[Qt] HTML5 Drag and Drop demos not working

[Aparna Nandyal]

Steps to reproduce the problem:

1. Open QtTestBrowser or a sample QWebView program which does (QWebView view; view.show(); view.load(QUrl("any urls given below"));
2. Load any of the URLs - http://html5demos.com/drag, http://html5demos.com/drag-anything, http://shapeshed.com/examples/drag-and-drop/, http://html5tutorial.net/examples/html5-drag-and-drop.html or other popular demos for html5 D&D.
3. Follow the instructions given in the url. All the URLs allow dragging of some content and dropping it off in designated area.

Expected results:
Drag and drop works fine as stated in the URL

Actual result:
Drop is not working as mentioned in the url. Unable to drop the content.

[Benjamin Poulain]

Created attachment 88223 [details]
Patch

[Benjamin Poulain]

Covered by existing tests but the DRT does not yet have support for Drag and Drop unfortunatelly.

[Benjamin Poulain]

*** Bug 52601 has been marked as a duplicate of this bug. ***

[Aparna Nandyal]

This fix does not solve the problem with all D&D urls mentioned below. http://html5tutorial.net/examples/html5-drag-and-drop.html example still fails with this fix. 

I have been working to fix the issue with that.

Analysis:
1. For html5 D&D, preventDefault is used to allow dropping in dragOver.

  addEvent(bin, 'dragover', function (e) {
    if (e.preventDefault) e.preventDefault(); // allows us to drop
    this.className = 'over';
    e.dataTransfer.dropEffect = 'copy';
    alert('Hahaha');
    return false;
  });


2. In some implementations it returns false instead of calling preventDefault (IE expects return false) to allow dropping.

  addEvent(bin, 'dragover', function (e) {
    this.className = 'over';
    e.dataTransfer.dropEffect = 'copy';
    alert('Hahaha');
    return false; //allows us to drop
  });


3. If preventDefault is called on the event, then m_defaultPrevented is set to true and droppping succeeds in webkit.
4. So we need to set, m_defaultPrevented even when false is returned (as in step 2) to let dropping succeed. 
5. setReturnValue of Event.h needs to be called.

Working on a fix for this.

[Aparna Nandyal]

Missed mentioning - Patch given by Benjamin is required, in addition to it we need to make changes mentioned in comment#4.

[Andreas Kling]

Comment on attachment 88223 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=88223&action=review

r=me

> Source/WebKit/qt/ChangeLog:12
> +        what action should take place. To adtop this behavior for Qt, we always accept drag enter events

Typo, s/adtop/adopt/

[Benjamin Poulain]

Committed r83442: <http://trac.webkit.org/changeset/83442>