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https://github.com/JakubMelka/PDF4QT.git
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Text drawing using FreeType library
This commit is contained in:
Jakub Melka
@ -20,6 +20,14 @@
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#include "pdfparser.h"
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#include "pdfnametounicode.h"
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#include <ft2build.h>
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#include <freetype/freetype.h>
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#include <freetype/ftglyph.h>
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#include <freetype/fterrors.h>
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#include <freetype/ftoutln.h>
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#include <QMutex>
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namespace pdf
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{
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@ -29,8 +37,271 @@ PDFFont::PDFFont(FontDescriptor fontDescriptor) :
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}
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/// Implementation of the PDFRealizedFont class using PIMPL pattern
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class PDFRealizedFontImpl
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{
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public:
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explicit PDFRealizedFontImpl();
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~PDFRealizedFontImpl();
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/// Fills the text sequence by interpreting byte array according font data and
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/// produces glyphs for the font.
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/// \param byteArray Array of bytes to be interpreted
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/// \param textSequence Text sequence to be filled
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void fillTextSequence(const QByteArray& byteArray, TextSequence& textSequence);
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private:
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friend class PDFRealizedFont;
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static constexpr const PDFReal FORMAT_26_6_MULTIPLIER = 1 / 64.0;
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struct Glyph
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{
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QPainterPath glyph;
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PDFReal advance;
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};
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static int outlineMoveTo(const FT_Vector* to, void* user);
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static int outlineLineTo(const FT_Vector* to, void* user);
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static int outlineConicTo(const FT_Vector* control, const FT_Vector* to, void* user);
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static int outlineCubicTo(const FT_Vector* control1, const FT_Vector* control2, const FT_Vector* to, void* user);
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/// Get glyph for unicode character. Throws exception, if glyph can't be found.
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const Glyph& getGlyphForUnicode(QChar character);
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/// Function checks, if error occured, and if yes, then exception is thrown
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static void checkFreeTypeError(FT_Error error);
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/// Mutex for accessing the glyph data
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QMutex m_mutex;
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/// Glyph cache, must be protected by the mutex above
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std::map<QChar, Glyph> m_glyphCache;
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/// For embedded fonts, this byte array contains embedded font data
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QByteArray m_embeddedFontData;
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/// Instance of FreeType library assigned to this font
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FT_Library m_library;
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/// Face of the font
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FT_Face m_face;
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/// Pixel size of the font
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PDFReal m_pixelSize;
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/// Parent font
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const PDFFont* m_parentFont;
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/// True, if font is embedded
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bool m_isEmbedded;
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/// True, if font has vertical writing system
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bool m_isVertical;
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};
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PDFRealizedFontImpl::PDFRealizedFontImpl() :
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m_library(nullptr),
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m_face(nullptr),
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m_pixelSize(0.0),
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m_parentFont(nullptr),
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m_isEmbedded(false),
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m_isVertical(false)
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{
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}
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PDFRealizedFontImpl::~PDFRealizedFontImpl()
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{
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if (m_face)
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{
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FT_Done_Face(m_face);
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m_face = nullptr;
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}
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if (m_library)
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{
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FT_Done_FreeType(m_library);
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m_library = nullptr;
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}
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}
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void PDFRealizedFontImpl::fillTextSequence(const QByteArray& byteArray, TextSequence& textSequence)
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{
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switch (m_parentFont->getFontType())
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{
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case FontType::Type1:
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case FontType::TrueType:
