Support set work sheet background image.

col.go

@@ -68,7 +68,7 @@ func (f *File) SetColWidth(sheet, startcol, endcol string, width float64) {
 //    |     |            |     (x2,y2)|
 //    +-----+------------+------------+
 //
-// Example of an object that covers some of the area from cell A1 to  B2.
+// Example of an object that covers some of the area from cell A1 to B2.
 //
 // Based on the width and height of the object we need to calculate 8 vars:
 //

excelize_test.go

@@ -208,3 +208,30 @@ func TestSetCellFormula(t *testing.T) {
 		t.Log(err)
 	}
 }
+
+func TestSetSheetBackground(t *testing.T) {
+	xlsx, err := OpenFile("./test/Workbook1.xlsx")
+	if err != nil {
+		t.Log(err)
+	}
+	err = xlsx.SetSheetBackground("sheet2", "./test/images/background.png")
+	if err != nil {
+		t.Log(err)
+	}
+	err = xlsx.SetSheetBackground("sheet2", "./test/Workbook1.xlsx")
+	if err != nil {
+		t.Log(err)
+	}
+	err = xlsx.SetSheetBackground("sheet2", "./test/images/background.jpg")
+	if err != nil {
+		t.Log(err)
+	}
+	err = xlsx.SetSheetBackground("sheet2", "./test/images/background.jpg")
+	if err != nil {
+		t.Log(err)
+	}
+	err = xlsx.Save()
+	if err != nil {
+		t.Log(err)
+	}
+}

file.go

@@ -27,7 +27,7 @@ func CreateFile() *File {
 	}
 }
 
-// Save provides function override the xlsx file with origin path.
+// Save provides function to override the xlsx file with origin path.
 func (f *File) Save() error {
 	buf := new(bytes.Buffer)
 	w := zip.NewWriter(buf)

lib.go

@@ -38,7 +38,7 @@ func ReadZipReader(r *zip.Reader) (map[string]string, int, error) {
 	return fileList, worksheets, nil
 }
 
-// Read XML content as string.
+// readXML provides function to read XML content as string.
 func (f *File) readXML(name string) string {
 	if content, ok := f.XLSX[name]; ok {
 		return content
@@ -46,7 +46,8 @@ func (f *File) readXML(name string) string {
 	return ""
 }
 
-// Update given file content in file list of XLSX.
+// saveFileList provides function to update given file content in file list of
+// XLSX.
 func (f *File) saveFileList(name string, content string) {
 	f.XLSX[name] = XMLHeader + content
 }
@@ -63,7 +64,8 @@ func readFile(file *zip.File) string {
 	return string(buff.Bytes())
 }
 
-// Convert integer to Excel sheet column title.
+// toAlphaString provides function to convert integer to Excel sheet column
+// title.
 func toAlphaString(value int) string {
 	if value < 0 {
 		return ""
@@ -77,7 +79,7 @@ func toAlphaString(value int) string {
 	return ans
 }
 
-// Convert Excel sheet column title to int.
+// titleToNumber provides function to convert Excel sheet column title to int.
 func titleToNumber(s string) int {
 	weight := 0.0
 	sum := 0

picture.go

@@ -135,7 +135,23 @@ func (f *File) addSheetDrawing(sheet string, rID int) {
 	if err != nil {
 		fmt.Println(err)
 	}
-	f.saveFileList(name, string(output))
+	f.saveFileList(name, replaceWorkSheetsRelationshipsNameSpace(string(output)))
+}
+
+// addSheetPicture provides function to add picture element to
+// xl/worksheets/sheet%d.xml by given sheet name and relationship index.
+func (f *File) addSheetPicture(sheet string, rID int) {
+	var xlsx xlsxWorksheet
+	name := "xl/worksheets/" + strings.ToLower(sheet) + ".xml"
+	xml.Unmarshal([]byte(f.readXML(name)), &xlsx)
+	xlsx.Picture = &xlsxPicture{
+		RID: "rId" + strconv.Itoa(rID),
+	}
+	output, err := xml.Marshal(xlsx)
+	if err != nil {
+		fmt.Println(err)
+	}
+	f.saveFileList(name, replaceWorkSheetsRelationshipsNameSpace(string(output)))
 }
 
