github.com/FenixAra/go@v0.0.0-20170127160404-96ea0918e670/src/image/geom_test.go (about)

     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(1, 2, 3, 4),
    32  		Rect(4, 6, 10, 10),
    33  		Rect(2, 3, 12, 5),
    34  		Rect(-1, -2, 0, 0),
    35  		Rect(-1, -2, 4, 6),
    36  		Rect(-10, -20, 30, 40),
    37  		Rect(8, 8, 8, 8),
    38  		Rect(88, 88, 88, 88),
    39  		Rect(6, 5, 4, 3),
    40  	}
    41  
    42  	// r.Eq(s) should be equivalent to every point in r being in s, and every
    43  	// point in s being in r.
    44  	for _, r := range rects {
    45  		for _, s := range rects {
    46  			got := r.Eq(s)
    47  			want := in(r, s) == nil && in(s, r) == nil
    48  			if got != want {
    49  				t.Errorf("Eq: r=%s, s=%s: got %t, want %t", r, s, got, want)
    50  			}
    51  		}
    52  	}
    53  
    54  	// The intersection should be the largest rectangle a such that every point
    55  	// in a is both in r and in s.
    56  	for _, r := range rects {
    57  		for _, s := range rects {
    58  			a := r.Intersect(s)
    59  			if err := in(a, r); err != nil {
    60  				t.Errorf("Intersect: r=%s, s=%s, a=%s, a not in r: %v", r, s, a, err)
    61  			}
    62  			if err := in(a, s); err != nil {
    63  				t.Errorf("Intersect: r=%s, s=%s, a=%s, a not in s: %v", r, s, a, err)
    64  			}
    65  			if a.Empty() == r.Overlaps(s) {
    66  				t.Errorf("Intersect: r=%s, s=%s, a=%s: empty=%t same as overlaps=%t",
    67  					r, s, a, a.Empty(), r.Overlaps(s))
    68  			}
    69  			largerThanA := [4]Rectangle{a, a, a, a}
    70  			largerThanA[0].Min.X--
    71  			largerThanA[1].Min.Y--
    72  			largerThanA[2].Max.X++
    73  			largerThanA[3].Max.Y++
    74  			for i, b := range largerThanA {
    75  				if b.Empty() {
    76  					// b isn't actually larger than a.
    77  					continue
    78  				}
    79  				if in(b, r) == nil && in(b, s) == nil {
    80  					t.Errorf("Intersect: r=%s, s=%s, a=%s, b=%s, i=%d: intersection could be larger",
    81  						r, s, a, b, i)
    82  				}
    83  			}
    84  		}
    85  	}
    86  
    87  	// The union should be the smallest rectangle a such that every point in r
    88  	// is in a and every point in s is in a.
    89  	for _, r := range rects {
    90  		for _, s := range rects {
    91  			a := r.Union(s)
    92  			if err := in(r, a); err != nil {
    93  				t.Errorf("Union: r=%s, s=%s, a=%s, r not in a: %v", r, s, a, err)
    94  			}
    95  			if err := in(s, a); err != nil {
    96  				t.Errorf("Union: r=%s, s=%s, a=%s, s not in a: %v", r, s, a, err)
    97  			}
    98  			if a.Empty() {
    99  				// You can't get any smaller than a.
   100  				continue
   101  			}
   102  			smallerThanA := [4]Rectangle{a, a, a, a}
   103  			smallerThanA[0].Min.X++
   104  			smallerThanA[1].Min.Y++
   105  			smallerThanA[2].Max.X--
   106  			smallerThanA[3].Max.Y--
   107  			for i, b := range smallerThanA {
   108  				if in(r, b) == nil && in(s, b) == nil {
   109  					t.Errorf("Union: r=%s, s=%s, a=%s, b=%s, i=%d: union could be smaller",
   110  						r, s, a, b, i)
   111  				}
   112  			}
   113  		}
   114  	}
   115  }