gecko-dev/layout/base/nsBidiPresUtils.h
L. David Baron 64f57e5d7f Bug 1300293 - Make nsBidiPresUtils track line boxes separately for the progress of TraverseFrames and ResolveParagraph. r=jfkthame
TraverseFrames gathers a bunch of frames into an array, and then at
forced breaks or the end of the block flushes its array by running
ResolveParagraph.  ResolveParagraph can sometimes cause lines to break,
so lines recorded during TraverseFrames may no longer be accurate during
ResolveParagraph.

It may look like the lines are only needed during ResolveParagraph and
we could handle the one issue in TraverseFrames that deals with
preformatted newlines by restructuring the code a tad.  However, in the
next patch, there will be an additional caller that needs the current
line during TraverseFrames to pass to CreateContinuation, which makes
such a structure less plausible.

This will also make it easier to produce a current line for the call to
SplitInlineAncestors within ResolveParagraph, which will be done in the
patch after the next.

Differential Revision: https://phabricator.services.mozilla.com/D38797

--HG--
extra : moz-landing-system : lando
2019-07-22 18:55:56 +00:00

576 lines
23 KiB
C++

/* -*- 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 nsBidiPresUtils_h___
#define nsBidiPresUtils_h___
#include "gfxContext.h"
#include "nsBidi.h"
#include "nsBidiUtils.h"
#include "nsHashKeys.h"
#include "nsCoord.h"
#include "nsTArray.h"
#include "nsLineBox.h"
#ifdef DrawText
# undef DrawText
#endif
struct BidiParagraphData;
struct BidiLineData;
class gfxContext;
class nsFontMetrics;
class nsIFrame;
class nsBlockFrame;
class nsPresContext;
struct nsSize;
template <class T>
class nsTHashtable;
namespace mozilla {
class ComputedStyle;
class LogicalMargin;
class WritingMode;
} // namespace mozilla
/**
* A structure representing some continuation state for each frame on the line,
* used to determine the first and the last continuation frame for each
* continuation chain on the line.
*/
struct nsFrameContinuationState : public nsVoidPtrHashKey {
explicit nsFrameContinuationState(const void* aFrame)
: nsVoidPtrHashKey(aFrame) {}
/**
* The first visual frame in the continuation chain containing this frame, or
* nullptr if this frame is the first visual frame in the chain.
*/
nsIFrame* mFirstVisualFrame{nullptr};
/**
* The number of frames in the continuation chain containing this frame, if
* this frame is the first visual frame of the chain, or 0 otherwise.
*/
uint32_t mFrameCount{0};
/**
* TRUE if this frame is the first visual frame of its continuation chain on
* this line and the chain has some frames on the previous lines.
*/
bool mHasContOnPrevLines{false};
/**
* TRUE if this frame is the first visual frame of its continuation chain on
* this line and the chain has some frames left for next lines.
*/
bool mHasContOnNextLines{false};
};
// A table of nsFrameContinuationState objects.
//
// This state is used between calls to nsBidiPresUtils::IsFirstOrLast.
struct nsContinuationStates {
static constexpr size_t kArrayMax = 32;
// We use the array to gather up all the continuation state objects. If in
// the end there are more than kArrayMax of them, we convert it to a hash
// table for faster lookup.
bool mUseTable = false;
AutoTArray<nsFrameContinuationState, kArrayMax> mValues;
nsTHashtable<nsFrameContinuationState> mTable;
void Insert(nsIFrame* aFrame) {
if (MOZ_UNLIKELY(mUseTable)) {
mTable.PutEntry(aFrame);
return;
}
if (MOZ_LIKELY(mValues.Length() < kArrayMax)) {
mValues.AppendElement(aFrame);
return;
}
for (const auto& entry : mValues) {
mTable.PutEntry(entry.GetKey());
}
mTable.PutEntry(aFrame);
mValues.Clear();
mUseTable = true;
}
nsFrameContinuationState* Get(nsIFrame* aFrame) {
MOZ_ASSERT(mValues.IsEmpty() != mTable.IsEmpty(),
"expect entries to either be in mValues or in mTable");
if (mUseTable) {
return mTable.GetEntry(aFrame);
}
for (size_t i = 0, len = mValues.Length(); i != len; ++i) {
if (mValues[i].GetKey() == aFrame) {
return &mValues[i];
}
}
return nullptr;
}
};
/**
* A structure representing a logical position which should be resolved
* into its visual position during BiDi processing.
