Fix threading issues in iOS and macOS printing plugin

printing/ios/printing/Sources/printing/PrintJob.swift

@@ -84,7 +84,8 @@ public class PrintJob: UIPrintPageRenderer, UIPrintInteractionControllerDelegate
             controller.delegate = self
 
             let printInfo = UIPrintInfo.printInfo()
-            printInfo.jobName = jobName!
+            let strippedJobName = jobName!.hasSuffix(".pdf") ? String(jobName!.dropLast(4)) : jobName!
+            printInfo.jobName = strippedJobName
             printInfo.outputType = .general
             if orientation != nil {
                 printInfo.orientation = orientation!
@@ -185,7 +186,8 @@ public class PrintJob: UIPrintPageRenderer, UIPrintInteractionControllerDelegate
             orientation = UIPrintInfo.Orientation.landscape
         }
 
-        jobName = name
+        // Strip .pdf extension as UIPrintInteractionController appends it automatically
+        jobName = name.hasSuffix(".pdf") ? String(name.dropLast(4)) : name
         printerName = printerID
 
         let controller = UIPrintInteractionController.shared

printing/ios/printing/Sources/printing/PrintingPlugin.swift

@@ -185,7 +185,9 @@ public class PrintingPlugin: NSObject, FlutterPlugin {
             "job": printJob.index,
         ] as [String: Any]
 
-        channel.invokeMethod("onLayout", arguments: arg)
+        DispatchQueue.main.async {
+            self.channel.invokeMethod("onLayout", arguments: arg)
+        }
     }
 
     /// send completion status to flutter
@@ -195,8 +197,10 @@ public class PrintingPlugin: NSObject, FlutterPlugin {
             "error": error as Any,
             "job": printJob.index,
         ]
-        channel.invokeMethod("onCompleted", arguments: data)
         jobs.removeValue(forKey: UInt32(printJob.index))
+        DispatchQueue.main.async {
+            self.channel.invokeMethod("onCompleted", arguments: data)
+        }
     }
 
     /// send html to pdf data result to flutter
@@ -205,7 +209,9 @@ public class PrintingPlugin: NSObject, FlutterPlugin {
             "doc": FlutterStandardTypedData(bytes: pdfData),
             "job": printJob.index,
         ]
-        channel.invokeMethod("onHtmlRendered", arguments: data)
+        DispatchQueue.main.async {
+            self.channel.invokeMethod("onHtmlRendered", arguments: data)
+        }
     }
 
     /// send html to pdf conversion error to flutter
@@ -214,7 +220,9 @@ public class PrintingPlugin: NSObject, FlutterPlugin {
             "error": error,
             "job": printJob.index,
         ]
-        channel.invokeMethod("onHtmlError", arguments: data)
+        DispatchQueue.main.async {
+            self.channel.invokeMethod("onHtmlError", arguments: data)
+        }
     }
 
     /// send pdf to raster data result to flutter
@@ -225,14 +233,18 @@ public class PrintingPlugin: NSObject, FlutterPlugin {
             "height": height,
             "job": printJob.index,
         ]
-        channel.invokeMethod("onPageRasterized", arguments: data)
+        DispatchQueue.main.async {
+            self.channel.invokeMethod("onPageRasterized", arguments: data)
+        }
     }
 
     public func onPageRasterEnd(printJob: PrintJob, error: String?) {
         let data: NSDictionary = [
             "job": printJob.index,
             "error": error as Any,
         ]
-        channel.invokeMethod("onPageRasterEnd", arguments: data)
+        DispatchQueue.main.async {
+            self.channel.invokeMethod("onPageRasterEnd", arguments: data)
+        }
     }
 }

printing/lib/src/print_job.dart

@@ -15,6 +15,7 @@
  */
 
 import 'dart:async';
+import 'dart:math';
 import 'dart:typed_data';
 
 import 'callback.dart';
@@ -57,7 +58,7 @@ class PrintJobs {
   /// Create a list print jobs
   PrintJobs();
 
-  static var _currentIndex = 0;
+  static int _currentIndex = Random().nextInt(0x7FFFFFFF);
 
   final _printJobs = <int, PrintJob>{};
 

printing/macos/printing/Sources/printing/PrintJob.swift

@@ -29,9 +29,11 @@ public class PrintJob: NSView, NSSharingServicePickerDelegate {
     private var printOperation: NSPrintOperation?
     private var pdfDocument: CGPDFDocument?
     private var page: CGPDFPage?
-    private let semaphore = DispatchSemaphore(value: 0)
+    private var isWaitingForDocument = false
+    private var documentReceived = false
     private var dynamic = false
     private var _window: NSWindow?
+    private var lastLayoutParams: (width: CGFloat, height: CGFloat, marginLeft: CGFloat, marginTop: CGFloat, marginRight: CGFloat, marginBottom: CGFloat)?
 
     public init(printing: PrintingPlugin, index: Int) {
         self.printing = printing
@@ -44,6 +46,13 @@ public class PrintJob: NSView, NSSharingServicePickerDelegate {
         fatalError("init(coder:) has not been implemented")
     }
 
