Changeset 38926

Timestamp:

2024-04-16T15:22:42+12:00 (7 weeks ago)

Author:

anupama

Message:

1. I couldn't get JavaScript to Java communication working in webswing, in order to stop the application and do cleanup when the user navigates away from the collage webswing applet/application page. But instead, I found I could call the kill() method on the webswing instance which will call application exit, which I had set up to handle the cleanup code. So the mystery of why JS to Java doesn't work remains, but the problem of shutting down the app neatly on navigating away is resolved. 2. Java webswing methods only to be called when run in webswing mode.

Location:

main/trunk/greenstone3

Files:

• src/java/org/greenstone/applet/GsdlCollageApplet/GsdlCollageApplet.java (modified) (8 diffs)
• src/java/org/greenstone/applet/phind/JPhind.java (modified) (3 diffs)
• src/java/org/greenstone/gsdl3/service/GsdlCollageBrowse.java (modified) (1 diff)
• web/interfaces/default/transform/pages/webswing-collage.xsl (modified) (4 diffs)

main/trunk/greenstone3/src/java/org/greenstone/applet/GsdlCollageApplet/GsdlCollageApplet.java

@@ -4 +4 @@
 import org.webswing.toolkit.api.action.WebActionEvent;
 import org.webswing.toolkit.api.action.WebActionListener;
+
+import org.webswing.toolkit.api.url.*;
 
 //import java.applet.Applet;
@@ -39 +41 @@
     private int Y_DIM = 300;
 
+    boolean isWebswing = false; // if run as webswing
     // To run this GsdlCollageApplet as Application instead of as Applet
-    boolean isWebswingApplication = false; // if run as webswing *and* application (not applet)
     boolean isRunAsApplet = true;
     // set only if JPhind object is run as an application
@@ -163 +165 @@
     //}
 
-    // Handle getting called by webswing JavaScript:
-    // when the user navigates away from the webswing app's web page, do cleanup
-    // https://www.webswing.org/docs/23.2/integrate/jslink.html#invoking-java-from-javascript
-    // https://vaadin.com/directory/component/webswing-vaadin1
-    org.webswing.toolkit.api.WebswingUtil.getWebswingApi().addBrowserActionListener(new org.webswing.toolkit.api.action.WebActionListener() {
-        @Override
-        public void actionPerformed(org.webswing.toolkit.api.action.WebActionEvent actionEvent) {
-            switch (actionEvent.getActionName()) {
-            case "navigatingAway":
-            // do cleanup
-            System.err.println("@@@@ In Java collage addBrowserActionListener on navigatingAway - called");
-            GsdlCollageApplet.this.stopRunning();
-            break;
-            case "testJavaCall":
-            org.webswing.toolkit.api.WebswingUtil.getWebswingApi().sendActionEvent("javaToWebswingJSConsoleLog", "GsdlCollageApplet got TEST call !!", null);
-            //WebswingUtil.getWebswingApi().sendActionEvent("@@@ javaToWebswingJSConsoleLog", "GsdlCollageApplet - testjavaCall handler got your message", null);
-            }
-        }
-        });
-    
     this.addMouseListener(new CollageMouseAdapter());
     }
@@ -233 +215 @@
     }
     
