ebiten/internal/loop/run.go

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// Copyright 2016 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
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package loop
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import (
"sync"
"time"
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"github.com/hajimehoshi/ebiten/internal/ui"
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)
func CurrentFPS() float64 {
return currentRunContext.currentFPS()
}
func IsRunning() bool {
return currentRunContext.isRunning()
}
func IsRunningSlowly() bool {
return currentRunContext.isRunningSlowly()
}
type runContext struct {
running bool
fps float64
runningSlowly bool
m sync.RWMutex
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}
var currentRunContext runContext
func (c *runContext) startRunning() {
c.m.Lock()
defer c.m.Unlock()
c.running = true
}
func (c *runContext) isRunning() bool {
c.m.Lock()
defer c.m.Unlock()
return c.running
}
func (c *runContext) endRunning() {
c.m.Lock()
defer c.m.Unlock()
c.running = false
}
func (c *runContext) currentFPS() float64 {
c.m.RLock()
defer c.m.RUnlock()
if !c.running {
// TODO: Should panic here?
return 0
}
return c.fps
}
func (c *runContext) updateFPS(fps float64) {
c.m.Lock()
defer c.m.Unlock()
c.fps = fps
}
func (c *runContext) isRunningSlowly() bool {
c.m.RLock()
defer c.m.RUnlock()
if !c.running {
// TODO: Should panic here?
return false
}
return c.runningSlowly
}
func (c *runContext) setRunningSlowly(isRunningSlowly bool) {
c.m.Lock()
defer c.m.Unlock()
c.runningSlowly = isRunningSlowly
}
type GraphicsContext interface {
SetSize(width, height, scale int) error
Update() error
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Pause() error
Resume() error
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}
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func Run(g GraphicsContext, width, height, scale int, title string, fps int) error {
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currentRunContext.startRunning()
defer currentRunContext.endRunning()
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if err := ui.CurrentUI().Start(width, height, scale, title); err != nil {
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return err
}
// TODO: Use the error value
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defer ui.CurrentUI().Terminate()
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frames := 0
n := now()
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beforeForUpdate := n
beforeForFPS := n
for {
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e, err := ui.CurrentUI().Update()
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if err != nil {
return err
}
switch e := e.(type) {
case ui.ScreenSizeEvent:
if err := g.SetSize(e.Width, e.Height, e.ActualScale); err != nil {
return err
}
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case ui.CloseEvent:
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return nil
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case ui.RenderEvent:
n2 := now()
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// If beforeForUpdate is too old, we assume that screen is not shown.
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if 5*int64(time.Second)/int64(fps) < n2-beforeForUpdate {
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currentRunContext.setRunningSlowly(false)
beforeForUpdate = n2
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} else {
// Note that generally t is a little different from 1/60[sec].
t := n2 - beforeForUpdate
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currentRunContext.setRunningSlowly(t*int64(fps) >= int64(time.Second*5/2))
tt := int(t * int64(fps) / int64(time.Second))
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// As t is not accurate 1/60[sec], errors are accumulated.
// To make the FPS stable, set tt 1 if t is a little less than 1/60[sec].
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if tt == 0 && (int64(time.Second)/int64(fps)-int64(5*time.Millisecond)) < t {
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tt = 1
}
for i := 0; i < tt; i++ {
if err := g.Update(); err != nil {
return err
}
}
if err := ui.CurrentUI().SwapBuffers(); err != nil {
return err
}
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beforeForUpdate += int64(tt) * int64(time.Second) / int64(fps)
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frames++
}
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if err := ui.CurrentUI().FinishRendering(); err != nil {
return err
}
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// Calc the current FPS.
if time.Second <= time.Duration(n2-beforeForFPS) {
currentRunContext.updateFPS(float64(frames) * float64(time.Second) / float64(n2-beforeForFPS))
beforeForFPS = n2
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frames = 0
}
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case ui.PauseEvent:
if err := g.Pause(); err != nil {
return err
}
case ui.ResumeEvent:
if err := g.Resume(); err != nil {
return err
}
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default:
panic("not reach")
}
}
}