excelize/picture.go

// Copyright 2016 - 2022 The excelize Authors. All rights reserved. Use of
// this source code is governed by a BSD-style license that can be found in
// the LICENSE file.
//
// Package excelize providing a set of functions that allow you to write to and
// read from XLAM / XLSM / XLSX / XLTM / XLTX files. Supports reading and
// writing spreadsheet documents generated by Microsoft Excel™ 2007 and later.
// Supports complex components by high compatibility, and provided streaming
// API for generating or reading data from a worksheet with huge amounts of
// data. This library needs Go version 1.15 or later.

package excelize

import (
	"bytes"
	"encoding/xml"
	"image"
	"io"
	"os"
	"path"
	"path/filepath"
	"strconv"
	"strings"
)

// parsePictureOptions provides a function to parse the format settings of
// the picture with default value.
func parsePictureOptions(opts *PictureOptions) *PictureOptions {
	if opts == nil {
		return &PictureOptions{
			PrintObject: boolPtr(true),
			Locked:      boolPtr(false),
			XScale:      float64Ptr(defaultPictureScale),
			YScale:      float64Ptr(defaultPictureScale),
		}
	}
	if opts.PrintObject == nil {
		opts.PrintObject = boolPtr(true)
	}
	if opts.Locked == nil {
		opts.Locked = boolPtr(false)
	}
	if opts.XScale == nil {
		opts.XScale = float64Ptr(defaultPictureScale)
	}
	if opts.YScale == nil {
		opts.YScale = float64Ptr(defaultPictureScale)
	}
	return opts
}

// AddPicture provides the method to add picture in a sheet by given picture
// format set (such as offset, scale, aspect ratio setting and print settings)
// and file path, supported image types: EMF, EMZ, GIF, JPEG, JPG, PNG, SVG,
// TIF, TIFF, WMF, and WMZ. This function is concurrency safe. For example:
//
//	package main
//
//	import (
//	    "fmt"
//	    _ "image/gif"
//	    _ "image/jpeg"
//	    _ "image/png"
//
//	    "github.com/xuri/excelize/v2"
//	)
//
//	func main() {
//	    f := excelize.NewFile()
//	    // Insert a picture.
//	    if err := f.AddPicture("Sheet1", "A2", "image.jpg", nil); err != nil {
//	        fmt.Println(err)
//	    }
//	    // Insert a picture scaling in the cell with location hyperlink.
//	    enable, scale := true, 0.5
//	    if err := f.AddPicture("Sheet1", "D2", "image.png",
//	        &excelize.PictureOptions{
//	            XScale:        &scale,
//	            YScale:        &scale,
//	            Hyperlink:     "#Sheet2!D8",
//	            HyperlinkType: "Location",
//	        },
//	    ); err != nil {
//	        fmt.Println(err)
//	    }
//	    // Insert a picture offset in the cell with external hyperlink, printing and positioning support.
//	    if err := f.AddPicture("Sheet1", "H2", "image.gif",
//	        &excelize.PictureOptions{
//	            PrintObject:     &enable,
//	            LockAspectRatio: false,
//	            OffsetX:         15,
//	            OffsetY:         10,
//	            Hyperlink:       "https://github.com/xuri/excelize",
//	            HyperlinkType:   "External",
//	            Positioning:     "oneCell",
//	        },
//	    ); err != nil {
//	        fmt.Println(err)
//	    }
//	    if err := f.SaveAs("Book1.xlsx"); err != nil {
//	        fmt.Println(err)
//	    }
//	}
//
// The optional parameter "Autofit" specifies if you make image size auto-fits the
// cell, the default value of that is 'false'.
//
// The optional parameter "Hyperlink" specifies the hyperlink of the image.
//
// The optional parameter "HyperlinkType" defines two types of
// hyperlink "External" for website or "Location" for moving to one of the
// cells in this workbook. When the "hyperlink_type" is "Location",
// coordinates need to start with "#".
//
// The optional parameter "Positioning" defines two types of the position of an
// image in an Excel spreadsheet, "oneCell" (Move but don't size with
// cells) or "absolute" (Don't move or size with cells). If you don't set this
// parameter, the default positioning is move and size with cells.
//
// The optional parameter "PrintObject" indicates whether the image is printed
// when the worksheet is printed, the default value of that is 'true'.
//
// The optional parameter "LockAspectRatio" indicates whether lock aspect
// ratio for the image, the default value of that is 'false'.
//
// The optional parameter "Locked" indicates whether lock the image. Locking
// an object has no effect unless the sheet is protected.
//
// The optional parameter "OffsetX" specifies the horizontal offset of the
// image with the cell, the default value of that is 0.
//
// The optional parameter "XScale" specifies the horizontal scale of images,
// the default value of that is 1.0 which presents 100%.
//
// The optional parameter "OffsetY" specifies the vertical offset of the
// image with the cell, the default value of that is 0.
//
// The optional parameter "YScale" specifies the vertical scale of images,
// the default value of that is 1.0 which presents 100%.
func (f *File) AddPicture(sheet, cell, picture string, opts *PictureOptions) error {
	var err error
	// Check picture exists first.
	if _, err = os.Stat(picture); os.IsNotExist(err) {
		return err
	}
	ext, ok := supportedImageTypes[path.Ext(picture)]
	if !ok {
		return ErrImgExt
	}
	file, _ := os.ReadFile(filepath.Clean(picture))
	_, name := filepath.Split(picture)
	return f.AddPictureFromBytes(sheet, cell, name, ext, file, opts)
}

