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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */
#ifndef nsILineIterator_h___
#define nsILineIterator_h___
#include "nscore.h"
#include "nsINode.h"
#include "nsRect.h"
#include "mozilla/Attributes.h"
#include "mozilla/Result.h"
#include "mozilla/WritingModes.h"
class nsIFrame;
/**
* Line iterator API.
*
* Lines are numbered from 0 to N, where 0 is the top line and N is
* the bottom line.
*
* Obtain this interface from frames via nsIFrame::GetLineIterator.
* This iterator belongs to the frame from which it was obtained, and should
* not be deleted by the caller.
* Note that any modification of the frame will invalidate the iterator!
* Users must get a new iterator any time the target may have been touched.
*/
class nsILineIterator {
protected:
~nsILineIterator() = default;
public:
/**
* The number of lines in the block
*/
virtual int32_t GetNumLines() const = 0;
/**
* Returns whether our lines are rtl.
*/
virtual bool IsLineIteratorFlowRTL() = 0;
struct LineInfo {
/** The first frame on the line. */
nsIFrame* mFirstFrameOnLine = nullptr;
/** The numbers of frames on the line. */
int32_t mNumFramesOnLine = 0;
/**
* The bounding box of the line (which is based on the in-flow position of
* the frames on the line; if a frame was moved because of relative
* positioning then its coordinates may be outside the line bounds)
*/
nsRect mLineBounds;
/** Whether the line is wrapped at the end */
bool mIsWrapped = false;
/**
* Return last frame of the line if there is no enough siblings of
* mFirstFrameOnLine.
* Otherwise, nullptr including in the unexpected error cases.
*/
nsIFrame* GetLastFrameOnLine() const;
};
// Return miscellaneous information about a line.
virtual mozilla::Result<LineInfo, nsresult> GetLine(int32_t aLineNumber) = 0;
/**
* Given a frame that's a child of the block, find which line its on
* and return that line index, as long as it's at least as big as
* aStartLine. Returns -1 if the frame cannot be found on lines
* starting with aStartLine.
*/
virtual int32_t FindLineContaining(nsIFrame* aFrame,
int32_t aStartLine = 0) = 0;
// Given a line number and a coordinate, find the frame on the line
// that is nearest to aPos along the inline axis. (The block-axis coord
// of aPos is irrelevant.)
// The aPosIsBeforeFirstFrame and aPosIsAfterLastFrame flags are updated
// appropriately.
NS_IMETHOD FindFrameAt(int32_t aLineNumber, nsPoint aPos,
nsIFrame** aFrameFound, bool* aPosIsBeforeFirstFrame,
bool* aPosIsAfterLastFrame) = 0;
// Check whether visual and logical order of frames within a line are
// identical.
// If not, return the first and last visual frames
NS_IMETHOD CheckLineOrder(int32_t aLine, bool* aIsReordered,
nsIFrame** aFirstVisual,
nsIFrame** aLastVisual) = 0;
};
namespace mozilla {
// Helper struct for FindFrameAt.
struct LineFrameFinder {
LineFrameFinder(const nsPoint& aPos, const nsSize& aContainerSize,
WritingMode aWM, bool aIsReversed)
: mPos(aWM, aPos, aContainerSize),
mContainerSize(aContainerSize),
mWM(aWM),
mIsReversed(aIsReversed) {}
void Scan(nsIFrame*);
void Finish(nsIFrame**, bool* aPosIsBeforeFirstFrame,
bool* aPosIsAfterLastFrame);
const LogicalPoint mPos;
const nsSize mContainerSize;
const WritingMode mWM;
const bool mIsReversed;
bool IsDone() const { return mDone; }
private:
bool mDone = false;
nsIFrame* mFirstFrame = nullptr;
nsIFrame* mClosestFromStart = nullptr;
nsIFrame* mClosestFromEnd = nullptr;
};
} // namespace mozilla
/**
* Helper intended to be used in a scope where we're using an nsILineIterator
* and want to verify that no DOM mutations (which would invalidate the
* iterator) occur while we're using it.
*/
class MOZ_RAII AutoAssertNoDomMutations final {
#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
nsMutationGuard mGuard;
#endif
public:
~AutoAssertNoDomMutations() { MOZ_DIAGNOSTIC_ASSERT(!mGuard.Mutated(0)); }
};
#endif /* nsILineIterator_h___ */
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