geom_test.go

Documentation: image

		 1  // Copyright 2015 The Go Authors. All rights reserved.
		 2  // Use of this source code is governed by a BSD-style
		 3  // license that can be found in the LICENSE file.
		 4  
		 5  package image
		 6  
		 7  import (
		 8  	"fmt"
		 9  	"testing"
		10  )
		11  
		12  func TestRectangle(t *testing.T) {
		13  	// in checks that every point in f is in g.
		14  	in := func(f, g Rectangle) error {
		15  		if !f.In(g) {
		16  			return fmt.Errorf("f=%s, f.In(%s): got false, want true", f, g)
		17  		}
		18  		for y := f.Min.Y; y < f.Max.Y; y++ {
		19  			for x := f.Min.X; x < f.Max.X; x++ {
		20  				p := Point{x, y}
		21  				if !p.In(g) {
		22  					return fmt.Errorf("p=%s, p.In(%s): got false, want true", p, g)
		23  				}
		24  			}
		25  		}
		26  		return nil
		27  	}
		28  
		29  	rects := []Rectangle{
		30  		Rect(0, 0, 10, 10),
		31  		Rect(10, 0, 20, 10),
		32  		Rect(1, 2, 3, 4),
		33  		Rect(4, 6, 10, 10),
		34  		Rect(2, 3, 12, 5),
		35  		Rect(-1, -2, 0, 0),
		36  		Rect(-1, -2, 4, 6),
		37  		Rect(-10, -20, 30, 40),
		38  		Rect(8, 8, 8, 8),
		39  		Rect(88, 88, 88, 88),
		40  		Rect(6, 5, 4, 3),
		41  	}
		42  
		43  	// r.Eq(s) should be equivalent to every point in r being in s, and every
		44  	// point in s being in r.
		45  	for _, r := range rects {
		46  		for _, s := range rects {
		47  			got := r.Eq(s)
		48  			want := in(r, s) == nil && in(s, r) == nil
		49  			if got != want {
		50  				t.Errorf("Eq: r=%s, s=%s: got %t, want %t", r, s, got, want)
		51  			}
		52  		}
		53  	}
		54  
		55  	// The intersection should be the largest rectangle a such that every point
		56  	// in a is both in r and in s.
		57  	for _, r := range rects {
		58  		for _, s := range rects {
		59  			a := r.Intersect(s)
		60  			if err := in(a, r); err != nil {
		61  				t.Errorf("Intersect: r=%s, s=%s, a=%s, a not in r: %v", r, s, a, err)
		62  			}
		63  			if err := in(a, s); err != nil {
		64  				t.Errorf("Intersect: r=%s, s=%s, a=%s, a not in s: %v", r, s, a, err)
		65  			}
		66  			if isZero, overlaps := a == (Rectangle{}), r.Overlaps(s); isZero == overlaps {
		67  				t.Errorf("Intersect: r=%s, s=%s, a=%s: isZero=%t same as overlaps=%t",
		68  					r, s, a, isZero, overlaps)
		69  			}
		70  			largerThanA := [4]Rectangle{a, a, a, a}
		71  			largerThanA[0].Min.X--
		72  			largerThanA[1].Min.Y--
		73  			largerThanA[2].Max.X++
		74  			largerThanA[3].Max.Y++
		75  			for i, b := range largerThanA {
		76  				if b.Empty() {
		77  					// b isn't actually larger than a.
		78  					continue
		79  				}
		80  				if in(b, r) == nil && in(b, s) == nil {
		81  					t.Errorf("Intersect: r=%s, s=%s, a=%s, b=%s, i=%d: intersection could be larger",
		82  						r, s, a, b, i)
		83  				}
		84  			}
		85  		}
		86  	}
		87  
		88  	// The union should be the smallest rectangle a such that every point in r
		89  	// is in a and every point in s is in a.
		90  	for _, r := range rects {
		91  		for _, s := range rects {
		92  			a := r.Union(s)
		93  			if err := in(r, a); err != nil {
		94  				t.Errorf("Union: r=%s, s=%s, a=%s, r not in a: %v", r, s, a, err)
		95  			}
		96  			if err := in(s, a); err != nil {
		97  				t.Errorf("Union: r=%s, s=%s, a=%s, s not in a: %v", r, s, a, err)
		98  			}
		99  			if a.Empty() {
	 100  				// You can't get any smaller than a.
	 101  				continue
	 102  			}
	 103  			smallerThanA := [4]Rectangle{a, a, a, a}
	 104  			smallerThanA[0].Min.X++
	 105  			smallerThanA[1].Min.Y++
	 106  			smallerThanA[2].Max.X--
	 107  			smallerThanA[3].Max.Y--
	 108  			for i, b := range smallerThanA {
	 109  				if in(r, b) == nil && in(s, b) == nil {
	 110  					t.Errorf("Union: r=%s, s=%s, a=%s, b=%s, i=%d: union could be smaller",
	 111  						r, s, a, b, i)
	 112  				}
	 113  			}
	 114  		}
	 115  	}
	 116  }
	 117
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