-    isWebswingApplication = appParams.getOrDefault("webswing", "0").equals("1") ? true : false;
+    isWebswing = appParams.getOrDefault("webswing", "0").equals("1") ? true : false;
+
+    // Handle getting called by webswing JavaScript (but only if run in webswing mode):
+    // when the user navigates away from the webswing app's web page, do cleanup
+    // https://www.webswing.org/docs/23.2/integrate/jslink.html#invoking-java-from-javascript
+    // https://vaadin.com/directory/component/webswing-vaadin1
+    if(isWebswing) {
+
+        System.err.println("#### isWebswing, about to add listeners");
+        
+        WebswingUtil.getWebswingApi().addBrowserActionListener(new WebActionListener() {
+            //@Override
+            public void actionPerformed(WebActionEvent actionEvent) {
+
+            System.err.println("******** JavaScript to Java: actionPerformed called.");
+            //System.err.println("actionEvent = ");
+            
+            switch (actionEvent.getActionName()) {
+            case "navigatingAway":
+                // do cleanup
+                System.err.println("@@@@ In Java collage addBrowserActionListener - on navigatingAway called");
+                GsdlCollageApplet.this.stopRunning();
+                break;
+            case "testJavaCall":
+                WebswingUtil.getWebswingApi().sendActionEvent("javaToWebswingJSConsoleLog", "GsdlCollageApplet got TEST call !!", null);
+                //WebswingUtil.getWebswingApi().sendActionEvent("javaToWebswingJSConsoleLog", "GsdlCollageApplet - testjavaCall handler got your message", null);
+            }           
+            }
+        });
+    }
+    
     // Need these parameters set before init(), so that the display works
     int w = this.getWidth();
@@ -554 +566 @@
         if(isRunAsApplet) {
             GsdlCollageApplet.this.getAppletContext().showDocument(from_url,"gsdlDoc");
-        } else if(isWebswingApplication) {
+        } else if(isWebswing) {
             WebswingUtil.getWebswingApi().sendActionEvent("openURL",
                       from_url.toString() + " - " +"gsdlDoc",
@@ -611 +623 @@
     public void stop() 
     {
+    System.err.println("\n\n*** Stopping collage Applet: stopping threads...");
     //download_thread_.stop();
     //display_thread_.stop();
@@ -714 +727 @@
     /**
      * After building the GS3 Multimedia collection, try running this Application as:
-java -cp ./web/applet/GsdlCollageApplet.jar:./web/WEB-INF/lib/log4j-1.2.8.jar:./web/WEB-INF/classes org.greenstone.applet.GsdlCollageApplet.GsdlCollageApplet --statusbar 0 --baseurl "http://localhost:8383/greenstone3/" --library library --collection smallbea --gsdlversion 3 --hrefMustHave "library/sites/localsite/collect/smallbea" --documentroot greenstone3 --verbosity 3 --imageType ".jpg%.png" --imageMustNotHave "interfaces/" --classifier "CL2.3" --maxDepth 500 --maxDisplay 25 --refreshDelay 1500 --isJava2 auto --bgcolor "#96c29a" --width 645 --height 780
+java -cp ./web/applet/GsdlCollageApplet.jar:./web/WEB-INF/lib/log4j-1.2.8.jar:./web/WEB-INF/classes:./web/ext/webswing/api/webswing-api.jar org.greenstone.applet.GsdlCollageApplet.GsdlCollageApplet --statusbar 0 --baseurl "http://localhost:8383/greenstone3/" --library library --collection smallbea --gsdlversion 3 --hrefMustHave "library/sites/localsite/collect/smallbea" --documentroot greenstone3 --verbosity 3 --imageType ".jpg%.png" --imageMustNotHave "interfaces/" --classifier "CL2.3" --maxDepth 500 --maxDisplay 25 --refreshDelay 1500 --isJava2 auto --bgcolor "#96c29a" --width 645 --height 780
      */
     public static void main(String[] args) {
@@ -759 +772 @@
         frame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent e) {
-            // WHY doesn't javascript console log unless I prefix webswing package name??
-            //WebswingUtil.getWebswingApi().sendActionEvent("@@@ javaToWebswingJSConsoleLog", "GsdlCollageApplet - quitting now", null);
-            org.webswing.toolkit.api.WebswingUtil.getWebswingApi().sendActionEvent("javaToWebswingJSConsoleLog", "GsdlCollageApplet about to QUIT !!", null);
-            
+            if(collageApp.isWebswing) {         
+            WebswingUtil.getWebswingApi().sendActionEvent("javaToWebswingJSConsoleLog", "GsdlCollageApplet - quitting now", null);
+            //org.webswing.toolkit.api.WebswingUtil.getWebswingApi().sendActionEvent("javaToWebswingJSConsoleLog", "GsdlCollageApplet about to QUIT !!", null);
+            }
             collageApp.showStatus("Stopping threads");
-            System.err.println("\n\n*** Closing applet: stopping threads...");
+            System.err.println("\n\n*** Closing collage Application: stopping threads...");
             collageApp.stopRunning();
             

