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authorMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
committerMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
commit5f8de423f190bbb79a62f804151bc24824fa32d8 (patch)
tree10027f336435511475e392454359edea8e25895d /layout/generic/nsIScrollableFrame.h
parent49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff)
downloaduxp-5f8de423f190bbb79a62f804151bc24824fa32d8.tar.gz
Add m-esr52 at 52.6.0
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * interface that provides scroll APIs implemented by scrollable frames
+ */
+
+#ifndef nsIScrollFrame_h___
+#define nsIScrollFrame_h___
+
+#include "nsCoord.h"
+#include "DisplayItemClip.h"
+#include "ScrollbarStyles.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/gfx/Point.h"
+#include "nsIScrollbarMediator.h"
+#include "Units.h"
+#include "FrameMetrics.h"
+
+#define NS_DEFAULT_VERTICAL_SCROLL_DISTANCE 3
+#define NS_DEFAULT_HORIZONTAL_SCROLL_DISTANCE 5
+
+class nsBoxLayoutState;
+class nsIScrollPositionListener;
+class nsIFrame;
+class nsPresContext;
+class nsIContent;
+class nsRenderingContext;
+class nsIAtom;
+class nsDisplayListBuilder;
+
+namespace mozilla {
+struct ContainerLayerParameters;
+namespace layers {
+class Layer;
+} // namespace layers
+} // namespace mozilla
+
+/**
+ * Interface for frames that are scrollable. This interface exposes
+ * APIs for examining scroll state, observing changes to scroll state,
+ * and triggering scrolling.
+ */
+class nsIScrollableFrame : public nsIScrollbarMediator {
+public:
+ typedef mozilla::CSSIntPoint CSSIntPoint;
+ typedef mozilla::ContainerLayerParameters ContainerLayerParameters;
+ typedef mozilla::layers::FrameMetrics FrameMetrics;
+ typedef mozilla::layers::ScrollSnapInfo ScrollSnapInfo;
+
+ NS_DECL_QUERYFRAME_TARGET(nsIScrollableFrame)
+
+ /**
+ * Get the frame for the content that we are scrolling within
+ * this scrollable frame.
+ */
+ virtual nsIFrame* GetScrolledFrame() const = 0;
+
+ /**
+ * Get the styles (NS_STYLE_OVERFLOW_SCROLL, NS_STYLE_OVERFLOW_HIDDEN,
+ * or NS_STYLE_OVERFLOW_AUTO) governing the horizontal and vertical
+ * scrollbars for this frame.
+ */
+ virtual mozilla::ScrollbarStyles GetScrollbarStyles() const = 0;
+
+ enum { HORIZONTAL = 0x01, VERTICAL = 0x02 };
+ /**
+ * Return the scrollbars which are visible. It's OK to call this during reflow
+ * of the scrolled contents, in which case it will reflect the current
+ * assumptions about scrollbar visibility.
+ */
+ virtual uint32_t GetScrollbarVisibility() const = 0;
+ /**
+ * Returns the directions in which scrolling is perceived to be allowed.
+ * A direction is perceived to be allowed if there is a visible scrollbar
+ * for that direction or if the scroll range is at least one device pixel.
+ */
+ uint32_t GetPerceivedScrollingDirections() const;
+ /**
+ * Return the actual sizes of all possible scrollbars. Returns 0 for scrollbar
+ * positions that don't have a scrollbar or where the scrollbar is not visible.
+ * Do not call this while this frame's descendants are being reflowed, it won't be
+ * accurate.
+ */
+ virtual nsMargin GetActualScrollbarSizes() const = 0;
+ /**
+ * Return the sizes of all scrollbars assuming that any scrollbars that could
+ * be visible due to overflowing content, are. This can be called during reflow
+ * of the scrolled contents.
+ */
+ virtual nsMargin GetDesiredScrollbarSizes(nsBoxLayoutState* aState) = 0;
+ /**
+ * Return the sizes of all scrollbars assuming that any scrollbars that could
+ * be visible due to overflowing content, are. This can be called during reflow
+ * of the scrolled contents.
+ */
+ virtual nsMargin GetDesiredScrollbarSizes(nsPresContext* aPresContext,
+ nsRenderingContext* aRC) = 0;
+ /**
+ * Return the width for non-disappearing scrollbars.
