I see.
If you have a function that on the C++ side returns a double array, what
would be your preferred way to make this accessible in JS? I don't know the
length of the array beforehand.
I played around with EM_ASM_INT.
JSHelper fillRandomArray()
{
int len = rand()%10 + 10;
int pointer = EM_ASM_INT({
var buffer = Module._malloc($0 * 4);
return buffer;
}, len);
int* a = (int*)pointer;
for (int i = 0; i < len-1; i++)
{
a[i] = i*3;
}
JSHelper js;
js.pointer = pointer;
js.length
return js;
}
and in my .js file
var nByte = 4;
var charByte = 1;
var jsInfo = Module.fillRandomArray();
var buffer = jsInfo.pointer;
for (var i = 0; i < jsInfo.length; i++)
{
console.log(Module.getValue(buffer + i*nByte, 'i32'));
}
This works but this seems a bit too complicated for something (seemingly)
simple. I've also tried a version where I return just a std::vector which
works just fine but our C++ code base tries to avoid using STL for some
reasons. Is this a reasonable solution?
On Wednesday, 26 October 2016 19:37:06 UTC+2, Alon Zakai wrote:
>
> It depends what you mean. A pointer in emscripten (in general) is just an
> integer. So it's fine to pass pointers into and out of compiled code,
> including WebIDL glue. The WebIDL glue does add functionality on top, by
> converting a return value of a wrapped class into a JS object wrapper. It
> also handles an input parameter that is a JS object wrapper, converting it
> into the integer for the compiled method underneath (it's also fine to just
> pass that integer as a parameter).
>
> On Tue, Oct 25, 2016 at 10:32 PM, Philipp Gloor <[email protected]
> <javascript:>> wrote:
>
>> OK thanks. And did I understand correctly that pointers only work for
>> non-primitive data types?
>>
>> On 26 October 2016 at 00:11, Alon Zakai <[email protected] <javascript:>>
>> wrote:
>>
>>> Yes, WebIDL focuses on simple types that map directly to JS (numbers,
>>> pointers, etc). embind has more functionality for sophisticated mappings of
>>> C++ classes, like std::vector.
>>>
>>> On Tue, Oct 25, 2016 at 2:39 PM, Philipp Gloor <[email protected]
>>> <javascript:>> wrote:
>>>
>>>> I have a C++ function that should return a vector of doubles but on the
>>>> WebIDL
>>>> doc page
>>>> <https://kripken.github.io/emscripten-site/docs/porting/connecting_cpp_and_javascript/WebIDL-Binder.html>
>>>> I
>>>> found nothing that could help me.
>>>>
>>>> The header file:
>>>>
>>>> #ifndef __JSAPI_H__
>>>> #define __JSAPI_H__
>>>>
>>>> #include <string>
>>>> #include "annotation.h"
>>>>
>>>> class JSAPI
>>>> {
>>>> Annotation* annotations;
>>>> public:
>>>> char* getAnnotContent(int annotID);
>>>> std::vector<double> getAnnotRect(int annotID);
>>>>
>>>> };
>>>>
>>>> #endif
>>>>
>>>> And the implementation
>>>>
>>>> #include "jsapi.h"
>>>>
>>>>
>>>> char* JSAPI::getAnnotContent(int annotID)
>>>> {
>>>> return annotations[annotID].content;
>>>> }
>>>>
>>>> std::vector<double> JSAPI::getAnnotRect(int annotID)
>>>> {
>>>> return annotations[annotID].rect;
>>>> }
>>>>
>>>> And I'm looking for the proper definition of
>>>>
>>>> interface JSAPI
>>>> {
>>>> void JSAPI();
>>>> DOMString getAnnotContent(long annotID);
>>>> std::vector<double> getAnnotRect(long annotID);
>>>> };
>>>>
>>>> Is something like this even possible? Or do I need to switch to embind
>>>> for this?
>>>>
>>>> --
>>>> You received this message because you are subscribed to the Google
>>>> Groups "emscripten-discuss" group.
>>>> To unsubscribe from this group and stop receiving emails from it, send
>>>> an email to [email protected]
>>>> <javascript:>.
>>>> For more options, visit https://groups.google.com/d/optout.
>>>>
>>>
>>> --
>>> You received this message because you are subscribed to a topic in the
>>> Google Groups "emscripten-discuss" group.
>>> To unsubscribe from this topic, visit
>>> https://groups.google.com/d/topic/emscripten-discuss/18GjJeGOq08/unsubscribe
>>> .
>>> To unsubscribe from this group and all its topics, send an email to
>>> [email protected] <javascript:>.
>>> For more options, visit https://groups.google.com/d/optout.
>>>
>>
>> --
>> You received this message because you are subscribed to the Google Groups
>> "emscripten-discuss" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to [email protected] <javascript:>.
>> For more options, visit https://groups.google.com/d/optout.
>>
>
>
--
You received this message because you are subscribed to the Google Groups
"emscripten-discuss" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/d/optout.
