Add a way to set graphics in a header/footer

The full functionality of the VML drawing is not addressed here. However
this seems to work for embedding regular images.

picture.go

@@ -295,6 +295,15 @@ func (f *File) addSheetLegacyDrawing(sheet string, rID int) {
 	}
 }
 
+// addSheetLegacyDrawing provides a function to add legacy drawing element to
+// xl/worksheets/sheet%d.xml by given worksheet name and relationship index.
+func (f *File) addSheetLegacyDrawingHF(sheet string, rID int) {
+	ws, _ := f.workSheetReader(sheet)
+	ws.LegacyDrawingHF = &xlsxLegacyDrawingHF{
+		RID: "rId" + strconv.Itoa(rID),
+	}
+}
+
 // addSheetDrawing provides a function to add drawing element to
 // xl/worksheets/sheet%d.xml by given worksheet name and relationship index.
 func (f *File) addSheetDrawing(sheet string, rID int) {

sheet.go

@@ -1239,7 +1239,7 @@ func attrValToBool(name string, attrs []xml.Attr) (val bool, err error) {
 //	                        |
 //	 &F                     | Current workbook's file name
 //	                        |
-//	 &G                     | Drawing object as background (Not support currently)
+//	 &G                     | Drawing object as background (Use SetLegacyDrawingHF)
 //	                        |
 //	 &H                     | Shadow text format
 //	                        |

vml.go

@@ -1070,3 +1070,83 @@ func extractVMLFont(font []decodeVMLFont) []RichTextRun {
 	}
 	return runs
 }
+
+// SetLegacyDrawingHF provides a mechanism to set the graphics that
+// can be referenced in the Header/Footer defitions via &G.
+//
+// The extension should be provided with a "." in front, e.g. ".png".
+// The width/height should have units in them, e.g. "100pt".
+func (f *File) SetLegacyDrawingHF(sheet string, g *HeaderFooterGraphics) error {
+	vmlID := f.countVMLDrawing() + 1
+
+	vml := &vmlDrawing{
+		XMLNSv: "urn:schemas-microsoft-com:vml",
+		XMLNSo: "urn:schemas-microsoft-com:office:office",
+		XMLNSx: "urn:schemas-microsoft-com:office:excel",
+		ShapeLayout: &xlsxShapeLayout{
+			Ext: "edit", IDmap: &xlsxIDmap{Ext: "edit", Data: vmlID},
+		},
+		ShapeType: &xlsxShapeType{
+			ID:             "_x0000_t75",
+			CoordSize:      "21600,21600",
+			Spt:            75,
+			PreferRelative: "t",
+			Path:           "m@4@5l@4@11@9@11@9@5xe",
+			Filled:         "f",
+			Stroked:        "f",
+			Stroke:         &xlsxStroke{JoinStyle: "miter"},
+			VFormulas: &vFormulas{
+				Formulas: []vFormula{
+					vFormula{Equation: "if lineDrawn pixelLineWidth 0"},
+					vFormula{Equation: "sum @0 1 0"},
+					vFormula{Equation: "sum 0 0 @1"},
+					vFormula{Equation: "prod @2 1 2"},
+					vFormula{Equation: "prod @3 21600 pixelWidth"},
+					vFormula{Equation: "prod @3 21600 pixelHeight"},
+					vFormula{Equation: "sum @0 0 1"},
+					vFormula{Equation: "prod @6 1 2"},
+					vFormula{Equation: "prod @7 21600 pixelWidth"},
+					vFormula{Equation: "sum @8 21600 0"},
+					vFormula{Equation: "prod @7 21600 pixelHeight"},
+					vFormula{Equation: "sum @10 21600 0"},
+				},
+			},
+			VPath: &vPath{ExtrusionOK: "f", GradientShapeOK: "t", ConnectType: "rect"},
+			Lock:  &oLock{Ext: "edit", AspectRatio: "t"},
+		},
+	}
+
+	style := fmt.Sprintf("position:absolute;margin-left:0;margin-top:0;width:%s;height:%s;z-index:1", g.Width, g.Height)
+	drawingVML := "xl/drawings/vmlDrawing" + strconv.Itoa(vmlID) + ".vml"
+	drawingVMLRels := "xl/drawings/_rels/vmlDrawing" + strconv.Itoa(vmlID) + ".vml.rels"
+
+	mediaStr := ".." + strings.TrimPrefix(f.addMedia(g.File, g.Extension), "xl")
+	imageID := f.addRels(drawingVMLRels, SourceRelationshipImage, mediaStr, "")
+
+	shape := xlsxShape{
+		ID:    "RH",
+		Spid:  "_x0000_s1025",
+		Type:  "#_x0000_t75",
+		Style: style,
+	}
+	s, _ := xml.Marshal(encodeShape{
+		ImageData: &vImageData{RelID: "rId" + strconv.Itoa(imageID)},
+		Lock:      &oLock{Ext: "edit", Rotation: "t"},
+	})
+	shape.Val = string(s[13 : len(s)-14])
+	vml.Shape = append(vml.Shape, shape)
+	f.VMLDrawing[drawingVML] = vml
+
+	sheetRelationshipsDrawingVML := "../drawings/vmlDrawing" + strconv.Itoa(vmlID) + ".vml"
+	sheetXMLPath, _ := f.getSheetXMLPath(sheet)
+	sheetRels := "xl/worksheets/_rels/" + strings.TrimPrefix(sheetXMLPath, "xl/worksheets/") + ".rels"
+
+	drawingID := f.addRels(sheetRels, SourceRelationshipDrawingVML, sheetRelationshipsDrawingVML, "")
+	f.addSheetNameSpace(sheet, SourceRelationship)
+	f.addSheetLegacyDrawingHF(sheet, drawingID)
+	err := f.setContentTypePartImageExtensions()
+	if err != nil {
+		return err
+	}
+	return f.setContentTypePartVMLExtensions()
+}

