Add examples/filter

examples/filter/main.go

@@ -0,0 +1,71 @@
+// 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
+
+package main
+
+import (
+	_ "image/png"
+	"log"
+
+	"github.com/hajimehoshi/ebiten"
+	"github.com/hajimehoshi/ebiten/ebitenutil"
+)
+
+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() {
+	var err error
+	// 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, _, err = ebitenutil.NewImageFromFile("_resources/images/ebiten.png", ebiten.FilterDefault)
+	if err != nil {
+		log.Fatal(err)
+	}
+	if err := ebiten.Run(update, screenWidth, screenHeight, 1, "Filter (Ebiten Demo)"); err != nil {
+		log.Fatal(err)
+	}
+}

image.go

@@ -256,6 +256,9 @@ type DrawImageOptions struct {
 	// Filter is a type of texture filter.
 	// The default (zero) value is FilterDefault.
 	//
+	// Filter can also be specified at NewImage* functions, but
+	// specifying filter at DrawImageOptions is recommended (as of 1.7.0-alpha).
+	//
 	// If both Filter specified at NewImage* and DrawImageOptions are FilterDefault,
 	// FilterNearest is used.
 	// If either is FilterDefault and the other is not, the latter is used.