*/
struct nsBidiPositionResolve {
// [in] Logical index within string.
int32_t logicalIndex;
// [out] Visual index within string.
// If the logical position was not found, set to kNotFound.
int32_t visualIndex;
// [out] Visual position of the character, from the left (on the X axis), in
// twips. Eessentially, this is the X position (relative to the rendering
// context) where the text was drawn + the font metric of the visual string to
// the left of the given logical position. If the logical position was not
// found, set to kNotFound.
int32_t visualLeftTwips;
// [out] Visual width of the character, in twips.
// If the logical position was not found, set to kNotFound.
int32_t visualWidth;
};
class nsBidiPresUtils {
public:
typedef mozilla::gfx::DrawTarget DrawTarget;
nsBidiPresUtils();
~nsBidiPresUtils();
/**
* Interface for the processor used by ProcessText. Used by process text to
* collect information about the width of subruns and to notify where each
* subrun should be rendered.
*/
class BidiProcessor {
public:
virtual ~BidiProcessor() {}
/**
* Sets the current text with the given length and the given direction.
*
* @remark The reason that the function gives a string instead of an index
* is that ProcessText copies and modifies the string passed to it, so
* passing an index would be impossible.
*
* @param aText The string of text.
* @param aLength The length of the string of text.
* @param aDirection The direction of the text. The string will never have
* mixed direction.
*/
virtual void SetText(const char16_t* aText, int32_t aLength,
nsBidiDirection aDirection) = 0;
/**
* Returns the measured width of the text given in SetText. If SetText was
* not called with valid parameters, the result of this call is undefined.
* This call is guaranteed to only be called once between SetText calls.
* Will be invoked before DrawText.
*/
virtual nscoord GetWidth() = 0;
/**
* Draws the text given in SetText to a rendering context. If SetText was
* not called with valid parameters, the result of this call is undefined.
* This call is guaranteed to only be called once between SetText calls.
*
* @param aXOffset The offset of the left side of the substring to be drawn
* from the beginning of the overall string passed to ProcessText.
* @param aWidth The width returned by GetWidth.
*/
virtual void DrawText(nscoord aXOffset, nscoord aWidth) = 0;
};
/**
* Make Bidi engine calculate the embedding levels of the frames that are
* descendants of a given block frame.
*
* @param aBlockFrame The block frame
*
* @lina 06/18/2000
*/
static nsresult Resolve(nsBlockFrame* aBlockFrame);
static nsresult ResolveParagraph(BidiParagraphData* aBpd);
static void ResolveParagraphWithinBlock(BidiParagraphData* aBpd);
/**
* Reorder this line using Bidi engine.
* Update frame array, following the new visual sequence.
*
* @return total inline size
*
* @lina 05/02/2000
*/
static nscoord ReorderFrames(nsIFrame* aFirstFrameOnLine,
int32_t aNumFramesOnLine,
mozilla::WritingMode aLineWM,
const nsSize& aContainerSize, nscoord aStart);
/**
* Format Unicode text, taking into account bidi capabilities
* of the platform. The formatting includes: reordering, Arabic shaping,
* symmetric and numeric swapping, removing control characters.
*
* @lina 06/18/2000
*/
static nsresult FormatUnicodeText(nsPresContext* aPresContext,
char16_t* aText, int32_t& aTextLength,
nsCharType aCharType);
/**
* Reorder plain text using the Unicode Bidi algorithm and send it to
* a rendering context for rendering.