+ */
+ virtual nscoord
+ GetNondisappearingScrollbarWidth(nsPresContext* aPresContext,
+ nsRenderingContext* aRC,
+ mozilla::WritingMode aWM) = 0;
+ /**
+ * GetScrolledRect is designed to encapsulate deciding which
+ * directions of overflow should be reachable by scrolling and which
+ * should not. Callers should NOT depend on it having any particular
+ * behavior (although nsXULScrollFrame currently does).
+ *
+ * This should only be called when the scrolled frame has been
+ * reflowed with the scroll port size given in mScrollPort.
+ *
+ * Currently it allows scrolling down and to the right for
+ * nsHTMLScrollFrames with LTR directionality and for all
+ * nsXULScrollFrames, and allows scrolling down and to the left for
+ * nsHTMLScrollFrames with RTL directionality.
+ */
+ virtual nsRect GetScrolledRect() const = 0;
+ /**
+ * Get the area of the scrollport relative to the origin of this frame's
+ * border-box.
+ * This is the area of this frame minus border and scrollbars.
+ */
+ virtual nsRect GetScrollPortRect() const = 0;
+ /**
+ * Get the offset of the scrollport origin relative to the scrolled
+ * frame origin. Typically the position will be non-negative.
+ * This will always be a multiple of device pixels.
+ */
+ virtual nsPoint GetScrollPosition() const = 0;
+ /**
+ * As GetScrollPosition(), but uses the top-right as origin for RTL frames.
+ */
+ virtual nsPoint GetLogicalScrollPosition() const = 0;
+ /**
+ * Get the area that must contain the scroll position. Typically
+ * (but not always, e.g. for RTL content) x and y will be 0, and
+ * width or height will be nonzero if the content can be scrolled in
+ * that direction. Since scroll positions must be a multiple of
+ * device pixels, the range extrema will also be a multiple of
+ * device pixels.
+ */
+ virtual nsRect GetScrollRange() const = 0;
+ /**
+ * Get the size of the scroll port to use when clamping the scroll
+ * position.
+ */
+ virtual nsSize GetScrollPositionClampingScrollPortSize() const = 0;
+ /**
+ * Return how much we would try to scroll by in each direction if
+ * asked to scroll by one "line" vertically and horizontally.
+ */
+ virtual nsSize GetLineScrollAmount() const = 0;
+ /**
+ * Return how much we would try to scroll by in each direction if
+ * asked to scroll by one "page" vertically and horizontally.
+ */
+ virtual nsSize GetPageScrollAmount() const = 0;
+
+ /**
+ * When a scroll operation is requested, we ask for instant, smooth,
+ * smooth msd, or normal scrolling.
+ *
+ * SMOOTH scrolls have a symmetrical acceleration and deceleration curve
+ * modeled with a set of splines that guarantee that the destination will be
+ * reached over a fixed time interval. SMOOTH will only be smooth if smooth
+ * scrolling is actually enabled. This behavior is utilized by keyboard and
+ * mouse wheel scrolling events.
+ *
+ * SMOOTH_MSD implements a physically based model that approximates the
+ * behavior of a mass-spring-damper system. SMOOTH_MSD scrolls have a
+ * non-symmetrical acceleration and deceleration curve, can potentially
+ * overshoot the destination on intermediate frames, and complete over a
+ * variable time interval. SMOOTH_MSD will only be smooth if cssom-view
+ * smooth-scrolling is enabled.
+ *
+ * INSTANT is always synchronous, NORMAL can be asynchronous.
+ *
+ * If an INSTANT scroll request happens while a SMOOTH or async scroll is
+ * already in progress, the async scroll is interrupted and we instantly
+ * scroll to the destination.
+ *
+ * If an INSTANT or SMOOTH scroll request happens while a SMOOTH_MSD scroll
+ * is already in progress, the SMOOTH_MSD scroll is interrupted without
+ * first scrolling to the destination.
+ */
+ enum ScrollMode { INSTANT, SMOOTH, SMOOTH_MSD, NORMAL };
+ /**
+ * Some platforms (OSX) may generate additional scrolling events even
+ * after the user has stopped scrolling, simulating a momentum scrolling
+ * effect resulting from fling gestures.