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{
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// We can use encoding
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QString text = m_parentFont->getTextUsingEncoding(byteArray);
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textSequence.items.reserve(textSequence.items.size() + text.size());
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for (const QChar& character : text)
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{
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const Glyph& glyph = getGlyphForUnicode(character);
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textSequence.items.emplace_back(&glyph.glyph, character, glyph.advance);
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}
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break;
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}
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default:
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{
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// Unhandled font type
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Q_ASSERT(false);
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break;
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}
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}
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}
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int PDFRealizedFontImpl::outlineMoveTo(const FT_Vector* to, void* user)
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{
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Glyph* glyph = reinterpret_cast<Glyph*>(user);
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glyph->glyph.moveTo(to->x * FORMAT_26_6_MULTIPLIER, to->y * FORMAT_26_6_MULTIPLIER);
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return 0;
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}
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int PDFRealizedFontImpl::outlineLineTo(const FT_Vector* to, void* user)
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{
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Glyph* glyph = reinterpret_cast<Glyph*>(user);
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glyph->glyph.lineTo(to->x * FORMAT_26_6_MULTIPLIER, to->y * FORMAT_26_6_MULTIPLIER);
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return 0;
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}
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int PDFRealizedFontImpl::outlineConicTo(const FT_Vector* control, const FT_Vector* to, void* user)
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{
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Glyph* glyph = reinterpret_cast<Glyph*>(user);
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glyph->glyph.cubicTo(control->x * FORMAT_26_6_MULTIPLIER, control->y * FORMAT_26_6_MULTIPLIER, control->x * FORMAT_26_6_MULTIPLIER, control->y * FORMAT_26_6_MULTIPLIER, to->x * FORMAT_26_6_MULTIPLIER, to->y * FORMAT_26_6_MULTIPLIER);
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return 0;
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}
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int PDFRealizedFontImpl::outlineCubicTo(const FT_Vector* control1, const FT_Vector* control2, const FT_Vector* to, void* user)
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{
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Glyph* glyph = reinterpret_cast<Glyph*>(user);
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glyph->glyph.cubicTo(control1->x * FORMAT_26_6_MULTIPLIER, control1->y * FORMAT_26_6_MULTIPLIER, control2->x * FORMAT_26_6_MULTIPLIER, control2->y * FORMAT_26_6_MULTIPLIER, to->x * FORMAT_26_6_MULTIPLIER, to->y * FORMAT_26_6_MULTIPLIER);
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return 0;
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}
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const PDFRealizedFontImpl::Glyph& PDFRealizedFontImpl::getGlyphForUnicode(QChar character)
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{
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QMutexLocker lock(&m_mutex);
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// First look into cache
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auto it = m_glyphCache.find(character);
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if (it != m_glyphCache.cend())
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{
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return it->second;
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}
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FT_UInt glyphIndex = FT_Get_Char_Index(m_face, character.unicode());
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if (glyphIndex)
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{
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Glyph glyph;
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FT_Outline_Funcs interface;
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interface.delta = 0;
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interface.shift = 0;
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interface.move_to = PDFRealizedFontImpl::outlineMoveTo;
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interface.line_to = PDFRealizedFontImpl::outlineLineTo;
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interface.conic_to = PDFRealizedFontImpl::outlineConicTo;
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interface.cubic_to = PDFRealizedFontImpl::outlineCubicTo;
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checkFreeTypeError(FT_Load_Glyph(m_face, glyphIndex, FT_LOAD_NO_BITMAP | FT_LOAD_NO_HINTING));
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checkFreeTypeError(FT_Outline_Decompose(&m_face->glyph->outline, &interface, &glyph));
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glyph.glyph.closeSubpath();
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glyph.advance = !m_isVertical ? m_face->glyph->advance.x : m_face->glyph->advance.y;
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glyph.advance *= FORMAT_26_6_MULTIPLIER;
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m_glyphCache[character] = qMove(glyph);
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return m_glyphCache[character];
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}
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else
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{
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throw PDFParserException(PDFTranslationContext::tr("Glyph for unicode character '%1' not found.").arg(character));
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}
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static Glyph dummy;
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return dummy;
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}
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void PDFRealizedFontImpl::checkFreeTypeError(FT_Error error)
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{
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if (error)
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{
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QString message;
