2 files changed, 80 insertions(+), 0 deletions(-)

A ascii/ascii.go
A ascii/option.go

@@ 0,0 1,47 @@
+// The ascii package can convert a image pixel to a raw char
+// base on it's RGBA value, in another word, input a image pixel
+// output a raw char ascii.
+package ascii
+
+import (
+	"image/color"
+	"math"
+	"reflect"
+)
+
+// Convert a pixel to a ASCII char string
+func ConvertPixelToASCII(pixel color.Color, options *Options) string {
+	defaultOptions := NewOptions()
+	defaultOptions.mergeOptions(options)
+
+	if defaultOptions.reverse {
+		defaultOptions.pixels = reverse(defaultOptions.pixels)
+	}
+
+	r := reflect.ValueOf(pixel).FieldByName("R").Uint()
+	g := reflect.ValueOf(pixel).FieldByName("G").Uint()
+	b := reflect.ValueOf(pixel).FieldByName("B").Uint()
+	a := reflect.ValueOf(pixel).FieldByName("A").Uint()
+	value := intensity(r, g, b, a)
+
+	// Choose the char
+	precision := float64(255 * 3 / (len(options.pixels) - 1))
+	rawChar := options.pixels[roundValue(float64(value)/precision)]
+	return string([]byte{rawChar})
+}
+
+func roundValue(value float64) int {
+	return int(math.Floor(value + 0.5))
+}
+
+func reverse(numbers []byte) []byte {
+	for i := 0; i < len(numbers)/2; i++ {
+		j := len(numbers) - i - 1
+		numbers[i], numbers[j] = numbers[j], numbers[i]
+	}
+	return numbers
+}
+
+func intensity(r, g, b, a uint64) uint64 {
+	return (r + g + b) * a / 255
+}

@@ 0,0 1,33 @@
+package ascii
+
+// Convert options
+type Options struct {
+	pixels  []byte
+	reverse bool
+	colored bool
+	bg      bool
+	fg      bool
+}
+
+// Default options
+var DefaultOptions = Options{
+	pixels:  []byte(" .,:;i1tfLCG08@"),
+	reverse: false,
+	colored: true,
+	bg:      false,
+	fg:      true,
+}
+
+// Create a new options
+func NewOptions() Options {
+	return DefaultOptions
+}
+
+// Merge options
+func (options *Options) mergeOptions(newOptions *Options) {
+	options.pixels = append([]byte{}, newOptions.pixels...)
+	options.reverse = newOptions.reverse
+	options.colored = newOptions.colored
+	options.bg = newOptions.bg
+	options.fg = newOptions.fg
+}