Previously we snapped the results of nsDisplayItem::GetBounds and
nsDisplayItem::GetOpaqueRegion internally. By tracking which display items were
inside transforms, we disabled snapping quite conservatively whenever an ancestor
had a transform, which is undesirable.
With this patch, we don't snap inside GetBounds or GetOpaqueRegion, but just return
a boolean flag indicating whether the item will draw with snapping or not. This flag
is conservative so that "true" means we will snap (if the graphics context has a transform
that allows snapping), but "false" means we might or might not snap (so it's always safe
to return false).
FrameLayerBuilder takes over responsibility for snapping item bounds. When it converts
display item bounds to layer pixel coordinates, it checks the snap flag returned from
the display item and checks whether the transform when we draw into the layer will be
a known scale (the ContainerParameters scale factors) plus integer translation. If both
are true, we snap the item bounds when converting to layer pixel coordinates. With
this approach, we can snap item bounds even when the items have ancestors with active
transforms.
* we know all types frames may be cast to at compile time, so instead of extensible GUID IIDs, use a big enum (see nsQueryFrame::FrameIID)
* eliminate all vestiges of refcounting, since frames aren't refcounted
Some frames (SVG frames in particular) still implement nsISupports-derived interfaces, for example nsISVGValue. There is a FrameIID for nsISVGValue that lets you go from a frame to the XPCOM interface, but you can't query back.
r+sr=roc
nsITextControlFrame didn't have an IID the first time around, but this wasn't a compile error because nsITextControlFrame::kFrameIID inherited from nsIFormControlFrame::kFrameIID. I've added a static analysis pass to verify the correct behavior, since I can't figure out a way to make the compiler do it.
--HG--
extra : rebase_source : 4894a2ca0278e2ab92f27459db77165f8348cf41
* we know all types frames may be cast to at compile time, so instead of extensible GUID IIDs, use a big enum (see nsQueryFrame::FrameIID)
* eliminate all vestiges of refcounting, since frames aren't refcounted
Some frames (SVG frames in particular) still implement nsISupports-derived interfaces, for example nsISVGValue. There is a FrameIID for nsISVGValue that lets you go from a frame to the XPCOM interface, but you can't query back.
r+sr=roc
This patch locally causes two REFTEST-UNEXPECTED-PASS for Bidi stuff. It's possible that I accidentally fixed a bug, but I'm not sure, so I'm going to wait for the tinderboxes to confirm my local results.
Robert O'Callahan
Wes Johnston
Matt Woodrow
Michael Wu
Craig Topper
L. David Baron
Robert O'Callahan
Timothy Nikkel
Zack Weinberg
Benjamin Smedberg
roc+@cs.cmu.edu
jwalden@mit.edu
dbaron%dbaron.org
roc+%cs.cmu.edu
gerv%gerv.net
dougt%netscape.com
dbaron%fas.harvard.edu
rods%netscape.com
dmose%mozilla.org
troy%netscape.com
kipp%netscape.com