Add printing completion

 # Changelog
 
+## 2.1.5
+
+- Add printing completion
+
 ## 2.1.4
 
 - Update example to show saved documents on iOS Files app

@@ -30,6 +30,8 @@ import android.print.PdfConvert;
 import android.print.PrintAttributes;
 import android.print.PrintDocumentAdapter;
 import android.print.PrintDocumentInfo;
+import android.print.PrintJob;
+import android.print.PrintJobInfo;
 import android.print.PrintManager;
 import android.print.pdf.PrintedPdfDocument;
 import android.webkit.WebView;
@@ -56,6 +58,7 @@ public class PrintingPlugin extends PrintDocumentAdapter implements MethodCallHa
     private final Activity activity;
     private final MethodChannel channel;
     private PrintedPdfDocument mPdfDocument;
+    private PrintJob printJob;
     private byte[] documentData;
     private String jobName;
     private LayoutResultCallback callback;
@@ -126,7 +129,33 @@ public class PrintingPlugin extends PrintDocumentAdapter implements MethodCallHa
 
     @Override
     public void onFinish() {
-        // noinspection ResultOfMethodCallIgnored
+        try {
+            while (true) {
+                int state = printJob.getInfo().getState();
+
+                if (state == PrintJobInfo.STATE_COMPLETED) {
+                    HashMap<String, Object> args = new HashMap<>();
+                    args.put("completed", true);
+                    channel.invokeMethod("onCompleted", args);
+                    break;
+                } else if (state == PrintJobInfo.STATE_CANCELED) {
+                    HashMap<String, Object> args = new HashMap<>();
+                    args.put("completed", false);
+                    channel.invokeMethod("onCompleted", args);
+                    break;
+                }
+
+                Thread.sleep(200);
+            }
+        } catch (Exception e) {
+            HashMap<String, Object> args = new HashMap<>();
+            args.put("completed", printJob.isCompleted());
+            args.put("error", e.getMessage());
+            channel.invokeMethod("onCompleted", args);
+        }
+
+        printJob = null;
+        mPdfDocument = null;
     }
 
     @Override
@@ -136,7 +165,7 @@ public class PrintingPlugin extends PrintDocumentAdapter implements MethodCallHa
                 jobName =
                         call.argument("name") == null ? "Document" : (String) call.argument("name");
                 assert jobName != null;
-                printManager.print(jobName, this, null);
+                printJob = printManager.print(jobName, this, null);
                 result.success(0);
                 break;
             case "writePdf":

@@ -30,9 +30,11 @@ class MyAppState extends State<MyApp> {
 
   Future<void> _printPdf() async {
     print('Print ...');
-    await Printing.layoutPdf(
+    final bool result = await Printing.layoutPdf(
         onLayout: (PdfPageFormat format) async =>
             (await generateDocument(format)).save());
+
+    print('Document printed: $result');
   }
 
   Future<void> _saveAsFile() async {

@@ -87,13 +87,24 @@ public class SwiftPrintingPlugin: NSObject, FlutterPlugin, UIPrintInteractionCon
         if !completed, error != nil {
             print("Unable to print: \(error?.localizedDescription ?? "unknown error")")
         }
+
+        let data: NSDictionary = [
+            "completed": completed,
+            "error": error?.localizedDescription as Any,
+        ]
+        channel?.invokeMethod("onCompleted", arguments: data)
+
         renderer = nil
     }
 
     func printPdf(_ name: String) {
         let printing = UIPrintInteractionController.isPrintingAvailable
         if !printing {
-            print("printing not available")
+            let data: NSDictionary = [
+                "completed": false,
+                "error": "Printing not available",
+            ]
+            channel?.invokeMethod("onCompleted", arguments: data)
             return
         }
 

@@ -22,6 +22,7 @@ mixin Printing {
   static const MethodChannel _channel = MethodChannel('printing');
   static LayoutCallback _onLayout;
   static Completer<List<int>> _onHtmlRendered;
+  static Completer<bool> _onCompleted;
 
   static Future<void> _handleMethod(MethodCall call) async {
     switch (call.method) {
@@ -38,6 +39,15 @@ mixin Printing {
           'doc': Uint8List.fromList(bytes),
         };
         return await _channel.invokeMethod('writePdf', params);
+      case 'onCompleted':
+        final bool completed = call.arguments['completed'];
+        final String error = call.arguments['error'];
+        if (completed == false && error != null) {
+          _onCompleted.completeError(error);
+        } else {
+          _onCompleted.complete(completed);
+        }
+        break;
       case 'onHtmlRendered':
         _onHtmlRendered.complete(call.arguments);
         break;
@@ -50,12 +60,20 @@ mixin Printing {
   /// Prints a Pdf document to a local printer using the platform UI
   /// the Pdf document is re-built in a [LayoutCallback] each time the
   /// user changes a setting like the page format or orientation.
-  static Future<void> layoutPdf(
-      {@required LayoutCallback onLayout, String name = 'Document'}) async {
+  ///
+  /// returns a future with a `bool` set to true if the document is printed
+  /// and false if it is canceled.
+  /// throws an exception in case of error
+  static Future<bool> layoutPdf({
+    @required LayoutCallback onLayout,
+    String name = 'Document',
+  }) async {
+    _onCompleted = Completer<bool>();
     _onLayout = onLayout;
     _channel.setMethodCallHandler(_handleMethod);
     final Map<String, dynamic> params = <String, dynamic>{'name': name};
-    return await _channel.invokeMethod('printPdf', params);
+    await _channel.invokeMethod<int>('printPdf', params);
+    return _onCompleted.future;
   }
 
   /// Prints a [PdfDocument] or a pdf stream to a local printer using the platform UI

@@ -4,7 +4,7 @@ description: Plugin that allows Flutter apps to generate and print documents to
 homepage: https://github.com/DavBfr/dart_pdf/tree/master/printing
 repository: https://github.com/DavBfr/dart_pdf
 issue_tracker: https://github.com/DavBfr/dart_pdf/issues
-version: 2.1.4
+version: 2.1.5
 
 environment:
   sdk: ">=2.1.0 <3.0.0"