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
-~----------~----~----~----~------~----~------~--~---