main/trunk/greenstone3/src/java/org/greenstone/applet/phind/JPhind.java

@@ -138 +138 @@
     implements ActionListener {
 
-    boolean isWebswingApplication = false; // if run as webswing *and* application (not applet)
+    // if run as webswing vs either commandline application or as applet through appletviewer
+    boolean isWebswing = false;
+    // if run as applet vs application
+    boolean isRunAsApplet = true;
     
-    boolean isRunAsApplet = true;
     // set only if JPhind object is run as an application
     URL docBaseURL = null;
@@ -284 +286 @@
     }
 
-    isWebswingApplication = appParams.getOrDefault("webswing", "0").equals("1") ? true : false;
+    isWebswing = appParams.getOrDefault("webswing", "0").equals("1") ? true : false;
     
     // manually calling (J)Applet method init()
@@ -730 +732 @@
             getAppletContext().showDocument(url);
         }
-        } else if(isWebswingApplication) {
+        } else if(isWebswing) { // webswing and not applet but application
         if (window.length() > 0) {
             WebswingUtil.getWebswingApi().sendActionEvent("openURL",

main/trunk/greenstone3/src/java/org/greenstone/gsdl3/service/GsdlCollageBrowse.java

@@ -91 +91 @@
     String siteName = this.site_home.substring(this.site_home.lastIndexOf("/sites/")+"/sites/".length());
     
-    String app_info = "<"+GSXML.APPLET_ELEM+" CODEBASE='applet' CODE='org.greenstone.applet.GsdlCollageApplet.GsdlCollageApplet.class' ARCHIVE='GsdlCollageApplet.jar' WIDTH='600' HEIGHT='300'>"; // w=645,h=780
+    String app_info = "<"+GSXML.APPLET_ELEM+" CODEBASE='applet' CODE='org.greenstone.applet.GsdlCollageApplet.GsdlCollageApplet.class' ARCHIVE='GsdlCollageApplet.jar, webswing-api.jar' WIDTH='600' HEIGHT='300'>"; // w=645,h=780
     app_info +="<param name='library' value='" + this.library_name + "'/>";
     app_info +="<param name='collection'   value='" + this.cluster_name + "'/>";

main/trunk/greenstone3/web/interfaces/default/transform/pages/webswing-collage.xsl

@@ -191 +191 @@
        
        //console.log("args: " +  webswingInstance0.options.args);
-    
+
+       // Allow sending user events to swing application
+       // https://www.webswing.org/docs/20.2/integrate/embed.html
+       //webswingInstance0.setControl(true);
+       
     function getParam(name) {
         name = name.replace(/[\[]/, "\\\[").replace(/[\]]/, "\\\]");
@@ -203 +207 @@
     <xsl:text disable-output-escaping="yes">
 
