Blue Print generating Go Program

blueprint.go

package main

import (
	"fmt"
	"image"
	"image/color"
	"image/png"
	"os"
)

var (
	Pantone2706C = color.RGBA{
		R: 206,
		G: 216,
		B: 247,
		A: 255,
	}
	Pantone2726C = color.RGBA{
		R: 48,
		G: 87,
		B: 225,
		A: 255,
	}
	PantoneGreen0921C = color.RGBA{
		R: 162,
		G: 252,
		B: 206,
		A: 255,
	}
	Pantone7479C = color.RGBA{
		R: 49,
		G: 222,
		B: 124,
		A: 255,
	}
)

type BluePrint struct {
	img              *image.RGBA
	size             image.Point
	backgroundColor  color.RGBA
	lineColor        color.RGBA
	thinLineSpacing  int
	thickLineSpacing int
}

func (b *BluePrint) SetBackgroundColor(c color.RGBA) *BluePrint {
	b.backgroundColor = c
	return b
}

func (b *BluePrint) SetLineColor(c color.RGBA) *BluePrint {
	b.lineColor = c
	return b
}

func (b *BluePrint) SetThickLineSpacing(i int) *BluePrint {
	b.thickLineSpacing = i
	return b
}

func (b *BluePrint) SetThinLineSpacing(i int) *BluePrint {
	b.thinLineSpacing = i
	return b
}

func (b *BluePrint) Render(file *os.File) error {
	for i := 0; i < b.size.X; i++ {
		for j := 0; j < b.size.Y; j++ {
			b.img.Set(i, j, b.backgroundColor)
			b.handleLines(i, j)
		}
	}

	err := png.Encode(file, b.img)
	if err != nil {
		fmt.Println(err)
	}

	err = file.Close()
	if err != nil {
		fmt.Println(err)
	}
	return nil
}

func (b *BluePrint) handleLines(i, j int) {
	if i%b.thinLineSpacing == 0 {
		b.img.Set(i, j, b.lineColor)
	}
	if b.isThickLinePixel(i, j) {
		b.img.Set(i, j, b.lineColor)
	}
}

func (b *BluePrint) isThickLinePixel(i, j int) bool {
	switch {
	case i%b.thickLineSpacing == 0 || j%b.thinLineSpacing == 0:
		return true
	case i+1 < b.size.X && (i+1)%b.thickLineSpacing == 0:
		return true
	case j+1 < b.size.Y && (j+1)%b.thickLineSpacing == 0:
		return true
	case i-1 > 0 && (i-1)%b.thickLineSpacing == 0:
		return true
	case j-1 > 0 && (j-1)%b.thickLineSpacing == 0:
		return true
	default:
		return false
	}
}

func NewBluePrint(size image.Point) *BluePrint {
	img := image.NewRGBA(image.Rect(0, 0, size.X, size.Y))
	return &BluePrint{img: img, size: size}
}

func main() {
	bp := NewBluePrint(image.Pt(1000, 1000)).
		SetBackgroundColor(Pantone2726C).
		SetLineColor(Pantone2706C).
		SetThickLineSpacing(100).
		SetThinLineSpacing(20)

	f, err := os.Create("blue.png")
	if err != nil {
		fmt.Println(err)
	}

	err = bp.Render(f)
	if err != nil {
		fmt.Println(err)
	}

	bp.SetBackgroundColor(PantoneGreen0921C).
		SetLineColor(Pantone7479C)

	f, err = os.Create("green.png")
	if err != nil {
		fmt.Println(err)
	}

	err = bp.Render(f)
	if err != nil {
		fmt.Println(err)
	}
}