/*

* Copyright (c) 1999-2009 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

* Text caching for TAGMA: cacheing of text and formats extracted from a text source,

*

*/

#include "TMSTD.H"

#include <bidi.h>

inline TBool IsSurrogate(TText a) { return 0xD800 == (a & 0xF800); }

inline TBool IsHighSurrogate(TText a) { return 0xD800 == (a & 0xFC00); }

inline TBool IsLowSurrogate(TText a) { return 0xDC00 == (a & 0xFC00); }

inline TChar JoinSurrogates(TText aHigh, TText aLow)

	{

	return ((aHigh - 0xd7f7) << 10) + aLow;

	}

inline TText16 GetHighSurrogate(TUint aChar)

	{

	return STATIC_CAST(TText16, 0xD7C0 + (aChar >> 10));

	}

inline TText16 GetLowSurrogate(TUint aChar)

	{

	return STATIC_CAST(TText16, 0xDC00 | (aChar & 0x3FF));

	}

TUint RTmTextCache::Char(TInt aPos)

	{

	if (aPos < 0 || aPos > iDocumentLength)

		return 0xFFFF;

	if (aPos == iDocumentLength)

		return CEditableText::EParagraphDelimiter;

	if (aPos < iTextStart || aPos >= iTextStart + iTextLength)

		{

		TPtrC p;

		GetText(aPos,KMaxTInt,p);

		}

	if ( IsHighSurrogate( iText[aPos-iTextStart] ) ) 

		{

		if (iTextStart+iTextLength-aPos > 1)

			{

			TText high = iText[aPos-iTextStart];

			TText low = iText[aPos-iTextStart+1];

			if ( IsLowSurrogate( low ) )

			    return JoinSurrogates( high, low );

			else

			    // If the corrupt surrogate, it is treated as what it is mapped

			    return iSource.Map( high );

			}

		else

			{

			// If the corrupt surrogate, it is treated as what it is mapped

			return iSource.Map( iText[aPos-iTextStart] );

			}

		}

	else

		{

		return iText[aPos - iTextStart];

		}

	}

/**

Measure the width of some text, substituting glyphs where necessary.

@param aStart Start position of text in document

@param aEnd (Exclusive) end position of text in document

@param aRightToLeft True if the text is right-to-left

@param aMaxAdvance Measurement will stop if this advance is exceeded

@param aOutput Output form text measurement function

@param aExtraChar

	Fetch this much context beyond aEnd. This helps when the text is to be

	truncated, and aEnd is not certain to be at a cluster boundary.

@return Advance width. Side-bearings are not included. */

TInt RTmTextCache::AdvanceWidthL(TInt aStart, TInt aEnd, TBool aRightToLeft,

						  TInt aMaxAdvance, CFbsFont::TMeasureTextOutput* aOutput, TInt aExtraChar)

	{

	// Get the displayed text, up to the copy fit width if necessary.

	TInt length = aEnd - aStart;

	TText buffer[KMaxTextChunkSize + 2 + 1];

	if (length > KMaxTextChunkSize)

		TmPanic(ETextWidthBufferOverflow);

	CTmTextFontCache *font = NULL;

	// Get the text in logical order. If a custom interface to draw (in later stages)

	// the text in context exists, then measure the text with context.

	TInt error;

	if (Source().GetExtendedInterface(KTmCustomExtensionUid))

		{

		error = GetDisplayedText(aStart, aEnd + aExtraChar,

								  aRightToLeft ? ELogicalRightToLeft : ELeftToRight,

								  buffer,iContextCharPerChunk, 0, &font);

		}

		else

			{

			error = GetDisplayedText(aStart, aEnd + aExtraChar,

								  aRightToLeft ? ELogicalRightToLeft : ELeftToRight,

								  buffer,0, 0, &font);

			}

	// Don't push font onto cleanup stack because this method only leaves below.

	// If there was an error in GetDisplayedText, font will have been closed

	if (error)

		User::Leave(error);

	CFont::TMeasureTextInput input;

 	input.iFlags = aRightToLeft?

 		CFont::TMeasureTextInput::EFVisualOrderRightToLeft

 		: CFont::TMeasureTextInput::EFVisualOrder;

   	// Create a new buffer which will have the context  as well

   	TPtrC inputText(buffer, length + 2 + aExtraChar);

   	input.iStartInputChar = 1;

   	input.iEndInputChar = input.iStartInputChar + length;

   	input.iMaxBounds = aMaxAdvance;

   	input.iFlags |= CFont::TMeasureTextInput::EFIncludePenPositionInBoundsCheck;

 	CFbsFont::TMeasureTextOutput output;

 	CFbsFont::TMeasureTextOutput* pOutput = aOutput? aOutput : &output;

 	// Measure this text in the context supplied. Any punctuations in this chunk

 	// will now be measured based on this context.

