diff --git a/examples/minify/main.go b/examples/minify/main.go new file mode 100644 index 000000000..707441788 --- /dev/null +++ b/examples/minify/main.go @@ -0,0 +1,92 @@ +// 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 + +// This example is an experiment to minify images with various filters. +// When linear filter is used, mipmap images should be used for high-quality rendering (#578). + +package main + +import ( + "bytes" + "image" + _ "image/jpeg" + "log" + "math" + + "github.com/hajimehoshi/ebiten" + "github.com/hajimehoshi/ebiten/ebitenutil" + "github.com/hajimehoshi/ebiten/examples/resources/images" +) + +const ( + screenWidth = 640 + screenHeight = 800 +) + +var ( + gophersImage *ebiten.Image +) + +func update(screen *ebiten.Image) error { + if ebiten.IsDrawingSkipped() { + return nil + } + + ebitenutil.DebugPrint(screen, "Minifying images (Nearest filter vs Linear filter)") + + for i, f := range []ebiten.Filter{ebiten.FilterNearest, ebiten.FilterLinear} { + y := 0 + for j := 0; j < 12; j++ { + w, h := gophersImage.Size() + + op := &ebiten.DrawImageOptions{} + s := 1.0 / math.Pow(2, float64(j)/2) + op.GeoM.Scale(s, s) + op.GeoM.Translate(32+float64(i*(w+4)), 32+float64(y)) + op.Filter = f + screen.DrawImage(gophersImage, op) + + y += int(float64(h)*s) + 4 + } + } + + 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.Gophers_jpg)) + 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. + gophersImage, _ = ebiten.NewImageFromImage(img, ebiten.FilterDefault) + + if err := ebiten.Run(update, screenWidth, screenHeight, 1, "Minify (Ebiten Demo)"); err != nil { + log.Fatal(err) + } +}