/* -*- 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 "nsISupports.h" #include "nsCoord.h" #include "nsPresContext.h" #include "mozilla/gfx/Point.h" #define NS_DEFAULT_VERTICAL_SCROLL_DISTANCE 3 #define NS_DEFAULT_HORIZONTAL_SCROLL_DISTANCE 5 class nsBoxLayoutState; class nsIScrollPositionListener; class nsIFrame; /** * 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 nsQueryFrame { public: typedef mozilla::gfx::Point Point; NS_DECL_QUERYFRAME_TARGET(nsIScrollableFrame) /** * Get the frame for the content that we are scrolling within * this scrollable frame. */ virtual nsIFrame* GetScrolledFrame() const = 0; typedef nsPresContext::ScrollbarStyles ScrollbarStyles; /** * 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 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; /** * 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; /** * 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 or normal * scrolling. SMOOTH will only be smooth if smooth scrolling is actually * enabled. INSTANT is always synchronous, NORMAL can be asynchronous. * If an INSTANT request happens while a smooth or async scroll is already in * progress, the async scroll is interrupted and we instantly scroll to the * destination. */ enum ScrollMode { INSTANT, SMOOTH, NORMAL }; /** * 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) = 0; /** * 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. * Ensures that GetScrollPositionCSSPixels (the scroll position after * rounding to CSS pixels) will be exactly aScrollPosition. * The scroll mode is INSTANT. */ virtual void ScrollToCSSPixels(nsIntPoint aScrollPosition) = 0; /** * 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). * The scroll mode is INSTANT. */ virtual void ScrollToCSSPixelsApproximate(const Point& aScrollPosition) = 0; /** * Returns the scroll position in integer CSS pixels, rounded to the nearest * pixel. */ virtual nsIntPoint GetScrollPositionCSSPixels() = 0; /** * When scrolling by a relative amount, we can choose various units. */ enum ScrollUnit { DEVICE_PIXELS, LINES, PAGES, WHOLE }; /** * 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) = 0; /** * 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; /** * Obtain the XUL box for the horizontal or vertical scrollbar, or null * if there is no such box. Avoid using this, but may be useful for * setting up a scrollbar mediator if you want to redirect scrollbar * input. */ virtual nsIFrame* GetScrollbarBox(bool aVertical) = 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() = 0; /** * Call this when the layer(s) induced by active scrolling are being * completely redrawn. */ virtual void ResetScrollPositionForLayerPixelAlignment() = 0; }; #endif