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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 */
#ifndef nsILineIterator_h___
#define nsILineIterator_h___
#include "nscore.h"
#include "nsINode.h"
#include "nsRect.h"
#include "mozilla/Attributes.h"
#include "mozilla/Result.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 {
~nsILineIterator() = default;
* The number of lines in the block
virtual int32_t GetNumLines() const = 0;
* The prevailing direction of lines.
* @return true if the CSS direction property for the block is
* "rtl", otherwise false
*XXX after bug 924851 change this to return a UBiDiDirection
virtual bool GetDirection() = 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 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;
* 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_STACK_CLASS AutoAssertNoDomMutations final {
nsMutationGuard mGuard;
~AutoAssertNoDomMutations() { MOZ_DIAGNOSTIC_ASSERT(!mGuard.Mutated(0)); }
#endif /* nsILineIterator_h___ */