 	TInt width = font->Font().MeasureText(inputText, &input, pOutput);

 	// Do not report initial Zero-Width Joiner or 0xFFFF

 	if (0 != pOutput->iChars)

 		--pOutput->iChars;

	// Find the new context at the end of this chunk. This will be used to pass on to the next chunk.

	// If the context hasn't changed, pass on the previous context.

	TUint last;

	TInt textLength = input.iStartInputChar + pOutput->iChars;

	TChar::TBdCategory cat = TChar::ELeftToRight;

	while (textLength != 0)

		{

		TUint charSize = 1;

		last = *(inputText.Ptr() + textLength);

		if ( IsSurrogate( last ) && textLength > 1 ) 

			{

			TText low = *(inputText.Ptr() + textLength);

			TText high = *(inputText.Ptr() + textLength - 1);

			if ( IsLowSurrogate( low ) && IsHighSurrogate( high ) )

				{

				charSize = 2;

				last = JoinSurrogates( high, low );

				}

			else

			    {

			    // If the corrupt surrogate, it is treated as what it is mapped

			    last = iSource.Map( last );

			    }

			}

		cat = TChar(last).GetBdCategory();

		if (last != 65535 && textLength !=0 &&

			(cat == TChar::ELeftToRight ||

			 cat == TChar::ERightToLeft ||

			 cat == TChar::ERightToLeftArabic))

			{

			iContextCharPerChunk = last;

			}

		textLength -= charSize;

		}

	// Check if this chunk is a punctuation chunk. If it is not, the context in the byte code for this chunk

	// will be NULL. Otherwise it will just be the previous context.

	if (cat == TChar::ELeftToRight ||

		 cat == TChar::ERightToLeft ||

		 cat == TChar::ERightToLeftArabic ||

		 cat == TChar::EWhitespace)

		{

		iContextCharInByteCode = NULL;

		}

	else

		iContextCharInByteCode = iContextCharPerChunk;

	font->Close();

	return width;

	}

/** Measure the width of some text, substituting glyphs where necessary.

@param aStart Start position of text in document

@param aEnd (Exclusive) end position of text in document

@param aRightToLeft True if the text is right-to-left

@return width including side-bearings */

TInt RTmTextCache::TotalWidthL(TInt aStart, TInt aEnd,

	TBool aRightToLeft)

	{

 	CFbsFont::TMeasureTextOutput output;

 	TInt width = AdvanceWidthL(aStart, aEnd, aRightToLeft, KMaxTInt, &output);

 	// Add on any protruding side-bearings

 	if (width < output.iBounds.iBr.iX)

 		width = output.iBounds.iBr.iX;

 	if (output.iBounds.iTl.iX < 0)

 		width -= output.iBounds.iTl.iX;

 	return width;

	}

/*

Get source text starting at aPos and not more than (aMaxEndChar - aPos) characters.

If aFormat is non-null get the format.

@param aFont If aFont is not null, on return contains a pointer to an opened CTmTextFontCache*

		The caller must call Close on aFont when finished with the font.

@return Failure condition from getting the font, if any.

*/

TInt RTmTextCache::GetText(TInt aPos,TInt aMaxEndChar,TPtrC& aText,TTmCharFormat* aFormat,CTmTextFontCache** aFont)

	{

	TInt error = KErrNone;

	if (aPos < iTextStart || aPos >= iTextStart + iTextLength)

		{

		iTextStart = aPos;

		iTextBuffer.Zero();

		TPtrC p;

		TTmCharFormat new_format;

		iSource.GetText(iTextStart,p,new_format);

		if (!(new_format.iFontSpec == iFormat.iFontSpec))

			{

			ReleaseFont();

			}

		iFormat = new_format;

		iText = p.Ptr();

		iTextLength = p.Length();

		if (iTextLength == 0)

			TmPanic(EZeroLengthTextSupplied);

		}

	int offset = aPos - iTextStart;

	aText.Set(iText + offset,iTextLength - offset);

	if (aText.Length() > aMaxEndChar - aPos)

		{

		const TText* p = aText.Ptr();

		aText.Set(p,aMaxEndChar - aPos);

