Make Downloader::getContentSize asynchronous

[pandamicro]

jsb.load_remote_img block the main thread a while to check the file size.

[0xJimmyBeh]

@pandamicro

Is there any milestone for this enhancement in the coming release?

Or is there any temporarily solution for this blocking main thread problem?

Thanks.

Any idea when is this going to be fixed, cc.loader.loadImg blocks main thread even loading local imgs!

[pandamicro]

Loading local imgs won't use the downloader to check file size, so it's not the same issue. But if your local images are too large, it will take a little while to load the texture into memory. You can use cc.textureCache.addImageAsync which is asynchonous.

[0xJimmyBeh]

Why there is no cc.textureCache.addImageAsync API show in the doc?

http://www.cocos2d-x.org/reference/html5-js/V3.3/symbols/cc.textureCache.html

So any idea how to load online images asynchronous?

Thanks.

[pandamicro]

Oh, you are right, it was not well considered, I created an issue here:
#1507

Load online images is asynchronous, which I describe in the current issue is that the getContentSize API is synchronous so it blocks sometimes for just a tiny amount of time.

[0xJimmyBeh]

I understand the issue is on getContentSize as you described.

To make my question more precise, i should ask
"How to load online images Fully asynchronous" as getContentSize API is part of the code.

And thanks for the info in the issue #1507.

Is it i just need to make the change as below to the frameworks/js-bindings/bindings/script/jsb_boot.js to solve the blocking issue?
pandamicro@2a124b5

[pandamicro]

pandamicro/cocos2d-js@2a124b5 will only solve the issue of @vktrsm

I will find some time to do this issue as soon as possible, sorry for keeping you guys waiting

[0xJimmyBeh]

I'm looking forward to hearing good news from you.

Thanks for your effort!

@pandamicro Thx for the fix!! We didnt understand why addImgAsync was removed on 3.0 (was working in 2.2, docs say is merged into addImage and makes async load when callback is provided, but this was untrue), thats why I was trying to use loadImg.

Again thanks.

[thangenius]

I've made a workaround for this issue by modifying the below code to jsbinding/binding/manual/extensions/jsb_cocos2dx_extension_manual.cpp (cocos2d-js 3.2):

1. line 971, change download(..) function as follow
   void __JSDownloaderDelegator::download(JSContext *cx, JSObject *obj,
   const std::string &url, const jsval &callback) {
   auto t = std::thread(cx, obj, url, callback {
   new __JSDownloaderDelegator(cx, obj, url, callback);
   });
   t.detach();
   }
2. line 900 of constructor __JSDownloaderDelegator::__JSDownloaderDelegator(), change
   _downloader->downloadToBufferASync(_url, _buffer, _size);
   to
   _downloader->downloadToBufferSync(_url, _buffer, _size);
   (make this change to avoid another thread to be created to download)
3. Finally, include std::thread in the include section
   #include

Hope this helps while waiting for the official fix :)