зеркало из https://github.com/mozilla/gecko-dev.git
108 строки
4.4 KiB
C++
108 строки
4.4 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_ScrollPositionUpdate_h_
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#define mozilla_ScrollPositionUpdate_h_
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#include <cstdint>
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#include <iosfwd>
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#include "nsPoint.h"
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#include "mozilla/ScrollOrigin.h"
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#include "mozilla/ScrollTypes.h"
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#include "Units.h"
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namespace mozilla {
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enum class ScrollUpdateType {
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// A scroll update to a specific destination, regardless of the current
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// scroll position.
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Absolute,
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// A scroll update by a specific amount, based off a given starting scroll
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// position. XXX Fold this into PureRelative, it should be relatively
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// straightforward after bug 1655733.
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Relative,
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// A scroll update by a specific amount, where only the delta is provided.
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// The delta should be applied to whatever the current scroll position is
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// on the receiver side.
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PureRelative,
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};
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/**
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* This class represents an update to the scroll position that is initiated by
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* something on the main thread. A list of these classes is accumulated by
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* scrollframes on the main thread, and the list is sent over as part of a
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* paint transaction to the compositor. The compositor can then iterate through
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* the scroll updates and apply/merge them with scrolling that has already
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* occurred independently on the compositor side.
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*/
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class ScrollPositionUpdate {
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public:
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// Constructor for IPC use only.
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explicit ScrollPositionUpdate();
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// Create a ScrollPositionUpdate for a newly created (or reconstructed)
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// scrollframe.
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static ScrollPositionUpdate NewScrollframe(uint32_t aGeneration,
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nsPoint aInitialPosition);
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// Create a ScrollPositionUpdate for a new absolute/instant scroll, to
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// the given destination.
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static ScrollPositionUpdate NewScroll(uint32_t aGeneration,
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ScrollOrigin aOrigin,
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nsPoint aDestination);
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// Create a ScrollPositionUpdate for a new relative/instant scroll, with
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// the given source/destination.
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static ScrollPositionUpdate NewRelativeScroll(uint32_t aGeneration,
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nsPoint aSource,
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nsPoint aDestination);
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// Create a ScrollPositionUpdate for a new absolute/smooth scroll, which
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// animates smoothly to the given destination from whatever the current
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// scroll position is in the receiver.
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static ScrollPositionUpdate NewSmoothScroll(uint32_t aGeneration,
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ScrollOrigin aOrigin,
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nsPoint aDestination);
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// Create a ScrollPositionUpdate for a new pure-relative scroll. The
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// aMode parameter controls whether or not this is a smooth animation or
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// instantaneous scroll.
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static ScrollPositionUpdate NewPureRelativeScroll(uint32_t aGeneration,
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ScrollOrigin aOrigin,
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ScrollMode aMode,
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const nsPoint& aDelta);
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bool operator==(const ScrollPositionUpdate& aOther) const;
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uint32_t GetGeneration() const;
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ScrollUpdateType GetType() const;
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ScrollMode GetMode() const;
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ScrollOrigin GetOrigin() const;
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// GetDestination is only valid for Absolute and Relative types; it asserts
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// otherwise.
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CSSPoint GetDestination() const;
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// GetSource is only valid for the Relative type; it asserts otherwise.
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CSSPoint GetSource() const;
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// GetDelta is only valid for the PureRelative type; it asserts otherwise.
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CSSPoint GetDelta() const;
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friend std::ostream& operator<<(std::ostream& aStream,
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const ScrollPositionUpdate& aUpdate);
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private:
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uint32_t mScrollGeneration;
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// Refer to the ScrollUpdateType documentation for what the types mean.
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// All fields are populated for all types, except as noted below.
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ScrollUpdateType mType;
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ScrollMode mScrollMode;
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ScrollOrigin mScrollOrigin;
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// mDestination is not populated when mType == PureRelative.
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CSSPoint mDestination;
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// mSource is not populated when mType == Absolute || mType == PureRelative.
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CSSPoint mSource;
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// mDelta is not populated when mType == Absolute || mType == Relative.
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CSSPoint mDelta;
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};
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} // namespace mozilla
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#endif // mozilla_ScrollPositionUpdate_h_
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