// AddPictureFromBytes provides the method to add picture in a sheet by given
// picture format set (such as offset, scale, aspect ratio setting and print
// settings), file base name, extension name and file bytes, supported image
// types: EMF, EMZ, GIF, JPEG, JPG, PNG, SVG, TIF, TIFF, WMF, and WMZ. For
// example:
//
//	package main
//
//	import (
//	    "fmt"
//	    _ "image/jpeg"
//	    "os"
//
//	    "github.com/xuri/excelize/v2"
//	)
//
//	func main() {
//	    f := excelize.NewFile()
//
//	    file, err := os.ReadFile("image.jpg")
//	    if err != nil {
//	        fmt.Println(err)
//	    }
//	    if err := f.AddPictureFromBytes("Sheet1", "A2", "Excel Logo", ".jpg", file, nil); err != nil {
//	        fmt.Println(err)
//	    }
//	    if err := f.SaveAs("Book1.xlsx"); err != nil {
//	        fmt.Println(err)
//	    }
//	}
func (f *File) AddPictureFromBytes(sheet, cell, name, extension string, file []byte, opts *PictureOptions) error {
	var drawingHyperlinkRID int
	var hyperlinkType string
	ext, ok := supportedImageTypes[extension]
	if !ok {
		return ErrImgExt
	}
	options := parsePictureOptions(opts)
	img, _, err := image.DecodeConfig(bytes.NewReader(file))
	if err != nil {
		return err
	}
	// Read sheet data.
	ws, err := f.workSheetReader(sheet)
	if err != nil {
		return err
	}
	ws.Lock()
	// Add first picture for given sheet, create xl/drawings/ and xl/drawings/_rels/ folder.
	drawingID := f.countDrawings() + 1
	drawingXML := "xl/drawings/drawing" + strconv.Itoa(drawingID) + ".xml"
	drawingID, drawingXML = f.prepareDrawing(ws, drawingID, sheet, drawingXML)
	drawingRels := "xl/drawings/_rels/drawing" + strconv.Itoa(drawingID) + ".xml.rels"
	mediaStr := ".." + strings.TrimPrefix(f.addMedia(file, ext), "xl")
	drawingRID := f.addRels(drawingRels, SourceRelationshipImage, mediaStr, hyperlinkType)
	// Add picture with hyperlink.
	if options.Hyperlink != "" && options.HyperlinkType != "" {
		if options.HyperlinkType == "External" {
			hyperlinkType = options.HyperlinkType
		}
		drawingHyperlinkRID = f.addRels(drawingRels, SourceRelationshipHyperLink, options.Hyperlink, hyperlinkType)
	}
	ws.Unlock()
	err = f.addDrawingPicture(sheet, drawingXML, cell, name, ext, drawingRID, drawingHyperlinkRID, img, options)
	if err != nil {
		return err
	}
	if err = f.addContentTypePart(drawingID, "drawings"); err != nil {
		return err
	}
	f.addSheetNameSpace(sheet, SourceRelationship)
	return err
}