+    private func layoutParamsChanged(_ new: (width: CGFloat, height: CGFloat, marginLeft: CGFloat, marginTop: CGFloat, marginRight: CGFloat, marginBottom: CGFloat)) -> Bool {
+        guard let last = lastLayoutParams else { return true }
+        return last.width != new.width || last.height != new.height ||
+               last.marginLeft != new.marginLeft || last.marginTop != new.marginTop ||
+               last.marginRight != new.marginRight || last.marginBottom != new.marginBottom
+    }
+
     // Return the number of pages available for printing
     override public func knowsPageRange(_ range: NSRangePointer) -> Bool {
         let size = printOperation!.showsPrintPanel ? printOperation!.printPanel.printInfo.paperSize : printOperation!.printInfo.paperSize
@@ -52,18 +61,38 @@ public class PrintJob: NSView, NSSharingServicePickerDelegate {
         setBoundsSize(size)
 
         if dynamic {
-            printing.onLayout(
-                printJob: self,
+            let currentParams = (
                 width: printOperation!.printInfo.paperSize.width,
                 height: printOperation!.printInfo.paperSize.height,
                 marginLeft: printOperation!.printInfo.leftMargin,
                 marginTop: printOperation!.printInfo.topMargin,
                 marginRight: printOperation!.printInfo.rightMargin,
                 marginBottom: printOperation!.printInfo.bottomMargin
             )
-
-            // Block the main thread, waiting for a document
-            semaphore.wait()
+
+            if layoutParamsChanged(currentParams) {
+                lastLayoutParams = currentParams
+
+                printing.onLayout(
+                    printJob: self,
+                    width: currentParams.width,
+                    height: currentParams.height,
+                    marginLeft: currentParams.marginLeft,
+                    marginTop: currentParams.marginTop,
+                    marginRight: currentParams.marginRight,
+                    marginBottom: currentParams.marginBottom
+                )
+
+                // Wait for document using RunLoop to keep main thread responsive
+                isWaitingForDocument = true
+                documentReceived = false
+                let runLoop = RunLoop.current
+                let timeout = Date(timeIntervalSinceNow: 30.0)
+                while !documentReceived && Date() < timeout {
+                    runLoop.run(mode: .default, before: Date(timeIntervalSinceNow: 0.1))
+                }
+                isWaitingForDocument = false
+            }
         }
 
         if pdfDocument != nil {
@@ -95,8 +124,8 @@ public class PrintJob: NSView, NSSharingServicePickerDelegate {
         pdfDocument = CGPDFDocument(dataProvider!)
 
         if dynamic {
-            // Unblock the main thread
-            semaphore.signal()
+            // Signal that document is ready
+            documentReceived = true
             return
         }
 
@@ -136,6 +165,7 @@ public class PrintJob: NSView, NSSharingServicePickerDelegate {
     public func printPdf(name: String, withPageSize size: CGSize, andMargin _: CGRect, withPrinter printer: String?, dynamically dyn: Bool, andWindow window: NSWindow) {
         dynamic = dyn
         _window = window
+        lastLayoutParams = nil
         let sharedInfo = NSPrintInfo.shared
         let sharedDict = sharedInfo.dictionary()
         let printInfoDict = NSMutableDictionary(dictionary: sharedDict)
@@ -184,8 +214,9 @@ public class PrintJob: NSView, NSSharingServicePickerDelegate {
 
     func cancelJob(_ error: String?) {
         pdfDocument = nil
+        lastLayoutParams = nil
         if dynamic {
-            semaphore.signal()
+            documentReceived = true
         } else {
             printing.onCompleted(printJob: self, completed: false, error: error as NSString?)
         }

printing/macos/printing/Sources/printing/PrintingPlugin.swift

@@ -37,7 +37,9 @@ public func net_nfet_printing_set_error(job: UInt32, message: UnsafePointer<CCha
 public class PrintingPlugin: NSObject, FlutterPlugin {
     private static var instance: PrintingPlugin?
     private var channel: FlutterMethodChannel
-    public var jobs = [UInt32: PrintJob]()
+    // Shared jobs across all plugin instances (for multi-window support)
+    private static var sharedJobs = [UInt32: PrintJob]()
+    private static let jobsLock = NSLock()
     private var registrar: FlutterPluginRegistrar
 
     init(_ channel: FlutterMethodChannel, _ registrar: FlutterPluginRegistrar) {
@@ -49,12 +51,18 @@ public class PrintingPlugin: NSObject, FlutterPlugin {
 
     @objc
     public static func setDocument(job: UInt32, doc: UnsafePointer<UInt8>, size: UInt64) {
-        instance!.jobs[job]?.setDocument(Data(bytes: doc, count: Int(size)))
+        jobsLock.lock()
+        let printJob = sharedJobs[job]
+        jobsLock.unlock()
+        printJob?.setDocument(Data(bytes: doc, count: Int(size)))
     }
 
     @objc
     public static func setError(job: UInt32, message: UnsafePointer<CChar>) {
-        instance!.jobs[job]?.cancelJob(String(cString: message))
+        jobsLock.lock()
+        let printJob = sharedJobs[job]
+        jobsLock.unlock()
+        printJob?.cancelJob(String(cString: message))
     }
 
     /// Entry point
@@ -78,7 +86,10 @@ public class PrintingPlugin: NSObject, FlutterPlugin {
             let marginBottom = CGFloat((args["marginBottom"] as! NSNumber).floatValue)
             let printJob = PrintJob(printing: self, index: args["job"] as! Int)
             let dynamic = args["dynamic"] as! Bool
-            jobs[args["job"] as! UInt32] = printJob
+
+            PrintingPlugin.jobsLock.lock()
+            PrintingPlugin.sharedJobs[args["job"] as! UInt32] = printJob
+            PrintingPlugin.jobsLock.unlock()
 
             guard let window = registrar.view?.window else {
                 result(NSNumber(value: 0))
@@ -191,7 +202,10 @@ public class PrintingPlugin: NSObject, FlutterPlugin {
             "job": printJob.index,
         ]
         channel.invokeMethod("onCompleted", arguments: data)
-        jobs.removeValue(forKey: UInt32(printJob.index))
+
+        PrintingPlugin.jobsLock.lock()
+        PrintingPlugin.sharedJobs.removeValue(forKey: UInt32(printJob.index))
+        PrintingPlugin.jobsLock.unlock()
     }
 
     /// send html to pdf data result to flutter