1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/layout/base/nsBidiPresUtils.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,513 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
1.5 + *
1.6 + * This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#ifndef nsBidiPresUtils_h___
1.11 +#define nsBidiPresUtils_h___
1.12 +
1.13 +#include "nsBidi.h"
1.14 +#include "nsBidiUtils.h"
1.15 +#include "nsHashKeys.h"
1.16 +#include "nsCoord.h"
1.17 +
1.18 +#ifdef DrawText
1.19 +#undef DrawText
1.20 +#endif
1.21 +
1.22 +struct BidiParagraphData;
1.23 +struct BidiLineData;
1.24 +class nsIFrame;
1.25 +class nsBlockFrame;
1.26 +class nsPresContext;
1.27 +class nsRenderingContext;
1.28 +class nsBlockInFlowLineIterator;
1.29 +class nsStyleContext;
1.30 +template<class T> class nsTHashtable;
1.31 +namespace mozilla { class WritingMode; }
1.32 +
1.33 +/**
1.34 + * A structure representing some continuation state for each frame on the line,
1.35 + * used to determine the first and the last continuation frame for each
1.36 + * continuation chain on the line.
1.37 + */
1.38 +struct nsFrameContinuationState : public nsVoidPtrHashKey
1.39 +{
1.40 + nsFrameContinuationState(const void *aFrame) : nsVoidPtrHashKey(aFrame) {}
1.41 +
1.42 + /**
1.43 + * The first visual frame in the continuation chain containing this frame, or
1.44 + * nullptr if this frame is the first visual frame in the chain.
1.45 + */
1.46 + nsIFrame* mFirstVisualFrame;
1.47 +
1.48 + /**
1.49 + * The number of frames in the continuation chain containing this frame, if
1.50 + * this frame is the first visual frame of the chain, or 0 otherwise.
1.51 + */
1.52 + uint32_t mFrameCount;
1.53 +
1.54 + /**
1.55 + * TRUE if this frame is the first visual frame of its continuation chain on
1.56 + * this line and the chain has some frames on the previous lines.
1.57 + */
1.58 + bool mHasContOnPrevLines;
1.59 +
1.60 + /**
1.61 + * TRUE if this frame is the first visual frame of its continuation chain on
1.62 + * this line and the chain has some frames left for next lines.
1.63 + */
1.64 + bool mHasContOnNextLines;
1.65 +};
1.66 +
1.67 +/*
1.68 + * Following type is used to pass needed hashtable to reordering methods
1.69 + */
1.70 +typedef nsTHashtable<nsFrameContinuationState> nsContinuationStates;
1.71 +
1.72 +/**
1.73 + * A structure representing a logical position which should be resolved
1.74 + * into its visual position during BiDi processing.
1.75 + */
1.76 +struct nsBidiPositionResolve
1.77 +{
1.78 + // [in] Logical index within string.
1.79 + int32_t logicalIndex;
1.80 + // [out] Visual index within string.
1.81 + // If the logical position was not found, set to kNotFound.
1.82 + int32_t visualIndex;
1.83 + // [out] Visual position of the character, from the left (on the X axis), in twips.
1.84 + // 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.
1.85 + // If the logical position was not found, set to kNotFound.
1.86 + int32_t visualLeftTwips;
1.87 + // [out] Visual width of the character, in twips.
1.88 + // If the logical position was not found, set to kNotFound.
1.89 + int32_t visualWidth;
1.90 +};
1.91 +
1.92 +class nsBidiPresUtils {
1.93 +public:
1.94 + nsBidiPresUtils();
1.95 + ~nsBidiPresUtils();
1.96 +
1.97 + /**
1.98 + * Interface for the processor used by ProcessText. Used by process text to
1.99 + * collect information about the width of subruns and to notify where each
1.100 + * subrun should be rendered.
1.101 + */
1.102 + class BidiProcessor {
1.103 + public:
1.104 + virtual ~BidiProcessor() { }
1.105 +
1.106 + /**
1.107 + * Sets the current text with the given length and the given direction.
