QScintilla/Exporters/ExporterPDF.py

# -*- coding: utf-8 -*-

# Copyright (c) 2007 - 2009 Detlev Offenbach <detlev@die-offenbachs.de>
#

"""
Module implementing an exporter for PDF.
"""

# This code is a port of the C++ code found in SciTE 1.74
# Original code: Copyright 1998-2006 by Neil Hodgson <neilh@scintilla.org>


from PyQt4.QtCore import *
from PyQt4.QtGui import *
from PyQt4.Qsci import QsciScintilla

from .ExporterBase import ExporterBase

import Preferences

PDF_FONT_DEFAULT = 1    # Helvetica
PDF_FONTSIZE_DEFAULT = 10
PDF_SPACING_DEFAULT = 1.2
PDF_MARGIN_DEFAULT = 72 # 1.0"
PDF_ENCODING = "WinAnsiEncoding"

PDFfontNames = [
    "Courier", "Courier-Bold", "Courier-Oblique", "Courier-BoldOblique",
    "Helvetica", "Helvetica-Bold", "Helvetica-Oblique", "Helvetica-BoldOblique",
    "Times-Roman", "Times-Bold", "Times-Italic", "Times-BoldItalic"
]
PDFfontAscenders =  [629, 718, 699]
PDFfontDescenders = [157, 207, 217]
PDFfontWidths =     [600,   0,   0]

PDFpageSizes = {
    # name   : (height, width)
    "Letter" : (792, 612), 
    "A4"     : (842, 595), 
}

class PDFStyle(object):
    """
    Simple class to store the values of a PDF style.
    """
    def __init__(self):
        """
        Constructor
        """
        self.fore = ""
        self.font = 0

class PDFObjectTracker(object):
    """
    Class to conveniently handle the tracking of PDF objects
    so that the cross-reference table can be built (PDF1.4Ref(p39))
    All writes to the file are passed through a PDFObjectTracker object.
    """
    def __init__(self, file):
        """
        Constructor
        
        @param file file object open for writing (file)
        """
        self.file = file
        self.offsetList = []
        self.index = 1
        
    def write(self, objectData):
        """
        Public method to write the data to the file.
        
        @param objectData data to be written (integer or string)
        """
        if isinstance(objectData, int):
            self.file.write("%d" % objectData)
        else:
            self.file.write(objectData)
        
    def add(self, objectData):
        """
        Public method to add a new object.
        
        @param objectData data to be added (integer or string)
        @return object number assigned to the supplied data (integer)
        """
        self.offsetList.append(self.file.tell())
        self.write(self.index)
        self.write(" 0 obj\n")
        self.write(objectData)
        self.write("endobj\n")
        ind = self.index
        self.index += 1
        return ind
        
    def xref(self):
        """
        Public method to build the xref table.
        
        @return file offset of the xref table (integer)
        """
        xrefStart = self.file.tell()
        self.write("xref\n0 ")
        self.write(self.index)
        # a xref entry *must* be 20 bytes long (PDF1.4Ref(p64))
        # so extra space added; also the first entry is special
        self.write("\n0000000000 65535 f \n")
        ind = 0
        while ind < len(self.offsetList):
            self.write("%010d 00000 n \n" % self.offsetList[ind])
            ind += 1
        return xrefStart

class PDFRender(object):
    """
    Class to manage line and page rendering. 
    
    Apart from startPDF, endPDF everything goes in via add() and nextLine()
    so that line formatting and pagination can be done properly.
    """
    def __init__(self):
        """
        Constructor
        """
        self.pageStarted = False
        self.firstLine = False
        self.pageCount = 0
        self.pageData = ""
        self.style = {}
        self.segStyle = ""
        self.segment = ""
        self.pageMargins = {
            "left"   : 72, 
            "right"  : 72, 
            "top"    : 72, 
            "bottom" : 72, 
        }
        self.fontSize = 0
        self.fontSet = 0
        self.leading = 0.0
        self.pageWidth = 0
        self.pageHeight = 0
        self.pageContentStart = 0
        self.xPos = 0.0
        self.yPos = 0.0
        self.justWhiteSpace = False
        self.oT = None
        
    def fontToPoints(self, thousandths):
        """
        Public method to convert the font size to points.
        
