imagefn - flip.go

     1  package imagefn
     2  
     3  import (
     4  	"image"
     5  	"image/color"
     6  )
     7  
     8  type flipX struct {
     9  	image.Image
    10  	dx int
    11  }
    12  
    13  type flipXSet struct {
    14  	flipX
    15  	setter
    16  }
    17  
    18  func FlipX(i image.Image) image.Image {
    19  	switch i := i.(type) {
    20  	case *flipX:
    21  		return i.Image
    22  	case *flipXSet:
    23  		return i.Image
    24  	case *flipY:
    25  		return Rotate180(i.Image)
    26  	case *flipYSet:
    27  		return Rotate180(i.Image)
    28  	case *rotate180:
    29  		return FlipY(i.Image)
    30  	case *rotate180Set:
    31  		return FlipY(i.Image)
    32  	}
    33  	b := i.Bounds()
    34  	f := flipX{
    35  		Image: i,
    36  		dx:    b.Max.X + b.Min.X,
    37  	}
    38  	if s, ok := i.(setter); ok {
    39  		return &flipXSet{
    40  			flipX:  f,
    41  			setter: s,
    42  		}
    43  	}
    44  	return &f
    45  }
    46  
    47  func (f *flipX) At(x, y int) color.Color {
    48  	return f.Image.At(f.dx-x-1, y)
    49  }
    50  
    51  func (f *flipX) SubImage(r image.Rectangle) image.Image {
    52  	r.Min.X = f.dx - r.Min.X
    53  	r.Max.X = f.dx - r.Max.X
    54  	return FlipX(SubImage(f.Image, r.Canon()))
    55  }
    56  
    57  func (f *flipXSet) Set(x, y int, c color.Color) {
    58  	f.setter.Set(f.dx-x-1, y, c)
    59  }
    60  
    61  type flipY struct {
    62  	image.Image
    63  	dy int
    64  }
    65  
    66  type flipYSet struct {
    67  	flipY
    68  	setter
    69  }
    70  
    71  func FlipY(i image.Image) image.Image {
    72  	switch i := i.(type) {
    73  	case *flipX:
    74  		return Rotate180(i.Image)
    75  	case *flipXSet:
    76  		return Rotate180(i.Image)
    77  	case *flipY:
    78  		return i.Image
    79  	case *flipYSet:
    80  		return i.Image
    81  	case *rotate180:
    82  		return FlipX(i.Image)
    83  	case *rotate180Set:
    84  		return FlipX(i.Image)
    85  	}
    86  	b := i.Bounds()
    87  	f := flipY{
    88  		Image: i,
    89  		dy:    b.Max.Y + b.Min.Y,
    90  	}
    91  	if s, ok := i.(setter); ok {
    92  		return &flipYSet{
    93  			flipY:  f,
    94  			setter: s,
    95  		}
    96  	}
    97  	return &f
    98  }
    99  
   100  func (f *flipY) At(x, y int) color.Color {
   101  	return f.Image.At(x, f.dy-y-1)
   102  }
   103  
   104  func (f *flipY) SubImage(r image.Rectangle) image.Image {
   105  	r.Min.Y = f.dy - r.Min.Y
   106  	r.Max.Y = f.dy - r.Max.Y
   107  	return FlipY(SubImage(f.Image, r.Canon()))
   108  }
   109  
   110  func (f *flipYSet) Set(x, y int, c color.Color) {
   111  	f.setter.Set(x, f.dy-y-1, c)
   112  }