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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 */
#include "gfxSkipChars.h"
#include "nsBidiUtils.h"
class nsIContent;
struct nsStyleText;
namespace mozilla {
namespace dom {
class Text;
} // namespace mozilla
#define BIG_TEXT_NODE_SIZE 4096
#define CH_NBSP 160
#define CH_SHY 173
#define CH_CJKSP 12288 // U+3000 IDEOGRAPHIC SPACE (CJK Full-Width Space)
class nsTextFrameUtils {
// These constants are used as textrun flags for textframe textruns.
// If you add a flag, please add support for it in gfxTextRun::Dump.
enum class Flags : uint16_t {
// The following flags are set by TransformText
// the text has at least one untransformed tab character
HasTab = 0x01,
// the original text has at least one soft hyphen character
HasShy = 0x02,
UnusedFlags = 0x04,
// Flag used in textrun construction to *prevent* hiding of fallback text
// for pending user-fonts (used for Canvas2d text).
DontSkipDrawingForPendingUserFonts = 0x08,
// The following flags are set by nsTextFrame
IsSimpleFlow = 0x10,
IncomingWhitespace = 0x20,
TrailingWhitespace = 0x40,
CompressedLeadingWhitespace = 0x80,
NoBreaks = 0x100,
IsTransformed = 0x200,
// This gets set if there's a break opportunity at the end of the textrun.
// We normally don't use this break opportunity because the following text
// will have a break opportunity at the start, but it's useful for line
// layout to know about it in case the following content is not text
HasTrailingBreak = 0x400,
// This is set if the textrun was created for a textframe whose
// NS_FRAME_IS_IN_SINGLE_CHAR_MI flag is set. This occurs if the textframe
// belongs to a MathML <mi> element whose embedded text consists of a
// single character.
IsSingleCharMi = 0x800,
// This is set if the text run might be observing for glyph changes.
MightHaveGlyphChanges = 0x1000,
// For internal use by the memory reporter when accounting for
// storage used by textruns.
// Because the reporter may visit each textrun multiple times while
// walking the frame trees and textrun cache, it needs to mark
// textruns that have been seen so as to avoid multiple-accounting.
RunSizeAccounted = 0x2000,
// The following are defined by gfxTextRunFactory rather than here,
// so that it also has access to the _INCOMING and MATH_SCRIPT flags
// for shaping purposes.
// They live in the gfxShapedText::mFlags field rather than the
// gfxTextRun::mFlags2 field.
// These constants are used in TransformText to represent context information
// from previous textruns.
* Returns true if aChars/aLength are something that make a space
* character not be whitespace when they follow the space character
* (combining mark or join control, ignoring intervening direction
* controls).
static bool IsSpaceCombiningSequenceTail(const char16_t* aChars,
int32_t aLength);
static bool IsSpaceCombiningSequenceTail(const uint8_t* aChars,
int32_t aLength) {
return false;
enum CompressionMode {
* Create a text run from a run of Unicode text. The text may have whitespace
* compressed. A preformatted tab is sent to the text run as a single space.
* (Tab spacing must be performed by textframe later.) Certain other
* characters are discarded.
* @param aCompression control what is compressed to a
* single space character: no compression, compress spaces (not followed
* by combining mark) and tabs, compress those plus newlines, or
* no compression except newlines are discarded.
* @param aIncomingFlags a flag indicating whether there was whitespace
* or an Arabic character preceding this text. We set it to indicate if
* there's an Arabic character or whitespace preceding the end of this text.
template <class CharT>
static CharT* TransformText(const CharT* aText, uint32_t aLength,
CharT* aOutput, CompressionMode aCompression,
uint8_t* aIncomingFlags, gfxSkipChars* aSkipChars,
nsTextFrameUtils::Flags* aAnalysisFlags);
* Returns whether aChar is a character that nsTextFrameUtils::TransformText
* might mark as skipped. This is used by
* SVGTextContentElement::GetNumberOfChars to know whether reflowing frames,
* so that we have the results of TransformText, is required, or whether we
* can use a fast path instead.
template <class CharT>
static bool IsSkippableCharacterForTransformText(CharT aChar);
static void AppendLineBreakOffset(nsTArray<uint32_t>* aArray,
uint32_t aOffset) {
if (aArray->Length() > 0 && (*aArray)[aArray->Length() - 1] == aOffset) {
static uint32_t ComputeApproximateLengthWithWhitespaceCompression(
mozilla::dom::Text* aText, const nsStyleText* aStyleText);
class nsSkipCharsRunIterator {
enum LengthMode {
nsSkipCharsRunIterator(const gfxSkipCharsIterator& aStart,
LengthMode aLengthIncludesSkipped, uint32_t aLength)
: mIterator(aStart),
mLengthIncludesSkipped(aLengthIncludesSkipped) {}
void SetVisitSkipped() { mVisitSkipped = true; }
void SetOriginalOffset(int32_t aOffset) {
void SetSkippedOffset(uint32_t aOffset) {
// guaranteed to return only positive-length runs
bool NextRun();
bool IsSkipped() const { return mSkipped; }
// Always returns something > 0
int32_t GetRunLength() const { return mRunLength; }
const gfxSkipCharsIterator& GetPos() const { return mIterator; }
int32_t GetOriginalOffset() const { return mIterator.GetOriginalOffset(); }
uint32_t GetSkippedOffset() const { return mIterator.GetSkippedOffset(); }
gfxSkipCharsIterator mIterator;
int32_t mRemainingLength;
int32_t mRunLength;
bool mSkipped;
bool mVisitSkipped;
bool mLengthIncludesSkipped;