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< title > Ebiten example - highdpi< / title >
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< h2 > Ebiten example - highdpi< / h2 >
< iframe src = "highdpi.content.html" width = "640" height = "480" > < / iframe >
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< div class = "card" > < pre class = "card-body" > < code class = "language-go" > // + build example jsgo
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package main
import (
" fmt"
" image"
_ " image/jpeg"
" log"
" net/http"
" github.com/hajimehoshi/ebiten"
" github.com/hajimehoshi/ebiten/ebitenutil"
)
var (
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count int
highDPIImage *ebiten.Image
highDPIImageCh = make(chan *ebiten.Image)
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)
func init() {
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// Licensed under Public Domain
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// https://commons.wikimedia.org/wiki/File:As08-16-2593.jpg
const url = " https://upload.wikimedia.org/wikipedia/commons/1/1f/As08-16-2593.jpg"
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// Load the image asynchronously.
go func() {
res, err := http.Get(url)
if err != nil {
log.Fatal(err)
}
defer res.Body.Close()
img, _, err := image.Decode(res.Body)
if err != nil {
log.Fatal(err)
}
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eimg, err := ebiten.NewImageFromImage(img, ebiten.FilterDefault)
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if err != nil {
log.Fatal(err)
}
highDPIImageCh < - eimg
close(highDPIImageCh)
}()
}
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func update(screen *ebiten.Image) error {
if highDPIImage == nil {
// Use select and ' default' clause for non-blocking receiving.
select {
case img := < -highDPIImageCh:
highDPIImage = img
default:
}
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}
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if ebiten.IsRunningSlowly() {
return nil
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}
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if highDPIImage == nil {
ebitenutil.DebugPrint(screen, " Loading the image..." )
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return nil
}
scale := ebiten.DeviceScaleFactor()
sw, sh := screen.Size()
w, h := highDPIImage.Size()
op := & ebiten.DrawImageOptions{}
// Move the images' s center to the upper left corner.
op.GeoM.Translate(float64(-w)/2, float64(-h)/2)
// The image is just too big. Adjust the scale.
op.GeoM.Scale(0.25, 0.25)
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// Scale the image by the device ratio so that the rendering result can be same
// on various (diffrent-DPI) environments.
op.GeoM.Scale(scale, scale)
// Move the image' s center to the screen' s center.
op.GeoM.Translate(float64(sw)/2, float64(sh)/2)
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op.Filter = ebiten.FilterLinear
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screen.DrawImage(highDPIImage, op)
ebitenutil.DebugPrint(screen, fmt.Sprintf(" Device Scale Ratio: %0.2f" , scale))
return nil
}
func main() {
const (
screenWidth = 640
screenHeight = 480
)
// Pass the invert of scale so that Ebiten' s auto scaling by device scale is disabled.
s := ebiten.DeviceScaleFactor()
if err := ebiten.Run(update, int(screenWidth*s), int(screenHeight*s), 1/s, " High DPI (Ebiten Demo)" ); err != nil {
log.Fatal(err)
}
}
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< p > © 2013 Hajime Hoshi< / p >
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