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