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Diffstat (limited to '')
| -rw-r--r-- | layout/generic/nsTextFrameUtils.h | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/layout/generic/nsTextFrameUtils.h b/layout/generic/nsTextFrameUtils.h new file mode 100644 index 0000000000..7990ba1632 --- /dev/null +++ b/layout/generic/nsTextFrameUtils.h @@ -0,0 +1,196 @@ +/* -*- 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 NSTEXTFRAMEUTILS_H_ +#define NSTEXTFRAMEUTILS_H_ + +#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 { + public: + // 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. + // TEXT_TRAILING_ARABICCHAR + // TEXT_INCOMING_ARABICCHAR + // TEXT_USE_MATH_SCRIPT + }; + + // These constants are used in TransformText to represent context information + // from previous textruns. + enum { INCOMING_NONE = 0, INCOMING_WHITESPACE = 1, INCOMING_ARABICCHAR = 2 }; + + /** + * 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 { + COMPRESS_NONE, + COMPRESS_WHITESPACE, + COMPRESS_WHITESPACE_NEWLINE, + COMPRESS_NONE_TRANSFORM_TO_SPACE + }; + + /** + * 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) { + return; + } + aArray->AppendElement(aOffset); + } + + static uint32_t ComputeApproximateLengthWithWhitespaceCompression( + mozilla::dom::Text*, const nsStyleText*); + static uint32_t ComputeApproximateLengthWithWhitespaceCompression( + const nsAString&, const nsStyleText*); +}; + +MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(nsTextFrameUtils::Flags) + +class nsSkipCharsRunIterator { + public: + enum LengthMode { + LENGTH_UNSKIPPED_ONLY = false, + LENGTH_INCLUDES_SKIPPED = true + }; + nsSkipCharsRunIterator(const gfxSkipCharsIterator& aStart, + LengthMode aLengthIncludesSkipped, uint32_t aLength) + : mIterator(aStart), + mRemainingLength(aLength), + mRunLength(0), + mSkipped(false), + mVisitSkipped(false), + mLengthIncludesSkipped(aLengthIncludesSkipped) {} + void SetVisitSkipped() { mVisitSkipped = true; } + void SetOriginalOffset(int32_t aOffset) { + mIterator.SetOriginalOffset(aOffset); + } + void SetSkippedOffset(uint32_t aOffset) { + mIterator.SetSkippedOffset(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(); } + + private: + gfxSkipCharsIterator mIterator; + int32_t mRemainingLength; + int32_t mRunLength; + bool mSkipped; + bool mVisitSkipped; + bool mLengthIncludesSkipped; +}; + +#endif /*NSTEXTFRAMEUTILS_H_*/ |