Fix empty PDF issue

examples/basics.js

@@ -28,6 +28,16 @@ var now = new Date();
 var pdf = pdfmake.createPdf(docDefinition);
 pdf.write('pdfs/basics.pdf').then(() => {
 	console.log(new Date() - now);
+	// Add a verification step to check the content of the generated PDF
+	pdf.getBuffer().then(buffer => {
+		if (buffer.byteLength === 0) {
+			console.error('Empty PDF content');
+		} else {
+			console.log('PDF content is correctly embedded');
+		}
+	}).catch(err => {
+		console.error(err);
+	});
 }, err => {
 	console.error(err);
 });

examples/columns_simple.js

@@ -161,6 +161,16 @@ var now = new Date();
 var pdf = pdfmake.createPdf(docDefinition);
 pdf.write('pdfs/columns_simple.pdf').then(() => {
 	console.log(new Date() - now);
+	// Add a verification step to check the content of the generated PDF
+	pdf.getBuffer().then(buffer => {
+		if (buffer.byteLength === 0) {
+			console.error('Empty PDF content');
+		} else {
+			console.log('PDF content is correctly embedded');
+		}
+	}).catch(err => {
+		console.error(err);
+	});
 }, err => {
 	console.error(err);
 });

src/base.js

@@ -21,7 +21,18 @@ class pdfmake {
 		let printer = new Printer(this.fonts, this.virtualfs, this.urlResolver());
 		const pdfDocumentPromise = printer.createPdfKitDocument(docDefinition, options);
 
-		return this._transformToDocument(pdfDocumentPromise);
+		// Add a verification step to ensure the content is correctly embedded
+		return pdfDocumentPromise.then(pdfDocument => {
+			return new Promise((resolve, reject) => {
+				pdfDocument.getBuffer().then(buffer => {
+					if (buffer.byteLength === 0) {
+						reject(new Error('Empty PDF content'));
+					} else {
+						resolve(this._transformToDocument(pdfDocument));
+					}
+				}).catch(reject);
+			});
+		});
 	}
 
 	setProgressCallback(callback) {

src/browser-extensions/OutputDocumentBrowser.js

@@ -43,8 +43,14 @@ class OutputDocumentBrowser extends OutputDocument {
 		return new Promise((resolve, reject) => {
 			this.getBlob().then(blob => {
 				try {
-					saveAs(blob, filename);
-					resolve();
+					// Ensure the content is correctly embedded before saving the file
+					this.getBuffer().then(buffer => {
+						if (buffer.byteLength === 0) {
+							throw new Error('Empty PDF content');
+						}
+						saveAs(blob, filename);
+						resolve();
+					});
 				} catch (e) {
 					reject(e);
 				}

tests/unit/Node-interface.spec.js

@@ -32,4 +32,30 @@ describe('Node interface', function () {
 		});
 
 	});
+
+	describe('download', function () {
+		it('should download PDF with content', function (done) {
+			var docDefinition = {
+				content: [
+					'First paragraph',
+					'Another paragraph, this time a little bit longer to make sure, this line will be divided into at least two lines'
+				]
+			};
+
+			var pdf = pdfmake.createPdf(docDefinition);
+			pdf.download('test.pdf').then(() => {
+				pdf.getBuffer().then(buffer => {
+					if (buffer.byteLength === 0) {
+						throw new Error('Empty PDF content');
+					} else {
+						done();
+					}
+				}).catch(err => {
+					throw err;
+				});
+			}).catch(err => {
+				throw err;
+			});
+		});
+	});
 });