Merge pull request #72 from PSPDFKit/akshat/dismiss-callback-example

Added dismiss callback and its implementation in the example.

Author: aksh1t

android/src/main/java/com/pspdfkit/flutter/pspdfkit/EventDispatcher.java

@@ -0,0 +1,54 @@
+///
+///  Copyright © 2021 PSPDFKit GmbH. All rights reserved.
+///
+///  THIS SOURCE CODE AND ANY ACCOMPANYING DOCUMENTATION ARE PROTECTED BY INTERNATIONAL COPYRIGHT LAW
+///  AND MAY NOT BE RESOLD OR REDISTRIBUTED. USAGE IS BOUND TO THE PSPDFKIT LICENSE AGREEMENT.
+///  UNAUTHORIZED REPRODUCTION OR DISTRIBUTION IS SUBJECT TO CIVIL AND CRIMINAL PENALTIES.
+///  This notice may not be removed from this file.
+///
+
+package com.pspdfkit.flutter.pspdfkit;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import io.flutter.plugin.common.MethodChannel;
+
+/**
+ * Internal singleton class used to communicate between activities and the PSPDFKit Flutter plugin.
+ */
+public class EventDispatcher {
+    @Nullable
+    private static EventDispatcher instance;
+    /**
+     * A channel for sending events from Java to Flutter. This is set as soon as
+     * the plugin is registered.
+     */
+    @Nullable
+    private MethodChannel channel = null;
+
+    private EventDispatcher() {
+    }
+
+    @NonNull
+    public static synchronized EventDispatcher getInstance() {
+        if (instance == null) {
+            instance = new EventDispatcher();
+        }
+        return instance;
+    }
+
+    public void setChannel(@Nullable MethodChannel channel) {
+        this.channel = channel;
+    }
+
+    public void notifyActivityOnPause() {
+        sendEvent("flutterPdfActivityOnPause");
+    }
+
+    private void sendEvent(@NonNull final String method) {
+        if (channel != null) {
+            channel.invokeMethod(method, null, null);
+        }
+    }
+}

android/src/main/java/com/pspdfkit/flutter/pspdfkit/FlutterPdfActivity.java

@@ -3,6 +3,7 @@
 import android.os.Bundle;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
 import com.pspdfkit.document.PdfDocument;
 import com.pspdfkit.ui.PdfActivity;
@@ -17,8 +18,8 @@
  */
 public class FlutterPdfActivity extends PdfActivity {
 
-    private static FlutterPdfActivity currentActivity;
-    private static AtomicReference<Result> loadedDocumentResult = new AtomicReference<>();
+    @Nullable private static FlutterPdfActivity currentActivity;
+    @NonNull private static final AtomicReference<Result> loadedDocumentResult = new AtomicReference<>();
 
     public static void setLoadedDocumentResult(Result result) {
         loadedDocumentResult.set(result);
@@ -30,6 +31,13 @@ protected void onCreate(Bundle bundle) {
         bindActivity();
     }
 
+    @Override
+    protected void onPause() {
+        // Notify the Flutter PSPDFKit plugin that the activity is going to enter the onPause state.
+        EventDispatcher.getInstance().notifyActivityOnPause();
+        super.onPause();
+    }
+
     @Override
     protected void onDestroy() {
         super.onDestroy();
@@ -66,6 +74,7 @@ private void releaseActivity() {
         currentActivity = null;
     }
 
+    @Nullable
     public static FlutterPdfActivity getCurrentActivity() {
         return currentActivity;
     }

android/src/main/java/com/pspdfkit/flutter/pspdfkit/PspdfkitPlugin.java

@@ -59,12 +59,13 @@
  * PSPDFKit plugin to load PDF and image documents.
  */
 public class PspdfkitPlugin implements MethodCallHandler, PluginRegistry.RequestPermissionsResultListener {
+    @NonNull private static final EventDispatcher eventDispatcher = EventDispatcher.getInstance();
     private static final String LOG_TAG = "PSPDFKitPlugin";
     private static final String FILE_SCHEME = "file:///";
-    private final Context context;
-    private final Registrar registrar;
+    @NonNull private final Context context;
+    @NonNull private final Registrar registrar;
     /** Atomic reference that prevents sending twice the permission result and throwing exception. */
-    private AtomicReference<Result> permissionRequestResult;
+    @NonNull private final AtomicReference<Result> permissionRequestResult;
 
     private PspdfkitPlugin(Registrar registrar) {
         this.context = registrar.activeContext();
@@ -79,13 +80,13 @@ public static void registerWith(Registrar registrar) {
         final MethodChannel channel = new MethodChannel(registrar.messenger(), "pspdfkit");
         PspdfkitPlugin pspdfkitPlugin = new PspdfkitPlugin(registrar);
         channel.setMethodCallHandler(pspdfkitPlugin);
+        eventDispatcher.setChannel(channel);
         registrar.addRequestPermissionsResultListener(pspdfkitPlugin);
     }
 
     @Override
     public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
         String fullyQualifiedName;
-        FlutterPdfActivity flutterPdfActivity;
         PdfDocument document;
 
         switch (call.method) {

example/lib/main.dart

@@ -268,8 +268,24 @@ class _HomePageState extends State<HomePage> with WidgetsBindingObserver {
     Pspdfkit.setLicenseKey("LICENSE_KEY_GOES_HERE");
   }
 
