libgo/go/image/geom_test.go

   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 }