		}

	if (aFormat)

		*aFormat = iFormat;

	if (aFont)

		{

		if (iFont == NULL)

			{

			TFontSpec fs;

			iFormat.iFontSpec.GetTFontSpec(fs);

			CFont *font = NULL;

			error = iDevice.GetNearestFontInTwips(font,fs);

			if (font != NULL)

				{

				iFont = CTmTextFontCache::New(iDevice, *font);

				if (iFont == NULL)

					{

					iDevice.ReleaseFont(font);

					error = KErrNoMemory;

					}

				}

			}

		if (iFont && error == KErrNone)

			{

			*aFont = iFont;

			iFont->Open();

			}

		}

	return error;

	}

/** Finds the extent of the run of characters that have the same format as

aFormat following aPos, up to aMaxEndChar.

@internalComponent */

TInt FollowOnTextEnd(TInt aPos, TInt aMaxEndChar,

	const TTmCharFormat& aFormat, MTmSource& aSource, TBool forcedExtend = EFalse)

	{

	TTmCharFormat format;

	TPtrC text;

	while (aPos < aMaxEndChar)

		{

		aSource.GetText(aPos, text, format);

		// The forcedExtend flag is used for only one case that to prevent single ZWJ being 

		// returned by RTmTextCache::GetTextL. Please see RTmTextCache::GetTextL.

		if (format != aFormat && !forcedExtend)

			return aPos;

		TInt length = text.Length();

		if (length == 0)

			return aPos;

		if (text[0] == CEditableText::EPictureCharacter)

			{

			return aPos;

			}

		aPos += length;

		}

	return aMaxEndChar;

	}

/** Copys the specified text from the source into the buffer.

@internalComponent */

void AppendTextToBuffer(TDes& aBuffer,

	TInt aStart, TInt aEnd, MTmSource& aSource)

	{

	TTmCharFormat dummy;

	while (aStart != aEnd)

		{

		TPtrC text;

		aSource.GetText(aStart, text, dummy);

		TInt textEnd = aStart + text.Length();

		__ASSERT_ALWAYS(aStart < textEnd, TmPanic(EZeroLengthTextSupplied));

		if (aEnd < textEnd)

			{

			// This run is overlong, so just append all that will fit

			aBuffer.Append(&text[0], aEnd - aStart);

			return;

			}

		aBuffer.Append(text);

		aStart = textEnd;

		}

	}

/** Same as GetText but will join text together if it has the same format.

@param

	aText the text returned. Is valid until the next call of GetText, GetTextL

	or Close.

@param aFont If aFont is not null, on return contains a pointer to an opened CTmTextFontCache*

		The caller must call Close on aFont when finished with the font.

@internalComponent */

TInt RTmTextCache::GetTextL(TInt aPos, TInt aMaxEndChar, TPtrC& aText,

	TTmCharFormat* aFormat, CTmTextFontCache** aFont)

	{

	TInt bufferEnd = iTextBufferStart + iTextBuffer.Length();

	if ( iTextBufferStart <= aPos && aPos < bufferEnd

		&& (aMaxEndChar < bufferEnd || iTextBufferEndsInFormatChange) )

		{

		TInt textEnd = Min(bufferEnd, aMaxEndChar);

		aText.Set(&iTextBuffer[aPos - iTextBufferStart], textEnd - aPos);

		if (aFormat)

			*aFormat = iFormat;

		if (aFont)

			{

			*aFont = iFont;

			iFont->Open();

			}

		return KErrNone;

		}

	TInt error =  GetText(aPos, aMaxEndChar, aText, aFormat, aFont);

	TBool forcedExtend = EFalse;

	const TText* ch = aText.Ptr();

	// When the text is just a ZWJ, the following text should be forced extended, because the ZWJ should

	// never be returned as a single text chunk.

	if (aText.Length() == 1 && *ch == KZeroWidthJoiner)

		forcedExtend = ETrue;

	if (error == KErrNone)

		{

		CleanupClosePushL(**aFont);

		TInt endOfAText = aPos + aText.Length();

		TInt end = FollowOnTextEnd(endOfAText, aMaxEndChar, iFormat, iSource, forcedExtend);

		if (end != endOfAText)

			{

			iTextBuffer.Zero();

			if (iTextBuffer.MaxLength() < end - aPos)

				iTextBuffer.ReAllocL(end - aPos);

			iTextBuffer.Append(aText);