-      var doButtonClick = function() {
-      console.log("button clicked");
-          webswingInstance0.performAction({actionName: "testJavaCall"});
-      }
       var unloaded = false;
+      
     (function (window, document) {
         var loader = function () {
@@ -239 +240 @@
        // event handlers got triggered. We use the unloaded var to ensure we cleanup only once
        if(!unloaded) {
+          if(typeof webswingInstance0.kill === 'function') { // it should exist
+          
+             console.log("@@@ Asking webswing to stop the collage application");
+         webswingInstance0.kill();
+         unloaded = true; // do not unload again, if multiple listeners call navigatingAway() callback function
+         console.log("@@@@ unloaded");
+          } // else cannot call method that does not exist
+       } else {
+          console.log("@@@@ already unloaded.");
+       }
+       /*   
        if(typeof webswingInstance0.performAction === 'function') {
-              //event.preventDefault(); // if listening for beforeunload event
-              console.log("@@@@ Calling Java to stop running the webswing collage app");
-              webswingInstance0.performAction({actionName: "navigatingAway"});
-              unloaded = true;
+       
+              //console.log("@@@@ Calling Java to stop running the webswing collage app");
+              //webswingInstance0.performAction({actionName: "navigatingAway"});
+          
+              // May need web sockets to tell the Java Application to terminate?
+              // https://vivekvijayan10.medium.com/how-to-communicate-between-or-send-data-from-javascript-to-java-through-sockets-a9bf22840b91
+
+              unloaded = true; // do not unload again, if multiple listeners call navigatingAway() callback function
           console.log("@@@@ unloaded");
-          //alert("check log");
+
         } else {
             console.log("performAction method DOESN'T exist on the webswing object!");
@@ -252 +268 @@
             console.log("@@@@ already unloaded.");
         }
-
+        */
     };
-    
-        window.addEventListener ? window.addEventListener("load", loader, false) : window.attachEvent("onload", loader);
-
+    window.addEventListener ? window.addEventListener("load", loader, false) : window.attachEvent("onload", loader);
+
+
+    // When the user navigates away from this page or reloads it, we want to
+    // shutdown the webswing Java application.  
+    
     // https://developer.mozilla.org/en-US/docs/Web/API/Window/unload_event
-    // unload has been deprecated, and so we try pagehide and visibilitychange events
-    window.addEventListener ? window.addEventListener("unload", navigatingAway, false) : window.attachEvent("onunload", navigatingAway);
+    // unload is discouraged as it is not always supported (some mobile devices),
+    // so we listen for pagehide events too. Visibilitychange events happen on minimising win
+    // or another tab getting focus. We do not want to stop the app on mere visibilitychange:
+    // https://dev.to/amersikira/top-3-ways-to-easily-detect-when-a-user-leaves-a-page-using-javascript-2ce4
+    
+    // Pagehide is also fired when user presses back button: https://developer.mozilla.org/en-US/docs/Web/API/Window/pagehide_event
+    // https://stackoverflow.com/questions/15925251/trigger-an-event-when-user-navigates-away
+    
+    // Order of registering may matter and be useful:
+    // https://stackoverflow.com/questions/31852179/javascript-event-listeners-firing-order
+    // https://stackoverflow.com/questions/2706109/are-javascript-dom-event-handlers-called-in-order-of-registration
+    // https://medium.com/@olofbaage/javascript-essentials-all-you-need-to-know-about-event-listeners-8ed889bffb8d
+    // Event support detection
+    // https://stackoverflow.com/questions/158673/onbeforeunload-support-detection
+    // https://stackoverflow.com/questions/2877393/detecting-support-for-a-given-javascript-event
+    // http://perfectionkills.com/detecting-event-support-without-browser-sniffing
+
+    // Does onUnload not leave enough time to get webswing to shutdown? OnBeforeUnload works
+    // https://caniuse.com/?search=beforeunload
+    window.addEventListener ? window.addEventListener("beforeunload", navigatingAway, false) : window.attachEvent("onbeforeunload", navigatingAway);
     window.addEventListener ? window.addEventListener("pagehide", navigatingAway, false) : window.attachEvent("onpagehide", navigatingAway);
-    window.addEventListener ? window.addEventListener("visibilitychange", navigatingAway, false) : window.attachEvent("onvisibilitychange", navigatingAway);    
+    //window.addEventListener ? window.addEventListener("visibilitychange", navigatingAway, false) : window.attachEvent("onvisibilitychange", navigatingAway);  
     
     })(window, document);
     </xsl:text>
   </script>
-  
- <button type="button" onclick="doButtonClick()">Click Me!</button> 
+
     </xsl:template>