package draw

Import Path
	image/draw (on go.dev)

Dependency Relation
	imports 3 packages, and imported by one package


Involved Source Files

	
		Package draw provides image composition functions.
		
		See "The Go image/draw package" for an introduction to this package:
		https://golang.org/doc/articles/image_draw.html


Code Examples

	
		package main
		
		import (
			"fmt"
			"image"
			"image/color"
			"image/draw"
			"math"
		)
		
		func main() {
			const width = 130
			const height = 50
		
			im := image.NewGray(image.Rectangle{Max: image.Point{X: width, Y: height}})
			for x := 0; x < width; x++ {
				for y := 0; y < height; y++ {
					dist := math.Sqrt(math.Pow(float64(x-width/2), 2)/3+math.Pow(float64(y-height/2), 2)) / (height / 1.5) * 255
					var gray uint8
					if dist > 255 {
						gray = 255
					} else {
						gray = uint8(dist)
					}
					im.SetGray(x, y, color.Gray{Y: 255 - gray})
				}
			}
			pi := image.NewPaletted(im.Bounds(), []color.Color{
				color.Gray{Y: 255},
				color.Gray{Y: 160},
				color.Gray{Y: 70},
				color.Gray{Y: 35},
				color.Gray{Y: 0},
			})
		
			draw.FloydSteinberg.Draw(pi, im.Bounds(), im, image.Point{})
			shade := []string{" ", "░", "▒", "▓", "█"}
			for i, p := range pi.Pix {
				fmt.Print(shade[p])
				if (i+1)%width == 0 {
					fmt.Print("\n")
				}
			}
		}




Package-Level Type Names (total 5)


	/* sort by:  |  */
	
		Drawer contains the [Draw] method.

		
			
				Draw aligns r.Min in dst with sp in src and then replaces the
				rectangle r in dst with the result of drawing src on dst.

		
			 Op
		
			  var FloydSteinberg


	
		Image is an image.Image with a Set method to change a single pixel.

		
			
				At returns the color of the pixel at (x, y).
				At(Bounds().Min.X, Bounds().Min.Y) returns the upper-left pixel of the grid.
				At(Bounds().Max.X-1, Bounds().Max.Y-1) returns the lower-right one.

			
				Bounds returns the domain for which At can return non-zero color.
				The bounds do not necessarily contain the point (0, 0).

			
				ColorModel returns the Image's color model.

			( Image) Set(x, y int, c color.Color)
		
			 RGBA64Image (interface)
			*image.Alpha
			*image.Alpha16
			*image.CMYK
			*image.Gray
			*image.Gray16
			*image.NRGBA
			*image.NRGBA64
			*image.Paletted
			*image.RGBA
			*image.RGBA64
		
			 Image : image.Image
		
			func Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point, op Op)
			func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op)
			func Drawer.Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point)
			func Op.Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point)


	
		Op is a Porter-Duff compositing operator.

		
			
				Draw implements the [Drawer] interface by calling the Draw function with this
				[Op].

		
			 Op : Drawer
		
			func Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point, op Op)
			func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op)
		
			const Over
			const Src


	
		Quantizer produces a palette for an image.

		
			
				Quantize appends up to cap(p) - len(p) colors to p and returns the
				updated palette suitable for converting m to a paletted image.



	
		RGBA64Image extends both the [Image] and [image.RGBA64Image] interfaces with a
		SetRGBA64 method to change a single pixel. SetRGBA64 is equivalent to
		calling Set, but it can avoid allocations from converting concrete color
		types to the [color.Color] interface type.

		
			
				At returns the color of the pixel at (x, y).
				At(Bounds().Min.X, Bounds().Min.Y) returns the upper-left pixel of the grid.
				At(Bounds().Max.X-1, Bounds().Max.Y-1) returns the lower-right one.

			
				Bounds returns the domain for which At can return non-zero color.
				The bounds do not necessarily contain the point (0, 0).

			
				ColorModel returns the Image's color model.

			
				RGBA64At returns the RGBA64 color of the pixel at (x, y). It is
				equivalent to calling At(x, y).RGBA() and converting the resulting
				32-bit return values to a color.RGBA64, but it can avoid allocations
				from converting concrete color types to the color.Color interface type.

			( RGBA64Image) Set(x, y int, c color.Color)
			( RGBA64Image) SetRGBA64(x, y int, c color.RGBA64)
		
			*image.Alpha
			*image.Alpha16
			*image.CMYK
			*image.Gray
			*image.Gray16
			*image.NRGBA
			*image.NRGBA64
			*image.Paletted
			*image.RGBA
			*image.RGBA64
		
			 RGBA64Image : Image
			 RGBA64Image : image.Image
			 RGBA64Image : image.RGBA64Image




Package-Level Functions (total 2)


	
		Draw calls [DrawMask] with a nil mask.


	
		DrawMask aligns r.Min in dst with sp in src and mp in mask and then replaces the rectangle r
		in dst with the result of a Porter-Duff composition. A nil mask is treated as opaque.




Package-Level Variables (only one)


	
		FloydSteinberg is a [Drawer] that is the [Src] [Op] with Floyd-Steinberg error
		diffusion.




Package-Level Constants (total 2)


	
		Over specifies ``(src in mask) over dst''.


	
		Src specifies ``src in mask''.