// deleteSheetRelationships provides a function to delete relationships in
// xl/worksheets/_rels/sheet%d.xml.rels by given worksheet name and
// relationship index.
func (f *File) deleteSheetRelationships(sheet, rID string) {
	name, ok := f.getSheetXMLPath(sheet)
	if !ok {
		name = strings.ToLower(sheet) + ".xml"
	}
	rels := "xl/worksheets/_rels/" + strings.TrimPrefix(name, "xl/worksheets/") + ".rels"
	sheetRels, _ := f.relsReader(rels)
	if sheetRels == nil {
		sheetRels = &xlsxRelationships{}
	}
	sheetRels.Lock()
	defer sheetRels.Unlock()
	for k, v := range sheetRels.Relationships {
		if v.ID == rID {
			sheetRels.Relationships = append(sheetRels.Relationships[:k], sheetRels.Relationships[k+1:]...)
		}
	}
	f.Relationships.Store(rels, sheetRels)
}

// 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) addSheetLegacyDrawing(sheet string, rID int) {
	ws, _ := f.workSheetReader(sheet)
	ws.LegacyDrawing = &xlsxLegacyDrawing{
		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) {
	ws, _ := f.workSheetReader(sheet)
	ws.Drawing = &xlsxDrawing{
		RID: "rId" + strconv.Itoa(rID),
	}
}

// addSheetPicture provides a function to add picture element to
// xl/worksheets/sheet%d.xml by given worksheet name and relationship index.
func (f *File) addSheetPicture(sheet string, rID int) error {
	ws, err := f.workSheetReader(sheet)
	if err != nil {
		return err
	}
	ws.Picture = &xlsxPicture{
		RID: "rId" + strconv.Itoa(rID),
	}
	return err
}

// countDrawings provides a function to get drawing files count storage in the
// folder xl/drawings.
func (f *File) countDrawings() int {
	var c1, c2 int
	f.Pkg.Range(func(k, v interface{}) bool {
		if strings.Contains(k.(string), "xl/drawings/drawing") {
			c1++
		}
		return true
	})
	f.Drawings.Range(func(rel, value interface{}) bool {
		if strings.Contains(rel.(string), "xl/drawings/drawing") {
			c2++
		}
		return true
	})
	if c1 < c2 {
		return c2
	}
	return c1
}

