Bug 64298 – positionForPoint is broken when a block is positioned relatively inside the parent

• Component: HTML Editing
• Status: RESOLVED FIXED

[Ryosuke Niwa]

When a block has the style "position: relative; left: 50px; padding-bottom: 20px;", hit-testing on the left of this block is broken.

[Ryosuke Niwa]

Created attachment 100325 [details]
demo

[Ryosuke Niwa]

The problem seems to be that RenderBox::location() is not updated for this node:
(gdb) p child->showTreeForThis()
BODY	0x107478e40
	#text	0x10a818690 "\n"
*	DIV	0x10a80cec0 STYLE=position: relative; left: 50px; padding-bottom: 20px; border: solid 1px
		#text	0x10a8186f0 "\nClick on the left of this box. The caret is placed at a wrong location.\n"
	#text	0x10a818e80 "\n"
	DIV	0x10a8172d0
		#text	0x10a826330 "Selected text:"
		CODE	0x10a819240
		DIV	0x1074701e0
			#text	0x107470510 "\n"
			SCRIPT	0x107470570
				#text	0x107470790 "\n\nfunction update() {\n    document.getElementById('log').textContent = window.getSelection().toString();\n}\n\n"
			#text	0x107472450 "\n\n\n"
$7 = void
(gdb) p child->location()
$8 = {
  m_x = 0, 
  m_y = 0
}

[Ryosuke Niwa]

RenderView 0x107474fa8                 	#document	0x108056000
  RenderBlock 0x107473cc8              	HTML	0x107473350
    RenderBody 0x10a817cb8             	BODY	0x107478e40
*     RenderBlock (relative positioned) 0x10a8120e8	DIV	0x10a80cec0 STYLE=position: relative; left: 50px; padding-bottom: 20px; border: solid 1px
        RenderText 0x10a8121b8         	#text	0x10a8186f0 "\nClick on the left of this box. The caret is placed at a wrong location.\n"
      RenderBlock 0x10a819108          	DIV	0x10a8172d0
        RenderBlock (anonymous) 0x107470458
          RenderText 0x10a8191d8       	#text	0x10a826330 "Selected text:"
          RenderInline 0x1074700f8     	CODE	0x10a819240
        RenderBlock 0x107470318        	DIV	0x1074701e0

[Simon Fraser (smfr)]

I find it hard to believe that hit testing on all position:relative blocks is broken.

[Ryosuke Niwa]

(In reply to comment #4)
> I find it hard to believe that hit testing on all position:relative blocks is broken.

It's broken when left or top is specified and the block is inside the parent.

[Ryosuke Niwa]

Created attachment 100364 [details]
demo 2

It's actually harder to find cases where hit-testing is working.

[Simon Fraser (smfr)]

But it's not. I can select the text just fine. This is something about placing the caret.

[Ryosuke Niwa]

(In reply to comment #7)
> But it's not. I can select the text just fine. This is something about placing the caret.

I can't select text properly in any of the boxes in "demo 2".

[Simon Fraser (smfr)]

demo 2 works fine for me. Maybe there's a chromium issue?

[Ryosuke Niwa]

(In reply to comment #9)
> demo 2 works fine for me. Maybe there's a chromium issue?

No, I'm using WebKit Nightly.  To demonstrate this bug, you have to start your mouse drag outside of the dark border but inside the light border.

[Ryosuke Niwa]

(In reply to comment #9)
> demo 2 works fine for me. Maybe there's a chromium issue?

For a future reference, I almost never use chromium port for testing.

[Ryosuke Niwa]

Created attachment 100376 [details]
fixes the bug

[Ryosuke Niwa]

Simon, sorry about the confusing :(  Hopefully this patch clarifies what needs to be fixed.

[WebKit Review Bot]

Comment on attachment 100376 [details]
fixes the bug

Attachment 100376 [details] did not pass chromium-ews (chromium-xvfb):
Output: http://queues.webkit.org/results/9010628

New failing tests:
fast/block/positioning/hittest-on-relative-positioned-children.html

[WebKit Review Bot]

Created attachment 100380 [details]
Archive of layout-test-results from ec2-cr-linux-03

The attached test failures were seen while running run-webkit-tests on the chromium-ews.
Bot: ec2-cr-linux-03  Port: Chromium  Platform: Linux-2.6.35-28-virtual-x86_64-with-Ubuntu-10.10-maverick

[Ryosuke Niwa]

Created attachment 100383 [details]
fixed the test

[Ryosuke Niwa]

Comment on attachment 100383 [details]
fixed the test

Clearing flags on attachment: 100383

Committed r90800: <http://trac.webkit.org/changeset/90800>

[Ryosuke Niwa]

All reviewed patches have been landed.  Closing bug.