*
* @param[in] aText the string to be rendered (in logical order)
* @param aLength the number of characters in the string
* @param aBaseLevel the base embedding level of the string
* odd values are right-to-left; even values are left-to-right, plus special
* constants as follows (defined in nsBidi.h)
* NSBIDI_LTR - left-to-right string
* NSBIDI_RTL - right-to-left string
* NSBIDI_DEFAULT_LTR - auto direction determined by first strong character,
* default is left-to-right
* NSBIDI_DEFAULT_RTL - auto direction determined by first strong character,
* default is right-to-left
*
* @param aPresContext the presentation context
* @param aRenderingContext the rendering context to render to
* @param aTextRunConstructionContext the rendering context to be used to
* construct the textrun (affects font hinting)
* @param aX the x-coordinate to render the string
* @param aY the y-coordinate to render the string
* @param[in,out] aPosResolve array of logical positions to resolve into
* visual positions; can be nullptr if this functionality is not required
* @param aPosResolveCount number of items in the aPosResolve array
*/
static nsresult RenderText(
const char16_t* aText, int32_t aLength, nsBidiLevel aBaseLevel,
nsPresContext* aPresContext, gfxContext& aRenderingContext,
DrawTarget* aTextRunConstructionDrawTarget, nsFontMetrics& aFontMetrics,
nscoord aX, nscoord aY, nsBidiPositionResolve* aPosResolve = nullptr,
int32_t aPosResolveCount = 0) {
return ProcessTextForRenderingContext(
aText, aLength, aBaseLevel, aPresContext, aRenderingContext,
aTextRunConstructionDrawTarget, aFontMetrics, MODE_DRAW, aX, aY,
aPosResolve, aPosResolveCount, nullptr);
}
static nscoord MeasureTextWidth(const char16_t* aText, int32_t aLength,
nsBidiLevel aBaseLevel,
nsPresContext* aPresContext,
gfxContext& aRenderingContext,
nsFontMetrics& aFontMetrics) {
nscoord length;
nsresult rv = ProcessTextForRenderingContext(
aText, aLength, aBaseLevel, aPresContext, aRenderingContext,
aRenderingContext.GetDrawTarget(), aFontMetrics, MODE_MEASURE, 0, 0,
nullptr, 0, &length);
return NS_SUCCEEDED(rv) ? length : 0;
}
/**
* Check if a line is reordered, i.e., if the child frames are not
* all laid out left-to-right.
* @param aFirstFrameOnLine : first frame of the line to be tested
* @param aNumFramesOnLine : number of frames on this line
* @param[out] aLeftMost : leftmost frame on this line
* @param[out] aRightMost : rightmost frame on this line
*/
static bool CheckLineOrder(nsIFrame* aFirstFrameOnLine,
int32_t aNumFramesOnLine, nsIFrame** aLeftmost,
nsIFrame** aRightmost);
/**
* Get the frame to the right of the given frame, on the same line.
* @param aFrame : We're looking for the frame to the right of this frame.
* If null, return the leftmost frame on the line.
* @param aFirstFrameOnLine : first frame of the line to be tested
* @param aNumFramesOnLine : number of frames on this line
*/
static nsIFrame* GetFrameToRightOf(const nsIFrame* aFrame,
nsIFrame* aFirstFrameOnLine,
int32_t aNumFramesOnLine);
/**
* Get the frame to the left of the given frame, on the same line.
* @param aFrame : We're looking for the frame to the left of this frame.
* If null, return the rightmost frame on the line.
* @param aFirstFrameOnLine : first frame of the line to be tested
* @param aNumFramesOnLine : number of frames on this line
*/
static nsIFrame* GetFrameToLeftOf(const nsIFrame* aFrame,
nsIFrame* aFirstFrameOnLine,
int32_t aNumFramesOnLine);
static nsIFrame* GetFirstLeaf(nsIFrame* aFrame);
/**
* Get the bidi data of the given (inline) frame.
*/
static mozilla::FrameBidiData GetFrameBidiData(nsIFrame* aFrame);
/**
* Get the bidi embedding level of the given (inline) frame.
*/
static nsBidiLevel GetFrameEmbeddingLevel(nsIFrame* aFrame);
/**
* Get the bidi base level of the given (inline) frame.
*/
static nsBidiLevel GetFrameBaseLevel(nsIFrame* aFrame);
/**
* Get an nsBidiDirection representing the direction implied by the
* bidi base level of the frame.
* @return NSBIDI_LTR (left-to-right) or NSBIDI_RTL (right-to-left)
* NSBIDI_MIXED will never be returned.
*/
static nsBidiDirection ParagraphDirection(nsIFrame* aFrame) {
return DIRECTION_FROM_LEVEL(GetFrameBaseLevel(aFrame));
}
/**
* Get an nsBidiDirection representing the direction implied by the
* bidi embedding level of the frame.
* @return NSBIDI_LTR (left-to-right) or NSBIDI_RTL (right-to-left)
* NSBIDI_MIXED will never be returned.