// addDrawingPicture provides a function to add picture by given sheet,
// drawingXML, cell, file name, width, height relationship index and format
// sets.
func (f *File) addDrawingPicture(sheet, drawingXML, cell, file, ext string, rID, hyperlinkRID int, img image.Config, opts *PictureOptions) error {
	col, row, err := CellNameToCoordinates(cell)
	if err != nil {
		return err
	}
	width, height := img.Width, img.Height
	if opts.AutoFit {
		width, height, col, row, err = f.drawingResize(sheet, cell, float64(width), float64(height), opts)
		if err != nil {
			return err
		}
	} else {
		width = int(float64(width) * *opts.XScale)
		height = int(float64(height) * *opts.YScale)
	}
	col--
	row--
	colStart, rowStart, colEnd, rowEnd, x2, y2 := f.positionObjectPixels(sheet, col, row, opts.OffsetX, opts.OffsetY, width, height)
	content, cNvPrID, err := f.drawingParser(drawingXML)
	if err != nil {
		return err
	}
	twoCellAnchor := xdrCellAnchor{}
	twoCellAnchor.EditAs = opts.Positioning
	from := xlsxFrom{}
	from.Col = colStart
	from.ColOff = opts.OffsetX * EMU
	from.Row = rowStart
	from.RowOff = opts.OffsetY * EMU
	to := xlsxTo{}
	to.Col = colEnd
	to.ColOff = x2 * EMU
	to.Row = rowEnd
	to.RowOff = y2 * EMU
	twoCellAnchor.From = &from
	twoCellAnchor.To = &to
	pic := xlsxPic{}
	pic.NvPicPr.CNvPicPr.PicLocks.NoChangeAspect = opts.LockAspectRatio
	pic.NvPicPr.CNvPr.ID = cNvPrID
	pic.NvPicPr.CNvPr.Descr = file
	pic.NvPicPr.CNvPr.Name = "Picture " + strconv.Itoa(cNvPrID)
	if hyperlinkRID != 0 {
		pic.NvPicPr.CNvPr.HlinkClick = &xlsxHlinkClick{
			R:   SourceRelationship.Value,
			RID: "rId" + strconv.Itoa(hyperlinkRID),
		}
	}
	pic.BlipFill.Blip.R = SourceRelationship.Value
	pic.BlipFill.Blip.Embed = "rId" + strconv.Itoa(rID)
	if ext == ".svg" {
		pic.BlipFill.Blip.ExtList = &xlsxEGOfficeArtExtensionList{
			Ext: []xlsxCTOfficeArtExtension{
				{
					URI: ExtURISVG,
					SVGBlip: xlsxCTSVGBlip{
						XMLNSaAVG: NameSpaceDrawing2016SVG.Value,
						Embed:     pic.BlipFill.Blip.Embed,
					},
				},
			},
		}
	}
	pic.SpPr.PrstGeom.Prst = "rect"

	twoCellAnchor.Pic = &pic
	twoCellAnchor.ClientData = &xdrClientData{
		FLocksWithSheet:  *opts.Locked,
		FPrintsWithSheet: *opts.PrintObject,
	}
	content.Lock()
	defer content.Unlock()
	content.TwoCellAnchor = append(content.TwoCellAnchor, &twoCellAnchor)
	f.Drawings.Store(drawingXML, content)
	return err
}

// countMedia provides a function to get media files count storage in the
// folder xl/media/image.
func (f *File) countMedia() int {
	count := 0
	f.Pkg.Range(func(k, v interface{}) bool {
		if strings.Contains(k.(string), "xl/media/image") {
			count++
		}
		return true
	})
	return count
}

// addMedia provides a function to add a picture into folder xl/media/image by
// given file and extension name. Duplicate images are only actually stored once
// and drawings that use it will reference the same image.
func (f *File) addMedia(file []byte, ext string) string {
	count := f.countMedia()
	var name string
	f.Pkg.Range(func(k, existing interface{}) bool {
		if !strings.HasPrefix(k.(string), "xl/media/image") {
			return true
		}
		if bytes.Equal(file, existing.([]byte)) {
			name = k.(string)
			return false
		}
		return true
	})
	if name != "" {
		return name
	}
	media := "xl/media/image" + strconv.Itoa(count+1) + ext
	f.Pkg.Store(media, file)
	return media
}

// setContentTypePartImageExtensions provides a function to set the content
// type for relationship parts and the Main Document part.
func (f *File) setContentTypePartImageExtensions() error {
	imageTypes := map[string]string{
		"jpeg": "image/", "png": "image/", "gif": "image/", "svg": "image/", "tiff": "image/",
		"emf": "image/x-", "wmf": "image/x-", "emz": "image/x-", "wmz": "image/x-",
	}
	content, err := f.contentTypesReader()
	if err != nil {
		return err
	}
	content.Lock()
	defer content.Unlock()
	for _, file := range content.Defaults {
		delete(imageTypes, file.Extension)
	}
	for extension, prefix := range imageTypes {
		content.Defaults = append(content.Defaults, xlsxDefault{
			Extension:   extension,
			ContentType: prefix + extension,
		})
	}
	return err
}

