/* -*- 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; 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. A predicted landing * position determined by the APZC is used to select the best matching * snap point, allowing touchscreen fling gestures to navigate between * snap points. * @param aDestination The desired landing position of the fling, which * is used to select the best matching snap point. */ virtual void FlingSnap(const mozilla::CSSPoint& aDestination) = 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 image * 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 image 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; /** * 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 * FrameMetrics contributed by this frame, append it to aOutput. */ virtual mozilla::Maybe ComputeFrameMetrics( 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 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 image visibility updated. */ virtual void NotifyImageVisibilityUpdate() = 0; /** * Returns true if this scroll frame had a display port at the last image * visibility update and fills in aDisplayPort with that displayport. Returns * false otherwise, and doesn't touch aDisplayPort. */ virtual bool GetDisplayPortAtLastImageVisibilityUpdate(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; }; #endif