*/
static nsBidiDirection FrameDirection(nsIFrame* aFrame) {
return DIRECTION_FROM_LEVEL(GetFrameEmbeddingLevel(aFrame));
}
static bool IsFrameInParagraphDirection(nsIFrame* aFrame) {
return ParagraphDirection(aFrame) == FrameDirection(aFrame);
}
enum Mode { MODE_DRAW, MODE_MEASURE };
/**
* Reorder plain text using the Unicode Bidi algorithm and send it to
* a processor for rendering or measuring
*
* @param[in] aText the string to be processed (in logical order)
* @param aLength the number of characters in the string
* @param aBaseLevel the base embedding level of the string
* odd values are right-to-left; even values are left-to-right, plus special
* constants as follows (defined in nsBidi.h)
* NSBIDI_LTR - left-to-right string
* NSBIDI_RTL - right-to-left string
* NSBIDI_DEFAULT_LTR - auto direction determined by first strong character,
* default is left-to-right
* NSBIDI_DEFAULT_RTL - auto direction determined by first strong character,
* default is right-to-left
*
* @param aPresContext the presentation context
* @param aprocessor the bidi processor
* @param aMode the operation to process
* MODE_DRAW - invokes DrawText on the processor for each substring
* MODE_MEASURE - does not invoke DrawText on the processor
* Note that the string is always measured, regardless of mode
* @param[in,out] aPosResolve array of logical positions to resolve into
* visual positions; can be nullptr if this functionality is not required
* @param aPosResolveCount number of items in the aPosResolve array
* @param[out] aWidth Pointer to where the width will be stored (may be null)
*/
static nsresult ProcessText(const char16_t* aText, int32_t aLength,
nsBidiLevel aBaseLevel,
nsPresContext* aPresContext,
BidiProcessor& aprocessor, Mode aMode,
nsBidiPositionResolve* aPosResolve,
int32_t aPosResolveCount, nscoord* aWidth,
nsBidi* aBidiEngine);
/**
* Use style attributes to determine the base paragraph level to pass to the
* bidi algorithm.
*
* If |unicode-bidi| is set to "[-moz-]plaintext", returns NSBIDI_DEFAULT_LTR,
* in other words the direction is determined from the first strong character
* in the text according to rules P2 and P3 of the bidi algorithm, or LTR if
* there is no strong character.
*
* Otherwise returns NSBIDI_LTR or NSBIDI_RTL depending on the value of
* |direction|
*/
static nsBidiLevel BidiLevelFromStyle(mozilla::ComputedStyle* aComputedStyle);
private:
static nsresult ProcessTextForRenderingContext(
const char16_t* aText, int32_t aLength, nsBidiLevel aBaseLevel,
nsPresContext* aPresContext, gfxContext& aRenderingContext,
DrawTarget* aTextRunConstructionDrawTarget, nsFontMetrics& aFontMetrics,
Mode aMode,
nscoord aX, // DRAW only
nscoord aY, // DRAW only
nsBidiPositionResolve* aPosResolve, /* may be null */
int32_t aPosResolveCount, nscoord* aWidth /* may be null */);
/**
* Traverse the child frames of the block element and:
* Set up an array of the frames in logical order
* Create a string containing the text content of all the frames
* If we encounter content that requires us to split the element into more
* than one paragraph for bidi resolution, resolve the paragraph up to that
* point.
*/
static void TraverseFrames(nsIFrame* aCurrentFrame, BidiParagraphData* aBpd);
/**
* Perform a recursive "pre-traversal" of the child frames of a block or
* inline container frame, to determine whether full bidi resolution is
* actually needed.
* This explores the same frames as TraverseFrames (above), but is less
* expensive and may allow us to avoid performing the full TraverseFrames
* operation.
* @param aFirstChild frame to start traversal from
* @param[in/out] aCurrContent the content node that we've most recently
* scanned for RTL characters (so that when descendant frames refer
* to the same content, we can avoid repeatedly scanning it).
* @return true if it finds that bidi is (or may be) required,
* false if no potentially-bidi content is present.
*/
static bool ChildListMayRequireBidi(nsIFrame* aFirstChild,
nsIContent** aCurrContent);
/**
* Position ruby content frames (ruby base/text frame).
* Called from RepositionRubyFrame.
*/
static void RepositionRubyContentFrame(
nsIFrame* aFrame, mozilla::WritingMode aFrameWM,
const mozilla::LogicalMargin& aBorderPadding);
/*
* Position ruby frames. Called from RepositionFrame.
*/
static nscoord RepositionRubyFrame(
nsIFrame* aFrame, nsContinuationStates* aContinuationStates,
const mozilla::WritingMode aContainerWM,
const mozilla::LogicalMargin& aBorderPadding);
/*
* Position aFrame and its descendants to their visual places. Also if aFrame
* is not leaf, resize it to embrace its children.