// setContentTypePartVMLExtensions provides a function to set the content type
// for relationship parts and the Main Document part.
func (f *File) setContentTypePartVMLExtensions() error {
	var vml bool
	content, err := f.contentTypesReader()
	if err != nil {
		return err
	}
	content.Lock()
	defer content.Unlock()
	for _, v := range content.Defaults {
		if v.Extension == "vml" {
			vml = true
		}
	}
	if !vml {
		content.Defaults = append(content.Defaults, xlsxDefault{
			Extension:   "vml",
			ContentType: ContentTypeVML,
		})
	}
	return err
}

// addContentTypePart provides a function to add content type part
// relationships in the file [Content_Types].xml by given index.
func (f *File) addContentTypePart(index int, contentType string) error {
	setContentType := map[string]func() error{
		"comments": f.setContentTypePartVMLExtensions,
		"drawings": f.setContentTypePartImageExtensions,
	}
	partNames := map[string]string{
		"chart":         "/xl/charts/chart" + strconv.Itoa(index) + ".xml",
		"chartsheet":    "/xl/chartsheets/sheet" + strconv.Itoa(index) + ".xml",
		"comments":      "/xl/comments" + strconv.Itoa(index) + ".xml",
		"drawings":      "/xl/drawings/drawing" + strconv.Itoa(index) + ".xml",
		"table":         "/xl/tables/table" + strconv.Itoa(index) + ".xml",
		"pivotTable":    "/xl/pivotTables/pivotTable" + strconv.Itoa(index) + ".xml",
		"pivotCache":    "/xl/pivotCache/pivotCacheDefinition" + strconv.Itoa(index) + ".xml",
		"sharedStrings": "/xl/sharedStrings.xml",
	}
	contentTypes := map[string]string{
		"chart":         ContentTypeDrawingML,
		"chartsheet":    ContentTypeSpreadSheetMLChartsheet,
		"comments":      ContentTypeSpreadSheetMLComments,
		"drawings":      ContentTypeDrawing,
		"table":         ContentTypeSpreadSheetMLTable,
		"pivotTable":    ContentTypeSpreadSheetMLPivotTable,
		"pivotCache":    ContentTypeSpreadSheetMLPivotCacheDefinition,
		"sharedStrings": ContentTypeSpreadSheetMLSharedStrings,
	}
	s, ok := setContentType[contentType]
	if ok {
		if err := s(); err != nil {
			return err
		}
	}
	content, err := f.contentTypesReader()
	if err != nil {
		return err
	}
	content.Lock()
	defer content.Unlock()
	for _, v := range content.Overrides {
		if v.PartName == partNames[contentType] {
			return err
		}
	}
	content.Overrides = append(content.Overrides, xlsxOverride{
		PartName:    partNames[contentType],
		ContentType: contentTypes[contentType],
	})
	return err
}

// getSheetRelationshipsTargetByID provides a function to get Target attribute
// value in xl/worksheets/_rels/sheet%d.xml.rels by given worksheet name and
// relationship index.
func (f *File) getSheetRelationshipsTargetByID(sheet, rID string) string {
	name, ok := f.getSheetXMLPath(sheet)
	if !ok {
		name = strings.ToLower(sheet) + ".xml"
	}
	rels := "xl/worksheets/_rels/" + strings.TrimPrefix(name, "xl/worksheets/") + ".rels"
	sheetRels, _ := f.relsReader(rels)
	if sheetRels == nil {
		sheetRels = &xlsxRelationships{}
	}
	sheetRels.Lock()
	defer sheetRels.Unlock()
	for _, v := range sheetRels.Relationships {
		if v.ID == rID {
			return v.Target
		}
	}
	return ""
}