+  void flutterPdfActivityOnPauseHandler() {
+    print("flutterPdfActivityOnPauseHandler");
+  }
+
+  void pdfViewControllerWillDismissHandler() {
+    print("pdfViewControllerWillDismissHandler");
+  }
+
+  void pdfViewControllerDidDismissHandler() {
+    print("pdfViewControllerDidDismissHandler");
+  }
+
   @override
   Widget build(BuildContext context) {
+    Pspdfkit.flutterPdfActivityOnPause = () => flutterPdfActivityOnPauseHandler();
+    Pspdfkit.pdfViewControllerWillDismiss = () => pdfViewControllerWillDismissHandler();
+    Pspdfkit.pdfViewControllerDidDismiss = () => pdfViewControllerDidDismissHandler();
+
     currentTheme = MediaQuery.of(context).platformBrightness == Brightness.light ? lightTheme : darkTheme;
     bool isIOS = Theme.of(context).platform == TargetPlatform.iOS;
     if (isIOS) {

ios/Classes/PspdfkitPlugin.m

@@ -11,15 +11,17 @@
 @import PSPDFKit;
 @import PSPDFKitUI;
 
-@interface PspdfkitPlugin()
+static FlutterMethodChannel *channel;
+
+@interface PspdfkitPlugin() <PSPDFViewControllerDelegate>
 @property (nonatomic) PSPDFViewController *pdfViewController;
 @end
 
 @implementation PspdfkitPlugin
 + (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar {
-    FlutterMethodChannel* channel = [FlutterMethodChannel
-                                     methodChannelWithName:@"pspdfkit"
-                                     binaryMessenger:[registrar messenger]];
+    channel = [FlutterMethodChannel
+               methodChannelWithName:@"pspdfkit"
+               binaryMessenger:[registrar messenger]];
     PspdfkitPlugin* instance = [[PspdfkitPlugin alloc] init];
     [registrar addMethodCallDelegate:instance channel:channel];
 }
@@ -88,6 +90,7 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
         self.pdfViewController = [[PSPDFViewController alloc] initWithDocument:document configuration:psPdfConfiguration];
         self.pdfViewController.appearanceModeManager.appearanceMode = [self appearanceMode:configurationDictionary];
         self.pdfViewController.pageIndex = [self pageIndex:configurationDictionary];
+        self.pdfViewController.delegate = self;
 
         if ((id)configurationDictionary != NSNull.null) {
             [self setLeftBarButtonItems:configurationDictionary[@"leftBarButtonItems"]];
@@ -175,6 +178,15 @@ - (PSPDFConfiguration *)configuration:(NSDictionary *)dictionary isImageDocument
     }];
 }
 
+#pragma mark - PSPDFViewControllerDelegate
+
+- (void)pdfViewControllerWillDismiss:(PSPDFViewController *)pdfController {
+    [channel invokeMethod:@"pdfViewControllerWillDismiss" arguments:nil];
+}
+
+- (void)pdfViewControllerDidDismiss:(PSPDFViewController *)pdfController {
+    [channel invokeMethod:@"pdfViewControllerDidDismiss" arguments:nil];
+}
 
 #pragma mark - Customize the Toolbar
 

lib/pspdfkit.dart

@@ -9,6 +9,7 @@
 library pspdfkit;
 
 import 'dart:async';
+import 'dart:ui';
 
 import 'package:flutter/services.dart';
 
@@ -17,7 +18,15 @@ part 'configuration_options.dart';
 
 /// PSPDFKit plugin to load PDF and image documents on both platform iOS and Android.
 class Pspdfkit {
-  static const MethodChannel _channel = const MethodChannel('pspdfkit');
+  static MethodChannel _privateChannel = null;
+
+  static MethodChannel get _channel {
+    if (_privateChannel == null) {
+      _privateChannel = const MethodChannel('pspdfkit');
+      _privateChannel.setMethodCallHandler(_platformCallHandler);
+    }
+    return _privateChannel;
+  }
 
   /// Gets the PSPDFKit framework version.
   static Future<String> get frameworkVersion async =>
@@ -93,4 +102,29 @@ class Pspdfkit {
         return AndroidPermissionStatus.notDetermined;
     }
   }
+
+  static VoidCallback flutterPdfActivityOnPause;
+  static VoidCallback pdfViewControllerWillDismiss;
+  static VoidCallback pdfViewControllerDidDismiss;
+
+  static Future<void> _platformCallHandler(MethodCall call) {
+    try {
+      switch (call.method) {
+        case 'flutterPdfActivityOnPause':
+          flutterPdfActivityOnPause();
+          break;
+        case 'pdfViewControllerWillDismiss':
+          pdfViewControllerWillDismiss();
+          break;
+        case 'pdfViewControllerDidDismiss':
+          pdfViewControllerDidDismiss();
+          break;
+        default:
+          print('Unknowm method ${call.method} ');
+      }
+    } catch (e) {
+      print(e);
+    }
+    return Future.value();
+  }
 }