sl@0: // Copyright (c) 2002-2010 Nokia Corporation and/or its subsidiary(-ies).
sl@0: // All rights reserved.
sl@0: // This component and the accompanying materials are made available
sl@0: // under the terms of "Eclipse Public License v1.0"
sl@0: // which accompanies this distribution, and is available
sl@0: // at the URL "http://www.eclipse.org/legal/epl-v10.html".
sl@0: //
sl@0: // Initial Contributors:
sl@0: // Nokia Corporation - initial contribution.
sl@0: //
sl@0: // Contributors:
sl@0: //
sl@0: // Description:
sl@0: //
sl@0: 
sl@0: #include "BidiCompact.h"
sl@0: #include "BidiCopy.h"
sl@0: #include <textbase.h>
sl@0: 
sl@0: static const TInt KZeroWidthJoiner = 0x200D;
sl@0: // This gets round the compiler warning about converting
sl@0: // EFRightToLeft to unsigned long.
sl@0: inline TUint FRightToLeft() { return static_cast<TUint>(TRunInfoCompact::EFRightToLeft); }
sl@0: 
sl@0: /**
sl@0: Constructs a run description without considering optimisations based
sl@0: on the text itself.
sl@0: @param aStart Index of the start of the run.
sl@0: @param aLength Length of the run.
sl@0: @param aReverse ETrue if the run is right-to-left.
sl@0: @internalTechnology
sl@0: */
sl@0: TRunInfoCompact::TRunInfoCompact(TInt aStart, TInt aLength,
sl@0: 	TBool aReverse)
sl@0: 	: iStart(aStart), iLengthAndType(aLength)
sl@0: 	{
sl@0: 	if (aReverse)
sl@0: 		iLengthAndType |= FRightToLeft();
sl@0: 	}
sl@0: 
sl@0: /**
sl@0: Constructs a run description.
sl@0: 
sl@0: @param aStart Index of the start of the run.
sl@0: @param aLength Length of the run.
sl@0: @param aReverse ETrue if the run is right-to-left.
sl@0: @param aText The text that this run refers to (starting at index 0, not
sl@0: the start of the run). This is required only to determine if optimisations 
sl@0: to the re-ordering are possible.
sl@0: @internalTechnology
sl@0: */
sl@0: TRunInfoCompact::TRunInfoCompact(TInt aStart, TInt aLength,
sl@0: 	TBool aReverse, const TText* aText)
sl@0: 	: iStart(aStart), iLengthAndType(aLength)
sl@0: 	{
sl@0: 	ASSERT(0 <= aLength);
sl@0: 	ASSERT(aLength < 0x10000000);
sl@0: 	ASSERT(0 <= aStart);
sl@0: 	if (!aReverse)
sl@0: 		return;
sl@0: 	iLengthAndType |= FRightToLeft();
sl@0: 	TUint32 flags = EFNoPairsNoCombiners | EFNoMirroredCharacters;
sl@0: 	aText += aStart;
sl@0: 
sl@0: 	for (const TText* end = aText + aLength; aText < end && flags; ++aText)
sl@0: 		{
sl@0: 		TInt code = *aText;
sl@0: 		if ((code & 0xF800) == 0xD800)
sl@0: 			{
sl@0: 			flags &= ~EFNoPairsNoCombiners;
sl@0: 			if ((code & 0xFC00) == 0xDC00
sl@0: 				&& aText + 1 < end
sl@0: 				&& (aText[1] & 0xFC00) == 0xD800)
sl@0: 				{
sl@0: 				code = (aText[1] << 10) + (code & 0x3FF)
sl@0: 					+ (0x10000 - 0xD800*0x400);
sl@0: 				++aText;
sl@0: 				}
sl@0: 			}
sl@0: 		TChar c = code;
sl@0: 		if (c.GetCombiningClass() != 0)
sl@0: 			flags &= ~EFNoPairsNoCombiners;
sl@0: 		if (BidiCopy::Mirror(code) != code)
sl@0: 			flags &= ~EFNoMirroredCharacters;
sl@0: 		}
sl@0: 	iLengthAndType |= flags;
sl@0: 	}
sl@0: 
sl@0: /**
sl@0: Attempts to extend a run.
