ebiten/examples/highdpi/main.go

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// Copyright 2018 The Ebiten Authors
//
// 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.
// +build example jsgo
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package main
import (
"fmt"
_ "image/jpeg"
"log"
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"github.com/hajimehoshi/ebiten/v2"
"github.com/hajimehoshi/ebiten/v2/ebitenutil"
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)
var (
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highDPIImageCh = make(chan *ebiten.Image)
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)
func init() {
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// Licensed under Public Domain
// 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() {
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img, err := ebitenutil.NewImageFromURL(url)
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if err != nil {
log.Fatal(err)
}
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highDPIImageCh <- img
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close(highDPIImageCh)
}()
}
type Game struct {
highDPIImage *ebiten.Image
}
func (g *Game) Update() error {
// TODO: DeviceScaleFactor() might return different values for different monitors.
// Add a mode to adjust the screen size along with the current device scale (#705).
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// Now this example uses the device scale initialized at the beginning of this application.
if g.highDPIImage != nil {
return nil
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}
// Use select and 'default' clause for non-blocking receiving.
select {
case img := <-highDPIImageCh:
g.highDPIImage = img
default:
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}
return nil
}
func (g *Game) Draw(screen *ebiten.Image) {
if g.highDPIImage == nil {
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ebitenutil.DebugPrint(screen, "Loading the image...")
return
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}
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sw, sh := screen.Size()
w, h := g.highDPIImage.Size()
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op := &ebiten.DrawImageOptions{}
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// Move the images's center to the upper left corner.
op.GeoM.Translate(float64(-w)/2, float64(-h)/2)
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// 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
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// on various (different-DPI) environments.
scale := ebiten.DeviceScaleFactor()
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op.GeoM.Scale(scale, scale)
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// Move the image's center to the screen's center.
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op.GeoM.Translate(float64(sw)/2, float64(sh)/2)
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op.Filter = ebiten.FilterLinear
screen.DrawImage(g.highDPIImage, op)
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ebitenutil.DebugPrint(screen, fmt.Sprintf("(Init) Device Scale Ratio: %0.2f", scale))
}
func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
// The unit of outsideWidth/Height is device-independent pixels.
// By multiplying them by the device scale factor, we can get a hi-DPI screen size.
s := ebiten.DeviceScaleFactor()
return int(float64(outsideWidth) * s), int(float64(outsideHeight) * s)
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}
func main() {
ebiten.SetWindowSize(640, 480)
ebiten.SetWindowTitle("High DPI (Ebiten Demo)")
if err := ebiten.RunGame(&Game{}); err != nil {
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log.Fatal(err)
}
}