What I try to do is to call back to the embedding browser c/c++ function
from javascript in a web page
in order to achieve some kind of notifications.
By following the jsapi pattern such as jsbool.c, I implemented an
notification object and registered it
at runtime as a global object. I expect the object acts like a native object
in js such as Boolean.
In a web page, I have javascript to instantiate the object and call on its
method.
However, I haven't succeeded yet.
The followings are the simplified code segments:
(1). c/c++ code embedded in the browser app:
/*notification object*/
static JSBool
jscallback_Notify(JSContext *cx, JSObject *obj, uintN argc, jsval *argv,
jsval *rval)
{
FILE *fp = fopen("jsbc.txt", "a+");
if(fp)
{
fprintf(fp, "jscallback gets called\n");
fclose(fp);
}
return JS_TRUE;
}
static JSFunctionSpec jscallback_functions[] = {
{"Notify", jscallback_Notify, 0, 0, 0},
{0, 0, 0, 0, 0}
};
static JSClass jscallback_class = {
"JSCB", 0,
JS_PropertyStub, JS_PropertyStub, JS_PropertyStub, JS_PropertyStub,
JS_EnumerateStub, JS_ResolveStub, JS_ConvertStub, JS_FinalizeStub
};
static JSBool
JSCB(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
{
return JS_TRUE;
}
/*creat, register and initialise*/
nsCOMPtr<nsIJSRuntimeService> rtsvc =
do_GetService("@mozilla.org/js/xpc/RuntimeService;1", &rv);
if(NS_FAILED(rv) || NS_FAILED(rtsvc->GetRuntime(&rt)) || !rt)
goto clean;
jscontext = JS_NewContext(rt, 1000);
if(!jscontext)
goto clean;
xpc = do_GetService(nsIXPConnect::GetCID(), &rv);
if(NS_FAILED(rv) || !xpc)
goto clean;
cxstack = do_GetService("@mozilla.org/js/xpc/ContextStack;1", &rv);
if(NS_FAILED(rv))
goto clean;
if(NS_FAILED(cxstack->Push(jscontext)))
goto clean;
jscb = JS_NewObject(jscontext, &jscallback_class, NULL, NULL);
if(!jscb)
goto clean;
if(!JS_InitStandardClasses(jscontext, jscb))
goto clean;
if(!JS_DefineFunctions(jscontext, jscb, jscallback_functions))
goto clean;
// if(NS_FAILED(xpc->InitClasses(jscontext, jscb)))
if(!JS_InitClass(jscontext, jscb, NULL, &jscallback_class, JSCB,
0, NULL, jscallback_functions, NULL, NULL))
goto clean;
(2). javascript in the web page
<script language="javascript">
function test_notif()
{
var t = new JSCB();
t.Notify();
}
</script>
<body onload="test_notif()">
</body>
However, the file defined in the jscallback_Notify method was never created.
In the other words, the object hasn't been created properly. I don't know
what I missed out so far. I didn't use xpconnect here to avoid loading
module,
createinstance such procedures. I may be wrong. Any suggestion welcomed.
Thanks.