vmlDrawing.go

@@ -20,7 +20,7 @@ type vmlDrawing struct {
 	XMLNSv      string           `xml:"xmlns:v,attr"`
 	XMLNSo      string           `xml:"xmlns:o,attr"`
 	XMLNSx      string           `xml:"xmlns:x,attr"`
-	XMLNSmv     string           `xml:"xmlns:mv,attr"`
+	XMLNSmv     string           `xml:"xmlns:mv,attr,omitempty"`
 	ShapeLayout *xlsxShapeLayout `xml:"o:shapelayout"`
 	ShapeType   *xlsxShapeType   `xml:"v:shapetype"`
 	Shape       []xlsxShape      `xml:"v:shape"`
@@ -44,6 +44,7 @@ type xlsxIDmap struct {
 type xlsxShape struct {
 	XMLName     xml.Name `xml:"v:shape"`
 	ID          string   `xml:"id,attr"`
+	Spid        string   `xml:"o:spid,attr,omitempty"`
 	Type        string   `xml:"type,attr"`
 	Style       string   `xml:"style,attr"`
 	Button      string   `xml:"o:button,attr,omitempty"`
@@ -57,12 +58,17 @@ type xlsxShape struct {
 
 // xlsxShapeType directly maps the shapetype element.
 type xlsxShapeType struct {
-	ID        string      `xml:"id,attr"`
-	CoordSize string      `xml:"coordsize,attr"`
-	Spt       int         `xml:"o:spt,attr"`
-	Path      string      `xml:"path,attr"`
-	Stroke    *xlsxStroke `xml:"v:stroke"`
-	VPath     *vPath      `xml:"v:path"`
+	ID             string      `xml:"id,attr"`
+	CoordSize      string      `xml:"coordsize,attr"`
+	Spt            int         `xml:"o:spt,attr"`
+	PreferRelative string      `xml:"o:preferrelative,attr,omitempty"`
+	Path           string      `xml:"path,attr"`
+	Filled         string      `xml:"filled,attr,omitempty"`
+	Stroked        string      `xml:"stroked,attr,omitempty"`
+	Stroke         *xlsxStroke `xml:"v:stroke"`
+	VFormulas      *vFormulas  `xml:"v:formulas"`
+	VPath          *vPath      `xml:"v:path"`
+	Lock           *oLock      `xml:"o:lock"`
 }
 