1.108 + *
1.109 + * @remark The reason that the function gives a string instead of an index
1.110 + * is that ProcessText copies and modifies the string passed to it, so
1.111 + * passing an index would be impossible.
1.112 + *
1.113 + * @param aText The string of text.
1.114 + * @param aLength The length of the string of text.
1.115 + * @param aDirection The direction of the text. The string will never have
1.116 + * mixed direction.
1.117 + */
1.118 + virtual void SetText(const char16_t* aText,
1.119 + int32_t aLength,
1.120 + nsBidiDirection aDirection) = 0;
1.121 +
1.122 + /**
1.123 + * Returns the measured width of the text given in SetText. If SetText was
1.124 + * not called with valid parameters, the result of this call is undefined.
1.125 + * This call is guaranteed to only be called once between SetText calls.
1.126 + * Will be invoked before DrawText.
1.127 + */
1.128 + virtual nscoord GetWidth() = 0;
1.129 +
1.130 + /**
1.131 + * Draws the text given in SetText to a rendering context. If SetText was
1.132 + * not called with valid parameters, the result of this call is undefined.
1.133 + * This call is guaranteed to only be called once between SetText calls.
1.134 + *
1.135 + * @param aXOffset The offset of the left side of the substring to be drawn
1.136 + * from the beginning of the overall string passed to ProcessText.
1.137 + * @param aWidth The width returned by GetWidth.
1.138 + */
1.139 + virtual void DrawText(nscoord aXOffset,
1.140 + nscoord aWidth) = 0;
1.141 + };
1.142 +
1.143 + /**
1.144 + * Make Bidi engine calculate the embedding levels of the frames that are
1.145 + * descendants of a given block frame.
1.146 + *
1.147 + * @param aBlockFrame The block frame
1.148 + *
1.149 + * @lina 06/18/2000
1.150 + */
1.151 + static nsresult Resolve(nsBlockFrame* aBlockFrame);
1.152 + static nsresult ResolveParagraph(nsBlockFrame* aBlockFrame,
1.153 + BidiParagraphData* aBpd);
1.154 + static void ResolveParagraphWithinBlock(nsBlockFrame* aBlockFrame,
1.155 + BidiParagraphData* aBpd);
1.156 +
1.157 + /**
1.158 + * Reorder this line using Bidi engine.
1.159 + * Update frame array, following the new visual sequence.
1.160 + *
1.161 + * @lina 05/02/2000
1.162 + */
1.163 + static void ReorderFrames(nsIFrame* aFirstFrameOnLine,
1.164 + int32_t aNumFramesOnLine,
1.165 + mozilla::WritingMode aLineWM,
1.166 + nscoord& aLineWidth);
1.167 +
1.168 + /**
1.169 + * Format Unicode text, taking into account bidi capabilities
1.170 + * of the platform. The formatting includes: reordering, Arabic shaping,
1.171 + * symmetric and numeric swapping, removing control characters.
1.172 + *
1.173 + * @lina 06/18/2000
1.174 + */
1.175 + static nsresult FormatUnicodeText(nsPresContext* aPresContext,
1.176 + char16_t* aText,
1.177 + int32_t& aTextLength,
1.178 + nsCharType aCharType,
1.179 + bool aIsOddLevel);
1.180 +
1.181 + /**
1.182 + * Reorder plain text using the Unicode Bidi algorithm and send it to
1.183 + * a rendering context for rendering.
