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 (
"math"
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"sync/atomic"
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"github.com/hajimehoshi/ebiten/internal/loop"
"github.com/hajimehoshi/ebiten/internal/ui"
)
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// FPS represents how many times game updating happens in a second.
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const FPS = 60
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// 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 loop.CurrentFPS()
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}
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var (
isRunningSlowly = int32(0)
)
func setRunningSlowly(slow bool) {
v := int32(0)
if slow {
v = 1
}
atomic.StoreInt32(&isRunningSlowly, v)
}
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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 {
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return atomic.LoadInt32(&isRunningSlowly) != 0
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}
var theGraphicsContext atomic.Value
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// 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.
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//
// The size unit is device-independent pixel.
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func Run(f func(*Image) error, width, height int, scale float64, title string) error {
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ch := make(chan error)
go func() {
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g := newGraphicsContext(f)
theGraphicsContext.Store(g)
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if err := loop.Run(g, width, height, scale, title, FPS); err != nil {
ch <- err
}
close(ch)
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}()
// TODO: Use context in Go 1.7?
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if err := ui.RunMainThreadLoop(ch); err != nil {
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return err
}
return nil
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}
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// RunWithoutMainLoop runs the game, but don't call the loop on the main (UI) thread.
// Different from Run, this function returns immediately.
//
// Typically, Ebiten users don't have to call this directly.
// Instead, functions in github.com/hajimehoshi/ebiten/mobile module call this.
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//
// The size unit is device-independent pixel.
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func RunWithoutMainLoop(f func(*Image) error, width, height int, scale float64, title string) <-chan error {
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ch := make(chan error)
go func() {
g := newGraphicsContext(f)
theGraphicsContext.Store(g)
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if err := loop.Run(g, width, height, scale, title, FPS); err != nil {
ch <- err
}
close(ch)
}()
return ch
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}
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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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// Unit is device-independent pixel.
//
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// This function is concurrent-safe.
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func SetScreenSize(width, height int) {
if !loop.IsRunning() {
panic("ebiten: Run is not called yet")
}
if width <= 0 || height <= 0 {
panic("ebiten: width and height must be positive")
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}
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if _, err := ui.SetScreenSize(width, height); err != nil {
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panic(err)
}
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}
// SetScreenScale 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 float64) {
if !loop.IsRunning() {
panic("ebiten: Run is not called yet")
}
if scale <= 0 {
panic("ebiten: scale must be positive")
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}
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if _, err := ui.SetScreenScale(scale); err != nil {
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panic(err)
}
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}
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// ScreenScale returns the current screen scale.
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//
// If Run is not called, this returns NaN.
//
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// This function is concurrent-safe.
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func ScreenScale() float64 {
if !loop.IsRunning() {
return math.NaN()
}
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return ui.ScreenScale()
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}