 // xlsxStroke directly maps the stroke element.
@@ -72,10 +78,28 @@ type xlsxStroke struct {
 
 // vPath directly maps the v:path element.
 type vPath struct {
+	ExtrusionOK     string `xml:"o:extrusionok,attr,omitempty"`
 	GradientShapeOK string `xml:"gradientshapeok,attr,omitempty"`
 	ConnectType     string `xml:"o:connecttype,attr"`
 }
 
+// oLock directly maps the o:lock element.
+type oLock struct {
+	Ext         string `xml:"v:ext,attr"`
+	Rotation    string `xml:"rotation,attr,omitempty"`
+	AspectRatio string `xml:"aspectratio,attr,omitempty"`
+}
+
+// vFormulas directly maps to the v:formulas element
+type vFormulas struct {
+	Formulas []vFormula `xml:"v:f"`
+}
+
+// vFormula directly maps to the v:f element
+type vFormula struct {
+	Equation string `xml:"eqn,attr"`
+}
+
 // vFill directly maps the v:fill element. This element must be defined within a
 // Shape element.
 type vFill struct {
@@ -106,6 +130,13 @@ type vTextBox struct {
 	Div   *xlsxDiv `xml:"div"`
 }
 
+// vImageData directly maps the v:imagedata element. This element must be
+// defined within a Shape element.
+type vImageData struct {
+	RelID string `xml:"o:relid,attr"`
+	Title string `xml:"o:title,attr,omitempty"`
+}
+
 // xlsxDiv directly maps the div element.
 type xlsxDiv struct {
 	Style string    `xml:"style,attr"`
@@ -254,7 +285,9 @@ type encodeShape struct {
 	Shadow     *vShadow     `xml:"v:shadow"`
 	Path       *vPath       `xml:"v:path"`
 	TextBox    *vTextBox    `xml:"v:textbox"`
+	ImageData  *vImageData  `xml:"v:imagedata"`
 	ClientData *xClientData `xml:"x:ClientData"`
+	Lock       *oLock       `xml:"o:lock"`
 }
 
 // formCtrlPreset defines the structure used to form control presets.
@@ -301,3 +334,12 @@ type FormControl struct {
 	Type         FormControlType
 	Format       GraphicOptions
 }
+
+// HeaderFooterGraphics defines the settings for an image to be
+// accessible from the header/footer options.
+type HeaderFooterGraphics struct {
+	File      []byte
+	Extension string
+	Width     string
+	Height    string
+}

vml_test.go

@@ -412,3 +412,23 @@ func TestExtractFormControl(t *testing.T) {
 	_, err := extractFormControl(string(MacintoshCyrillicCharset))
 	assert.EqualError(t, err, "XML syntax error on line 1: invalid UTF-8")
 }
+
+func ExampleFile_SetLegacyDrawingHF() {
+	f := NewFile()
+	sheet := "Sheet1"
+	headerFooterOptions := HeaderFooterOptions{
+		OddHeader: "&LExcelize&R&G",
+	}
+	f.SetHeaderFooter(sheet, &headerFooterOptions)
+	file, _ := os.ReadFile("test/images/excel.png")
+	f.SetLegacyDrawingHF(sheet, &HeaderFooterGraphics{
+		Extension: ".png",
+		File:      file,
+		Width:     "50pt",
+		Height:    "32pt",
+	})
+	f.SetCellValue(sheet, "A1", "Example")
+	out, _ := os.CreateTemp("", "header-graphics-*.xlsx")
+	f.Write(out)
+	f.Close()
+}