GDD2011JP DevQuiz Go!

gopng.go

package main

import (
    "fmt"
    "io"
    "strings"
    "image/png"
)

func CountColor(pngdata io.Reader) int {
    colors := make(map[string] bool)
    img,_:= png.Decode(pngdata)
    x, y := img.Bounds().Max.X, img.Bounds().Max.Y
    for i := 0; i < x; i++ {
        for j:= 0; j < y; j++ {
             r,g,b,_ := img.At(i,j).RGBA()
             index := fmt.Sprintf("%x%x%x",r,g,b)
             colors[index] = true
        }
   } 
    return len(colors)
}