sl@0: 
sl@0: @param aToBeAdded The run to be merged.
sl@0: @return ETrue if extension succeeded, EFalse if not.
sl@0: @internalTechnology
sl@0: */
sl@0: TBool TRunInfoCompact::AddRun(const TRunInfoCompact& aToBeAdded)
sl@0: 	{
sl@0: 	TInt length = Length();
sl@0: 	if (length == 0)
sl@0: 		{
sl@0: 		*this = aToBeAdded;
sl@0: 		return ETrue;
sl@0: 		}
sl@0: 
sl@0: 	// Are both runs in the same direction?
sl@0: 	if ((iLengthAndType ^ aToBeAdded.iLengthAndType) & FRightToLeft())
sl@0: 		return EFalse;
sl@0: 
sl@0: 	TBool rightToLeft = TypeFlags() & EFRightToLeft;
sl@0: 	TInt end = rightToLeft?
sl@0: 		Start() - Length() : Start() + Length();
sl@0: 
sl@0: 	if (end != aToBeAdded.Start())
sl@0: 		return EFalse;
sl@0: 
sl@0: 	length += aToBeAdded.Length();
sl@0: 
sl@0: 	iLengthAndType = length | (TypeFlags() & aToBeAdded.TypeFlags());
sl@0: 
sl@0: 	if (rightToLeft)
sl@0: 		iStart -= aToBeAdded.Length();
sl@0: 
sl@0: 	return ETrue;
sl@0: 	}
sl@0: 
sl@0: /**
sl@0: Reorders text described by this run according to aContext. Allow 6 extra
sl@0: bytes for a truncation.
sl@0: @param aDestination	Where to write this run of visually-ordered text to.
sl@0: @param aContext The source of the text to be ordered.
sl@0: @return	The first byte not written to: in other words, what aDestination
sl@0: should be updated to.
sl@0: @internalTechnology
sl@0: */
sl@0: TText* TRunInfoCompact::Reorder(TText* aDestination,
sl@0: 	const TRunInfoCompact::TReorderingContext& aContext) const
sl@0: 	{
sl@0: 	TInt start = Start();
sl@0: 	if (aContext.iEnd < start)
sl@0: 		// does not overlap
sl@0: 		return aDestination;
sl@0: 	TInt end = Start() + Length();
sl@0: 	if (end <= aContext.iStart)
sl@0: 		// does not overlap
sl@0: 		return aDestination;
sl@0: 	TBool startJoins = EFalse;
sl@0: 	if (start <= aContext.iStart)
sl@0: 		{
sl@0: 		start = aContext.iStart;
sl@0: 		startJoins = aContext.iJoinsAtStart;
sl@0: 		}
sl@0: 	TBool truncated = EFalse;
sl@0: 	TBool endJoins = EFalse;
sl@0: 	if (aContext.iEnd <= end)
sl@0: 		{
sl@0: 		if (aContext.iEnd < end
sl@0: 			&& aContext.iTruncation != 0xFFFF)
sl@0: 			truncated = ETrue;
sl@0: 		end = aContext.iEnd;
sl@0: 		endJoins = aContext.iJoinsAtEnd;
sl@0: 		}
sl@0: 	TInt length = end - start;
sl@0: 	if (length == 0 && !truncated)
sl@0: 		return aDestination;
sl@0: 	ASSERT(0 <= length);
sl@0: 	const TText* source = aContext.iSource + start;
sl@0: 	if (TypeFlags() & FRightToLeft())
sl@0: 		{
sl@0: 		// Right-to-left
sl@0: 		if (truncated)
sl@0: 			aDestination = BidiCopy::OutputTChar(aDestination, aContext.iTruncation);
sl@0: 		if (endJoins)
sl@0: 			*(aDestination++) = KZeroWidthJoiner;
sl@0: 		if (TypeFlags() & EFNoPairsNoCombiners)
sl@0: 			{
sl@0: 			// Simple
sl@0: 			aDestination = TypeFlags() & EFNoMirroredCharacters?
