painter

README

🎨 Painter (WIP)

A simple utility Golang package to help you with drawing on images

This package is currently work-in-progress and subject to change at any time.

Installation

$ go get github.com/haashemi/painter@main

Example

There are some examples in the examples folder, but here is one of them.

package main

import (
	"image/color"
	"math"

	"github.com/haashemi/painter"
)

func main() {
	img := painter.New(width, height)

	black := color.NRGBA{0, 0, 0, 255}
	white := color.NRGBA{255, 255, 255, 255}

	painter.DrawLinearGradient(img, img.Rect, math.Pi/4, black, white)

	painter.SavePNG(img, "painter.png")
}

Contributions

All type of contributions are highly appreciated. <3

Documentation

Overview

Painter is a simple image.NRGBA utility packages which helps you with drawing on images.

Index

• Variables
• func Decode(r io.Reader) (image.Image, error)
• func Draw(img *image.NRGBA, rect image.Rectangle, process PixelProcessor)
• func DrawColor(img *image.NRGBA, rect image.Rectangle, c color.NRGBA)
• func DrawLinearGradient(img *image.NRGBA, rect image.Rectangle, angle float64, ...)
• func DrawRadialGradient(img *image.NRGBA, rect image.Rectangle, startColor, endColor color.NRGBA, ...)
• func MergeColors(background, foreground color.NRGBA) color.NRGBA
• func MixNRGBA(a float64, x, y color.NRGBA) color.NRGBA
• func New(width, height int) *image.NRGBA
• func Paste(dst *image.NRGBA, src image.Image, x, y int)
• func SaveJPEG(img image.Image, path string, o *jpeg.Options) error
• func SavePNG(img image.Image, path string) error
• type PixelProcessor

Variables

var Workers int = runtime.NumCPU()

Workers defines the goroutines count used for some methods like Draw.

Functions

func Decode

func Decode(r io.Reader) (image.Image, error)

Decode calls the image.Decode and returns the image.

It's useful when you're not sure about the image type and also want to be safe from it.

func Draw

func Draw(img *image.NRGBA, rect image.Rectangle, process PixelProcessor)

Draw is a low-level method which loops through each pixel in rect's range concurrently and sets the merged & processed color on them.

func DrawColor

func DrawColor(img *image.NRGBA, rect image.Rectangle, c color.NRGBA)

DrawColor replaces each pixel's color with the specified color c. It fully takes care of transparent colors.

func DrawLinearGradient

func DrawLinearGradient(img *image.NRGBA, rect image.Rectangle, angle float64, startColor, endColor color.NRGBA)

LinearGradient draws a linear gradient on the image from startColor to endColor with in the passed angle in radians. It fully takes care of transparent colors.

func DrawRadialGradient

func DrawRadialGradient(img *image.NRGBA, rect image.Rectangle, startColor, endColor color.NRGBA, center image.Point)

DrawRadialGradient draws a radial gradient on the image from startColor to endColor. startColor starts from provided center point. It fully takes care of transparent colors.

func MergeColors

func MergeColors(background, foreground color.NRGBA) color.NRGBA

MergeNRGBA merges two image/color.NRGBA colors.

func MixNRGBA

func MixNRGBA(a float64, x, y color.NRGBA) color.NRGBA

MixNRGBA merges two colors with the provided alpha.

"a" should be between 0 and 1.

TODO: Support multiple colors

func New

func New(width, height int) *image.NRGBA

New returns a new image.NRGBA in the specified width and height.

func Paste

func Paste(dst *image.NRGBA, src image.Image, x, y int)

func SaveJPEG

func SaveJPEG(img image.Image, path string, o *jpeg.Options) error

SaveJPEG creates a file in the specified path and encodes the image as jpeg to it.

func SavePNG

func SavePNG(img image.Image, path string) error

SavePNG creates a file in the specified path and encodes the image as png to it.

Types

type PixelProcessor

type PixelProcessor func(x, y int) color.NRGBA

PixelProcessor returns a image/color.NRGBA for the specified image coordinates. It will be called concurrently.