js/SwtBrowserJsPart.java

   1 package org.argeo.app.swt.js;
   2
   3 import java.net.URI;
   4 import java.util.ArrayList;
   5 import java.util.List;
   6 import java.util.Locale;
   7 import java.util.concurrent.CompletableFuture;
   8 import java.util.concurrent.CompletionStage;
   9 import java.util.function.Function;
  10
  11 import org.argeo.api.cms.CmsLog;
  12 import org.argeo.api.cms.ux.CmsView;
  13 import org.argeo.app.ux.js.JsClient;
  14 import org.argeo.cms.swt.CmsSwtUtils;
  15 import org.eclipse.swt.SWT;
  16 import org.eclipse.swt.browser.Browser;
  17 import org.eclipse.swt.browser.BrowserFunction;
  18 import org.eclipse.swt.browser.ProgressEvent;
  19 import org.eclipse.swt.browser.ProgressListener;
  20 import org.eclipse.swt.layout.GridData;
  21 import org.eclipse.swt.layout.GridLayout;
  22 import org.eclipse.swt.widgets.Composite;
  23 import org.eclipse.swt.widgets.Control;
  24 import org.eclipse.swt.widgets.Display;
  25
  26 /**
  27  * A part using a {@link Browser} and remote JavaScript components on the client
  28  * side.
  29  */
  30 public class SwtBrowserJsPart implements JsClient {
  31         private final static CmsLog log = CmsLog.getLog(SwtBrowserJsPart.class);
  32
  33         private final static String GLOBAL_THIS_ = "globalThis.";
  34
  35         private final Browser browser;
  36         private final CompletableFuture<Boolean> readyStage = new CompletableFuture<>();
  37
  38         /**
  39          * Tasks that were requested before the context was ready. Typically
  40          * configuration methods on the part while the user interfaces is being build.
  41          */
  42         private List<PreReadyToDo> preReadyToDos = new ArrayList<>();
  43
  44         public SwtBrowserJsPart(Composite parent, int style, String url) {
  45                 CmsView cmsView = CmsSwtUtils.getCmsView(parent);
  46                 this.browser = new Browser(parent, 0);
  47                 if (parent.getLayout() instanceof GridLayout)
  48                         browser.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
  49                 // TODO other layouts
  50
  51                 URI u = cmsView.toBackendUri(url);
  52                 browser.setUrl(u.toString());
  53                 browser.addProgressListener(new ProgressListener() {
  54                         static final long serialVersionUID = 1L;
  55
  56                         @Override
  57                         public void completed(ProgressEvent event) {
  58                                 try {
  59                                         init();
  60                                         loadExtensions();
  61                                         // execute todos in order
  62                                         for (PreReadyToDo toDo : preReadyToDos) {
  63                                                 toDo.run();
  64                                         }
  65                                         preReadyToDos.clear();
  66                                         readyStage.complete(true);
  67                                 } catch (Exception e) {
  68                                         log.error("Cannot initialise " + url + " in browser", e);
  69                                         readyStage.complete(false);
  70                                 }
  71                         }
  72
  73                         @Override
  74                         public void changed(ProgressEvent event) {
  75                         }
  76                 });
  77         }
  78
  79         /*
  80          * LIFECYCLE
  81          */
  82
  83         /**
  84          * Called when the page has been loaded, typically in order to initialise
  85          * JavaScript objects. One MUST use {@link #doExecute(String, Object...)} in
  86          * order to do so, since the context is not yet considered ready and calls to
  87          * {@link #evaluate(String, Object...)} will block.
  88          */
  89         protected void init() {
  90         }
  91
  92         /**
  93          * To be overridden with calls to {@link #loadExtension(String)}.
  94          */
  95         protected void loadExtensions() {
  96
  97         }
  98
  99         protected void loadExtension(String url) {
 100                 URI u = CmsSwtUtils.getCmsView(getControl()).toBackendUri(url);
 101                 browser.evaluate(String.format(Locale.ROOT, "import('%s')", u.toString()));
 102         }
 103
 104         public CompletionStage<Boolean> getReadyStage() {
 105                 return readyStage.minimalCompletionStage();
 106         }
 107
 108         /*
 109          * JAVASCRIPT ACCESS
 110          */
 111
 112         @Override
 113         public Object evaluate(String js, Object... args) {
 114                 assert browser.getDisplay().equals(Display.findDisplay(Thread.currentThread())) : "Not the proper UI thread.";
 115                 if (!readyStage.isDone())
 116                         throw new IllegalStateException("Methods returning a result can only be called after UI initialisation.");
 117                 if (browser.isDisposed())
 118                         return null;
 119                 Object result = browser.evaluate(String.format(Locale.ROOT, js, args));
 120                 return result;
 121         }
 122
 123         @Override
 124         public void execute(String js, Object... args) {
 125                 String jsToExecute = String.format(Locale.ROOT, js, args);
 126                 if (readyStage.isDone()) {
 127                         if (browser.isDisposed())
 128                                 return;
 129                         boolean success = browser.execute(jsToExecute);
 130                         if (!success)
 131                                 throw new RuntimeException("JavaScript execution failed.");
 132                 } else {
 133                         PreReadyToDo toDo = new PreReadyToDo(jsToExecute);
 134                         preReadyToDos.add(toDo);
 135                 }
 136         }
 137
 138         @Override
 139         public String createJsFunction(String name, Function<Object[], Object> toDo) {
 140                 // browser functions must be directly on window (RAP specific)
 141                 new BrowserFunction(browser, name) {
 142
 143                         @Override
 144                         public Object function(Object[] arguments) {
 145                                 Object result = toDo.apply(arguments);
 146                                 return result;
 147                         }
 148
 149                 };
 150                 return "window." + name;
 151         }
 152
 153         /**
 154          * Directly executes, even if {@link #getReadyStage()} is not completed. Except
 155          * in initialisation, {@link #evaluate(String, Object...)} should be used
 156          * instead.
 157          */
 158         protected void doExecute(String js, Object... args) {
 159                 if (browser.isDisposed())
 160                         return;
 161                 browser.execute(String.format(Locale.ROOT, js, args));
 162         }
 163
 164         @Override
 165         public String getJsVarName(String name) {
 166                 return GLOBAL_THIS_ + name;
 167         }
 168
 169         class PreReadyToDo implements Runnable {
 170                 private String js;
 171
 172                 public PreReadyToDo(String js) {
 173                         this.js = js;
 174                 }
 175
 176                 @Override
 177                 public void run() {
 178                         if (browser.isDisposed())
 179                                 return;
 180                         boolean success = browser.execute(js);
 181                         if (!success && log.isTraceEnabled())
 182                                 log.error("Pre-ready JavaScript failed: " + js);
 183                 }
 184         }
 185
 186         /*
 187          * ACCESSORS
 188          */
 189
 190         public Control getControl() {
 191                 return browser;
 192         }
 193
 194 }