This closes qax-os#1405, add new function SetSheetBackgroundFromBytes…

… used for setting background image by given image data

Change-Id: I83baac1107f66dfa5d9d2eebfa7e40f9f49b79d5

picture.go

@@ -13,10 +13,12 @@ package excelize
 
 import (
 	"bytes"
+	"compress/gzip"
 	"encoding/json"
 	"encoding/xml"
 	"image"
 	"io"
+	"io/ioutil"
 	"os"
 	"path"
 	"path/filepath"
@@ -721,3 +723,155 @@ func (f *File) drawingResize(sheet, cell string, width, height float64, opts *pi
 	w, h = int(width*opts.XScale), int(height*opts.YScale)
 	return
 }
+
+// getImageDataFormat provides a function to query format of image data
+// by given data.
+func getImageDataFormat(data []byte) string {
+	if len(data) == 0 {
+		return ""
+	}
+	for ext, cmpFunc := range supportedImageHeaderFormat {
+		if cmpFunc(data) {
+			return ext
+		}
+	}
+	return ""
+}
+
+// isGIF provides a function to determine whether the format of given image data is gif
+func isGIF(data []byte) bool {
+	pattern := []byte{0x47, 0x49, 0x46, 0x38}
+	if len(data) < len(pattern) {
+		return false
+	}
+	return bytes.Equal(data[0:len(pattern)], pattern)
+}
+
+func isJPEG(data []byte) bool {
+	pattern := []byte{0xFF, 0xD8, 0xFF}
+	if len(data) < len(pattern) {
+		return false
+	}
+	return bytes.Equal(data[0:len(pattern)], pattern)
+}
+
+// isPNG provides a function to determine whether the format of given image data is png
+func isPNG(data []byte) bool {
+	pattern := []byte{0x89, 0x50, 0x4E}
+	if len(data) < len(pattern) {
+		return false
+	}
+	return bytes.Equal(data[0:len(pattern)], pattern)
+}
+
+// isTIFF provides a function to determine whether the format of given image data is tiff
+func isTIFF(data []byte) bool {
+	patterns := [][]byte{
+		{0x4D, 0x4D},
+		{0x49, 0x49},
+	}
+	for _, pattern := range patterns {
+		if len(data) < len(pattern) {
+			continue
+		}
+		if bytes.Equal(data[0:len(pattern)], pattern) {
+			return true
+		}
+	}
+	return false
+}
+
+// isEMF provides a function to determine whether the format of given image data is emf
+func isEMF(data []byte) bool {
+	patterns := [][]byte{
+		{0x01, 0x00, 0x00, 0x00, 0x58, 0x00, 0x00, 0x00},
+		{0x01, 0x00, 0x00, 0x00, 0x74, 0x00, 0x00, 0x00},
+	}
+	for _, pattern := range patterns {
+		if len(data) < len(pattern) {
+			continue
+		}
+		if bytes.Equal(data[0:len(pattern)], pattern) {
+			return true
+		}
+	}
+	return false
+}
+
+// isWMF provides a function to determine whether the format of given image data is wmf
+func isWMF(data []byte) bool {
+	patterns := [][]byte{
+		{0x01, 0x00, 0x09, 0x00},
+		{0x02, 0x00, 0x09, 0x00},
+		{0xD7, 0xCD, 0xC6, 0x9A},
+	}
+	for _, pattern := range patterns {
+		if len(data) < len(pattern) {
+			continue
+		}
+		if bytes.Equal(data[0:len(pattern)], pattern) {
+			return true
+		}
+	}
+	return false
+}
+
+// isEMZ provides a function to determine whether the format of given image data is emz
+func isEMZ(data []byte) bool {
+	pattern := []byte{0x1F, 0x8B}
+	if len(data) < len(pattern) {
+		return false
+	}
+	isEqual := bytes.Equal(data[0:len(pattern)], pattern)
+	if !isEqual {
+		return false
+	}
+	b := bytes.NewBuffer(data)
+	reader, err := gzip.NewReader(b)
+	if err != nil {
+		return false
+	}
+	res, err := ioutil.ReadAll(reader)
+	if err != nil {
+		return false
+	}
+	return isEMF(res)
+}
+
+// isWMZ provides a function to determine whether the format of given image data is wmz
+func isWMZ(data []byte) bool {
+	pattern := []byte{0x1F, 0x8B}
+	if len(data) < len(pattern) {
+		return false
+	}
+	isEqual := bytes.Equal(data[0:len(pattern)], pattern)
+	if !isEqual {
+		return false
+	}
+	b := bytes.NewBuffer(data)
+	reader, err := gzip.NewReader(b)
+	if err != nil {
+		return false
+	}
+	res, err := ioutil.ReadAll(reader)
+	if err != nil {
+		return false
+	}
+	return isWMF(res)
+}
+
+// isSVG provides a function to determine whether the format of given image data is svg
+func isSVG(data []byte) bool {
+	type Result struct {
+		XMLName xml.Name `xml:"svg"`
+	}
+	var res Result
+	err := xml.Unmarshal(data, &res)
+	if err != nil {
+		return false
+	}
+	if res.XMLName.Local == "svg" {
+		return true
+	}
+	return false
+}