        @return point size of the font (integer)
        """
        return self.fontSize * thousandths / 1000.0
        
    def setStyle(self, style_):
        """
        Public method to set a style.
        
        @param style_ style to be set (integer)
        @return the PDF string to set the given style (string)
        """
        styleNext = style_
        if style_ == -1:
            styleNext = self.styleCurrent
        
        buf = ""
        if styleNext != self.styleCurrent or style_ == -1:
            if self.style[self.styleCurrent].font != self.style[styleNext].font or \
               style_ == -1:
                buf += "/F%d %d Tf " % (self.style[styleNext].font + 1, self.fontSize)
            if self.style[self.styleCurrent].fore != self.style[styleNext].fore or \
               style_ == -1:
                buf += "%srg " % self.style[styleNext].fore
        return buf
        
    def startPDF(self):
        """
        Public method to start the PDF document.
        """
        if self.fontSize <= 0:
            self.fontSize = PDF_FONTSIZE_DEFAULT
        
        # leading is the term for distance between lines
        self.leading = self.fontSize * PDF_SPACING_DEFAULT
        
        # sanity check for page size and margins
        pageWidthMin = int(self.leading) + \
                       self.pageMargins["left"] + self.pageMargins["right"]
        if self.pageWidth < pageWidthMin:
            self.pageWidth = pageWidthMin
        pageHeightMin = int(self.leading) + \
                       self.pageMargins["top"] + self.pageMargins["bottom"]
        if self.pageHeight < pageHeightMin:
            self.pageHeight = pageHeightMin
        
        # start to write PDF file here (PDF1.4Ref(p63))
        # ASCII>127 characters to indicate binary-possible stream
        self.oT.write("%PDF-1.3\n%�쏢\n")
        self.styleCurrent = QsciScintilla.STYLE_DEFAULT
        
        # build objects for font resources; note that font objects are
        # *expected* to start from index 1 since they are the first objects
        # to be inserted (PDF1.4Ref(p317))
        for i in range(4):
            buffer = \
                "<</Type/Font/Subtype/Type1/Name/F%d/BaseFont/%s/Encoding/%s>>\n" % \
                (i + 1, PDFfontNames[self.fontSet * 4 + i], PDF_ENCODING)
            self.oT.add(buffer)
        
        self.pageContentStart = self.oT.index
        
    def endPDF(self):
        """
        Public method to end the PDF document.
        """
        if self.pageStarted:
            # flush buffers
            self.endPage()
        
        # refer to all used or unused fonts for simplicity
        resourceRef = self.oT.add(
            "<</ProcSet[/PDF/Text]\n/Font<</F1 1 0 R/F2 2 0 R/F3 3 0 R/F4 4 0 R>> >>\n")
        
        # create all the page objects (PDF1.4Ref(p88))
        # forward reference pages object; calculate its object number
        pageObjectStart = self.oT.index
        pagesRef = pageObjectStart + self.pageCount
        for i in range(self.pageCount):
            buffer = "<</Type/Page/Parent %d 0 R\n" \
                     "/MediaBox[ 0 0 %d %d]\n" \
                     "/Contents %d 0 R\n" \
                     "/Resources %d 0 R\n>>\n" % \
                     (pagesRef, self.pageWidth, self.pageHeight, 
                      self.pageContentStart + i, resourceRef)
            self.oT.add(buffer)
        
        # create page tree object (PDF1.4Ref(p86))
        self.pageData = "<</Type/Pages/Kids[\n"
        for i in range(self.pageCount):
            self.pageData += "%d 0 R\n" % (pageObjectStart + i)
        self.pageData += "]/Count %d\n>>\n" % self.pageCount
        self.oT.add(self.pageData)
        