sl@0: 				BidiCopy::CopyBackwards(aDestination, source, length)
sl@0: 				: BidiCopy::CopyBackwardsWithMirroring(aDestination, source, length);
sl@0: 			}
sl@0: 		else
sl@0: 			// Respect groups
sl@0: 			aDestination = BidiCopy::CopyGroupsBackwards(aDestination, source, length);
sl@0: 		if (startJoins)
sl@0: 			*aDestination++ = KZeroWidthJoiner;
sl@0: 		return aDestination;
sl@0: 		}
sl@0: 	// Left-to-right
sl@0: 	if (startJoins)
sl@0: 		*aDestination++ = KZeroWidthJoiner;
sl@0: 	Mem::Copy(aDestination, source, length * sizeof(TText));
sl@0: 	aDestination += length;
sl@0: 	if (endJoins)
sl@0: 		*aDestination++ = KZeroWidthJoiner;
sl@0: 	if (truncated)
sl@0: 		aDestination = BidiCopy::OutputTChar(aDestination, aContext.iTruncation);
sl@0: 	return aDestination;
sl@0: 	}
sl@0: 
sl@0: /**
sl@0: Converts an array of aArraySize TBidirectionalState::TRunInfos into a
sl@0: compact form.
sl@0: 
sl@0: @param aBuffer Memory to output to, or null just to find out how large the output
sl@0: array will need to be.
sl@0: @param aText The text that aRunArray refers to.
sl@0: @param aRunArray The array to be converted.
sl@0: @param aArraySize The length of aRunArray.
sl@0: @return The length of the output array.
sl@0: @internalTechnology
sl@0: */
sl@0: TInt TRunInfoCompact::Convert(TRunInfoCompact* aBuffer, const TDesC& aText,
sl@0: 	const TBidirectionalState::TRunInfo* aRunArray, TInt aArraySize)
sl@0: 	{
sl@0: 	const TText* text = aText.Ptr();
sl@0: 	TInt outputSize =  0;
sl@0: 
sl@0: 	TRunInfoCompact currentRun;
sl@0: 	while (aArraySize)
sl@0: 		{
sl@0: 		TRunInfoCompact newRun(aRunArray->iStart, aRunArray->iLength,
sl@0: 			aRunArray->iDirection, text);
sl@0: 		--aArraySize;
sl@0: 		if (!currentRun.AddRun(newRun))
sl@0: 			{
sl@0: 			if (aBuffer)
sl@0: 				*aBuffer++ = currentRun;
sl@0: 			++outputSize;
sl@0: 			currentRun = newRun;
sl@0: 			}
sl@0: 		++aRunArray; //point to next run
sl@0: 		}
sl@0: 	if (0 < currentRun.Length())
sl@0: 		{
sl@0: 		if (aBuffer)
sl@0: 			*aBuffer++ = currentRun;
sl@0: 		++outputSize;
sl@0: 		}
sl@0: 
sl@0: 	return outputSize;
sl@0: 	}
sl@0: 
sl@0: /**
sl@0: Utility tells whether a character will form a join with the previous
sl@0: base character.
sl@0: 
sl@0: @param aText The text.
sl@0: @param aIndex The index into aText of the character to test.
sl@0: @return ETrue if there is a join before the character.
sl@0: */
sl@0: TBool TRunInfoCompact::JoinBefore(const TText* aText, TInt aIndex)
sl@0: 	{
sl@0: 	TInt charUnderTest = aText[aIndex];
sl@0: 	if (!CFont::CharactersJoin(charUnderTest, KZeroWidthJoiner))
sl@0: 		// Character does not join with anything, so we
sl@0: 		// will not do any more work.
sl@0: 		return EFalse;
sl@0: 	while (aIndex != 0)
sl@0: 		{
sl@0: 		--aIndex;
sl@0: 		TInt c = aText[aIndex];
sl@0: 		// If it is an Arabic point, we will skip it.
sl@0: 		if (0x64B <= c && c < 0x671
sl@0: 			&& !(0x656 <= c && c < 0x670))
sl@0: 			continue;
sl@0: 		return CFont::CharactersJoin(charUnderTest, c);
sl@0: 		}
sl@0: 	return EFalse;
sl@0: 	}