 // countDrawings provides function to get drawing files count storage in the
@@ -270,13 +286,10 @@ func (f *File) addMedia(file string, ext string) {
 	f.XLSX[media] = string(dat)
 }
 
-// addDrawingContentTypePart provides function to add image part relationships
-// in http://purl.oclc.org/ooxml/officeDocument/relationships/image and
-// appropriate content type.
-func (f *File) addDrawingContentTypePart(index int) {
+func (f *File) setContentTypePartImageExtensions() {
 	var imageTypes = map[string]bool{"jpeg": false, "png": false, "gif": false}
 	var content xlsxTypes
-	xml.Unmarshal([]byte(f.readXML(`[Content_Types].xml`)), &content)
+	xml.Unmarshal([]byte(f.readXML("[Content_Types].xml")), &content)
 	for _, v := range content.Defaults {
 		_, ok := imageTypes[v.Extension]
 		if ok {
@@ -291,6 +304,17 @@ func (f *File) addDrawingContentTypePart(index int) {
 			})
 		}
 	}
+	output, _ := xml.Marshal(content)
+	f.saveFileList("[Content_Types].xml", string(output))
+}
+
+// addDrawingContentTypePart provides function to add image part relationships
+// in http://purl.oclc.org/ooxml/officeDocument/relationships/image and
+// appropriate content type.
+func (f *File) addDrawingContentTypePart(index int) {
+	f.setContentTypePartImageExtensions()
+	var content xlsxTypes
+	xml.Unmarshal([]byte(f.readXML("[Content_Types].xml")), &content)
 	for _, v := range content.Overrides {
 		if v.PartName == "/xl/drawings/drawing"+strconv.Itoa(index)+".xml" {
 			output, _ := xml.Marshal(content)
@@ -303,7 +327,7 @@ func (f *File) addDrawingContentTypePart(index int) {
 		ContentType: "application/vnd.openxmlformats-officedocument.drawing+xml",
 	})
 	output, _ := xml.Marshal(content)
-	f.saveFileList(`[Content_Types].xml`, string(output))
+	f.saveFileList("[Content_Types].xml", string(output))
 }
 
 // getSheetRelationshipsTargetByID provides function to get Target attribute

sheet.go

@@ -3,7 +3,10 @@ package excelize
 import (
 	"bytes"
 	"encoding/xml"
+	"errors"
 	"fmt"
+	"os"
+	"path"
 	"strconv"
 	"strings"
 )
@@ -193,8 +196,8 @@ func (f *File) GetActiveSheetIndex() int {
 		xml.Unmarshal([]byte(f.readXML(buffer.String())), &xlsx)
 		for _, sheetView := range xlsx.SheetViews.SheetView {
 			if sheetView.TabSelected {
-				id, _ := strconv.Atoi(strings.TrimPrefix(v.ID, "rId"))
-				return id
+				ID, _ := strconv.Atoi(strings.TrimPrefix(v.ID, "rId"))
+				return ID
 			}
 		}
 		buffer.Reset()
@@ -258,3 +261,28 @@ func (f *File) GetSheetMap() map[int]string {
 	}
 	return sheetMap
 }
+
+// SetSheetBackground provides function to set background picture by given sheet
+// index.
+func (f *File) SetSheetBackground(sheet, picture string) error {
+	var supportTypes = map[string]string{".gif": ".gif", ".jpg": ".jpeg", ".jpeg": ".jpeg", ".png": ".png"}
+	var err error
+	// Check picture exists first.
+	if _, err = os.Stat(picture); os.IsNotExist(err) {
+		return err
+	}
+	ext, ok := supportTypes[path.Ext(picture)]
+	if !ok {
+		return errors.New("Unsupported image extension")
+	}
+	// Read sheet data.
+	var xlsx xlsxWorksheet
+	name := "xl/worksheets/" + strings.ToLower(sheet) + ".xml"
+	xml.Unmarshal([]byte(f.readXML(name)), &xlsx)
+	pictureID := f.countMedia() + 1
+	rID := f.addSheetRelationships(sheet, SourceRelationshipImage, "../media/image"+strconv.Itoa(pictureID)+ext, "")
+	f.addSheetPicture(sheet, rID)
+	f.addMedia(picture, ext)
+	f.setContentTypePartImageExtensions()
+	return err
+}