On 14 juin, 20:28, markmccall <[email protected]> wrote:
> I am integrating a 3rd party JavaScript library into my GWT 2.0
> application and I have succeeded in invoking the libary using basic
> JSNI but I want to take the integration even further so that callers
> of the library never have to code any JSNI, if possible. The 3rd
> party library has a class Foo with a JSON structure as a constructore
> parameter.
JSON is a data format, what you're talking about is a JavaScript
object, which you probably generally write directly as an object
literal (the thing within braces, with comma-separated name:value
pairs)
> The structure contains simple properties as well as
> predefined functions where users of this library can place custom own
> behavior. Foo will call those functions to invoke the custom behavior
> at time of is own choosing. In the example below I have shown 2
> functions called 'onBeforeCompute' and 'onAfterCompute' which would be
> invoked during Foo's loadData prcoess. The normal JSNI implementation
> would look something like this:
>
> public native JavaScriptObject setUp() /*-{
> var config = {
> prop1: 'val1',
> prop2: 'val2',
> onBeforeCompute: function(someparam) {
> // do something custom here
> },
> onAfterCompute: function(someparam1, someparam2) {
> // do something custom here
> }};
>
> var foo = $wnd.Foo(config);
> foo.loadData(...)
>
> }-*/
>
> I would like to wrap all of this code up so that my applications that
> use the 3rd party library never have to code any JSNI, if possible. I
> am envisioning something like this:
>
> public class MyWidget extends Composite
> {
> public MyWidget()
> {
> Config config = new Config();
> config.setProp1("val1");
> config.setProp2("val2");
> config.setOnBeforeHandler(new MyOnBeforeComputeHandler());
> config.setOnAfterHandler(new MyOnAfterComputeHandler());
> Foo foo1 = new Foo(config);
> SimplePanel panel = new SimplePanel(foo1);
> initWidget(panel);
> foo1.loadData(...);
> }
>
> }
>
> public class MyOnBeforeComputeHandler implements
> OnBeforeComputeHandler // interface definition excluded for brevity
> {
> public void onBeforeCompute(JavaScriptObject someparam)
> {
> // do something custom here
> }
>
> }
>
> public class MyOnAfterComputeHandler implements
> OnAfterComputeHandler // interface definition excluded for brevity
> {
> public void onAfterComputeHandler(JavaScriptObject someparam1,
> JavaScriptObject someparam2)
> {
> // do something custom here
> }
>
> }
>
> Setting the simple properties on the Config class is easy - I can
> simply use the JSONObject, but I do not know how to deal with the
> onBeforeCompute and onAfterCompute functions that are part of the
> Config object
>
> public class Config
> {
> private JSONObject jsonPeer = new JSONObject();
Why not use a JavaScriptObject "overlay type"?
> public void setProp1(String value){ jsonPeer.put ("prop1", value)};
> public void setProp2(String value){ jsonPeer.put ("prop2", value)};
> public asJson() {return jsonPeer.getJavaScriptObject());
> public void setPreLoadHandler(PreLoadHandler handler) { ??? }
> public void setPostLoadHandler(PostLoadHandler handler) { ??? }
>
> }
>
> Am I on the right track? Is there a better way?
Re-written as an overlay type:
public final class Config extends JavaScriptObject {
public static Config newInstance() /*-{ }-*/;
protected Config() { }
public native void setProp1(String value) /*-{ this.prop1 = value; }-
*/;
public native void setProp2(String value) /*-{ this.prop2 = value;}-
*/;
public native void setPreLoadHandler(PreLoadHandler handler) /*-{
var that = this;
this.onBeforeCompute = $entry(function(someparam) {
[email protected]::onBeforeCompute(Lcom/
google/gwt/core/client/JavaScriptObject;)(someparam);
});
}-*/;
public native void setPostLoadHandler(PostLoadHandler handler) /*-{
var that = this;
this.onBeforeCompute = $entry(function(someparam) {
[email protected]::onAfterCompute(Lcom/
google/gwt/core/client/JavaScriptObject;Lcom/google/gwt/core/client/
JavaScriptObject;)(someparam1, someparam2);
});
}-*/;
}
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