+ * SYNTHESIZED_MOMENTUM_EVENT indicates that the scrolling is being requested
+ * by such a synthesized event and may be ignored if another scroll has
+ * been started since the last actual user input.
+ */
+ enum ScrollMomentum { NOT_MOMENTUM, SYNTHESIZED_MOMENTUM_EVENT };
+ /**
+ * @note This method might destroy the frame, pres shell and other objects.
+ * Clamps aScrollPosition to GetScrollRange and sets the scroll position
+ * to that value.
+ * @param aRange If non-null, specifies area which contains aScrollPosition
+ * and can be used for choosing a performance-optimized scroll position.
+ * Any point within this area can be chosen.
+ * The choosen point will be as close as possible to aScrollPosition.
+ */
+ virtual void ScrollTo(nsPoint aScrollPosition, ScrollMode aMode,
+ const nsRect* aRange = nullptr,
+ nsIScrollbarMediator::ScrollSnapMode aSnap
+ = nsIScrollbarMediator::DISABLE_SNAP) = 0;
+ /**
+ * @note This method might destroy the frame, pres shell and other objects.
+ * Scrolls to a particular position in integer CSS pixels.
+ * Keeps the exact current horizontal or vertical position if the current
+ * position, rounded to CSS pixels, matches aScrollPosition. If
+ * aScrollPosition.x/y is different from the current CSS pixel position,
+ * makes sure we only move in the direction given by the difference.
+ *
+ * When aMode is SMOOTH, INSTANT, or NORMAL, GetScrollPositionCSSPixels (the
+ * scroll position after rounding to CSS pixels) will be exactly
+ * aScrollPosition at the end of the scroll animation.
+ *
+ * When aMode is SMOOTH_MSD, intermediate animation frames may be outside the
+ * range and / or moving in any direction; GetScrollPositionCSSPixels will be
+ * exactly aScrollPosition at the end of the scroll animation unless the
+ * SMOOTH_MSD animation is interrupted.
+ */
+ virtual void ScrollToCSSPixels(const CSSIntPoint& aScrollPosition,
+ nsIScrollableFrame::ScrollMode aMode
+ = nsIScrollableFrame::INSTANT) = 0;
+ /**
+ * @note This method might destroy the frame, pres shell and other objects.
+ * Scrolls to a particular position in float CSS pixels.
+ * This does not guarantee that GetScrollPositionCSSPixels equals
+ * aScrollPosition afterward. It tries to scroll as close to
+ * aScrollPosition as possible while scrolling by an integer
+ * number of layer pixels (so the operation is fast and looks clean).
+ */
+ virtual void ScrollToCSSPixelsApproximate(const mozilla::CSSPoint& aScrollPosition,
+ nsIAtom *aOrigin = nullptr) = 0;
+
+ /**
+ * Returns the scroll position in integer CSS pixels, rounded to the nearest
+ * pixel.
+ */
+ virtual CSSIntPoint GetScrollPositionCSSPixels() = 0;
+ /**
+ * When scrolling by a relative amount, we can choose various units.
+ */
+ enum ScrollUnit { DEVICE_PIXELS, LINES, PAGES, WHOLE };
+ /**
+ * @note This method might destroy the frame, pres shell and other objects.
+ * Modifies the current scroll position by aDelta units given by aUnit,
+ * clamping it to GetScrollRange. If WHOLE is specified as the unit,
+ * content is scrolled all the way in the direction(s) given by aDelta.
+ * @param aOverflow if non-null, returns the amount that scrolling
+ * was clamped by in each direction (how far we moved the scroll position
+ * to bring it back into the legal range). This is never negative. The
+ * values are in device pixels.
+ */
+ virtual void ScrollBy(nsIntPoint aDelta, ScrollUnit aUnit, ScrollMode aMode,
+ nsIntPoint* aOverflow = nullptr,
+ nsIAtom* aOrigin = nullptr,
+ ScrollMomentum aMomentum = NOT_MOMENTUM,
+ nsIScrollbarMediator::ScrollSnapMode aSnap
+ = nsIScrollbarMediator::DISABLE_SNAP) = 0;
+
+ /**
+ * Perform scroll snapping, possibly resulting in a smooth scroll to
+ * maintain the scroll snap position constraints. Velocity sampled from
+ * main thread scrolling is used to determine best matching snap point
+ * when called after a fling gesture on a trackpad or mouse wheel.
