Bug 126653

Summary:

Subpixel layout: RenderMultiColumnBlock::computeColumnCountAndWidth() needs flooring.

Product:

WebKit

Reporter:

zalan <zalan>

Component:

Layout and Rendering

Assignee:

zalan <zalan>

Status:

RESOLVED INVALID

Severity:

Normal

CC:

jonlee, simon.fraser, webkit-bug-importer

Priority:

Keywords:

InRadar

Version:

528+ (Nightly build)

Hardware:

Unspecified

OS:

Unspecified

Bug Depends on:

Bug Blocks:

126283

Attachments:

Description	Flags
rendering snapshots	none

Description zalan 2014-01-08 11:59:43 PST

This is rather similar to bug 126646. We produce an off by one pixel rendering when subpixel is on, though flooring it to CSS pixel would defeat the purpose of subpixel positioning the column content.

m_columnWidth = std::max<LayoutUnit>(0, (availWidth - ((m_columnCount - 1) * colGap)) / m_columnCount);

failed cases:
fast/multicol/newmulticol/column-rules-fixed-height.html
fast/multicol/newmulticol/columns-shorthand-parsing.html
fast/multicol/newmulticol/layers-in-multicol.html

Comment 1 Simon Fraser (smfr) 2014-01-08 15:26:08 PST

Talk to Hyatt.

Comment 2 zalan 2014-01-15 13:07:43 PST

Created attachment 221301 [details]
rendering snapshots

Comment 3 Radar WebKit Bug Importer 2014-01-15 13:08:31 PST

<rdar://problem/15827900>

Comment 4 zalan 2014-01-15 13:09:25 PST

FF(v26) rendering is in-between subpixel off and subpixel on. Prefer current subpixel rendering.