This makes APZ behave nicely with most uses of a css transform:scale.
Summary of changes:
- FrameMetrics::mCumulativeResolution now includes the css-driven resolution
in addition to the pres-shell resolution.
- Displayports are now stored in Screen pixels rather than Layer pixels.
This is what we want anyways (as we'd like the displayport size to remain
constant as a fraction of the screen size), but it was necessary to make
this change as part of this patch because continuing to store them in
Layer pixels in the presence of a css-driven resolution would have
required a bunch of infrastructure to implement correctly.
Remaining work:
- Layout painting a scrollable layer at a resolution different from the
scale induced by the css transform causes problems. These will go away
with bug 1076192.
- Different resolutions on the x and y axes are not supported. This is
tracked by bug 1039967.
This makes APZ behave nicely with most uses of a css transform:scale.
Summary of changes:
- FrameMetrics::mCumulativeResolution now includes the css-driven resolution
in addition to the pres-shell resolution.
- Displayports are now stored in Screen pixels rather than Layer pixels.
This is what we want anyways (as we'd like the displayport size to remain
constant as a fraction of the screen size), but it was necessary to make
this change as part of this patch because continuing to store them in
Layer pixels in the presence of a css-driven resolution would have
required a bunch of infrastructure to implement correctly.
Remaining work:
- Layout painting a scrollable layer at a resolution different from the
scale induced by the css transform causes problems. These will go away
with bug 1076192.
- Different resolutions on the x and y axes are not supported. This is
tracked by bug 1039967.
- Added SCROLL_SMOOTH_AUTO flag to nsIPresShell to enable selection of
scroll behavior through CSS.
- Updated Element and Window scrolling DOM methods to enable smooth scrolling
set through the scroll-behavior CSS property.
- Keyboard, scroll bar, mousewheel, and any other events that scroll smoothly
with the general.smoothScroll preference enabled will now scroll instantly
if the scroll frame has "scroll-behavior: instant" applied through CSS.
When we have a display port the dirty rect for root scroll frames is going to be the display port already when it is passed in. The display port can contain a somewhat arbitrary area of the scroll frame, there is no reason is has to include the scrollbars, which are laid out at the desktop scrollport (and adjusted as necessary in the compositor).
As well as BuildDisplayListForChild, we need the dirty rect to be set for the creation of the nsDisplayWrapList or nsDisplayOwnLayer in AppendToTop.
This code is no longer needed because tiling is enabled on all
scrollable layers on B2G, and so we only draw tile-sized chunks
of the displayport. Therefore the textures created will never
exceed the max texture size. On non-B2G platforms this code is
not used anyway so there is no effect. Going forward we should
always be enabling tiling before enabling APZ on new platforms
so it is unlikely that we will need this code.
- Extended nsIScrollableFrame and nsGfxScrollFrame to return destination
of smooth scrolls which are to be animated on the compositor thread.
- Added apz.smooth_scroll_repaint_interval preference.
- Implemented AsyncPanZoomController::PanZoomState::SMOOTH_MSD_SCROLL state
and AsyncPanZoomController::SmoothScrollAnimation class to animate smooth
scroll animations on the compositor thread.
- Extended FrameMetrics to report requests for smooth scrolls to be animated
on the compositor thread and their corresponding destination positions.
- AsyncPanZoomController now checks FrameMetrics for requests to perform
smooth scrolling on the compositor thread. It will ensure that they
are cancelled as needed by mousewheel, touchpanel, keyboard, and
CSSOM-View instant scrolling DOM methods.
- The layout/generic/test/test_scroll_behavior.html mochitest has been
commented as depending on Bug 1062609 before being enabled for APZ.
- Verify that instant scroll-behavior is synchronous.
- Verify that smooth scroll-behavior is asynchronous.
- Verify that smooth scroll-behavior is triggered by CSSOM-View DOM methods.
- Verify that instant scroll-behavior interrupts smooth scroll-behavior
animation.
- Verify that smooth scroll-behavior is not framerate dependant.
- Verify that smooth scroll-behavior physics simulations used by animations
converge and allow the animation to reach completion.
- CSSOM-View scroll-behavior smooth scroll animations must produce the same
results indendently of frame-rate:
- Reference samples of scroll position for each frame are captured from a
smooth scroll at 120fps for variations in X-Distance, Y-Distance.
- Test samples are captured from an animation with the same parameters at
varying framerates.
- Variance in position at each sampled interval is compared to the 120fps
reference. To pass the test, the position of each test sample must match
the reference position with a tolerance of one test sample frame's range
of motion. This range of motion is calculated by the position delta of
the reference samples one test frame duration before and after.
- The duration of the reference sample animation and the test sample
animation must match within 1 frame to pass the test.
- The simulation driving the animation must converge and stop on the
destination position for the test to pass.
- When a smooth scroll is being processed on a frame, mouse wheel and trackpad
momentum scroll event updates will no longer cancel the SMOOTH or SMOOTH_MSD
scroll animations, enabling scripts that depend on them to be responsive
without forcing the user to wait for the fling animations to completely stop.
- Added nsIScrollableFrame::ScrollMode::SMOOTH_MSD to differentiate
existing smooth scrolls used by keyboard and mousewheel events from the
CSSOM-View scroll-behavior's MSD motion scrolling.
- Implemented ScrollFrameHelper::AsyncSmoothMSDScroll, which takes the role
of ScrollFrameHelper::AsyncScroll when SMOOTH_MSD scrolls are requested.
- Implemented glue code to handle callbacks from AsyncSmoothMSDScroll and
to hand off velocity between the classes when one scroll animation is
interrupted by another.
