I checked the link. Overlay types could surely make my life easier in terms of wrapping Protovis but as long as I cannot access $wnd.pv through JSNI, I cannot use them.
On Jul 20, 11:28 pm, wsaleem <[email protected]> wrote: > 2) is the pure JS scenario, which I trying to port to GWT using JSNI. > I fail, though, as the very first command > vis = new $wnd.pv.Panel().canvas("PVis"); > fails with the following JavaScript exception > $wnd.pv has no properties > I will see if the overlay types help. Thanks for the pointer! > > On Jul 20, 7:48 pm, Adam T <[email protected]> wrote: > > > It could still be a similar thing; I'm not 100% clear what you are > > trying to do above, but it looks like your steps are: > > > 1) Load an external JavaScript library, e.g. "protovis.js" > > 2) Run some other JavaScript which creates something in the DOM, e.g. > > the vis = new pv.Panel().canvas("PVis"); .....vis.render(); part > > 3) In GWT access the rendered PVis component. > > > If that's correct, then by moving the "protovis.js" to the .gwt.xml > > part your ensuring that the library loads before your GWT, but it is > > still possible that part (2) is executing after your GWT code, and > > hence it is not available to your GWT code when it runs. You could > > wrap that code in it's own file and load through the <script> tag > > (though I'm not sure about ordering in the gwt.xl file). > > > I'd also suggest you use some debugging tools (Firebug for example in > > Firefox) to look at what your code is doing, that should show you the > > scoping of pv etc. > > > (though you might be better off writing a wrapper using JavaScript > > Overlay types (http://googlewebtoolkit.blogspot.com/2008/08/getting-to- > > really-know-gwt-part-2.html) that would let you merge GWT and the > > protovis library in a more natural style, than the approach you're > > taking just now) > > > Good luck, > > > //Adam > > > On 20 Juli, 17:41, wsaleem <[email protected]> wrote: > > > > Adam, I added > > > <script src="protovis.js" /> > > > to the .gwt.xml. > > > > No change! > > > > On Jul 20, 4:24 pm, Adam T <[email protected]> wrote: > > > > > Hi, > > > > > It might be the case that in both cases your GWT code is loaded and > > > > executing before the browser has loaded your externally referenced > > > > JavaScript file. To remove that possiblity, you can place the > > > > <script> tag you have in the HTML into your module's .gwt.xml > > > > definition, i.e. > > > > > <module> > > > > <inherits name='com.google.gwt.user.User' /> > > > > <script type="text/javascript" src="protovis.js"> > > > > </module> > > > > > With this sett up, the GWT boostrap code should ensure the library > > > > JavaScript is loaded before your GWT code executes. > > > > > //Adam > > > > > On 19 Juli, 18:19, wsaleem <[email protected]> wrote: > > > > > > I am not a JS developer and use it pretty much by example, so it might > > > > > be that I am missing something really basic below. > > > > > > I have come across problems using JSNI in the following 2 scenarios: > > > > > > 1. > > > > > I use Google Visualization API successfully in JS as follows: > > > > > ******************** > > > > > HTML file > > > > > <script type="text/javascript" > > > > > src="http://www.google.com/jsapi";></ > > > > > script> > > > > > JS file > > > > > google.load('visualization', '1', {'packages':['piechart']}); // > > > > > <== future JSNI problems occur here > > > > > var chart = new google.visualization.LineChart > > > > > (document.getElementById('GoogleVisChart')); > > > > > // other JS commands to draw the chart > > > > > ********** > > > > > and then try to write a wrapper using GWT JSNI as follows: > > > > > ******************** > > > > > HTML file > > > > > <script type="text/javascript" > > > > > src="http://www.google.com/jsapi";></ > > > > > script> > > > > > JAVA file > > > > > class GChart { > > > > > static { _init(); } > > > > > private static native void _init() /*-{ // <=== ERROR at this > > > > > function > > > > > $wnd.google.load('visualization', '1', {'packages': > > > > > ['piechart']}); > > > > > }-*/; > > > > > > JavaScriptObject gvis; > > > > > public GChart( String id ) { gvis = _chart( id ); } > > > > > private native JavaScriptObject _chart( String id ) /*-{ > > > > > return new $wnd.google.visualization.LineChart > > > > > ($wnd.document.getElementById( id ) ); > > > > > }-*/; > > > > > // methods to draw the chart through native functions > > > > > ********** > > > > > The GWT compiler gives the following error for the above code > > > > > ******************** > > > > > [ERROR] Unable to load module entry point class > > > > > com.google.gwt.app.testGViz.client.TestGViz (see associated exception > > > > > for details) > > > > > java.lang.RuntimeException: Failed to invoke native method: > > > > > @com.google.gwt.app.testGViz.client.GChart::_init() with 0 arguments. > > > > > at > > > > > com.google.gwt.dev.shell.moz.LowLevelMoz.invoke(LowLevelMoz.java: > > > > > 132) > > > > > at com.google.gwt.dev.shell.moz.ModuleSpaceMoz.doInvoke > > > > > (ModuleSpaceMoz.java:98) > > > > > at > > > > > com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java: > > > > > 447) > > > > > at com.google.gwt.dev.shell.ModuleSpace.invokeNativeVoid > > > > > (ModuleSpace.java:248) > > > > > at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeVoid > > > > > (JavaScriptHost.java:107) > > > > > at > > > > > com.google.gwt.app.testGViz.client.GChart._init(GChart.java) > > > > > at > > > > > com.google.gwt.app.testGViz.client.GChart.<clinit>(GChart.java:7) > > > > > at com.google.gwt.app.testGViz.client.TestGViz.onModuleLoad > > > > > (TestGViz.java:21) > > > > > at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) > > > > > at sun.reflect.NativeMethodAccessorImpl.invoke > > > > > (NativeMethodAccessorImpl.java:39) > > > > > at sun.reflect.DelegatingMethodAccessorImpl.invoke > > > > > (DelegatingMethodAccessorImpl.java:25) > > > > > at java.lang.reflect.Method.invoke(Method.java:597) > > > > > at > > > > > com.google.gwt.dev.shell.ModuleSpace.onLoad(ModuleSpace.java:320) > > > > > at com.google.gwt.dev.shell.BrowserWidget.attachModuleSpace > > > > > (BrowserWidget.java:329) > > > > > at com.google.gwt.dev.shell.moz.BrowserWidgetMoz.access$100 > > > > > (BrowserWidgetMoz.java:35) > > > > > at com.google.gwt.dev.shell.moz.BrowserWidgetMoz > > > > > $ExternalObjectImpl.gwtOnLoad(BrowserWidgetMoz.java:59) > > > > > at > > > > > org.eclipse.swt.internal.gtk.OS._g_main_context_iteration(Native > > > > > Method) > > > > > at > > > > > org.eclipse.swt.internal.gtk.OS.g_main_context_iteration(OS.java: > > > > > 1428) > > > > > at > > > > > org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:2840) > > > > > at > > > > > com.google.gwt.dev.GWTShell.pumpEventLoop(GWTShell.java:720) > > > > > at com.google.gwt.dev.GWTShell.run(GWTShell.java:593) > > > > > at com.google.gwt.dev.GWTShell.main(GWTShell.java:357) > > > > > ********** > > > > > Moving the statement in the native _init function to the constructor > > > > > does not help either. To get it to work, I have to move it out to the > > > > > HTML file > > > > > ******************** > > > > > HTML file > > > > > <script type="text/javascript" > > > > > src="http://www.google.com/jsapi";></ > > > > > script> > > > > > <script type="text/javascript"> > > > > > google.load('visualization', '1', {'packages':['piechart']}); > > > > > </script> > > > > > ********** > > > > > This was also suggested > > > > > inhttp://groups.google.com/group/Google-Web-Toolkit/browse_thread/threa... > > > > > Although this works, I do not understand why I could no do the > > > > > google.load through JSNI. > > > > > In the meanwhile, this is not an issue as GWT now provides its own > > > > > wrappers for the Google Visualization API. But, I would still like to > > > > > understand the error. > > > > > > 2. > > > > > I am trying this time to write a wrapper for another Visualization > > > > > library, Protovis. An example JS use case is as follows: > > > > > ******************** > > > > > HTML file > > > > > <script type="text/javascript" src="protovis.js"></script> > > > > > JS file > > > > > var vis = new pv.Panel().canvas("PVis"); // <== future JSNI > > > > > problems occur at this point > > > > > var line = vis.add(pv.Line); > > > > > // add data and attributes to line > > > > > vis.render(); > > > > > ********** > > > > > I write a GWT wrapper as follows > > > > > ******************** > > > > > JAVA file > > > > > class PChart { > > > > > JavaScriptObject pvis; > > > > > public PChart( String id ) { pvis = _chart( id ); } > > > > > private native JavaScriptObject _chart( String id ) /*-{ > > > > > return new $wnd.pv.Panel().canvas( id ); // <=== ERROR at > > > > > this line > > > > > } -*/; > > > > > // other stuff > > > > > ********** > > > > > The GWT compiler returns the following error at the indicated line > > > > > ******************** > > > > > com.google.gwt.core.client.JavaScriptException: (TypeError): $wnd.pv > > > > > has no properties > > > > > ********** > > > > > > I do not understand what I am doing wrong. Can someone help me to get > > > > > this to work? > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/Google-Web-Toolkit?hl=en -~----------~----~----~----~------~----~------~--~---