// GetPicture provides a function to get picture base name and raw content
// embed in spreadsheet by given worksheet and cell name. This function
// returns the file name in spreadsheet and file contents as []byte data
// types. This function is concurrency safe. For example:
//
//	f, err := excelize.OpenFile("Book1.xlsx")
//	if err != nil {
//	    fmt.Println(err)
//	    return
//	}
//	defer func() {
//	    if err := f.Close(); err != nil {
//	        fmt.Println(err)
//	    }
//	}()
//	file, raw, err := f.GetPicture("Sheet1", "A2")
//	if err != nil {
//	    fmt.Println(err)
//	    return
//	}
//	if err := os.WriteFile(file, raw, 0644); err != nil {
//	    fmt.Println(err)
//	}
func (f *File) GetPicture(sheet, cell string) (string, []byte, error) {
	col, row, err := CellNameToCoordinates(cell)
	if err != nil {
		return "", nil, err
	}
	col--
	row--
	ws, err := f.workSheetReader(sheet)
	if err != nil {
		return "", nil, err
	}
	if ws.Drawing == nil {
		return "", nil, err
	}
	target := f.getSheetRelationshipsTargetByID(sheet, ws.Drawing.RID)
	drawingXML := strings.ReplaceAll(target, "..", "xl")
	drawingRelationships := strings.ReplaceAll(
		strings.ReplaceAll(target, "../drawings", "xl/drawings/_rels"), ".xml", ".xml.rels")

	return f.getPicture(row, col, drawingXML, drawingRelationships)
}

// DeletePicture provides a function to delete charts in spreadsheet by given
// worksheet name and cell reference. Note that the image file won't be deleted
// from the document currently.
func (f *File) DeletePicture(sheet, cell string) error {
	col, row, err := CellNameToCoordinates(cell)
	if err != nil {
		return err
	}
	col--
	row--
	ws, err := f.workSheetReader(sheet)
	if err != nil {
		return err
	}
	if ws.Drawing == nil {
		return err
	}
	drawingXML := strings.ReplaceAll(f.getSheetRelationshipsTargetByID(sheet, ws.Drawing.RID), "..", "xl")
	return f.deleteDrawing(col, row, drawingXML, "Pic")
}

// getPicture provides a function to get picture base name and raw content
// embed in spreadsheet by given coordinates and drawing relationships.
func (f *File) getPicture(row, col int, drawingXML, drawingRelationships string) (ret string, buf []byte, err error) {
	var (
		wsDr            *xlsxWsDr
		ok              bool
		deWsDr          *decodeWsDr
		drawRel         *xlsxRelationship
		deTwoCellAnchor *decodeTwoCellAnchor
	)

	if wsDr, _, err = f.drawingParser(drawingXML); err != nil {
		return
	}
	if ret, buf = f.getPictureFromWsDr(row, col, drawingRelationships, wsDr); len(buf) > 0 {
		return
	}
	deWsDr = new(decodeWsDr)
	if err = f.xmlNewDecoder(bytes.NewReader(namespaceStrictToTransitional(f.readXML(drawingXML)))).
		Decode(deWsDr); err != nil && err != io.EOF {
		return
	}
	err = nil
	for _, anchor := range deWsDr.TwoCellAnchor {
		deTwoCellAnchor = new(decodeTwoCellAnchor)
		if err = f.xmlNewDecoder(strings.NewReader("<decodeTwoCellAnchor>" + anchor.Content + "</decodeTwoCellAnchor>")).
			Decode(deTwoCellAnchor); err != nil && err != io.EOF {
			return
		}
		if err = nil; deTwoCellAnchor.From != nil && deTwoCellAnchor.Pic != nil {
			if deTwoCellAnchor.From.Col == col && deTwoCellAnchor.From.Row == row {
				drawRel = f.getDrawingRelationships(drawingRelationships, deTwoCellAnchor.Pic.BlipFill.Blip.Embed)
				if _, ok = supportedImageTypes[filepath.Ext(drawRel.Target)]; ok {
					ret = filepath.Base(drawRel.Target)
					if buffer, _ := f.Pkg.Load(strings.ReplaceAll(drawRel.Target, "..", "xl")); buffer != nil {
						buf = buffer.([]byte)
					}
					return
				}
			}
		}
	}
	return
}

