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https://github.com/gytisrepecka/go-learning
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Added draw-image.go which draws circle using Midpoint circle algorithm. To output full circle I used to draw smaller circles inside up to center but eventually there are not filled pixels left.
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draw-image.go
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76
draw-image.go
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// Copyright 2018 Gytis Repečka. All rights reserved.
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// Use of this source code is governed by a GNU GPL
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// license that can be found in the LICENSE file.
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package main
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import (
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"fmt"
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"os"
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"image"
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"image/color"
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"image/png"
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"image/draw"
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)
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type Circle struct {
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imageToDraw draw.Image
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x, y, r int
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c color.Color
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}
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// https://en.wikipedia.org/wiki/Midpoint_circle_algorithm
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func (circle *Circle) Draw() {
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x := circle.r - 1
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y := 0
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dx := 1
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dy := 1
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err := dx - (circle.r * 2)
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for x > y {
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circle.imageToDraw.Set(circle.x + x, circle.y + y, circle.c)
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circle.imageToDraw.Set(circle.x + y, circle.y + x, circle.c)
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circle.imageToDraw.Set(circle.x - y, circle.y + x, circle.c)
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circle.imageToDraw.Set(circle.x - x, circle.y + y, circle.c)
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circle.imageToDraw.Set(circle.x - x, circle.y - y, circle.c)
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circle.imageToDraw.Set(circle.x - y, circle.y - x, circle.c)
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circle.imageToDraw.Set(circle.x + y, circle.y - x, circle.c)
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circle.imageToDraw.Set(circle.x + x, circle.y - y, circle.c)
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if err <= 0 {
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y++
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err += dy
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dy += 2
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}
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if err > 0 {
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x--
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dx += 2
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err += dx - (circle.r * 2)
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}
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}
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}
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func main() {
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outFileName := "draw-image.png"
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// Create 400x300 image
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imageToDraw := image.NewRGBA(image.Rect(0, 0, 400, 300))
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var myCircle Circle
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for r := 130; 0 < r; r-- {
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myCircle = Circle{imageToDraw, 200, 150, r, color.RGBA{0, 200, 0, 255}}
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myCircle.Draw()
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}
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f, errf := os.OpenFile(outFileName, os.O_WRONLY|os.O_CREATE, 0600)
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if errf != nil {
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fmt.Println(errf)
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return
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}
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defer f.Close()
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png.Encode(f, imageToDraw)
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fmt.Printf("Image written: %s\n", outFileName)
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}
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BIN
draw-image.png
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BIN
draw-image.png
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Binary file not shown.
After Width: | Height: | Size: 9.8 KiB |
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