go-chart/examples/bar_chart/main.go

package main

import (
	"fmt"
	"log"
	"net/http"
	"os"

	"github.com/wcharczuk/go-chart"
)

func drawChart(res http.ResponseWriter, req *http.Request) {
	sbc := chart.BarChart{
		Height:   512,
		BarWidth: 60,
		XAxis: chart.Style{
			Show: false,
		},
		YAxis: chart.YAxis{
			Style: chart.Style{
				Show: false,
			},
		},
		Bars: []chart.Value{
			{Value: 5.25, Label: "Blue"},
			{Value: 4.88, Label: "Green"},
			{Value: 4.74, Label: "Gray"},
			{Value: 3.22, Label: "Orange"},
			{Value: 3, Label: "Test"},
			{Value: 2.27, Label: "??"},
			{Value: 1, Label: "!!"},
		},
	}

	res.Header().Set("Content-Type", "image/png")
	err := sbc.Render(chart.PNG, res)
	if err != nil {
		fmt.Printf("Error rendering chart: %v\n", err)
	}
}

func port() string {
	if len(os.Getenv("PORT")) > 0 {
		return os.Getenv("PORT")
	}
	return "8080"
}

func main() {
	listenPort := fmt.Sprintf(":%s", port())
	fmt.Printf("Listening on %s\n", listenPort)
	http.HandleFunc("/", drawChart)
	log.Fatal(http.ListenAndServe(listenPort, nil))
}