			AppendTextToBuffer(iTextBuffer, endOfAText, end, iSource);

			iTextBufferStart = aPos;

			iTextBufferEndsInFormatChange = end < aMaxEndChar;

			aText.Set(iTextBuffer);

			}

		CleanupStack::Pop(*aFont);

		}

	return error;

	}

TBool RTmTextCache::IsArabicPoint(TInt aChar)

	{

	return 0x64B <= aChar && aChar < 0x671

		&& !(0x656 <= aChar && aChar < 0x670);

	}

TUint SupplementaryCharMap(MTmSource *aSource, TText aHigh, TText aLow)

    {

    TChar c(aHigh);

    if ( IsHighSurrogate( aHigh ) && IsLowSurrogate( aLow ))

        c = JoinSurrogates( aHigh, aLow );

    return aSource->Map(c);

    }

/**

Gets all the displayed text in the range aStart...aEnd and puts it into a

buffer that must be at least aEnd - aStart + 2 characters in length. If

aFormat is non-null gets the format of the first section of text. If aFont

is non-null gets the font for the first section of text. If aDirectionality

is EVisualRightToLeft reverses the text and mirrors appropriate characters.

Adds a zero-width joiner to the start and/or end of the text returned if

these are necessary for the correct contextual glyph choice. Adds a

0xFFFF to each end if this is not required.

@param aFont If aFont is not null, on return contains a pointer to an opened CTmTextFontCache*

		The caller must call Close on aFont when finished with the font.

@return Failure condition on getting font, if any.

@internalComponent

*/

TInt RTmTextCache::GetDisplayedText(TInt aStart, TInt aEnd,

									TDisplayedTextDirectionality aDirectionality, TText* aBuffer,TUint aContextChar,

									TTmCharFormat* aFormat, CTmTextFontCache** aFont)

	{

	__ASSERT_DEBUG(aStart <= aEnd, TmPanic(EBadArg));

	if (aContextChar == 0)

		aBuffer[0] = 0xFFFF;

	else

		aBuffer[0] = aContextChar;

	if (aEnd == aStart)

		return KErrGeneral;

	TPtrC text;

	TText* output = aBuffer;

	TTmCharFormat format;

	// might the (logically) first character join with the previous one?

	GetText(aStart, aStart + 1, text, &format);	

    if (aFormat)

        *aFormat = format;

	TInt c = iSource.Map(text[0]);

	if (IsHighSurrogate(text[0]))

		{

		GetText(aStart, aStart + 2, text, &format);

		if (aFormat)

			*aFormat = format;

		if (text.Length() >= 2)

			{

			if (IsLowSurrogate(text[1]))

				{

				c = SupplementaryCharMap(&iSource, text[0], text[1]);

				}

			else

				{

				c = iSource.Map(text[0]);	

				}

			}

		}

	if (0 < aStart && CFont::CharactersJoin(

		aDirectionality == ELeftToRight? KZeroWidthJoiner : c,

		aDirectionality == ELeftToRight? c : KZeroWidthJoiner))

		{

		TInt prev = aStart - 1;

		TTmCharFormat prevFormat;

		GetText(prev, aStart, text, &prevFormat);

		TInt prevChar = iSource.Map(text[0]);

		while (0 < prev && IsArabicPoint(prevChar))

			{

			GetText(--prev, aStart, text, &prevFormat);

			prevChar = iSource.Map(text[0]);

			}

		if (CFont::CharactersJoin(

			aDirectionality == ELeftToRight? prevChar : c,

			aDirectionality == ELeftToRight? c : prevChar)

			&& format == prevFormat)

			// Characters join at the beginning.

			*output = KZeroWidthJoiner;

		}

	output = aBuffer + 1;

	TInt error = KErrNone;

	while (aStart < aEnd)

		{

		TInt currentError = GetText(aStart, aEnd, text, &format, aFont);

		// do not have to push aFont onto clean-up stack because this is a non-leaving method

		if (aFont)

			error = currentError;

		aFont = NULL;

		TInt length = text.Length();

		aStart += length;

		const TText* input = text.Ptr();

		const TText* end = input + length;

		while (input < end)

			{

			if (IsHighSurrogate(*input))

				{

				if (input+1 < end && IsLowSurrogate(input[1]))

					{

					c = SupplementaryCharMap(&iSource, input[0], input[1]);

					input++;

					input++;

					*output++ = GetHighSurrogate( c );

					*output++ = GetLowSurrogate( c );

					}

				else

					{

					c = iSource.Map(input[0]);

					input++;

					*output++ = static_cast<TText>(c);

					}