5cddc1460e
Config provides a way to concurrently access Width and Height. Register provides a way for packages to run code on app state change without plumbing changes all the way to the process main function. This is motivated by gl/glutil.Image which needs to rebuild its textures on start/stop and can be deeply nested. (See golang.org/cl/9707 for the followup.) Tested manually on android and darwin/amd64. Doing this kind makes it clear any CL modifying this code needs a lot of manual testing right now, so some kind of trybot support is something I'm going to prioritise. Fixes golang/go#10686 Fixes golang/go#10461 Fixes golang/go#10442 Fixes golang/go#10226 Updates golang/go#10327 Change-Id: I2882ebf3995b6ed857cda823e94fbb17c54b43a8 Reviewed-on: https://go-review.googlesource.com/9708 Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
107 lines
2.7 KiB
Go
107 lines
2.7 KiB
Go
// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package app
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/*
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There are three notions of state at work in this package.
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The first is Unix process state. Because mobile devices can be compiled
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as -buildmode=c-shared and -buildmode=c-archive, there is code in this
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package executed by global constructor which runs before (and even is
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reponsible for triggering) the Go main function call. This is tracked
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by the mainCalled channel.
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The second is runState. An app may "Start" and "Stop" multiple times
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over the life of the unix process. This involes the creation and
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destruction of OpenGL windows and calling user Callbacks. Some user
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functions must block in the stop state.
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The third is Config, user-visible app configuration. It is only
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available after the app has started.
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*/
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import (
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"sync"
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"golang.org/x/mobile/geom"
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)
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// mainCalled is closed after the Go main and app.Run functions have
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// been called. This happens before an app enters the start state and
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// may happen before a window is created (on android).
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var mainCalled = make(chan struct{})
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var (
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configCurMu sync.Mutex // guards configCur pointer, not contents
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configCur Config
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configAlt Config // used to stage new state
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)
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func init() {
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// Configuration is not available while the app is stopped,
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// so we begin the program with configCurMu locked. It will
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// be locked whenever !running.
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configCurMu.Lock()
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}
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var (
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running = false
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startFuncs []func()
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stopFuncs []func()
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)
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func stateStart(callbacks []Callbacks) {
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if running {
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return
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}
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running = true
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configCurMu.Unlock() // GetConfig is now available
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for _, cb := range callbacks {
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if cb.Start != nil {
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cb.Start()
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}
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}
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}
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func stateStop(callbacks []Callbacks) {
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if !running {
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return
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}
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running = false
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configCurMu.Lock() // GetConfig is no longer available
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for _, cb := range callbacks {
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if cb.Stop != nil {
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cb.Stop()
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}
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}
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}
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// configSwap is called to replace configCur with configAlt and if
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// necessary inform the running the app. Calls to configSwap must be
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// made after updating configAlt.
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func configSwap(callbacks []Callbacks) {
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if !running {
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// configCurMu is already locked, and no-one else
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// is around to look at configCur, so we modify it
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// directly.
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configCur = configAlt
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geom.Width, geom.Height = configCur.Width, configCur.Height // TODO: remove
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return
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}
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configCurMu.Lock()
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old := configCur
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configCur = configAlt
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configCurMu.Unlock()
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geom.Width, geom.Height = configCur.Width, configCur.Height // TODO: remove
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for _, cb := range callbacks {
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if cb.Config != nil {
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cb.Config(configCur, old)
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}
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}
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}
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