+ */
+ virtual void ScrollSnap() = 0;
+
+ /**
+ * @note This method might destroy the frame, pres shell and other objects.
+ * This tells the scroll frame to try scrolling to the scroll
+ * position that was restored from the history. This must be called
+ * at least once after state has been restored. It is called by the
+ * scrolled frame itself during reflow, but sometimes state can be
+ * restored after reflows are done...
+ * XXX should we take an aMode parameter here? Currently it's instant.
+ */
+ virtual void ScrollToRestoredPosition() = 0;
+
+ /**
+ * Add a scroll position listener. This listener must be removed
+ * before it is destroyed.
+ */
+ virtual void AddScrollPositionListener(nsIScrollPositionListener* aListener) = 0;
+ /**
+ * Remove a scroll position listener.
+ */
+ virtual void RemoveScrollPositionListener(nsIScrollPositionListener* aListener) = 0;
+
+ /**
+ * Internal method used by scrollbars to notify their scrolling
+ * container of changes.
+ */
+ virtual void CurPosAttributeChanged(nsIContent* aChild) = 0;
+
+ /**
+ * Allows the docshell to request that the scroll frame post an event
+ * after being restored from history.
+ */
+ NS_IMETHOD PostScrolledAreaEventForCurrentArea() = 0;
+
+ /**
+ * Returns true if this scrollframe is being "actively scrolled".
+ * This basically means that we should allocate resources in the
+ * expectation that scrolling is going to happen.
+ */
+ virtual bool IsScrollingActive(nsDisplayListBuilder* aBuilder) = 0;
+ /**
+ * Returns true if the scrollframe is currently processing an async
+ * or smooth scroll.
+ */
+ virtual bool IsProcessingAsyncScroll() = 0;
+ /**
+ * Call this when the layer(s) induced by active scrolling are being
+ * completely redrawn.
+ */
+ virtual void ResetScrollPositionForLayerPixelAlignment() = 0;
+ /**
+ * Was the current presentation state for this frame restored from history?
+ */
+ virtual bool DidHistoryRestore() const = 0;
+ /**
+ * Clear the flag so that DidHistoryRestore() returns false until the next
+ * RestoreState call.
+ * @see nsIStatefulFrame::RestoreState
+ */
+ virtual void ClearDidHistoryRestore() = 0;
+ /**
+ * Determine if the passed in rect is nearly visible according to the frame
+ * visibility heuristics for how close it is to the visible scrollport.
+ */
+ virtual bool IsRectNearlyVisible(const nsRect& aRect) = 0;
+ /**
+ * Expand the given rect taking into account which directions we can scroll
+ * and how far we want to expand for frame visibility purposes.
+ */
+ virtual nsRect ExpandRectToNearlyVisible(const nsRect& aRect) const = 0;
+ /**
+ * Returns the origin that triggered the last instant scroll. Will equal
+ * nsGkAtoms::apz when the compositor's replica frame metrics includes the
+ * latest instant scroll.
+ */
+ virtual nsIAtom* LastScrollOrigin() = 0;
+ /**
+ * Sets a flag on the scrollframe that indicates the current scroll origin
+ * has been sent over in a layers transaction, and subsequent changes to
+ * the scroll position by "weaker" origins are permitted to overwrite the
+ * the scroll origin. Scroll origins that nsLayoutUtils::CanScrollOriginClobberApz
+ * returns false for are considered "weaker" than scroll origins for which
+ * that function returns true.
+ */
+ virtual void AllowScrollOriginDowngrade() = 0;
+ /**
+ * Returns the origin that triggered the last smooth scroll.
+ * Will equal nsGkAtoms::apz when the compositor's replica frame
+ * metrics includes the latest smooth scroll. The compositor will always
+ * perform an instant scroll prior to instantiating any smooth scrolls
+ * if LastScrollOrigin and LastSmoothScrollOrigin indicate that
+ * an instant scroll and a smooth scroll have occurred since the last
+ * replication of the frame metrics.
+ *
+ * This is set to nullptr to when the compositor thread acknowledges that
+ * the smooth scroll has been started. If the smooth scroll has been stomped
+ * by an instant scroll before the smooth scroll could be started by the
+ * compositor, this is set to nullptr to clear the smooth scroll.