1.184 + *
1.185 + * @param[in] aText the string to be rendered (in logical order)
1.186 + * @param aLength the number of characters in the string
1.187 + * @param aBaseLevel the base embedding level of the string
1.188 + * odd values are right-to-left; even values are left-to-right, plus special
1.189 + * constants as follows (defined in nsBidi.h)
1.190 + * NSBIDI_LTR - left-to-right string
1.191 + * NSBIDI_RTL - right-to-left string
1.192 + * NSBIDI_DEFAULT_LTR - auto direction determined by first strong character,
1.193 + * default is left-to-right
1.194 + * NSBIDI_DEFAULT_RTL - auto direction determined by first strong character,
1.195 + * default is right-to-left
1.196 + *
1.197 + * @param aPresContext the presentation context
1.198 + * @param aRenderingContext the rendering context to render to
1.199 + * @param aTextRunConstructionContext the rendering context to be used to construct the textrun (affects font hinting)
1.200 + * @param aX the x-coordinate to render the string
1.201 + * @param aY the y-coordinate to render the string
1.202 + * @param[in,out] aPosResolve array of logical positions to resolve into visual positions; can be nullptr if this functionality is not required
1.203 + * @param aPosResolveCount number of items in the aPosResolve array
1.204 + */
1.205 + static nsresult RenderText(const char16_t* aText,
1.206 + int32_t aLength,
1.207 + nsBidiLevel aBaseLevel,
1.208 + nsPresContext* aPresContext,
1.209 + nsRenderingContext& aRenderingContext,
1.210 + nsRenderingContext& aTextRunConstructionContext,
1.211 + nscoord aX,
1.212 + nscoord aY,
1.213 + nsBidiPositionResolve* aPosResolve = nullptr,
1.214 + int32_t aPosResolveCount = 0)
1.215 + {
1.216 + return ProcessTextForRenderingContext(aText, aLength, aBaseLevel, aPresContext, aRenderingContext,
1.217 + aTextRunConstructionContext, MODE_DRAW, aX, aY, aPosResolve, aPosResolveCount, nullptr);
1.218 + }
1.219 +
1.220 + static nscoord MeasureTextWidth(const char16_t* aText,
1.221 + int32_t aLength,
1.222 + nsBidiLevel aBaseLevel,
1.223 + nsPresContext* aPresContext,
1.224 + nsRenderingContext& aRenderingContext)
1.225 + {
1.226 + nscoord length;
1.227 + nsresult rv = ProcessTextForRenderingContext(aText, aLength, aBaseLevel, aPresContext,
1.228 + aRenderingContext, aRenderingContext,
1.229 + MODE_MEASURE, 0, 0, nullptr, 0, &length);
1.230 + return NS_SUCCEEDED(rv) ? length : 0;
1.231 + }
1.232 +
1.233 + /**
1.234 + * Check if a line is reordered, i.e., if the child frames are not
1.235 + * all laid out left-to-right.
1.236 + * @param aFirstFrameOnLine : first frame of the line to be tested
1.237 + * @param aNumFramesOnLine : number of frames on this line
1.238 + * @param[out] aLeftMost : leftmost frame on this line
1.239 + * @param[out] aRightMost : rightmost frame on this line
1.240 + */
1.241 + static bool CheckLineOrder(nsIFrame* aFirstFrameOnLine,
1.242 + int32_t aNumFramesOnLine,
1.243 + nsIFrame** aLeftmost,
1.244 + nsIFrame** aRightmost);
1.245 +
1.246 + /**
1.247 + * Get the frame to the right of the given frame, on the same line.
1.248 + * @param aFrame : We're looking for the frame to the right of this frame.
1.249 + * If null, return the leftmost frame on the line.
1.250 + * @param aFirstFrameOnLine : first frame of the line to be tested
1.251 + * @param aNumFramesOnLine : number of frames on this line
1.252 + */
1.253 + static nsIFrame* GetFrameToRightOf(const nsIFrame* aFrame,
1.254 + nsIFrame* aFirstFrameOnLine,
1.255 + int32_t aNumFramesOnLine);
1.256 +
1.257 + /**
1.258 + * Get the frame to the left of the given frame, on the same line.
1.259 + * @param aFrame : We're looking for the frame to the left of this frame.
1.260 + * If null, return the rightmost frame on the line.
1.261 + * @param aFirstFrameOnLine : first frame of the line to be tested
1.262 + * @param aNumFramesOnLine : number of frames on this line
1.263 + */
1.264 + static nsIFrame* GetFrameToLeftOf(const nsIFrame* aFrame,
1.265 + nsIFrame* aFirstFrameOnLine,
1.266 + int32_t aNumFramesOnLine);
1.267 +
1.268 + static nsIFrame* GetFirstLeaf(nsIFrame* aFrame);
1.269 +
1.270 + /**
1.271 + * Get the bidi embedding level of the given (inline) frame.