sheet.go

@@ -497,11 +497,27 @@ func (f *File) SetSheetBackground(sheet, picture string) error {
 		return ErrImgExt
 	}
 	file, _ := os.ReadFile(filepath.Clean(picture))
-	name := f.addMedia(file, ext)
+	return f.setSheetBackground(sheet, ext, file)
+}
+
+// SetSheetBackgroundFromBytes provides a function to set background picture
+// by given worksheet name and image data
+func (f *File) SetSheetBackgroundFromBytes(sheet string, picture []byte) error {
+	ext, ok := supportedImageTypes[getImageDataFormat(picture)]
+	if !ok {
+		return ErrImgExt
+	}
+	return f.setSheetBackground(sheet, ext, picture)
+}
+
+// setSheetBackground provides a function to set background picture by given
+// worksheet name,  file name extension and image data.
+func (f *File) setSheetBackground(sheet, ext string, imageData []byte) error {
+	name := f.addMedia(imageData, ext)
 	sheetXMLPath, _ := f.getSheetXMLPath(sheet)
 	sheetRels := "xl/worksheets/_rels/" + strings.TrimPrefix(sheetXMLPath, "xl/worksheets/") + ".rels"
 	rID := f.addRels(sheetRels, SourceRelationshipImage, strings.Replace(name, "xl", "..", 1), "")
-	if err = f.addSheetPicture(sheet, rID); err != nil {
+	if err := f.addSheetPicture(sheet, rID); err != nil {
 		return err
 	}
 	f.addSheetNameSpace(sheet, SourceRelationship)

sheet_test.go

@@ -3,6 +3,8 @@ package excelize
 import (
 	"encoding/xml"
 	"fmt"
+	"io/ioutil"
+	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
@@ -463,3 +465,21 @@ func TestAttrValToFloat(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, 42.1, got)
 }
+
+func TestSetSheetBackgroundFromBytes(t *testing.T) {
+	files := []string{"../../excelize.svg", "excel.emf", "excel.emz", "excel.gif", "excel.jpg", "excel.png", "excel.tif", "excel.wmf", "excel.wmz"}
+	f, err := OpenFile("./test/EmptyWorkbook.xlsx")
+	assert.NoError(t, err)
+	for i, file := range files {
+		img, err := os.Open(filepath.Join("test/images", file))
+		assert.NoError(t, err)
+		content, err := ioutil.ReadAll(img)
+		assert.NoError(t, err)
+		assert.NoError(t, img.Close())
+		assert.NoError(t, f.SetSheetBackgroundFromBytes("sheet1", content))
+		assert.NoError(t, f.SaveAs(fmt.Sprintf("test/TestSetSheetBackgroundFromBytes%d.xlsx", i)))
+	}
+	assert.Error(t, f.SetSheetBackgroundFromBytes("sheet1", nil), ErrImgExt)
+	assert.Error(t, f.SetSheetBackgroundFromBytes("sheet1", []byte{123, 243, 235, 34, 6, 56, 134, 87, 36, 255, 23, 52}), ErrImgExt)
+	assert.NoError(t, f.Close())
+}

xmlDrawing.go

@@ -171,6 +171,19 @@ var supportedImageTypes = map[string]string{
 	".tiff": ".tiff", ".wmf": ".wmf", ".wmz": ".wmz",
 }
 
+// supportedImageHeaderFormat defined supported image data format.
+var supportedImageHeaderFormat = map[string]func([]byte) bool{
+	".gif":  isGIF,
+	".jpeg": isJPEG,
+	".png":  isPNG,
+	".tiff": isTIFF,
+	".emf":  isEMF,
+	".wmf":  isWMF,
+	".emz":  isEMZ,
+	".wmz":  isWMZ,
+	".svg":  isSVG,
+}
+
 // supportedContentTypes defined supported file format types.
 var supportedContentTypes = map[string]string{
 	".xlam": ContentTypeAddinMacro,