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// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package imageutil
import (
"image"
"testing"
)
func area(r image.Rectangle) int {
dx, dy := r.Dx(), r.Dy()
if dx <= 0 || dy <= 0 {
return 0
}
return dx * dy
}
func TestBorder(t *testing.T) {
r := image.Rect(100, 200, 400, 300)
insets := []int{
-100,
-1,
+0,
+1,
+20,
+49,
+50,
+51,
+149,
+150,
+151,
}
for _, inset := range insets {
border := Border(r, inset)
outer, inner := r, r.Inset(inset)
if inset < 0 {
outer, inner = inner, outer
}
got := 0
for _, b := range border {
got += area(b)
}
want := area(outer) - area(inner)
if got != want {
t.Errorf("inset=%d: total area: got %d, want %d", inset, got, want)
}
for i, bi := range border {
for j, bj := range border {
if i <= j {
continue
}
if !bi.Intersect(bj).Empty() {
t.Errorf("inset=%d: %v and %v overlap", inset, bi, bj)
}
}
}
for _, b := range border {
if got := outer.Intersect(b); got != b {
t.Errorf("inset=%d: outer intersection: got %v, want %v", inset, got, b)
}
if got := inner.Intersect(b); !got.Empty() {
t.Errorf("inset=%d: inner intersection: got %v, want empty", inset, got)
}
}
}
}
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