ebiten/run.go

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// Copyright 2014 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 ebiten
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import (
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"errors"
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"sync"
"time"
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"github.com/hajimehoshi/ebiten/internal/ui"
)
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type runContext struct {
isRunning bool
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fps float64
newScreenWidth int
newScreenHeight int
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newScreenScale int
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isRunningSlowly bool
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m sync.RWMutex
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}
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var currentRunContext runContext
func (c *runContext) startRunning() {
c.m.Lock()
defer c.m.Unlock()
c.isRunning = true
}
func (c *runContext) endRunning() {
c.m.Lock()
defer c.m.Unlock()
c.isRunning = false
}
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func (c *runContext) FPS() float64 {
c.m.RLock()
defer c.m.RUnlock()
if !c.isRunning {
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// TODO: Should panic here?
return 0
}
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return c.fps
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}
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func (c *runContext) updateFPS(fps float64) {
c.m.Lock()
defer c.m.Unlock()
c.fps = fps
}
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func (c *runContext) IsRunningSlowly() bool {
c.m.RLock()
defer c.m.RUnlock()
if !c.isRunning {
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// TODO: Should panic here?
return false
}
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return c.isRunningSlowly
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}
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func (c *runContext) setRunningSlowly(isRunningSlowly bool) {
c.m.Lock()
defer c.m.Unlock()
c.isRunningSlowly = isRunningSlowly
}
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func (c *runContext) updateScreenSize(g *graphicsContext) error {
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c.m.Lock()
defer c.m.Unlock()
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if c.newScreenWidth == 0 && c.newScreenHeight == 0 && c.newScreenScale == 0 {
return nil
}
changed := false
if 0 < c.newScreenWidth || 0 < c.newScreenHeight {
c := ui.CurrentUI().SetScreenSize(c.newScreenWidth, c.newScreenHeight)
changed = changed || c
}
if 0 < c.newScreenScale {
c := ui.CurrentUI().SetScreenScale(c.newScreenScale)
changed = changed || c
}
if changed {
w, h := c.newScreenWidth, c.newScreenHeight
if err := g.setSize(w, h, ui.CurrentUI().ActualScreenScale()); err != nil {
return err
}
}
c.newScreenWidth = 0
c.newScreenHeight = 0
c.newScreenScale = 0
return nil
}
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func (c *runContext) SetScreenSize(width, height int) error {
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c.m.Lock()
defer c.m.Unlock()
if !c.isRunning {
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return errors.New("ebiten: SetScreenSize must be called during Run")
}
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if width <= 0 || height <= 0 {
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return errors.New("ebiten: width and height must be positive")
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}
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c.newScreenWidth = width
c.newScreenHeight = height
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return nil
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}
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func (c *runContext) SetScreenScale(scale int) error {
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c.m.Lock()
defer c.m.Unlock()
if !c.isRunning {
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return errors.New("ebiten: SetScreenScale must be called during Run")
}
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if scale <= 0 {
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return errors.New("ebiten: scale must be positive")
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}
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c.newScreenScale = scale
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return nil
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}
// FPS represents how many times game updating happens in a second.
const FPS = 60
// CurrentFPS returns the current number of frames per second of rendering.
//
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// This function is concurrent-safe.
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//
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// This value represents how many times rendering happens in 1/60 second and
// NOT how many times logical game updating (a passed function to Run) happens.
// Note that logical game updating is assured to happen 60 times in a second
// as long as the screen is active.
func CurrentFPS() float64 {
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return currentRunContext.FPS()
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}
// IsRunningSlowly returns true if the game is running too slowly to keep 60 FPS of rendering.
// The game screen is not updated when IsRunningSlowly is true.
// It is recommended to skip heavy processing, especially drawing, when IsRunningSlowly is true.
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//
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// This function is concurrent-safe.
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func IsRunningSlowly() bool {
return currentRunContext.IsRunningSlowly()
}
// Run runs the game.
// f is a function which is called at every frame.
// The argument (*Image) is the render target that represents the screen.
//
// This function must be called from the main thread.
// Note that ebiten bounds the main goroutine to the main OS thread by runtime.LockOSThread.
//
// The given function f is guaranteed to be called 60 times a second
// even if a rendering frame is skipped.
// f is not called when the screen is not shown.
func Run(f func(*Image) error, width, height, scale int, title string) error {
currentRunContext.startRunning()
defer currentRunContext.endRunning()
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if err := ui.CurrentUI().Start(width, height, scale, title); err != nil {
return err
}
defer ui.CurrentUI().Terminate()
graphicsContext, err := newGraphicsContext(width, height, ui.CurrentUI().ActualScreenScale())
if err != nil {
return err
}
frames := 0
n := ui.Now()
beforeForUpdate := n
beforeForFPS := n
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for {
// TODO: setSize should be called after swapping buffers?
if err := currentRunContext.updateScreenSize(graphicsContext); err != nil {
return err
}
if err := ui.CurrentUI().DoEvents(); err != nil {
return err
}
if ui.CurrentUI().IsClosed() {
return nil
}
now := ui.Now()
// If beforeForUpdate is too old, we assume that screen is not shown.
if int64(5*time.Second/FPS) < now-beforeForUpdate {
currentRunContext.setRunningSlowly(false)
beforeForUpdate = now
} else {
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// Note that generally t is a little different from 1/60[sec].
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t := now - beforeForUpdate
currentRunContext.setRunningSlowly(t*FPS >= int64(time.Second*5/2))
tt := int(t * FPS / int64(time.Second))
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// As t is not accurate 1/60[sec], errors are accumulated.
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// 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)/FPS-int64(5*time.Millisecond)) < t {
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tt = 1
}
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for i := 0; i < tt; i++ {
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if err := ui.CurrentUI().DoEvents(); err != nil {
return err
}
if ui.CurrentUI().IsClosed() {
return nil
}
if err := graphicsContext.update(f); err != nil {
return err
}
}
ui.CurrentUI().SwapBuffers()
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beforeForUpdate += int64(tt) * int64(time.Second) / FPS
frames++
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}
// Calc the current FPS.
if time.Second <= time.Duration(now-beforeForFPS) {
currentRunContext.updateFPS(float64(frames) * float64(time.Second) / float64(now-beforeForFPS))
beforeForFPS = now
frames = 0
}
}
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}
// SetScreenSize changes the (logical) size of the screen.
// This doesn't affect the current scale of the screen.
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//
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// This function is concurrent-safe.
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func SetScreenSize(width, height int) {
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if err := currentRunContext.SetScreenSize(width, height); err != nil {
panic(err)
}
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}
// SetScreenSize changes the scale of the screen.
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//
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// This function is concurrent-safe.
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func SetScreenScale(scale int) {
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if err := currentRunContext.SetScreenScale(scale); err != nil {
panic(err)
}
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}
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// ScreenScale returns the current screen scale.
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//
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// This function is concurrent-safe.
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func ScreenScale() int {
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return ui.CurrentUI().ScreenScale()
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}