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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
package main
import (
"fmt"
_ "image/jpeg"
"log"
"github.com/hajimehoshi/ebiten"
"github.com/hajimehoshi/ebiten/ebitenutil"
)
var (
count int
highDPIImage *ebiten.Image
highDPIImageCh = make(chan *ebiten.Image)
// scale represents the device scale when the application starts.
scale = 1.0
)
func init() {
// 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"
// Load the image asynchronously.
go func() {
img, err := ebitenutil.NewImageFromURL(url)
if err != nil {
log.Fatal(err)
}
highDPIImageCh <- img
close(highDPIImageCh)
}()
}
func update(screen *ebiten.Image) 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).
// Now this example uses the device scale initialized at the beginning of this application.
if highDPIImage == nil {
// Use select and 'default' clause for non-blocking receiving.
select {
case img := <-highDPIImageCh:
highDPIImage = img
default:
}
}
if ebiten.IsDrawingSkipped() {
return nil
}
if highDPIImage == nil {
ebitenutil.DebugPrint(screen, "Loading the image...")
return nil
}
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)
// Scale the image by the device ratio so that the rendering result can be same
// on various (different-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)
op.Filter = ebiten.FilterLinear
screen.DrawImage(highDPIImage, op)
ebitenutil.DebugPrint(screen, fmt.Sprintf("(Init) 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.
//
// Note that DeviceScaleFactor cannot be called from init() functions on some environments.
scale = ebiten.DeviceScaleFactor()
s := scale
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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