1.272 + */
1.273 + static nsBidiLevel GetFrameEmbeddingLevel(nsIFrame* aFrame);
1.274 +
1.275 + /**
1.276 + * Get the paragraph depth of the given (inline) frame.
1.277 + */
1.278 + static uint8_t GetParagraphDepth(nsIFrame* aFrame);
1.279 +
1.280 + /**
1.281 + * Get the bidi base level of the given (inline) frame.
1.282 + */
1.283 + static nsBidiLevel GetFrameBaseLevel(nsIFrame* aFrame);
1.284 +
1.285 + enum Mode { MODE_DRAW, MODE_MEASURE };
1.286 +
1.287 + /**
1.288 + * Reorder plain text using the Unicode Bidi algorithm and send it to
1.289 + * a processor for rendering or measuring
1.290 + *
1.291 + * @param[in] aText the string to be processed (in logical order)
1.292 + * @param aLength the number of characters in the string
1.293 + * @param aBaseLevel the base embedding level of the string
1.294 + * odd values are right-to-left; even values are left-to-right, plus special
1.295 + * constants as follows (defined in nsBidi.h)
1.296 + * NSBIDI_LTR - left-to-right string
1.297 + * NSBIDI_RTL - right-to-left string
1.298 + * NSBIDI_DEFAULT_LTR - auto direction determined by first strong character,
1.299 + * default is left-to-right
1.300 + * NSBIDI_DEFAULT_RTL - auto direction determined by first strong character,
1.301 + * default is right-to-left
1.302 + *
1.303 + * @param aPresContext the presentation context
1.304 + * @param aprocessor the bidi processor
1.305 + * @param aMode the operation to process
1.306 + * MODE_DRAW - invokes DrawText on the processor for each substring
1.307 + * MODE_MEASURE - does not invoke DrawText on the processor
1.308 + * Note that the string is always measured, regardless of mode
1.309 + * @param[in,out] aPosResolve array of logical positions to resolve into
1.310 + * visual positions; can be nullptr if this functionality is not required
1.311 + * @param aPosResolveCount number of items in the aPosResolve array
1.312 + * @param[out] aWidth Pointer to where the width will be stored (may be null)
1.313 + */
1.314 + static nsresult ProcessText(const char16_t* aText,
1.315 + int32_t aLength,
1.316 + nsBidiLevel aBaseLevel,
1.317 + nsPresContext* aPresContext,
1.318 + BidiProcessor& aprocessor,
1.319 + Mode aMode,
1.320 + nsBidiPositionResolve* aPosResolve,
1.321 + int32_t aPosResolveCount,
1.322 + nscoord* aWidth,
1.323 + nsBidi* aBidiEngine);
1.324 +
1.325 + /**
1.326 + * Make a copy of a string, converting from logical to visual order
1.327 + *
1.328 + * @param aSource the source string
1.329 + * @param aDest the destination string
1.330 + * @param aBaseDirection the base direction of the string
1.331 + * (NSBIDI_LTR or NSBIDI_RTL to force the base direction;
1.332 + * NSBIDI_DEFAULT_LTR or NSBIDI_DEFAULT_RTL to let the bidi engine
1.333 + * determine the direction from rules P2 and P3 of the bidi algorithm.
1.334 + * @see nsBidi::GetPara
1.335 + * @param aOverride if TRUE, the text has a bidi override, according to
1.336 + * the direction in aDir
1.337 + */
1.338 + static void CopyLogicalToVisual(const nsAString& aSource,
1.339 + nsAString& aDest,
1.340 + nsBidiLevel aBaseDirection,
1.341 + bool aOverride);
1.342 +
1.343 + /**
1.344 + * Use style attributes to determine the base paragraph level to pass to the
1.345 + * bidi algorithm.
1.346 + *
1.347 + * If |unicode-bidi| is set to "[-moz-]plaintext", returns NSBIDI_DEFAULT_LTR,
1.348 + * in other words the direction is determined from the first strong character
1.349 + * in the text according to rules P2 and P3 of the bidi algorithm, or LTR if
1.350 + * there is no strong character.
