On Thu, Sep 12, 2013 at 10:42 AM, Ian Hickson <i...@hixie.ch> wrote: > On Thu, 12 Sep 2013, Robert O'Callahan wrote: > > On Wed, Sep 11, 2013 at 11:24 AM, Ian Hickson <i...@hixie.ch> wrote: > > > On Wed, 11 Sep 2013, Robert O'Callahan wrote: > > > > Pinch-zoom is hard because we don't want to trigger reflows or other > > > > expensive behavior on pinch-zoom. I'd leave pinch-zoom out of it for > > > > now. > > > > > > Unless I'm missing something fundamental, changing the pixel density > > > doesn't cause a layout, it's changing the width that causes a layout. > > > > Changing pixel density does cause a layout in Gecko. For example we > > round CSS border widths to a whole number of device pixels. (This > > ensures that when page zoom is applied, all borders with the same > > specified width are rendered with the same visual width.) On some > > platforms (Windows), changing pixel density affects text hinting which > > affects text layout. > > So how do you do pinch-zoom under the hood on mobile devices? >
We don't change layout, we just rerender with transformed coordinates. This means that pinch-zoom can break apparent border-widths and you can get ugly hinting on platforms that use pinch-zoom and have fonts with aggressive hinting. We could continue to not change layout, and still change the pixel density of canvases during or after pinch-zoom. We could even change the pixel density of canvases inside scaling CSS transforms. Rob -- Jtehsauts tshaei dS,o n" Wohfy Mdaon yhoaus eanuttehrotraiitny eovni le atrhtohu gthot sf oirng iyvoeu rs ihnesa.r"t sS?o Whhei csha iids teoa stiheer :p atroa lsyazye,d 'mYaonu,r "sGients uapr,e tfaokreg iyvoeunr, 'm aotr atnod sgaoy ,h o'mGee.t" uTph eann dt hwea lmka'n? gBoutt uIp waanndt wyeonut thoo mken.o w * *
