example_test.go

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package draw_test
     6  
     7  import (
     8  	"fmt"
     9  	"image"
    10  	"image/color"
    11  	"image/draw"
    12  	"math"
    13  )
    14  
    15  func ExampleDrawer_floydSteinberg() {
    16  	const width = 130
    17  	const height = 50
    18  
    19  	im := image.NewGray(image.Rectangle{Max: image.Point{X: width, Y: height}})
    20  	for x := 0; x < width; x++ {
    21  		for y := 0; y < height; y++ {
    22  			dist := math.Sqrt(math.Pow(float64(x-width/2), 2)/3+math.Pow(float64(y-height/2), 2)) / (height / 1.5) * 255
    23  			var gray uint8
    24  			if dist > 255 {
    25  				gray = 255
    26  			} else {
    27  				gray = uint8(dist)
    28  			}
    29  			im.SetGray(x, y, color.Gray{Y: 255 - gray})
    30  		}
    31  	}
    32  	pi := image.NewPaletted(im.Bounds(), []color.Color{
    33  		color.Gray{Y: 255},
    34  		color.Gray{Y: 160},
    35  		color.Gray{Y: 70},
    36  		color.Gray{Y: 35},
    37  		color.Gray{Y: 0},
    38  	})
    39  
    40  	draw.FloydSteinberg.Draw(pi, im.Bounds(), im, image.Point{})
    41  	shade := []string{" ", "░", "▒", "▓", "█"}
    42  	for i, p := range pi.Pix {
    43  		fmt.Print(shade[p])
    44  		if (i+1)%width == 0 {
    45  			fmt.Print("\n")
    46  		}
    47  	}
    48  }
    49
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