1 // Copyright 2010 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.
12 // A Point is an X, Y coordinate pair. The axes increase right and down.
17 // String returns a string representation of p like "(3,4)".
18 func (p Point
) String() string {
19 return "(" + strconv
.Itoa(p
.X
) + "," + strconv
.Itoa(p
.Y
) + ")"
22 // Add returns the vector p+q.
23 func (p Point
) Add(q Point
) Point
{
24 return Point
{p
.X
+ q
.X
, p
.Y
+ q
.Y
}
27 // Sub returns the vector p-q.
28 func (p Point
) Sub(q Point
) Point
{
29 return Point
{p
.X
- q
.X
, p
.Y
- q
.Y
}
32 // Mul returns the vector p*k.
33 func (p Point
) Mul(k
int) Point
{
34 return Point
{p
.X
* k
, p
.Y
* k
}
37 // Div returns the vector p/k.
38 func (p Point
) Div(k
int) Point
{
39 return Point
{p
.X
/ k
, p
.Y
/ k
}
42 // In reports whether p is in r.
43 func (p Point
) In(r Rectangle
) bool {
44 return r
.Min
.X
<= p
.X
&& p
.X
< r
.Max
.X
&&
45 r
.Min
.Y
<= p
.Y
&& p
.Y
< r
.Max
.Y
48 // Mod returns the point q in r such that p.X-q.X is a multiple of r's width
49 // and p.Y-q.Y is a multiple of r's height.
50 func (p Point
) Mod(r Rectangle
) Point
{
51 w
, h
:= r
.Dx(), r
.Dy()
64 // Eq reports whether p and q are equal.
65 func (p Point
) Eq(q Point
) bool {
69 // ZP is the zero Point.
72 // Pt is shorthand for Point{X, Y}.
73 func Pt(X
, Y
int) Point
{
77 // A Rectangle contains the points with Min.X <= X < Max.X, Min.Y <= Y < Max.Y.
78 // It is well-formed if Min.X <= Max.X and likewise for Y. Points are always
79 // well-formed. A rectangle's methods always return well-formed outputs for
80 // well-formed inputs.
82 // A Rectangle is also an Image whose bounds are the rectangle itself. At
83 // returns color.Opaque for points in the rectangle and color.Transparent
85 type Rectangle
struct {
89 // String returns a string representation of r like "(3,4)-(6,5)".
90 func (r Rectangle
) String() string {
91 return r
.Min
.String() + "-" + r
.Max
.String()
94 // Dx returns r's width.
95 func (r Rectangle
) Dx() int {
96 return r
.Max
.X
- r
.Min
.X
99 // Dy returns r's height.
100 func (r Rectangle
) Dy() int {
101 return r
.Max
.Y
- r
.Min
.Y
104 // Size returns r's width and height.
105 func (r Rectangle
) Size() Point
{
112 // Add returns the rectangle r translated by p.
113 func (r Rectangle
) Add(p Point
) Rectangle
{
115 Point
{r
.Min
.X
+ p
.X
, r
.Min
.Y
+ p
.Y
},
116 Point
{r
.Max
.X
+ p
.X
, r
.Max
.Y
+ p
.Y
},
120 // Sub returns the rectangle r translated by -p.
121 func (r Rectangle
) Sub(p Point
) Rectangle
{
123 Point
{r
.Min
.X
- p
.X
, r
.Min
.Y
- p
.Y
},
124 Point
{r
.Max
.X
- p
.X
, r
.Max
.Y
- p
.Y
},
128 // Inset returns the rectangle r inset by n, which may be negative. If either
129 // of r's dimensions is less than 2*n then an empty rectangle near the center
130 // of r will be returned.
131 func (r Rectangle
) Inset(n
int) Rectangle
{
133 r
.Min
.X
= (r
.Min
.X
+ r
.Max
.X
) / 2
140 r
.Min
.Y
= (r
.Min
.Y
+ r
.Max
.Y
) / 2
149 // Intersect returns the largest rectangle contained by both r and s. If the
150 // two rectangles do not overlap then the zero rectangle will be returned.
151 func (r Rectangle
) Intersect(s Rectangle
) Rectangle
{
152 if r
.Min
.X
< s
.Min
.X
{
155 if r
.Min
.Y
< s
.Min
.Y
{
158 if r
.Max
.X
> s
.Max
.X
{
161 if r
.Max
.Y
> s
.Max
.Y
{
164 if r
.Min
.X
> r
.Max
.X || r
.Min
.Y
> r
.Max
.Y
{
170 // Union returns the smallest rectangle that contains both r and s.
171 func (r Rectangle
) Union(s Rectangle
) Rectangle
{
178 if r
.Min
.X
> s
.Min
.X
{
181 if r
.Min
.Y
> s
.Min
.Y
{
184 if r
.Max
.X
< s
.Max
.X
{
187 if r
.Max
.Y
< s
.Max
.Y
{
193 // Empty reports whether the rectangle contains no points.
194 func (r Rectangle
) Empty() bool {
195 return r
.Min
.X
>= r
.Max
.X || r
.Min
.Y
>= r
.Max
.Y
198 // Eq reports whether r and s contain the same set of points. All empty
199 // rectangles are considered equal.
200 func (r Rectangle
) Eq(s Rectangle
) bool {
201 return r
== s || r
.Empty() && s
.Empty()
204 // Overlaps reports whether r and s have a non-empty intersection.
205 func (r Rectangle
) Overlaps(s Rectangle
) bool {
206 return !r
.Empty() && !s
.Empty() &&
207 r
.Min
.X
< s
.Max
.X
&& s
.Min
.X
< r
.Max
.X
&&
208 r
.Min
.Y
< s
.Max
.Y
&& s
.Min
.Y
< r
.Max
.Y
211 // In reports whether every point in r is in s.
212 func (r Rectangle
) In(s Rectangle
) bool {
216 // Note that r.Max is an exclusive bound for r, so that r.In(s)
217 // does not require that r.Max.In(s).
218 return s
.Min
.X
<= r
.Min
.X
&& r
.Max
.X
<= s
.Max
.X
&&
219 s
.Min
.Y
<= r
.Min
.Y
&& r
.Max
.Y
<= s
.Max
.Y
222 // Canon returns the canonical version of r. The returned rectangle has minimum
223 // and maximum coordinates swapped if necessary so that it is well-formed.
224 func (r Rectangle
) Canon() Rectangle
{
225 if r
.Max
.X
< r
.Min
.X
{
226 r
.Min
.X
, r
.Max
.X
= r
.Max
.X
, r
.Min
.X
228 if r
.Max
.Y
< r
.Min
.Y
{
229 r
.Min
.Y
, r
.Max
.Y
= r
.Max
.Y
, r
.Min
.Y
234 // At implements the Image interface.
235 func (r Rectangle
) At(x
, y
int) color
.Color
{
236 if (Point
{x
, y
}).In(r
) {
239 return color
.Transparent
242 // Bounds implements the Image interface.
243 func (r Rectangle
) Bounds() Rectangle
{
247 // ColorModel implements the Image interface.
248 func (r Rectangle
) ColorModel() color
.Model
{
249 return color
.Alpha16Model
252 // ZR is the zero Rectangle.
255 // Rect is shorthand for Rectangle{Pt(x0, y0), Pt(x1, y1)}. The returned
256 // rectangle has minimum and maximum coordinates swapped if necessary so that
257 // it is well-formed.
258 func Rect(x0
, y0
, x1
, y1
int) Rectangle
{
265 return Rectangle
{Point
{x0
, y0
}, Point
{x1
, y1
}}