aw/go-resize
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Don't resize inputs with zero width or height

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Inputs having zero as both width and height were caught, but either one
alone caused a panic. This adds a test showing the old failing behavior
and adds a check for non-positive width/height. Since Resize doesn't
have an error return value, the behavior in this case is to return the
original image.

Fixes https://github.com/nfnt/resize/issues/52
This commit is contained in:
Adam Thomason 2016-11-15 15:39:27 -08:00
parent 891127d8d1
commit 874f89dba4
2 changed files with 20 additions and 0 deletions
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6
resize.go
View File

@ -78,6 +78,7 @@ var blur = 1.0
// If one of the parameters width or height is set to 0, its size will be calculated so that // If one of the parameters width or height is set to 0, its size will be calculated so that
// the aspect ratio is that of the originating image. // the aspect ratio is that of the originating image.
// The resizing algorithm uses channels for parallel computation. // The resizing algorithm uses channels for parallel computation.
// If the input image has width or height of 0, it is returned unchanged.
func Resize(width, height uint, img image.Image, interp InterpolationFunction) image.Image { func Resize(width, height uint, img image.Image, interp InterpolationFunction) image.Image {
scaleX, scaleY := calcFactors(width, height, float64(img.Bounds().Dx()), float64(img.Bounds().Dy())) scaleX, scaleY := calcFactors(width, height, float64(img.Bounds().Dx()), float64(img.Bounds().Dy()))
if width == 0 { if width == 0 {
@ -92,6 +93,11 @@ func Resize(width, height uint, img image.Image, interp InterpolationFunction) i
return img return img
} }
// Input image has no pixels
if img.Bounds().Dx() <= 0 || img.Bounds().Dy() <= 0 {
return img
}
if interp == NearestNeighbor { if interp == NearestNeighbor {
return resizeNearest(width, height, scaleX, scaleY, img, interp) return resizeNearest(width, height, scaleX, scaleY, img, interp)
} }

14
resize_test.go
View File

@ -37,6 +37,20 @@ func Test_ZeroImg(t *testing.T) {
} }
} }
func Test_HalfZeroImg(t *testing.T) {
zeroImg := image.NewGray16(image.Rect(0, 0, 0, 100))
m := Resize(0, 1, zeroImg, NearestNeighbor)
if m.Bounds() != zeroImg.Bounds() {
t.Fail()
}
m = Resize(1, 0, zeroImg, NearestNeighbor)
if m.Bounds() != zeroImg.Bounds() {
t.Fail()
}
}
func Test_CorrectResize(t *testing.T) { func Test_CorrectResize(t *testing.T) {
zeroImg := image.NewGray16(image.Rect(0, 0, 256, 256)) zeroImg := image.NewGray16(image.Rect(0, 0, 256, 256))