})
}
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