Changes between Version 12 and Version 13 of LayoutUnit


Ignore:
Timestamp:
May 22, 2012 2:50:28 PM (10 years ago)
Author:
eae@chromium.org
Comment:

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  • LayoutUnit

    v12 v13  
    11= Background =
    22
    3 To better support zooming, both on desktop and mobile devices, we are currently working on adding subpixel layout support WebKit. To do this we are changing the rendering tree to use subpixel units, called LayoutUnit, instead of integers to represent locations and sizes.
     3To better support zooming, both on desktop and mobile devices, we are currently working on adding subpixel layout support WebKit. To do this we are changing the rendering tree to use subpixel units, called LayoutUnit, instead of integers to represent locations and sizes. The feature is currently controlled by a flag, ENABLE_SUBPIXEL_LAYOUT. As of May 21, 2012 this flag is only turned on for chromium.
    44
    55This working is currently being undertaken by [mailto:leviw@chromium.org Levi Weintraub] and [mailto:eae@chromium.org Emil A Eklund], please talk to us directly or ask on webkit-dev or #webkit if you have any questions and/or concerns.
     
    9797= Notes =
    9898
    99 1: LayoutUnit is currently a typedef that maps to int. Once the subpixel branch has been merged this will map to AppUnit which is the underlying fixed point implementation. The eventual plan is to rename AppUnit to LayoutUnit and remove the typedef.
     991: LayoutUnit is currently a typedef that maps to FractionalLayoutUnit. Once most platforms have turned on subpixel positioning the plan is to rename FractionalLayoutUnit to LayoutUnit and remove the typedef. The same goes for the Point, Size and Rect classes.
    100100
    101 2: Based on Mozilla’s implementation. See the proposal [https://wiki.mozilla.org/Mozilla2:Units here] which was landed in [https://bugzilla.mozilla.org/show_bug.cgi?id=177805 this bug].
     1012: Based on Mozilla’s implementation. See the proposal [https://wiki.mozilla.org/Mozilla2:Units here] which was landed in [https://bugzilla.mozilla.org/show_bug.cgi?id=177805 this bug]. We might have to change this to 1/64 on embedded devices for performance reasons but for now it is 1/60.