graphics: Refactoring

image.go

@@ -377,12 +377,9 @@ func NewImage(width, height int, filter Filter) (*Image, error) {
 // Note that volatile images are internal only and will never be source of drawing.
 //
 // If width or height is less than 1 or more than device-dependent maximum size, newVolatileImage panics.
-//
-// Error returned by newVolatileImage is always nil as of 1.5.0-alpha.
 func newVolatileImage(width, height int) *Image {
 	i := &Image{
 		shareableImage: shareable.NewVolatileImage(width, height),
-		filter:         FilterDefault,
 	}
 	i.addr = i
 	runtime.SetFinalizer(i, (*Image).Dispose)

image_test.go

@@ -622,8 +622,8 @@ func BenchmarkDrawImage(b *testing.B) {
 }
 
 func TestImageLinear(t *testing.T) {
-	src, _ := NewImage(32, 32, FilterLinear)
-	dst, _ := NewImage(64, 64, FilterNearest)
+	src, _ := NewImage(32, 32, FilterDefault)
+	dst, _ := NewImage(64, 64, FilterDefault)
 	src.Fill(color.RGBA{0, 0xff, 0, 0xff})
 	ebitenutil.DrawRect(src, 8, 8, 16, 16, color.RGBA{0xff, 0, 0, 0xff})
 
@@ -632,6 +632,7 @@ func TestImageLinear(t *testing.T) {
 	op.GeoM.Scale(2, 2)
 	r := image.Rect(8, 8, 24, 24)
 	op.SourceRect = &r
+	op.Filter = FilterLinear
 	dst.DrawImage(src, op)
 
 	for j := 0; j < 64; j++ {