ebiten/docs/examples/highdpi.html
2018-01-29 23:39:30 +09:00

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<h2>Ebiten example - highdpi</h2>
<iframe src="highdpi.content.html" width="640" height="480"></iframe>
<div class="card"><pre class="card-body"><code class="language-go">// &#43;build example
package main
import (
&#34;fmt&#34;
&#34;image&#34;
_ &#34;image/jpeg&#34;
&#34;log&#34;
&#34;net/http&#34;
&#34;github.com/hajimehoshi/ebiten&#34;
&#34;github.com/hajimehoshi/ebiten/ebitenutil&#34;
)
var (
count int
highDPIImage *ebiten.Image
highDPIImageCh = make(chan *ebiten.Image)
)
func init() {
// Licensed under Public Domain
// https://commons.wikimedia.org/wiki/File:As08-16-2593.jpg
const url = &#34;https://upload.wikimedia.org/wikipedia/commons/1/1f/As08-16-2593.jpg&#34;
// 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)
}
eimg, err := ebiten.NewImageFromImage(img, ebiten.FilterLinear)
if err != nil {
log.Fatal(err)
}
highDPIImageCh &lt;- eimg
close(highDPIImageCh)
}()
}
func update(screen *ebiten.Image) error {
if highDPIImage == nil {
// Use select and &#39;default&#39; clause for non-blocking receiving.
select {
case img := &lt;-highDPIImageCh:
highDPIImage = img
default:
}
}
if ebiten.IsRunningSlowly() {
return nil
}
if highDPIImage == nil {
ebitenutil.DebugPrint(screen, &#34;Loading the image...&#34;)
return nil
}
scale := ebiten.DeviceScaleFactor()
sw, sh := screen.Size()
w, h := highDPIImage.Size()
op := &amp;ebiten.DrawImageOptions{}
// Move the images&#39;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)
// 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&#39;s center to the screen&#39;s center.
op.GeoM.Translate(float64(sw)/2, float64(sh)/2)
screen.DrawImage(highDPIImage, op)
ebitenutil.DebugPrint(screen, fmt.Sprintf(&#34;Device Scale Ratio: %0.2f&#34;, scale))
return nil
}
func main() {
const (
screenWidth = 640
screenHeight = 480
)
// Pass the invert of scale so that Ebiten&#39;s auto scaling by device scale is disabled.
s := ebiten.DeviceScaleFactor()
if err := ebiten.Run(update, int(screenWidth*s), int(screenHeight*s), 1/s, &#34;High DPI (Ebiten Demo)&#34;); err != nil {
log.Fatal(err)
}
}
</code></pre></div>
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