Hi
I'm using GWT 2.0.3
It seems to me that in hosted mode when I attempt to use (for example) a
float[] as a parameter to a native call it silently fails.
The documentation only refers very obliquely to this:
Although Java arrays are not directly usable in JavaScript, there are
some helper classes that efficiently achieve a similar effect: JsArray
<http://google-web-toolkit.googlecode.com/svn/javadoc/2.0/com/google/gwt/core/client/JsArray.html>,
JsArrayBoolean
<http://google-web-toolkit.googlecode.com/svn/javadoc/2.0/com/google/gwt/core/client/JsArrayBoolean.html>,
JsArrayInteger
<http://google-web-toolkit.googlecode.com/svn/javadoc/2.0/com/google/gwt/core/client/JsArrayInteger.html>,
JsArrayNumber
<http://google-web-toolkit.googlecode.com/svn/javadoc/2.0/com/google/gwt/core/client/JsArrayNumber.html>,
and JsArrayString
<http://google-web-toolkit.googlecode.com/svn/javadoc/2.0/com/google/gwt/core/client/JsArrayString.html>.
These classes are wrappers around a native JavaScript array.
And, in fact, this appears to be true. If you want an array of floats,
you must create them in a native method.
As an example, if you create a client function
public void myFunc(int x, int y, float[] z) {
do something with z here.
}
"z" will always be 'undefined' in hosted mode (although, oddly, it seems
that it can work in production mode.)
What does seem to work in both hosted and production mode is:
public static native JsArrayNumber getNativeArray () /*-{ return [ 0, 1,
-5, -1, -1, -5, 1, -1, -5]; }-*/;
public void myFunc2(int x, int y, JsArrayNumber z) {
// now if invoked something like myFunc2(5, 10, getNativeArray())
the array works as expected.
}
So, my questions are:
1. Is what I've just said correct?
2. If so, why doesn't the debug runtime system generate a warning when
encountering a 'float []' in hosted mode? Ok it crashes with an obscure
exception,
but that isn't very helpful.
If you need to initialize a float [] from a client side java program and
then pass that array to a native method, you have to do something like:
float [] floats = myinstance.myMethod2CreateFloatArray();
public static native JsArrayNumber createNew() /*-{ return new Array();
}-*/;
public static JsArrayNumber initArray(float [] f) {
JsArrayNumber a = createNew();
for (float fv :f)
a.push(fv);
return a;
};
This seems to work in both hosted and production mode. Any suggestions
as to a better way to do this would be appreciated.
I think the documentation should be a little bit more explicit about
this, I'd be happy to contribute.
Regards
Alan
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