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@master

Example

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

package main

import (
	"image/color"

	"github.com/haashemi/painter"
)

func main() {
	img := painter.New(Width, Height)

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

	painter.Render(img, painter.LinearGradient(45, black, white))

	err := painter.SavePNG(img, "painter.png")
	// handle the error
}

Contributions

All type of contributions are highly appreciated. <3

Documentation

Overview

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

Index

• func Clamp(x, minVal, maxVal float64) float64
• func MixRGBA(a float64, x, y color.RGBA) color.RGBA
• func New(width, height int) *image.RGBA
• func Radians(angle float64) float64
• func Render(img *image.RGBA, renderer Renderer)
• func SaveJPEG(img image.Image, path string, o *jpeg.Options) error
• func SavePNG(img image.Image, path string) error
• func SmoothStep(edge0, edge1, x float64) float64
• type Renderer
  • func LinearGradient(angle float64, startColor, endColor color.RGBA) Renderer
  • func RadialGradient(startColor, endColor color.RGBA, center image.Point) Renderer

Functions

func Clamp

func Clamp(x, minVal, maxVal float64) float64

Clamp returns the value of x constrained to the range minVal to maxVal.

more: https://thebookofshaders.com/glossary/?search=clamp

func MixRGBA

func MixRGBA(a float64, x, y color.RGBA) color.RGBA

MixRGBA merges to color with the provided alpha.

"a" should be between 0 and 1.

func New

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

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

func Radians

func Radians(angle float64) float64

Radians converts the degrees to radians.

func Render

func Render(img *image.RGBA, renderer Renderer)

Render calls the renderer in each pixel of the image in NumCPU*2 goroutines for better performance.

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.

func SmoothStep

func SmoothStep(edge0, edge1, x float64) float64

SmoothStep performs smooth Hermite interpolation between 0 and 1 when edge0 < x < edge1. This is useful in cases where a threshold function with a smooth transition is desired.

more: https://thebookofshaders.com/glossary/?search=smoothstep

Types

type Renderer

type Renderer func(img image.Image, point image.Point) color.RGBA

Renderer is a function which gets the image.Image and the current image.Point, and returns a image/color.RGBA for that point.

func LinearGradient

func LinearGradient(angle float64, startColor, endColor color.RGBA) Renderer

LinearGradient is a Renderer which draws a linear gradient on the image from startColor to endColor with in the passed angle in degrees.

func RadialGradient

func RadialGradient(startColor, endColor color.RGBA, center image.Point) Renderer

RadialGradient is a Renderer which draws a radial gradient on the image from startColor to endColor. startColor starts from provided center point.