+ */
+ virtual nsIAtom* LastSmoothScrollOrigin() = 0;
+ /**
+ * Returns the current generation counter for the scroll. This counter
+ * increments every time the scroll position is set.
+ */
+ virtual uint32_t CurrentScrollGeneration() = 0;
+ /**
+ * LastScrollDestination returns the destination of the most recently
+ * requested smooth scroll animation.
+ */
+ virtual nsPoint LastScrollDestination() = 0;
+ /**
+ * Clears the "origin of last scroll" property stored in this frame, if
+ * the generation counter passed in matches the current scroll generation
+ * counter.
+ */
+ virtual void ResetScrollInfoIfGeneration(uint32_t aGeneration) = 0;
+ /**
+ * Determine whether it is desirable to be able to asynchronously scroll this
+ * scroll frame.
+ */
+ virtual bool WantAsyncScroll() const = 0;
+ /**
+ * aLayer's animated geometry root is this frame. If there needs to be a
+ * ScrollMetadata contributed by this frame, append it to aOutput.
+ */
+ virtual mozilla::Maybe<mozilla::layers::ScrollMetadata> ComputeScrollMetadata(
+ mozilla::layers::Layer* aLayer,
+ nsIFrame* aContainerReferenceFrame,
+ const ContainerLayerParameters& aParameters,
+ const mozilla::DisplayItemClip* aClip) const = 0;
+
+ /**
+ * If this scroll frame is ignoring viewporting clipping
+ */
+ virtual bool IsIgnoringViewportClipping() const = 0;
+
+ /**
+ * Mark the scrollbar frames for reflow.
+ */
+ virtual void MarkScrollbarsDirtyForReflow() const = 0;
+
+ virtual void SetTransformingByAPZ(bool aTransforming) = 0;
+ virtual bool IsTransformingByAPZ() const = 0;
+
+ /**
+ * Notify this scroll frame that it can be scrolled by APZ. In particular,
+ * this is called *after* the APZ code has created an APZC for this scroll
+ * frame and verified that it is not a scrollinfo layer. Therefore, setting an
+ * async transform on it is actually user visible.
+ */
+ virtual void SetScrollableByAPZ(bool aScrollable) = 0;
+
+ /**
+ * Notify this scroll frame that it can be zoomed by APZ.
+ */
+ virtual void SetZoomableByAPZ(bool aZoomable) = 0;
+
+ /**
+ * Whether or not this frame uses containerful scrolling.
+ */
+ virtual bool UsesContainerScrolling() const = 0;
+
+ /**
+ * Determine if we should build a scrollable layer for this scroll frame and
+ * return the result. It will also record this result on the scroll frame.
+ * Pass the dirty rect in aDirtyRect. On return it will be set to the
+ * displayport if there is one (ie the dirty rect that should be used).
+ * This function may create a display port where one did not exist before if
+ * aAllowCreateDisplayPort is true. It is only allowed to be false if there
+ * has been a call with it set to true before on the same paint.
+ */
+ virtual bool DecideScrollableLayer(nsDisplayListBuilder* aBuilder,
+ nsRect* aDirtyRect,
+ bool aAllowCreateDisplayPort) = 0;
+
+ /**
+ * Notification that this scroll frame is getting its frame visibility updated.
+ */
+ virtual void NotifyApproximateFrameVisibilityUpdate() = 0;
+
+ /**
+ * Returns true if this scroll frame had a display port at the last frame
+ * visibility update and fills in aDisplayPort with that displayport. Returns
+ * false otherwise, and doesn't touch aDisplayPort.
+ */
+ virtual bool GetDisplayPortAtLastApproximateFrameVisibilityUpdate(nsRect* aDisplayPort) = 0;
+
+ /**
+ * This is called when a descendant scrollframe's has its displayport expired.
+ * This function will check to see if this scrollframe may safely expire its
+ * own displayport and schedule a timer to do that if it is safe.
+ */
+ virtual void TriggerDisplayPortExpiration() = 0;
+
+ /**
+ * Returns information required to determine where to snap to after a scroll.
+ */
+ virtual ScrollSnapInfo GetScrollSnapInfo() const = 0;
+
+ virtual void SetScrollsClipOnUnscrolledOutOfFlow() = 0;
+};
+
+#endif