Function TestTransformImage

transform_test.go:243–391

(t *testing.T)

}

func TestTransformImage(t *testing.T) {
	// ref is a 2x2 reference image containing four colors
	ref := newImage(2, 2, red, green, blue, yellow)

	// cropRef is a 4x4 image with four colors, each in 2x2 quarter
	cropRef := newImage(4, 4, red, red, green, green, red, red, green, green, blue, blue, yellow, yellow, blue, blue, yellow, yellow)

	// use simpler filter while testing that won't skew colors
	resampleFilter = imaging.Box

	tests := []struct {
		src  image.Image // source image to transform
		opt  Options     // options to apply during transform
		want image.Image // expected transformed image
	}{
		// no transformation
		{ref, emptyOptions, ref},

		// rotations
		{ref, Options{Rotate: 45}, ref}, // invalid rotation is a noop
		{ref, Options{Rotate: 360}, ref},
		{ref, Options{Rotate: 90}, newImage(2, 2, green, yellow, red, blue)},
		{ref, Options{Rotate: 180}, newImage(2, 2, yellow, blue, green, red)},
		{ref, Options{Rotate: 270}, newImage(2, 2, blue, red, yellow, green)},
		{ref, Options{Rotate: 630}, newImage(2, 2, blue, red, yellow, green)},
		{ref, Options{Rotate: -90}, newImage(2, 2, blue, red, yellow, green)},

		// flips
		{
			ref,
			Options{FlipHorizontal: true},
			newImage(2, 2, green, red, yellow, blue),
		},
		{
			ref,
			Options{FlipVertical: true},
			newImage(2, 2, blue, yellow, red, green),
		},
		{
			ref,
			Options{FlipHorizontal: true, FlipVertical: true},
			newImage(2, 2, yellow, blue, green, red),
		},
		{
			ref,
			Options{Rotate: 90, FlipHorizontal: true},
			newImage(2, 2, yellow, green, blue, red),
		},

		// resizing
		{ // can't resize larger than original image
			ref,
			Options{Width: 100, Height: 100},
			ref,
		},
		{ // can resize larger than original image
			ref,
			Options{Width: 4, Height: 4, ScaleUp: true},