Merge branch 'pr/123'

_examples/bar_chart/main.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+
+	"github.com/wcharczuk/go-chart"
+)
+
+func drawChart(res http.ResponseWriter, req *http.Request) {
+	sbc := chart.BarChart{
+		Title:      "Test Bar Chart",
+		TitleStyle: chart.StyleShow(),
+		Background: chart.Style{
+			Padding: chart.Box{
+				Top: 40,
+			},
+		},
+		Height:   512,
+		Width:    -1,
+		BarWidth: 60,
+		XAxis:    chart.StyleShow(),
+		YAxis: chart.YAxis{
+			Style: chart.StyleShow(),
+		},
+		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))
+}

bar_chart.go

@@ -60,6 +60,8 @@ func (bc BarChart) GetFont() *truetype.Font {
 func (bc BarChart) GetWidth() int {
 	if bc.Width == 0 {
 		return DefaultChartWidth
+	} else if bc.Width == -1 {
+		return bc.autoWidth()
 	}
 	return bc.Width
 }
@@ -88,6 +90,19 @@ func (bc BarChart) GetBarWidth() int {
 	return bc.BarWidth
 }
 
+func (bc BarChart) autoWidth() (totalWidth int) {
+
+	totalWidth = 0
+	barWidth := bc.GetBarWidth()
+	barSpacing := bc.GetBarSpacing()
+
+	for _, _ = range bc.Bars {
+		totalWidth += barWidth + barSpacing
+	}
+
+	return
+}
+
 // Render renders the chart with the given renderer to the given io.Writer.
 func (bc BarChart) Render(rp RendererProvider, w io.Writer) error {
 	if len(bc.Bars) == 0 {