// +build example jsgo

package main

import (
        "bytes"
        "image"
        _ "image/png"
        "log"

        "github.com/hajimehoshi/ebiten"
        "github.com/hajimehoshi/ebiten/ebitenutil"
        "github.com/hajimehoshi/ebiten/examples/resources/images"
)

const (
        screenWidth  = 640
        screenHeight = 480
)

var (
        ebitenImage *ebiten.Image
)

func update(screen *ebiten.Image) error {
        if ebiten.IsRunningSlowly() {
                return nil
        }

        ebitenutil.DebugPrint(screen, "Nearest Filter (default) VS Linear Filter")

        op := &ebiten.DrawImageOptions{}
        op.GeoM.Scale(4, 4)
        op.GeoM.Translate(64, 64)
        // By default, nearest filter is used.
        screen.DrawImage(ebitenImage, op)

        op = &ebiten.DrawImageOptions{}
        op.GeoM.Scale(4, 4)
        op.GeoM.Translate(64, 64+240)
        // Specify linear filter.
        op.Filter = ebiten.FilterLinear
        screen.DrawImage(ebitenImage, op)

        return nil
}

func main() {
        // Decode image from a byte slice instead of a file so that
        // this example works in any working directory.
        // If you want to use a file, there are some options:
        // 1) Use os.Open and pass the file to the image decoder.
        //    This is a very regular way, but doesn't work on browsers.
        // 2) Use ebitenutil.OpenFile and pass the file to the image decoder.
        //    This works even on browsers.
        // 3) Use ebitenutil.NewImageFromFile to create an ebiten.Image directly from a file.
        //    This also works on browsers.
        img, _, err := image.Decode(bytes.NewReader(images.Ebiten_png))
        if err != nil {
                log.Fatal(err)
        }

        // Specifying filter on NewImage[FromImage] is just for backward compatibility.
        // Now specifying filter at DrawImageOptions is recommended.
        // Specify FilterDefault here, that means to prefer filter specified at DrawImageOptions.
        ebitenImage, _ = ebiten.NewImageFromImage(img, ebiten.FilterDefault)

        if err := ebiten.Run(update, screenWidth, screenHeight, 1, "Filter (Ebiten Demo)"); err != nil {
                log.Fatal(err)
        }
}