github.com/gop9/olt@v0.0.0-20200202132135-d956aad50b08/gio/f32/f32.go (about)

     1  // SPDX-License-Identifier: Unlicense OR MIT
     2  
     3  /*
     4  Package f32 is a float32 implementation of package image's
     5  Point and Rectangle.
     6  
     7  The coordinate space has the origin in the top left
     8  corner with the axes extending right and down.
     9  */
    10  package f32
    11  
    12  // A Point is a two dimensional point.
    13  type Point struct {
    14  	X, Y float32
    15  }
    16  
    17  // A Rectangle contains the points (X, Y) where Min.X <= X < Max.X,
    18  // Min.Y <= Y < Max.Y.
    19  type Rectangle struct {
    20  	Min, Max Point
    21  }
    22  
    23  // Add return the point p+p2.
    24  func (p Point) Add(p2 Point) Point {
    25  	return Point{X: p.X + p2.X, Y: p.Y + p2.Y}
    26  }
    27  
    28  // Sub returns the vector p-p2.
    29  func (p Point) Sub(p2 Point) Point {
    30  	return Point{X: p.X - p2.X, Y: p.Y - p2.Y}
    31  }
    32  
    33  // Mul returns p scaled by s.
    34  func (p Point) Mul(s float32) Point {
    35  	return Point{X: p.X * s, Y: p.Y * s}
    36  }
    37  
    38  // Size returns r's width and height.
    39  func (r Rectangle) Size() Point {
    40  	return Point{X: r.Dx(), Y: r.Dy()}
    41  }
    42  
    43  // Dx returns r's width.
    44  func (r Rectangle) Dx() float32 {
    45  	return r.Max.X - r.Min.X
    46  }
    47  
    48  // Dy returns r's Height.
    49  func (r Rectangle) Dy() float32 {
    50  	return r.Max.Y - r.Min.Y
    51  }
    52  
    53  // Intersect returns the intersection of r and s.
    54  func (r Rectangle) Intersect(s Rectangle) Rectangle {
    55  	if r.Min.X < s.Min.X {
    56  		r.Min.X = s.Min.X
    57  	}
    58  	if r.Min.Y < s.Min.Y {
    59  		r.Min.Y = s.Min.Y
    60  	}
    61  	if r.Max.X > s.Max.X {
    62  		r.Max.X = s.Max.X
    63  	}
    64  	if r.Max.Y > s.Max.Y {
    65  		r.Max.Y = s.Max.Y
    66  	}
    67  	return r
    68  }
    69  
    70  // Union returns the union of r and s.
    71  func (r Rectangle) Union(s Rectangle) Rectangle {
    72  	if r.Min.X > s.Min.X {
    73  		r.Min.X = s.Min.X
    74  	}
    75  	if r.Min.Y > s.Min.Y {
    76  		r.Min.Y = s.Min.Y
    77  	}
    78  	if r.Max.X < s.Max.X {
    79  		r.Max.X = s.Max.X
    80  	}
    81  	if r.Max.Y < s.Max.Y {
    82  		r.Max.Y = s.Max.Y
    83  	}
    84  	return r
    85  }
    86  
    87  // Canon returns the canonical version of r, where Min is to
    88  // the upper left of Max.
    89  func (r Rectangle) Canon() Rectangle {
    90  	if r.Max.X < r.Min.X {
    91  		r.Min.X, r.Max.X = r.Max.X, r.Min.X
    92  	}
    93  	if r.Max.Y < r.Min.Y {
    94  		r.Min.Y, r.Max.Y = r.Max.Y, r.Min.Y
    95  	}
    96  	return r
    97  }
    98  
    99  // Empty reports whether r represents the empty area.
   100  func (r Rectangle) Empty() bool {
   101  	return r.Min.X >= r.Max.X || r.Min.Y >= r.Max.Y
   102  }
   103  
   104  // Add offsets r with the vector p.
   105  func (r Rectangle) Add(p Point) Rectangle {
   106  	return Rectangle{
   107  		Point{r.Min.X + p.X, r.Min.Y + p.Y},
   108  		Point{r.Max.X + p.X, r.Max.Y + p.Y},
   109  	}
   110  }
   111  
   112  // Sub offsets r with the vector -p.
   113  func (r Rectangle) Sub(p Point) Rectangle {
   114  	return 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},
   117  	}
   118  }