*
* @param aFrame The frame which itself and its children are
* going to be repositioned
* @param aIsEvenLevel TRUE means the embedding level of this frame
* is even (LTR)
* @param aStartOrEnd The distance to the start or the end of aFrame
* without considering its inline margin. If the
* container is reordering frames in reverse
* direction, it's the distance to the end,
* otherwise, it's the distance to the start.
* @param aContinuationStates A map from nsIFrame* to
* nsFrameContinuationState
* @return The isize aFrame takes, including margins.
*/
static nscoord RepositionFrame(nsIFrame* aFrame, bool aIsEvenLevel,
nscoord aStartOrEnd,
nsContinuationStates* aContinuationStates,
mozilla::WritingMode aContainerWM,
bool aContainerReverseOrder,
const nsSize& aContainerSize);
/*
* Initialize the continuation state(nsFrameContinuationState) to
* (nullptr, 0) for aFrame and its descendants.
*
* @param aFrame The frame which itself and its descendants will
* be initialized
* @param aContinuationStates A map from nsIFrame* to
* nsFrameContinuationState
*/
static void InitContinuationStates(nsIFrame* aFrame,
nsContinuationStates* aContinuationStates);
/*
* Determine if aFrame is first or last, and set aIsFirst and
* aIsLast values. Also set continuation states of
* aContinuationStates.
*
* A frame is first if it's the first appearance of its continuation
* chain on the line and the chain is on its first line.
* A frame is last if it's the last appearance of its continuation
* chain on the line and the chain is on its last line.
*
* N.B: "First appearance" and "Last appearance" in the previous
* paragraph refer to the frame's inline direction, not necessarily
* the line's.
*
* @param aContinuationStates A map from nsIFrame* to
* nsFrameContinuationState
* @param[in] aSpanDirMatchesLineDir TRUE means that the inline
* direction of aFrame is the same
* as its container
* @param[out] aIsFirst TRUE means aFrame is first frame
* or continuation
* @param[out] aIsLast TRUE means aFrame is last frame
* or continuation
*/
static void IsFirstOrLast(nsIFrame* aFrame,
nsContinuationStates* aContinuationStates,
bool aSpanInLineOrder /* in */,
bool& aIsFirst /* out */, bool& aIsLast /* out */);
/**
* Adjust frame positions following their visual order
*
* @param aFirstChild the first kid
* @return total inline size
*
* @lina 04/11/2000
*/
static nscoord RepositionInlineFrames(BidiLineData* aBld,
mozilla::WritingMode aLineWM,
const nsSize& aContainerSize,
nscoord aStart);
/**
* Helper method for Resolve()
* Truncate a text frame to the end of a single-directional run and possibly
* create a continuation frame for the remainder of its content.
*
* @param aFrame the original frame
* @param aLine the line box containing aFrame
* @param aNewFrame [OUT] the new frame that was created
* @param aStart [IN] the start of the content mapped by aFrame (and
* any fluid continuations)
* @param aEnd [IN] the offset of the end of the single-directional
* text run.
* @see Resolve()
* @see RemoveBidiContinuation()
*/
static inline nsresult EnsureBidiContinuation(
nsIFrame* aFrame, const nsLineList::iterator aLine, nsIFrame** aNewFrame,
int32_t aStart, int32_t aEnd);
/**
* Helper method for Resolve()
* Convert one or more bidi continuation frames created in a previous reflow
* by EnsureBidiContinuation() into fluid continuations.
* @param aFrame the frame whose continuations are to be removed
* @param aFirstIndex index of aFrame in mLogicalFrames
* @param aLastIndex index of the last frame to be removed
*
* @see Resolve()
* @see EnsureBidiContinuation()
*/
static void RemoveBidiContinuation(BidiParagraphData* aBpd, nsIFrame* aFrame,
int32_t aFirstIndex, int32_t aLastIndex);
static void CalculateCharType(nsBidi* aBidiEngine, const char16_t* aText,
int32_t& aOffset, int32_t aCharTypeLimit,
int32_t& aRunLimit, int32_t& aRunLength,
int32_t& aRunCount, uint8_t& aCharType,
uint8_t& aPrevCharType);
static void StripBidiControlCharacters(char16_t* aText, int32_t& aTextLength);
};
#endif /* nsBidiPresUtils_h___ */