Custom chart size.

Added helper functions to set the chart size.
Added the unit test

Signed-off-by: Eugene Dzhurinsky <jdevelop@gmail.com>

README.md

@@ -109,7 +109,7 @@ func main() {
     for k, v := range values {
         xlsx.SetCellValue("Sheet1", k, v)
     }
-    xlsx.AddChart("Sheet1", "E1", `{"type":"col3DClustered","series":[{"name":"Sheet1!$A$2","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$2:$D$2"},{"name":"Sheet1!$A$3","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$3:$D$3"},{"name":"Sheet1!$A$4","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$4:$D$4"}],"title":{"name":"Fruit 3D Clustered Column Chart"}}`)
+    xlsx.AddChart("Sheet1", "E1", `{"type":"col3DClustered","series":[{"name":"Sheet1!$A$2","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$2:$D$2"},{"name":"Sheet1!$A$3","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$3:$D$3"},{"name":"Sheet1!$A$4","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$4:$D$4"}],"title":{"name":"Fruit 3D Clustered Column Chart"}}`,excelize.ChartWidth(800), excelize.ChartHeight(600))
     // Save xlsx file by the given path.
     err := xlsx.SaveAs("./Book1.xlsx")
     if err != nil {

chart.go

@@ -351,7 +351,13 @@ func parseFormatChartSet(formatSet string) *formatChart {
 // maximum: Specifies that the fixed maximum, 0 is auto. The maximum property is optional. The default value is auto.
 // minimum: Specifies that the fixed minimum, 0 is auto. The minimum property is optional. The default value is auto.
 //
-func (f *File) AddChart(sheet, cell, format string) {
+func (f *File) AddChart(sheet, cell, format string, opts ...chartOpts) {
+
+	var defOpts = defaultChartOptions
+	for _, optF := range opts {
+		optF(&defOpts)
+	}
+
 	formatSet := parseFormatChartSet(format)
 	// Read sheet data.
 	xlsx := f.workSheetReader(sheet)
@@ -361,12 +367,40 @@ func (f *File) AddChart(sheet, cell, format string) {
 	drawingXML := "xl/drawings/drawing" + strconv.Itoa(drawingID) + ".xml"
 	drawingID, drawingXML = f.prepareDrawing(xlsx, drawingID, sheet, drawingXML)
 	drawingRID := f.addDrawingRelationships(drawingID, SourceRelationshipChart, "../charts/chart"+strconv.Itoa(chartID)+".xml", "")
-	f.addDrawingChart(sheet, drawingXML, cell, 480, 290, drawingRID, &formatSet.Format)
+	f.addDrawingChart(sheet, drawingXML, cell, defOpts.width, defOpts.height, drawingRID, &formatSet.Format)
 	f.addChart(formatSet)
 	f.addContentTypePart(chartID, "chart")
 	f.addContentTypePart(drawingID, "drawings")
 }
 
+type chartOptions struct {
+	width  int
+	height int
+}
+
+var defaultChartOptions = chartOptions{
+	width:  480,
+	height: 290,
+}
+
+type chartOpts func(opts *chartOptions)
+
+// ChartWidth sets the chart width.
+func ChartWidth(width int) chartOpts {
+	return func(opts *chartOptions) {
+		opts.width = width
+		return
+	}
+}
+
+// ChartHeight sets the chart height.
+func ChartHeight(height int) chartOpts {
+	return func(opts *chartOptions) {
+		opts.height = height
+		return
+	}
+}
+
 // countCharts provides function to get chart files count storage in the
 // folder xl/charts.
 func (f *File) countCharts() int {

chart_test.go

@@ -0,0 +1,66 @@
+package excelize
+
+import (
+	"bytes"
+	"encoding/xml"
+	"testing"
+)
+
+func TestChartSize(t *testing.T) {
+
+	var buffer bytes.Buffer
+
+	categories := map[string]string{"A2": "Small", "A3": "Normal", "A4": "Large", "B1": "Apple", "C1": "Orange", "D1": "Pear"}
+	values := map[string]int{"B2": 2, "C2": 3, "D2": 3, "B3": 5, "C3": 2, "D3": 4, "B4": 6, "C4": 7, "D4": 8}
+	xlsx := NewFile()
+	for k, v := range categories {
+		xlsx.SetCellValue("Sheet1", k, v)
+	}
+	for k, v := range values {
+		xlsx.SetCellValue("Sheet1", k, v)
+	}
+	xlsx.AddChart("Sheet1", "E4", `{"type":"col3DClustered","series":[{"name":"Sheet1!$A$2","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$2:$D$2"},{"name":"Sheet1!$A$3","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$3:$D$3"},{"name":"Sheet1!$A$4","categories":"Sheet1!$B$1:$D$1","values":"Sheet1!$B$4:$D$4"}],"title":{"name":"Fruit 3D Clustered Column Chart"}}`, ChartWidth(640), ChartHeight(480))
+	// Save xlsx file by the given path.
+	err := xlsx.Write(&buffer)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	newFile, err := OpenReader(&buffer)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	chartsNum := newFile.countCharts()
+	if chartsNum != 1 {
+		t.Fatalf("Expected 1 chart, actual %d", chartsNum)
+	}
+
+	var (
+		workdir decodeWsDr
+		anchor  decodeTwoCellAnchor
+	)
+
+	content, ok := newFile.XLSX["xl/drawings/drawing1.xml"]
+	if !ok {
+		t.Fatal("Can't open the chart")
+	}
+
+	err = xml.Unmarshal([]byte(content), &workdir)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = xml.Unmarshal([]byte("<decodeTwoCellAnchor>"+workdir.TwoCellAnchor[0].Content+"</decodeTwoCellAnchor>"), &anchor)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if anchor.From.Col != 4 || anchor.From.Row != 3 {
+		t.Fatalf("From: Expected column 4, row 3, actual column %d, row %d", anchor.From.Col, anchor.From.Row)
+	}
+	if anchor.To.Col != 14 || anchor.To.Row != 27 {
+		t.Fatalf("To: Expected column 14, row 27, actual column %d, row %d", anchor.To.Col, anchor.To.Row)
+	}
+
+}