647653 - It should be possible to create nsIDOMBlob in JavaScript XPCOM components

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Jan Gerber]

User-Agent:       Mozilla/5.0 (X11; Linux i686; rv:2.0) Gecko/20100101 Firefox/4.0
Build Identifier: 

It would be nice to be able to return nsIDOMBlob objects or implement nsIDOMBlob inside a custom xpcom element for an extension to make files/data available inside the DOM. i.e. like this:
 f = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsILocalFile);
 f.initWithPath(..);
 f.QueryInterface(Ci.nsIDOMBlob)

Right now there is no way to create an nsIDOMBlob from an nsILocalFile.
Trying to implement a Javascript XPCOM element with nsIDOMBlob interface was also seams to be impossbile since i.e nsIPartialFileInputStream is not abailable:

 Cc["@mozilla.org/network/partial-file-input-stream;1"]
   .createInstance(Ci.nsIPartialFileInputStream);

Its is also not quite clear how one could add a moz-filedata: url to implement
getInternalUrl in Kavascript.



Reproducible: Always

Comment 1

[Jan Gerber]

ongoing attempt to implement nsIDOMBlob in a JavaScript component,
it does not seam to call my getInternalUrl function. 
[Exception... "Component returned failure code: 0x804b000a (NS_ERROR_MALFORMED_URI) [nsIDOMFileReader.readAsBinaryString]" nsresult: "0x804b000a (NS_ERROR_MALFORMED_URI)"]

even if getInternalUrl would be called, it does not seam to be possible to add url to 
nsFileDataProtocolHandler from Javascript,
namely calling:
 nsFileDataProtocolHandler::AddFileDataEntry(url, this, aPrincipal);

Comment 2

[Jan Gerber]

Attachment: An attempt to support nsIDOMBlob in an extension

Comment 3

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

Is this a dupe of bug 607114?

Comment 4

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

Yes, accept Bug 607114 would have nicer syntax :-)

Comment 5

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

We didn't do this for components ... maybe we should.

Comment 6

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

This shouldn't be too hard to do, but I don't know if I should be adding the code to nsXPConnect::InitClasses, nsXPConnect::InitClassesWithNewWrappedGlobal, or both.

Blake?

Comment 7

[Blake Kaplan (:mrbkap) (inactive)]

On IRC, I floated the idea of just using a contract ID for this. But as that would be awkward, the answer to Kyle's question is that you need to add it to both.

You do need to be a little careful that you don't add it to Windows or ChromeWindows, though... I can't think of a clean way of doing that off the top of my head without checking the JSClass's name field :-/

Another option that might be cleaner would be to figure out a way to add the constructor in mozJSComponentLoader, the way that we add atob and dump to components' global objects.

Comment 8

[Jan Gerber]

Was any decision made how to move this forward?

Comment 9

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

(In reply to comment #8)
> Was any decision made how to move this forward?

Yeah, it should be pretty straightforward to add a constructor to the JS component loader.  I just need to sit down and do it.

Comment 10

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

Attachment: Patch

Comment 11

[Blake Kaplan (:mrbkap) (inactive)]

Comment on attachment 542950 [details] [diff] [review]
Patch

Review of attachment 542950 [details] [diff] [review]:
-----------------------------------------------------------------

::: js/src/xpconnect/loader/mozJSComponentLoader.cpp
@@ +260,5 @@
> +        return JS_FALSE;
> +    }
> +
> +    nsCOMPtr<nsIXPConnect> xpc =
> +        do_GetService(kXPConnectServiceContractID, &rv);

Why not use nsXPConnect::GetXPConnect()?

@@ +272,5 @@
> +        XPCThrower::Throw(NS_ERROR_UNEXPECTED, cx);
> +        return JS_FALSE;
> +    }
> +
> +    JSObject* glob = JS_GetGlobalForObject(cx, scope);

You can just use JS_GetGlobalForScopeChain here.

@@ +278,5 @@
> +    nsCOMPtr<nsIXPConnectJSObjectHolder> holder;
> +    jsval retval;
> +    rv = xpc->WrapNativeToJSVal(cx, glob, native, nsnull,
> +                                &NS_GET_IID(nsISupports),
> +                                PR_FALSE, &retval, nsnull);

It looks like your passing PR_FALSE for aAllowWrapping. I think that should be PR_TRUE.

Comment 12

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

(In reply to comment #11)
> Comment on attachment 542950 [details] [diff] [review] [review]
> Patch
> 
> Review of attachment 542950 [details] [diff] [review] [review]:
> -----------------------------------------------------------------
> 
> ::: js/src/xpconnect/loader/mozJSComponentLoader.cpp
> @@ +260,5 @@
> > +        return JS_FALSE;
> > +    }
> > +
> > +    nsCOMPtr<nsIXPConnect> xpc =
> > +        do_GetService(kXPConnectServiceContractID, &rv);
> 
> Why not use nsXPConnect::GetXPConnect()?

Oh hey, that's neat.

> @@ +272,5 @@
> > +        XPCThrower::Throw(NS_ERROR_UNEXPECTED, cx);
> > +        return JS_FALSE;
> > +    }
> > +
> > +    JSObject* glob = JS_GetGlobalForObject(cx, scope);
> 
> You can just use JS_GetGlobalForScopeChain here.

That's neat too.

> @@ +278,5 @@
> > +    nsCOMPtr<nsIXPConnectJSObjectHolder> holder;
> > +    jsval retval;
> > +    rv = xpc->WrapNativeToJSVal(cx, glob, native, nsnull,
> > +                                &NS_GET_IID(nsISupports),
> > +                                PR_FALSE, &retval, nsnull);
> 
> It looks like your passing PR_FALSE for aAllowWrapping. I think that should
> be PR_TRUE.

ok.

Comment 13

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

http://hg.mozilla.org/projects/build-system/rev/e6220bfcfd17

Comment 14

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

http://hg.mozilla.org/mozilla-central/rev/e6220bfcfd17

Comment 15

[Eric Shepherd [:sheppy]]

Am I correct that the change here is that you can now do "new File" in chrome code to create a DOM File object?

Comment 16

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

You can do new File in component scopes to create a DOM File object.  This has worked in chrome window scopes previously.

Comment 17

[Eric Shepherd [:sheppy]]

Documentation updated:

https://developer.mozilla.org/en/DOM/File#Gecko_notes
https://developer.mozilla.org/en/Extensions/Using_the_DOM_File_API_in_chrome_code#Notes

Also mentioned on Firefox 8 for developers.

Comment 18

[steve.chung7]

So how do you create an nsIDOMBlob object...?

Something like Cc["@mozilla.org/files/blob;1"].createInstance(Ci.nsIDOMBlob, [oFileBody], { type: "text/xml"});?

Thanks.

Comment 19

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

new Blob(arguments);

Comment 20

[steve.chung7]

Are you sure...?

I'm pretty sure I have to use XPCOM stuff...

[21:22:41.674] ReferenceError: Blob is not defined @ resource://gre/modules/XPIProvider.jsm -> jar:file:///Users/main/Library/Application%20Support/Firefox/Profiles/xfm2tq4r.default/extensions/[e-mail]!/bootstrap.js -> resource://gre/modules/commonjs/toolkit/loader.js -> resource://jid0-aae9xbnby78ijybb6jwvpakiykq-at-jetpack/s12chung/lib/main.js:32

Comment 21

[steve.chung7]

funny. someone just answered it on stackoverflow: http://stackoverflow.com/questions/19780396/use-blob-on-firefox-add-on

thanks for getting back so quickly though :). happy monday.

Comment 22

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

Oh ... that's some weird SDK thing then.