1.351 + *
1.352 + * Otherwise returns NSBIDI_LTR or NSBIDI_RTL depending on the value of
1.353 + * |direction|
1.354 + */
1.355 + static nsBidiLevel BidiLevelFromStyle(nsStyleContext* aStyleContext);
1.356 +
1.357 +private:
1.358 + static nsresult
1.359 + ProcessTextForRenderingContext(const char16_t* aText,
1.360 + int32_t aLength,
1.361 + nsBidiLevel aBaseLevel,
1.362 + nsPresContext* aPresContext,
1.363 + nsRenderingContext& aRenderingContext,
1.364 + nsRenderingContext& aTextRunConstructionContext,
1.365 + Mode aMode,
1.366 + nscoord aX, // DRAW only
1.367 + nscoord aY, // DRAW only
1.368 + nsBidiPositionResolve* aPosResolve, /* may be null */
1.369 + int32_t aPosResolveCount,
1.370 + nscoord* aWidth /* may be null */);
1.371 +
1.372 + /**
1.373 + * Traverse the child frames of the block element and:
1.374 + * Set up an array of the frames in logical order
1.375 + * Create a string containing the text content of all the frames
1.376 + * If we encounter content that requires us to split the element into more
1.377 + * than one paragraph for bidi resolution, resolve the paragraph up to that
1.378 + * point.
1.379 + */
1.380 + static void TraverseFrames(nsBlockFrame* aBlockFrame,
1.381 + nsBlockInFlowLineIterator* aLineIter,
1.382 + nsIFrame* aCurrentFrame,
1.383 + BidiParagraphData* aBpd);
1.384 +
1.385 + /*
1.386 + * Position aFrame and its descendants to their visual places. Also if aFrame
1.387 + * is not leaf, resize it to embrace its children.
1.388 + *
1.389 + * @param aFrame The frame which itself and its children are
1.390 + * going to be repositioned
1.391 + * @param aIsEvenLevel TRUE means the embedding level of this frame
1.392 + * is even (LTR)
1.393 + * @param[in,out] aStart IN value is the starting position of aFrame
1.394 + * (without considering its inline-start margin)
1.395 + * OUT value will be the ending position of aFrame
1.396 + * (after adding its inline-end margin)
1.397 + * @param aContinuationStates A map from nsIFrame* to nsFrameContinuationState
1.398 + */
1.399 + static void RepositionFrame(nsIFrame* aFrame,
1.400 + bool aIsEvenLevel,
1.401 + nscoord& aStart,
1.402 + nsContinuationStates* aContinuationStates,
1.403 + mozilla::WritingMode aLineWM,
1.404 + nscoord& aLineWidth);
1.405 +
1.406 + /*
1.407 + * Initialize the continuation state(nsFrameContinuationState) to
1.408 + * (nullptr, 0) for aFrame and its descendants.
1.409 + *
1.410 + * @param aFrame The frame which itself and its descendants will
1.411 + * be initialized
1.412 + * @param aContinuationStates A map from nsIFrame* to nsFrameContinuationState
1.413 + */
1.414 + static void InitContinuationStates(nsIFrame* aFrame,
1.415 + nsContinuationStates* aContinuationStates);
1.416 +
1.417 + /*
1.418 + * Determine if aFrame is leftmost or rightmost, and set aIsLeftMost and
1.419 + * aIsRightMost values. Also set continuation states of aContinuationStates.
1.420 + *
1.421 + * A frame is leftmost if it's the first appearance of its continuation chain
1.422 + * on the line and the chain is on its first line if it's LTR or the chain is
1.423 + * on its last line if it's RTL.
1.424 + * A frame is rightmost if it's the last appearance of its continuation chain
1.425 + * on the line and the chain is on its first line if it's RTL or the chain is
1.426 + * on its last line if it's LTR.
