Bug 55270 – [Qt] HTML 5 drag and drop uses incorrect text encoding

• Component: WebKit Misc.
• Status: RESOLVED WORKSFORME

[Brian Ellis]

Affected Platforms:
Mac OS X 10.6 (at least -- haven't tested on other platforms).

Reproduction:
Write the following JavaScript code in an element's onDragBegin event handler:

  evt.effectAllowed = 'copy';
  evt.dataTransfer.setData('text/plain', 'Hello, world!');

Render the element in a QWebView.

Now, drag the element into another application (like a text editor).  When dropped, the single character "H" will be displayed in the text editor.

Drag the element again, this time into a QLineEdit within the same application.  When dropped, the string "H e l l o ,   w o r l d !" will be displayed in the QLineEdit.

Cause:
The string is encoded in UTF-16 (likely because JavaScript encodes all strings as UTF-16), but the pasteboard is expecting UTF-8.  QtWebKit does not seem to perform the conversion when the drag data is copied to the pasteboard, so the net effect is that (for plain ASCII text like "Hello, world!") the data is interspersed with NULL bytes.  This causes most implementations to truncate after the first character; within the same application, though, the length information is preserved, and so the NULLs are rendered as spaces.

Workaround:
You can partially work around the bug for within-application drops by manually reinterpreting the data as UTF-16, like so:

  QByteArray text = mimeData->data("text/plain");
  const char* utf16 = text.constData();
  QString real_text = QString::fromUtf16(reinterpret_cast<const ushort*>(utf16), text.length() / 2);

Suggested Fix:
Convert strings coming from JavaScript to UTF-8 before copying them to the pasteboard.

[Benjamin Poulain]

Would you mind attaching the HTML file of your test case so this bug report is complete?

[Brian Ellis]

Created attachment 84004 [details]
Reproduction case for this bug.

Attached.

[Aparna Nandyal]

Can you please confirm if the problem seen is infact on the nightly build or an older QtWebKit that shipped with Qt.

I am able to see the problem on the older release of QtWebKit shipped with 4.7.0 but not with the code in the trunk.

[Benjamin Poulain]

(In reply to comment #3)
> I am able to see the problem on the older release of QtWebKit shipped with 4.7.0 but not with the code in the trunk.

I second that. I just tested on Mac and I don't have any problem on trunk.