// getPictureFromWsDr provides a function to get picture base name and raw
// content in worksheet drawing by given coordinates and drawing
// relationships.
func (f *File) getPictureFromWsDr(row, col int, drawingRelationships string, wsDr *xlsxWsDr) (ret string, buf []byte) {
	var (
		ok      bool
		anchor  *xdrCellAnchor
		drawRel *xlsxRelationship
	)
	wsDr.Lock()
	defer wsDr.Unlock()
	for _, anchor = range wsDr.TwoCellAnchor {
		if anchor.From != nil && anchor.Pic != nil {
			if anchor.From.Col == col && anchor.From.Row == row {
				if drawRel = f.getDrawingRelationships(drawingRelationships,
					anchor.Pic.BlipFill.Blip.Embed); drawRel != nil {
					if _, ok = supportedImageTypes[filepath.Ext(drawRel.Target)]; ok {
						ret = filepath.Base(drawRel.Target)
						if buffer, _ := f.Pkg.Load(strings.ReplaceAll(drawRel.Target, "..", "xl")); buffer != nil {
							buf = buffer.([]byte)
						}
						return
					}
				}
			}
		}
	}
	return
}

// getDrawingRelationships provides a function to get drawing relationships
// from xl/drawings/_rels/drawing%s.xml.rels by given file name and
// relationship ID.
func (f *File) getDrawingRelationships(rels, rID string) *xlsxRelationship {
	if drawingRels, _ := f.relsReader(rels); drawingRels != nil {
		drawingRels.Lock()
		defer drawingRels.Unlock()
		for _, v := range drawingRels.Relationships {
			if v.ID == rID {
				return &v
			}
		}
	}
	return nil
}

// drawingsWriter provides a function to save xl/drawings/drawing%d.xml after
// serialize structure.
func (f *File) drawingsWriter() {
	f.Drawings.Range(func(path, d interface{}) bool {
		if d != nil {
			v, _ := xml.Marshal(d.(*xlsxWsDr))
			f.saveFileList(path.(string), v)
		}
		return true
	})
}

// drawingResize calculate the height and width after resizing.
func (f *File) drawingResize(sheet, cell string, width, height float64, opts *PictureOptions) (w, h, c, r int, err error) {
	var mergeCells []MergeCell
	mergeCells, err = f.GetMergeCells(sheet)
	if err != nil {
		return
	}
	var rng []int
	var inMergeCell bool
	if c, r, err = CellNameToCoordinates(cell); err != nil {
		return
	}
	cellWidth, cellHeight := f.getColWidth(sheet, c), f.getRowHeight(sheet, r)
	for _, mergeCell := range mergeCells {
		if inMergeCell {
			continue
		}
		if inMergeCell, err = f.checkCellInRangeRef(cell, mergeCell[0]); err != nil {
			return
		}
		if inMergeCell {
			rng, _ = cellRefsToCoordinates(mergeCell.GetStartAxis(), mergeCell.GetEndAxis())
			_ = sortCoordinates(rng)
		}
	}
	if inMergeCell {
		cellWidth, cellHeight = 0, 0
		c, r = rng[0], rng[1]
		for col := rng[0]; col <= rng[2]; col++ {
			cellWidth += f.getColWidth(sheet, col)
		}
		for row := rng[1]; row <= rng[3]; row++ {
			cellHeight += f.getRowHeight(sheet, row)
		}
	}
	if float64(cellWidth) < width {
		asp := float64(cellWidth) / width
		width, height = float64(cellWidth), height*asp
	}
	if float64(cellHeight) < height {
		asp := float64(cellHeight) / height
		height, width = float64(cellHeight), width*asp
	}
	width, height = width-float64(opts.OffsetX), height-float64(opts.OffsetY)
	w, h = int(width**opts.XScale), int(height**opts.YScale)
	return
}