        # create catalog object (PDF1.4Ref(p83))
        buffer = "<</Type/Catalog/Pages %d 0 R >>\n" % pagesRef
        catalogRef = self.oT.add(buffer)
        
        # append the cross reference table (PDF1.4Ref(p64))
        xref = self.oT.xref()
        
        # end the file with the trailer (PDF1.4Ref(p67))
        buffer = "trailer\n<< /Size %d /Root %d 0 R\n>>\nstartxref\n%d\n%%%%EOF\n" % \
                 (self.oT.index, catalogRef, xref)
        self.oT.write(buffer)
        
    def add(self, ch, style_):
        """
        Public method to add a character to the page.
        
        @param ch character to add (string)
        @param style_ number of the style of the character (integer)
        """
        if not self.pageStarted:
            self.startPage()
        
        # get glyph width (TODO future non-monospace handling)
        glyphWidth = self.fontToPoints(PDFfontWidths[self.fontSet])
        self.xPos += glyphWidth
        
        # if cannot fit into a line, flush, wrap to next line
        if self.xPos > self.pageWidth - self.pageMargins["right"]:
            self.nextLine()
            self.xPos += glyphWidth
        
        # if different style, then change to style
        if style_ != self.styleCurrent:
            self.flushSegment()
            # output code (if needed) for new style
            self.segStyle = self.setStyle(style_)
            self.stylePrev = self.styleCurrent
            self.styleCurrent = style_
        
        # escape these characters
        if ch == ')' or ch == '(' or ch == '\\':
            self.segment += '\\'
        if ch != ' ':
            self.justWhiteSpace = False
        self.segment += ch # add to segment data
        
    def flushSegment(self):
        """
        Public method to flush a segment of data.
        """
        if len(self.segment) > 0:
            if self.justWhiteSpace:     # optimise
                self.styleCurrent = self.stylePrev
            else:
                self.pageData += self.segStyle
            self.pageData += "(%s)Tj\n" % self.segment
            self.segment = ""
            self.segStyle = ""
            self.justWhiteSpace = True
        
    def startPage(self):
        """
        Public method to start a new page.
        """
        self.pageStarted = True
        self.firstLine = True
        self.pageCount += 1
        fontAscender = self.fontToPoints(PDFfontAscenders[self.fontSet])
        self.yPos = self.pageHeight - self.pageMargins["top"] - fontAscender
        
        # start a new page
        buffer = "BT 1 0 0 1 %d %d Tm\n" % (self.pageMargins["left"], int(self.yPos))
        
        # force setting of initial font, colour
        self.segStyle = self.setStyle(-1)
        buffer += self.segStyle
        self.pageData = buffer
        self.xPos = self.pageMargins["left"]
        self.segment = ""
        self.flushSegment()
        
    def endPage(self):
        """
        Public method to end a page.
        """
        self.pageStarted = False
        self.flushSegment()
        
        # build actual text object; +3 is for "ET\n"
        # PDF1.4Ref(p38) EOL marker preceding endstream not counted
        textObj = "<</Length %d>>\nstream\n%sET\nendstream\n" % \
                  (len(self.pageData) - 1 + 3, self.pageData)
        self.oT.add(textObj)
        
    def nextLine(self):
        """
        Public method to start a new line.
        """
        if not self.pageStarted:
            self.startPage()
        
        self.xPos = self.pageMargins["left"]
        self.flushSegment()
        
