exceljs · guyonroche · Nov 4, 2019 · Aug 4, 2019 · Nov 2, 2019 · Nov 3, 2019
diff --git a/.gitignore b/.gitignore
@@ -21,6 +21,9 @@ tmp/*
 # WebStorm
 .idea
 
+# VS Code
+.vscode
+
 # Intellij IDEA
 exceljs.iml
 

diff --git a/lib/stream/xlsx/workbook-writer.js b/lib/stream/xlsx/workbook-writer.js
@@ -97,8 +97,16 @@ class WorkbookWriter {
   async commit() {
     // commit all worksheets, then add suplimentary files
     await this.promise;
+    await this.addMedia();
     await this._commitWorksheets();
-    await Promise.all([this.addContentTypes(), this.addApp(), this.addCore(), this.addSharedStrings(), this.addStyles(), this.addWorkbookRels()]);
+    await Promise.all([
+      this.addContentTypes(),
+      this.addApp(),
+      this.addCore(),
+      this.addSharedStrings(),
+      this.addStyles(),
+      this.addWorkbookRels(),
+    ]);
     await this.addWorkbook();
     return this._finalize();
   }
@@ -114,6 +122,16 @@ class WorkbookWriter {
     return this._worksheets.length || 1;
   }
 
+  addImage(image) {
+    const id = this.media.length;
+    this.media.push(Object.assign({}, image, {type: 'image'}));
+    return id;
+  }
+
+  getImage(id) {
+    return this.media[id];
+  }
+
   addWorksheet(name, options) {
     // it's possible to add a worksheet with different than default
     // shared string handling
@@ -197,6 +215,7 @@ class WorkbookWriter {
         worksheets: this._worksheets.filter(Boolean),
         sharedStrings: this.sharedStrings,
         commentRefs: this.commentRefs,
+        media: this.media,
       };
       const xform = new ContentTypesXform();
       const xml = xform.toXml(model);
@@ -205,6 +224,29 @@ class WorkbookWriter {
     });
   }
 
+  addMedia() {
+    return Promise.all(
+      this.media.map((medium, idx) => {
+        medium.name = `image${idx+1}.${medium.extension}`;
+        if (medium.type === 'image') {
+          const filename = `xl/media/${medium.name}`;
+          if (medium.filename) {
+            return this.zip.file(medium.filename, {name: filename});
+          }
+          if (medium.buffer) {
+            return this.zip.append(medium.buffer, {name: filename});
+          }
+          if (medium.base64) {
+            const dataimg64 = medium.base64;
+            const content = dataimg64.substring(dataimg64.indexOf(',') + 1);
+            return this.zip.append(content, {name: filename, base64: true});
+          }
+        }
+        throw new Error('Unsupported media');
+      })
+    );
+  }
+
   addApp() {
     return new Promise(resolve => {
       const model = {

diff --git a/lib/stream/xlsx/worksheet-writer.js b/lib/stream/xlsx/worksheet-writer.js
@@ -150,21 +150,11 @@ class WorksheetWriter {
     // auto filter
     this.autoFilter = options.autoFilter || null;
 
+    this._media = [];
+
     // start writing to stream now
     this._writeOpenWorksheet();
 
-    // background
-    if (options.background && options.background.type === 'image') {
-      const imageName = this._workbook.addMedia(options.background);
-      const pictureId = this._sheetRelsWriter.addMedia({
-        Target: `../media/${imageName}`,
-        Type: RelType.Image,
-      });
-      this._background = {
-        rId: pictureId,
-      };
-    }
-
     this.startedData = false;
   }
 
@@ -429,8 +419,21 @@ class WorksheetWriter {
     this._merges.push(dimensions);
   }
 
+  // =========================================================================
+
+  addBackgroundImage(imageId) {
+    this._background = {
+      imageId,
+    };
+  }
+
 
+  getBackgroundImageId() {
+    return this._background && this._background.imageId;
+  }
+
   // ================================================================================
+
   _write(text) {
     xmlBuffer.reset();
     xmlBuffer.addText(text);
@@ -571,7 +574,20 @@ class WorksheetWriter {
 
   _writeBackground() {
     if (this._background) {
-      this.stream.write(xform.picture.toXml(this._background));
+
+      if(this._background.imageId !== undefined){
+        const image = this._workbook.getImage(this._background.imageId);
+        const pictureId = this._sheetRelsWriter.addMedia({
+          Target: `../media/${image.name}`,
+          Type: RelType.Image,
+        });
+
+        this._background = {
+          ...this._background,
+          rId: pictureId,
+        };
+      }
+      this.stream.write(xform.picture.toXml({rId: this._background.rId}));
     }
   }
 

diff --git a/test/test-image-stream-writer.js b/test/test-image-stream-writer.js
@@ -0,0 +1,28 @@
+const path = require('path');
+const Excel = require('../lib/exceljs.nodejs.js');
+const HrStopwatch = require('./utils/hr-stopwatch');
+
+const [, , filename] = process.argv;
+
+const wb = new Excel.stream.xlsx.WorkbookWriter({filename});
+
+const imageId = wb.addImage({
+  filename: path.join(__dirname, 'data/image2.png'),
+  extension: 'png',
+});
+
+const ws = wb.addWorksheet('Foo');
+ws.addBackgroundImage(imageId);
+
+const stopwatch = new HrStopwatch();
+stopwatch.start();
+
+wb.commit()
+.then(() => {
+  const micros = stopwatch.microseconds;
+  console.log('Done.');
+  console.log('Time taken:', micros);
+})
+.catch(error => {
+  console.log(error.message);
+});