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if (const char* errorString = FT_Error_String(error))
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{
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message = QString::fromLatin1(errorString);
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}
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throw PDFParserException(PDFTranslationContext::tr("FreeType error code %1: message").arg(error).arg(message));
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}
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}
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PDFRealizedFont::~PDFRealizedFont()
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{
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delete m_impl;
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}
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void PDFRealizedFont::fillTextSequence(const QByteArray& byteArray, TextSequence& textSequence)
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{
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m_impl->fillTextSequence(byteArray, textSequence);
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}
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bool PDFRealizedFont::isHorizontalWritingSystem() const
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{
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return !m_impl->m_isVertical;
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}
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PDFRealizedFontPointer PDFRealizedFont::createRealizedFont(const PDFFont* font, PDFReal pixelSize)
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{
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PDFRealizedFontPointer result;
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std::unique_ptr<PDFRealizedFontImpl> implPtr(new PDFRealizedFontImpl());
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PDFRealizedFontImpl* impl = implPtr.get();
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impl->m_parentFont = font;
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const FontDescriptor* descriptor = font->getFontDescriptor();
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if (descriptor->isEmbedded())
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{
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PDFRealizedFontImpl::checkFreeTypeError(FT_Init_FreeType(&impl->m_library));
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if (!descriptor->fontFile.isEmpty())
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{
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impl->m_embeddedFontData = descriptor->fontFile;
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}
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else if (!descriptor->fontFile2.isEmpty())
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{
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impl->m_embeddedFontData = descriptor->fontFile2;
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}
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else if (!descriptor->fontFile3.isEmpty())
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{
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impl->m_embeddedFontData = descriptor->fontFile3;
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}
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// At this time, embedded font data should not be empty!
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Q_ASSERT(!impl->m_embeddedFontData.isEmpty());
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PDFRealizedFontImpl::checkFreeTypeError(FT_New_Memory_Face(impl->m_library, reinterpret_cast<const FT_Byte*>(impl->m_embeddedFontData.constData()), impl->m_embeddedFontData.size(), 0, &impl->m_face));
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PDFRealizedFontImpl::checkFreeTypeError(FT_Select_Charmap(impl->m_face, FT_ENCODING_UNICODE));
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PDFRealizedFontImpl::checkFreeTypeError(FT_Set_Pixel_Sizes(impl->m_face, 0, qRound(pixelSize)));
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impl->m_isVertical = impl->m_face->face_flags & FT_FACE_FLAG_VERTICAL;
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impl->m_isEmbedded = true;
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result.reset(new PDFRealizedFont(implPtr.release()));
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}
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else
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{
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// TODO: Support non-embedded fonts
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throw PDFParserException(PDFTranslationContext::tr("Only embedded fonts are supported."));
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}
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return result;
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}
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PDFFontPointer PDFFont::createFont(const PDFObject& object, const PDFDocument* document)
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{
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// TODO: Create font cache for realized fonts
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const PDFObject& dereferencedFontDictionary = document->getObject(object);
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if (!dereferencedFontDictionary.isDictionary())
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{
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@ -326,9 +597,13 @@ PDFSimpleFont::PDFSimpleFont(FontDescriptor fontDescriptor,
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}
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QRawFont PDFSimpleFont::getRealizedFont(PDFReal fontSize) const
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PDFRealizedFontPointer PDFSimpleFont::getRealizedFont(PDFReal fontSize) const
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{
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// TODO: Fix font creation to use also embedded fonts, font descriptor, etc.
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// TODO: Remove QRawFont
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return PDFRealizedFont::createRealizedFont(this, fontSize);
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/*
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QRawFont rawFont;
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if (m_fontDescriptor.isEmbedded())
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@ -362,7 +637,7 @@ QRawFont PDFSimpleFont::getRealizedFont(PDFReal fontSize) const
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rawFont = QRawFont::fromFont(font, QFontDatabase::Any);
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}
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return rawFont;
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return rawFont;*/
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}
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QString PDFSimpleFont::getTextUsingEncoding(const QByteArray& byteArray) const
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