Add support for Jpeg Images

@@ -6,6 +6,7 @@
 * Implement default fonts bounding box
 * Add Bézier Curve primitive
 * Implement drawShape
+* Add support for Jpeg images
 
 # 1.0.8
 * Fix monospace TTF font loading

@@ -36,6 +36,9 @@ class PdfImage extends PdfXObject {
   /// Process alphaChannel only
   final bool alphaChannel;
 
+  /// The image data is a jpeg image
+  final bool jpeg;
+
   /// Creates a new [PdfImage] instance.
   ///
   /// @param imgage an [Uint8List] value
@@ -48,7 +51,8 @@ class PdfImage extends PdfXObject {
       @required this.width,
       @required this.height,
       this.alpha = true,
-      this.alphaChannel = false})
+      this.alphaChannel = false,
+      this.jpeg = false})
       : assert(alphaChannel == false || alpha == true),
         assert(width != null),
         assert(height != null),
@@ -74,10 +78,21 @@ class PdfImage extends PdfXObject {
     } else {
       params["/ColorSpace"] = PdfStream.string("/DeviceRGB");
     }
+
+    if (jpeg) {
+      params["/Intent"] = PdfStream.string("/RelativeColorimetric");
+    }
   }
 
   @override
   void _prepare() {
+    if (jpeg) {
+      buf.putBytes(image);
+      params["/Filter"] = PdfStream.string("/DCTDecode");
+      super._prepare();
+      return;
+    }
+
     // write the pixels to the stream
     // print("Processing image ${img.width}x${img.height} pixels");
 

@@ -41,7 +41,10 @@ class PdfObjectStream extends PdfObject {
   void _prepare() {
     super._prepare();
 
-    if (pdfDocument.deflate != null) {
+    if (params.containsKey("/Filter")) {
+      // The data is already in the right format
+      _data = buf.output();
+    } else if (pdfDocument.deflate != null) {
       _data = pdfDocument.deflate(buf.output());
       params["/Filter"] = PdfStream.string("/FlateDecode");
     } else if (isBinary) {

+import 'dart:io';
+import 'dart:typed_data';
+
+import 'package:pdf/pdf.dart';
+import "package:test/test.dart";
+
+Future<Uint8List> download(String url) async {
+  var client = HttpClient();
+  var request = await client.getUrl(Uri.parse(url));
+  var response = await request.close();
+  var builder = await response.fold(BytesBuilder(), (b, d) => b..add(d));
+  var data = builder.takeBytes();
+  return Uint8List.fromList(data);
+}
+
+void main() {
+  test('Pdf1', () async {
+    var pdf = PdfDocument();
+    var page = PdfPage(pdf, pageFormat: PdfPageFormat.a4);
+
+    var image = PdfImage(pdf,
+        image: await download("https://www.nfet.net/nfet.jpg"),
+        width: 472,
+        height: 477,
+        jpeg: true,
+        alpha: false);
+
+    var g = page.getGraphics();
+    g.drawImage(image, 30.0, page.pageFormat.height - 507.0);
+
+    var file = File('file4.pdf');
+    file.writeAsBytesSync(pdf.save());
+  });
+}