fix(window): added window.print function (#5)

jotform · Feb 20, 2024 · ff4f749 · ff4f749
1 parent cdecd91
commit ff4f749
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Showing 2 changed files with 64 additions and 3 deletions.
diff --git a/android/src/main/java/com/reactnativecommunity/webview/RNCWebView.java b/android/src/main/java/com/reactnativecommunity/webview/RNCWebView.java
@@ -6,6 +6,11 @@
 import android.content.Context;
 import android.graphics.Rect;
 import android.os.Build;
+import android.os.Handler;
+import android.print.PrintAttributes;
+import android.print.PrintDocumentAdapter;
+import android.print.PrintJob;
+import android.print.PrintManager;
 import android.text.TextUtils;
 import android.util.AttributeSet;
 
@@ -85,6 +90,13 @@ public class RNCWebView extends WebView implements LifecycleEventListener {
     public RNCWebView(ThemedReactContext reactContext) {
         super(reactContext);
         this.createCatalystInstance();
+
+        // The bridge is necessary to support the window.print() functionality.
+        // Not sure, is there any significant drawback just to always create it,
+        // vs. any noticeable benefit to make the print() support and opt-in feature,
+        // that will ensure the brige creation if a flag is set on WebView in JS layer.
+        this.createRNCWebViewBridge(this);
+
         progressChangedFilter = new ProgressChangedFilter();
     }
 
@@ -284,10 +296,16 @@ public void callInjectedJavaScript() {
     }
 
     public void callInjectedJavaScriptBeforeContentLoaded() {
-        if (getSettings().getJavaScriptEnabled() &&
-                injectedJSBeforeContentLoaded != null &&
-                !TextUtils.isEmpty(injectedJSBeforeContentLoaded)) {
+        if (getSettings().getJavaScriptEnabled()) {
+          // This is necessary to support window.print() in the loaded web pages.
+          evaluateJavascriptWithFallback(
+            "(function(){window.print=function(){window.ReactNativeWebView.print();};})();"
+          );
+
+          if (injectedJSBeforeContentLoaded != null &&
+            !TextUtils.isEmpty(injectedJSBeforeContentLoaded)) {
             evaluateJavascriptWithFallback("(function() {\n" + injectedJSBeforeContentLoaded + ";\n})();");
+          }
         }
     }
 
@@ -393,6 +411,27 @@ protected class RNCWebViewBridge {
           mWebView = c;
         }
 
+        @JavascriptInterface
+        public void print() {
+          // This code is adopted from https://developer.android.com/training/printing/html-docs
+          // but all WebView methods must be called from the same thread, and this bridge method
+          // is called on a different thread, thus the need to post a runnable to the handler.
+          WebView view = this.mWebView;
+          Handler handler = view.getHandler();
+          handler.post(new Runnable() {
+            @Override
+            public void run() {
+              PrintManager manager = (PrintManager) view.getContext().getSystemService(Context.PRINT_SERVICE);
+              String jobName = view.getTitle();
+              PrintDocumentAdapter adapter = view.createPrintDocumentAdapter(jobName);
+              PrintJob job = manager.print(jobName, adapter, new PrintAttributes.Builder().build());
+              // NOTE: Here `job` can be kept around and used to further check on the print job status,
+              // but it is not required, according to the docs, so no need to do it for now.
+            }
+          });
+        }
+
+
         /**
          * This method is called whenever JavaScript running within the web view calls:
          * - window[JAVASCRIPT_INTERFACE].postMessage

diff --git a/apple/RNCWebViewImpl.m b/apple/RNCWebViewImpl.m
@@ -20,6 +20,7 @@
 static NSTimer *keyboardTimer;
 static NSString *const HistoryShimName = @"ReactNativeHistoryShim";
 static NSString *const MessageHandlerName = @"ReactNativeWebView";
+static NSString *const PrintingHandlerName = @"ReactNativeWebViewPrinting";
 static NSURLCredential* clientAuthenticationCredential;
 static NSDictionary* customCertificatesForHost;
 
@@ -412,6 +413,9 @@ - (WKWebViewConfiguration *)setUpWkWebViewConfig
   }
 #endif
 
+    // Sets up the window.print() support
+  [wkWebViewConfig.userContentController addScriptMessageHandler:[[RNCWeakScriptMessageDelegate alloc] initWithDelegate:self]
+                                                            name:PrintingHandlerName];
   // Shim the HTML5 history API:
   [wkWebViewConfig.userContentController addScriptMessageHandler:[[RNCWeakScriptMessageDelegate alloc] initWithDelegate:self]
                                                             name:HistoryShimName];
@@ -536,6 +540,7 @@ - (void)removeFromSuperview
   if (_webView) {
     [_webView.configuration.userContentController removeScriptMessageHandlerForName:HistoryShimName];
     [_webView.configuration.userContentController removeScriptMessageHandlerForName:MessageHandlerName];
+    [_webView.configuration.userContentController removeScriptMessageHandlerForName:PrintingHandlerName];
     [_webView removeObserver:self forKeyPath:@"estimatedProgress"];
     [_webView removeFromSuperview];
 #if !TARGET_OS_OSX
@@ -702,6 +707,10 @@ - (void)userContentController:(WKUserContentController *)userContentController
       [event addEntriesFromDictionary: @{@"data": message.body}];
       _onMessage(event);
     }
+  } else if ([message.name isEqualToString:PrintingHandlerName]) {
+    UIPrintInteractionController *ctrl = UIPrintInteractionController.sharedPrintController;
+    ctrl.printFormatter = _webView.viewPrintFormatter;
+    [ctrl presentAnimated:YES completionHandler:nil];
   }
 }
 
@@ -1667,6 +1676,19 @@ - (void)resetupScripts:(WKWebViewConfiguration *)wkWebViewConfig {
   WKUserScript *script = [[WKUserScript alloc] initWithSource:html5HistoryAPIShimSource injectionTime:WKUserScriptInjectionTimeAtDocumentStart forMainFrameOnly:YES];
   [wkWebViewConfig.userContentController addUserScript:script];
 
+    // This is for the window.print() support.
+  NSString *windowPrintSource = [NSString stringWithFormat:
+                                   @"(function() {"
+                                    " window.print = function() {"
+                                    "   window.webkit.messageHandlers.%@.postMessage('');"
+                                    " };"
+                                    "})();", PrintingHandlerName];
+  WKUserScript *windowPrintScript = [[WKUserScript alloc]
+                                     initWithSource:windowPrintSource
+                                     injectionTime:WKUserScriptInjectionTimeAtDocumentStart
+                                     forMainFrameOnly:YES];
+  [wkWebViewConfig.userContentController addUserScript:windowPrintScript];
+
   if(_sharedCookiesEnabled) {
     // More info to sending cookies with WKWebView
     // https://stackoverflow.com/questions/26573137/can-i-set-the-cookies-to-be-used-by-a-wkwebview/26577303#26577303