Use the JavaScript version of the loop, and call that just once from C++. If it's convenient from a packaging point of view, you can put it into a string literal in your C++ source, and compile/run it from there.
Calls between C++ and JavaScript (in both directions) are always going to have quite a bit of overhead; the best way to speed them up is to avoid doing too many of them. On Sat, May 16, 2020 at 10:36 PM Feng Wang <[email protected]> wrote: > Thanks Yang. But I have to define the processing algorithm in javascript. > > > > Feng Wang > 邮箱：[email protected] > > <https://maas.mail.163.com/dashi-web-extend/html/proSignature.html?ftlId=1&name=Feng+Wang&uid=jfwf2004%40gmail.com&iconUrl=https%3A%2F%2Fmail-online.nosdn.127.net%2Fqiyelogo%2FdefaultAvatar.png&items=%5B%22%E9%82%AE%E7%AE%B1%EF%BC%9Ajfwf2004%40gmail.com%22%5D> > > 签名由 网易邮箱大师 <https://mail.163.com/dashi/dlpro.html?from=mail88> 定制 > > On 05/16/2020 22:03, Yang Guo <[email protected]> wrote: > Put everything into an ArrayBuffer and call C++ just once. > > On Sat, May 16, 2020, 15:07 Feng Wang <[email protected]> wrote: > >> I have an image (1024x1024x3) that needs to be process pixel-by-pixel. >> The per-pixel processing code is written using javascript. I've found that >> it takes 277ms to loop through this handler in c++ code, and only 10ms to >> loop in javascript code. I want to know how to make the c++ call javascript >> function as fast as possible. >> >> //javascript per-pixel processing function >> var pixelfunction=function( rgb , index ) >> { >> var outval = (rgb[0]-rgb[1]/(rgb[0]+rgb[1]) ; >> return outval; >> } >> >> >> >> //c++ codes loop call pixelfunction >> ... >> v8::Function* pixelFunc = ...; // this Function pointer is pixelfunction >> in javascript. >> v8::Local<v8::Uint8Array> vals = ...; // >> v8::Local<Value> targs[2] ; >> for(int it = 0 ;it<1024*1024;++it) >> { >> vals = ...; // get r,g,b values from image ; >> targs[0] = vals; >> targs[1] = v8::Integer::New( global , it ); >> pixelFunc->Call( context , context->Global() , 2 , targs);//For >> convenience, I'm giving up the return value. >> } >> ... >> >> - >> //javascript loop call: >> var vals=new Uint8Array(3); >> for(var it = 0 ; it < 1024*1024 ; ++it ) >> { >> vals=...; //get r,g,b values from image >> pixelfunction( vals , it );//For convenience, I'm giving up the return >> value. >> } >> >> -- >> -- >> v8-dev mailing list >> [email protected] >> http://groups.google.com/group/v8-dev >> --- >> You received this message because you are subscribed to the Google Groups >> "v8-dev" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/v8-dev/dd3c7a28-1144-4e5f-a982-15e8558d7e5c%40googlegroups.com >> <https://groups.google.com/d/msgid/v8-dev/dd3c7a28-1144-4e5f-a982-15e8558d7e5c%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- > -- > v8-dev mailing list > [email protected] > http://groups.google.com/group/v8-dev > --- > You received this message because you are subscribed to the Google Groups > "v8-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/v8-dev/CAFSTc_g3hQ9P3bevpXqjux%2BZa%3DMcZmQRyjQ-uD62Mi3w_tkezg%40mail.gmail.com > <https://groups.google.com/d/msgid/v8-dev/CAFSTc_g3hQ9P3bevpXqjux%2BZa%3DMcZmQRyjQ-uD62Mi3w_tkezg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > -- > -- > v8-dev mailing list > [email protected] > http://groups.google.com/group/v8-dev > --- > You received this message because you are subscribed to the Google Groups > "v8-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/v8-dev/1589661290983.hsmxtszv0tk5ohvnejt3hcts%40android.mail.163.com > <https://groups.google.com/d/msgid/v8-dev/1589661290983.hsmxtszv0tk5ohvnejt3hcts%40android.mail.163.com?utm_medium=email&utm_source=footer> > . > -- -- v8-dev mailing list [email protected] http://groups.google.com/group/v8-dev --- You received this message because you are subscribed to the Google Groups "v8-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/v8-dev/CAKSzg3QOYeOcxrxLWvSXdrhhvcFD1%3DYn%2BxubmM%2BivcaUdzQ3-A%40mail.gmail.com.