1.427 + *
1.428 + * @param aContinuationStates A map from nsIFrame* to nsFrameContinuationState
1.429 + * @param[out] aIsLeftMost TRUE means aFrame is leftmost frame or continuation
1.430 + * @param[out] aIsRightMost TRUE means aFrame is rightmost frame or continuation
1.431 + */
1.432 + static void IsFirstOrLast(nsIFrame* aFrame,
1.433 + nsContinuationStates* aContinuationStates,
1.434 + bool& aIsFirst /* out */,
1.435 + bool& aIsLast /* out */);
1.436 +
1.437 + /**
1.438 + * Adjust frame positions following their visual order
1.439 + *
1.440 + * @param aFirstChild the first kid
1.441 + *
1.442 + * @lina 04/11/2000
1.443 + */
1.444 + static void RepositionInlineFrames(BidiLineData* aBld,
1.445 + nsIFrame* aFirstChild,
1.446 + mozilla::WritingMode aLineWM,
1.447 + nscoord& aLineWidth);
1.448 +
1.449 + /**
1.450 + * Helper method for Resolve()
1.451 + * Truncate a text frame to the end of a single-directional run and possibly
1.452 + * create a continuation frame for the remainder of its content.
1.453 + *
1.454 + * @param aFrame the original frame
1.455 + * @param aNewFrame [OUT] the new frame that was created
1.456 + * @param aFrameIndex [IN/OUT] index of aFrame in mLogicalFrames
1.457 + * @param aStart [IN] the start of the content mapped by aFrame (and
1.458 + * any fluid continuations)
1.459 + * @param aEnd [IN] the offset of the end of the single-directional
1.460 + * text run.
1.461 + * @see Resolve()
1.462 + * @see RemoveBidiContinuation()
1.463 + */
1.464 + static inline
1.465 + nsresult EnsureBidiContinuation(nsIFrame* aFrame,
1.466 + nsIFrame** aNewFrame,
1.467 + int32_t& aFrameIndex,
1.468 + int32_t aStart,
1.469 + int32_t aEnd);
1.470 +
1.471 + /**
1.472 + * Helper method for Resolve()
1.473 + * Convert one or more bidi continuation frames created in a previous reflow by
1.474 + * EnsureBidiContinuation() into fluid continuations.
1.475 + * @param aFrame the frame whose continuations are to be removed
1.476 + * @param aFirstIndex index of aFrame in mLogicalFrames
1.477 + * @param aLastIndex index of the last frame to be removed
1.478 + * @param aOffset [OUT] count of directional frames removed. Since
1.479 + * directional frames have control characters
1.480 + * corresponding to them in mBuffer, the pointers to
1.481 + * mBuffer in Resolve() will need to be updated after
1.482 + * deleting the frames.
1.483 + *
1.484 + * @see Resolve()
1.485 + * @see EnsureBidiContinuation()
1.486 + */
1.487 + static void RemoveBidiContinuation(BidiParagraphData* aBpd,
1.488 + nsIFrame* aFrame,
1.489 + int32_t aFirstIndex,
1.490 + int32_t aLastIndex,
1.491 + int32_t& aOffset);
1.492 + static void CalculateCharType(nsBidi* aBidiEngine,
1.493 + const char16_t* aText,
1.494 + int32_t& aOffset,
1.495 + int32_t aCharTypeLimit,
1.496 + int32_t& aRunLimit,
1.497 + int32_t& aRunLength,
1.498 + int32_t& aRunCount,
1.499 + uint8_t& aCharType,
1.500 + uint8_t& aPrevCharType);
1.501 +
1.502 + static void StripBidiControlCharacters(char16_t* aText,
1.503 + int32_t& aTextLength);
1.504 +
1.505 + static bool WriteLogicalToVisual(const char16_t* aSrc,
1.506 + uint32_t aSrcLength,
1.507 + char16_t* aDest,
1.508 + nsBidiLevel aBaseDirection,
1.509 + nsBidi* aBidiEngine);
1.510 +
1.511 + static void WriteReverse(const char16_t* aSrc,
1.512 + uint32_t aSrcLength,
1.513 + char16_t* aDest);
1.514 +};
1.515 +
1.516 +#endif /* nsBidiPresUtils_h___ */
