limage - rgb.go

     1  package limage
     2  
     3  import (
     4  	"image"
     5  	"image/color"
     6  
     7  	"vimagination.zapto.org/limage/lcolor"
     8  )
     9  
    10  // RGB is an image of RGB colours.
    11  type RGB struct {
    12  	Pix    []lcolor.RGB
    13  	Stride int
    14  	Rect   image.Rectangle
    15  }
    16  
    17  // NewRGB create a new RGB image with the given bounds.
    18  func NewRGB(r image.Rectangle) *RGB {
    19  	w, h := r.Dx(), r.Dy()
    20  
    21  	return &RGB{
    22  		Pix:    make([]lcolor.RGB, w*h),
    23  		Stride: w,
    24  		Rect:   r,
    25  	}
    26  }
    27  
    28  // At returns the colour at the given coords.
    29  func (r *RGB) At(x, y int) color.Color {
    30  	return r.RGBAt(x, y)
    31  }
    32  
    33  // Bounds returns the limits of the image.
    34  func (r *RGB) Bounds() image.Rectangle {
    35  	return r.Rect
    36  }
    37  
    38  // ColorModel returns a colour model that converts arbitrary colours to the RGB
    39  // space.
    40  func (r *RGB) ColorModel() color.Model {
    41  	return lcolor.RGBModel
    42  }
    43  
    44  // RGBAt returns the exact RGB colour at the given coords.
    45  func (r *RGB) RGBAt(x, y int) lcolor.RGB {
    46  	if !(image.Point{x, y}.In(r.Rect)) {
    47  		return lcolor.RGB{}
    48  	}
    49  
    50  	return r.Pix[r.PixOffset(x, y)]
    51  }
    52  
    53  // Opaque just returns true as the alpha channel is fixed.
    54  func (r *RGB) Opaque() bool {
    55  	return true
    56  }
    57  
    58  // PixOffset returns the index of the Pix array corresponding to the given
    59  // coords.
    60  func (r *RGB) PixOffset(x, y int) int {
    61  	return (y-r.Rect.Min.Y)*r.Stride + x - r.Rect.Min.X
    62  }
    63  
    64  // Set converts the given colour to the RGB space and sets it at the given
    65  // coords.
    66  func (r *RGB) Set(x, y int, c color.Color) {
    67  	if !(image.Point{x, y}.In(r.Rect)) {
    68  		return
    69  	}
    70  
    71  	rr, g, b, _ := c.RGBA()
    72  	r.Pix[r.PixOffset(x, y)] = lcolor.RGB{
    73  		R: uint8(rr >> 8),
    74  		G: uint8(g >> 8),
    75  		B: uint8(b >> 8),
    76  	}
    77  }
    78  
    79  // SetRGB directly set an RGB colour to the given coords.
    80  func (r *RGB) SetRGB(x, y int, rgb lcolor.RGB) {
    81  	if !(image.Point{x, y}.In(r.Rect)) {
    82  		return
    83  	}
    84  
    85  	r.Pix[r.PixOffset(x, y)] = rgb
    86  }
    87  
    88  // SubImage returns the Image viewable through the given bounds.
    89  func (r *RGB) SubImage(rt image.Rectangle) image.Image {
    90  	rt = rt.Intersect(r.Rect)
    91  
    92  	if rt.Empty() {
    93  		return &RGB{}
    94  	}
    95  
    96  	return &RGB{
    97  		Pix:    r.Pix[r.PixOffset(rt.Min.X, rt.Min.Y):],
    98  		Stride: r.Stride,
    99  		Rect:   rt,
   100  	}
   101  }
   102