        # PDF follows cartesian coords, subtract -> down
        self.yPos -= self.leading
        fontDescender = self.fontToPoints(PDFfontDescenders[self.fontSet])
        if self.yPos < self.pageMargins["bottom"] + fontDescender:
            self.endPage()
            self.startPage()
            return
        
        if self.firstLine:
            # avoid breakage due to locale setting
            f = int(self.leading * 10 + 0.5)
            buffer = "0 -%d.%d TD\n" % (f // 10, f % 10)
            self.firstLine = False
        else:
            buffer = "T*\n"
        self.pageData += buffer

class ExporterPDF(ExporterBase):
    """
    Class implementing an exporter for PDF.
    """
    def __init__(self, editor, parent = None):
        """
        Constructor
        
        @param editor reference to the editor object (QScintilla.Editor.Editor)
        @param parent parent object of the exporter (QObject)
        """
        ExporterBase.__init__(self, editor, parent)
    
    def __getPDFRGB(self, color):
        """
        Private method to convert a color object to the correct PDF color.
        
        @param color color object to convert (QColor)
        @return PDF color description (string)
        """
        pdfColor = ""
        for component in [color.red(), color.green(), color.blue()]:
            c = (component * 1000 + 127) // 255
            if c == 0 or c == 1000:
                pdfColor += "%d " % (c // 1000)
            else:
                pdfColor += "0.%03d " % c
        return pdfColor
        
    def exportSource(self):
        """
        Public method performing the export.
        """
        self.pr = PDFRender()
        
        filename = self._getFileName(self.trUtf8("PDF Files (*.pdf)"))
        if not filename:
            return
        
        try:
            QApplication.setOverrideCursor(QCursor(Qt.WaitCursor))
            QApplication.processEvents()
            
            self.editor.recolor(0, -1)
            lex = self.editor.getLexer()
            
            tabSize = Preferences.getEditor("TabWidth")
            if tabSize == 0:
                tabSize = 4
            
            # get magnification value to add to default screen font size
            self.pr.fontSize = Preferences.getEditorExporter("PDF/Magnification")
            
            # set font family according to face name
            fontName = Preferences.getEditorExporter("PDF/Font")
            self.pr.fontSet = PDF_FONT_DEFAULT
            if fontName == "Courier":
                self.pr.fontSet = 0
            elif fontName == "Helvetica":
                self.pr.fontSet = 1
            elif fontName == "Times":
                self.pr.fontSet = 2
            
            # page size: height, width, 
            pageSize = Preferences.getEditorExporter("PDF/PageSize")
            try:
                pageDimensions = PDFpageSizes[pageSize]
            except KeyError:
                pageDimensions = PDFpageSizes["A4"]
            self.pr.pageHeight = pageDimensions[0]
            self.pr.pageWidth = pageDimensions[1]
            
            # page margins: left, right, top, bottom
            # < 0 to use PDF default values
            val = Preferences.getEditorExporter("PDF/MarginLeft")
            if val < 0:
                self.pr.pageMargins["left"] = PDF_MARGIN_DEFAULT
            else:
                self.pr.pageMargins["left"] = val
            val = Preferences.getEditorExporter("PDF/MarginRight")
            if val < 0:
                self.pr.pageMargins["right"] = PDF_MARGIN_DEFAULT
            else:
                self.pr.pageMargins["right"] = val
            val = Preferences.getEditorExporter("PDF/MarginTop")
            if val < 0:
                self.pr.pageMargins["top"] = PDF_MARGIN_DEFAULT
            else:
                self.pr.pageMargins["top"] = val
            val = Preferences.getEditorExporter("PDF/MarginBottom")
            if val < 0:
                self.pr.pageMargins["bottom"] = PDF_MARGIN_DEFAULT
            else:
                self.pr.pageMargins["bottom"] = val
            
            # collect all styles available for that 'language'
            # or the default style if no language is available...
            if lex:
                istyle = 0
                while istyle <= QsciScintilla.STYLE_MAX:
                    if (istyle <= QsciScintilla.STYLE_DEFAULT or \
                        istyle > QsciScintilla.STYLE_LASTPREDEFINED):
                        if lex.description(istyle) or \
                           istyle == QsciScintilla.STYLE_DEFAULT:
                            style = PDFStyle()
                            
