.....perhaps you have the Javascript library in the wrong place and it
is not being loaded. I'd still suggest you get hold of a debug tool
in your browser to see what's loaded etc as you're going to need it
when you get into trying to access the library and going further, but,
the following works for me to access the library.
1. In my applications .gwt.xml file I have put: <script src="protovis-
r2.6.js"/>
2. I also have defined my module in the .gwt.xml file as follows:
<module rename-to='testAA'>
3. I'm using GWT1.6, so the protovis-r2.6.js file needs to go in
within the war file, i.e. it goes in the folder /war/testAA/
4. In my application I just create a simple JSNI method
public native JavaScriptObject getVis()/*-{
var vis = new $wnd.pv.Panel().canvas("test");
return vis;
}-*/;
5. In my onModuleLoad I simply call the method and alert the fact
that I have an object
public void onModuleLoad() {
JavaScriptObject v = getVis();
Window.alert(v.toString());
}
that tells me I have got a valid JavaScript object and I see no
exceptions or errors.
Hope that helps, or at least gives you some hints.
//Adam
On 21 Juli, 16:23, wsaleem <[email protected]> wrote:
> 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?
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