                            font = lex.font(istyle)
                            if font.italic():
                                style.font |= 2
                            if font.bold():
                                style.font |= 1
                            
                            colour = lex.color(istyle)
                            style.fore = self.__getPDFRGB(colour)
                            self.pr.style[istyle] = style
                        
                        # grab font size from default style
                        if istyle == QsciScintilla.STYLE_DEFAULT:
                            fontSize = QFontInfo(font).pointSize()
                            if fontSize > 0:
                                self.pr.fontSize += fontSize
                            else:
                                self.pr.fontSize = PDF_FONTSIZE_DEFAULT
                    
                    istyle += 1
            else:
                style = PDFStyle()
                
                font = Preferences.getEditorOtherFonts("DefaultFont")
                if font.italic():
                    style.font |= 2
                if font.bold():
                    style.font |= 1
                
                colour = self.editor.color()
                style.fore = self.__getPDFRGB(colour)
                self.pr.style[0] = style
                self.pr.style[QsciScintilla.STYLE_DEFAULT] = style
                
                fontSize = QFontInfo(font).pointSize()
                if fontSize > 0:
                    self.pr.fontSize += fontSize
                else:
                    self.pr.fontSize = PDF_FONTSIZE_DEFAULT
            
            try:
                f = open(filename, "w")
                
                # initialise PDF rendering
                ot = PDFObjectTracker(f)
                self.pr.oT = ot
                self.pr.startPDF()
                
                # do here all the writing
                lengthDoc = self.editor.length()
                
                if lengthDoc == 0:
                    self.pr.nextLine() # enable zero length docs
                else:
                    pos = 0
                    column = 0
                    utf8 = self.editor.isUtf8()
                    utf8Ch = ""
                    utf8Len = 0
                    
                    while pos < lengthDoc:
                        ch = self.editor.rawCharAt(pos)
                        style = self.editor.styleAt(pos)
                        
                        if ch == '\t':
                            # expand tabs
                            ts = tabSize - (column % tabSize)
                            column += ts
                            self.pr.add(' ' * ts, style)
                        elif ch == '\r' or ch == '\n':
                            if ch == '\r' and self.editor.rawCharAt(pos + 1) == '\n':
                                pos += 1
                            # close and begin a newline...
                            self.pr.nextLine()
                            column = 0
                        else:
                            # write the character normally...
                            if ord(ch) > 127 and utf8:
                                utf8Ch += ch
                                if utf8Len == 0:
                                    if (ord(utf8Ch[0]) & 0xF0) == 0xF0:
                                        utf8Len = 4
                                    elif (ord(utf8Ch[0]) & 0xE0) == 0xE0:
                                        utf8Len = 3
                                    elif (ord(utf8Ch[0]) & 0xC0) == 0xC0:
                                        utf8Len = 2
                                    column -= 1 # will be incremented again later
                                elif len(utf8Ch) == utf8Len:
                                    # convert utf-8 character to win ansi using cp1250
                                    ch = utf8Ch.decode('utf8')\
                                               .encode('cp1250', 'replace')
                                    self.pr.add(ch, style)
                                    utf8Ch = ""
                                    utf8Len = 0
                                else:
                                    column -= 1 # will be incremented again later
                            else:
                                self.pr.add(ch, style)
                            column += 1
                        
                        pos += 1
                
                # write required stuff and close the PDF file
                self.pr.endPDF()
                f.close()
            except IOError as err:
                QApplication.restoreOverrideCursor()
                QMessageBox.critical(self.editor,
                    self.trUtf8("Export source"),
                    self.trUtf8(
                        """<p>The source could not be exported to <b>{0}</b>.</p>"""
                        """<p>Reason: {1}</p>""")\
                        .format(filename, str(err)),
                    QMessageBox.StandardButtons(\
                        QMessageBox.Ok))
        finally:
            QApplication.restoreOverrideCursor()