gramps/src/docgen/GtkPrint.py

#
# Gramps - a GTK+/GNOME based genealogy program
#
# Copyright (C) 2000-2007  Donald N. Allingham
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#

# $Id$

"""Printing interface based on gtk.Print*.
"""

__revision__ = "$Revision$"

#------------------------------------------------------------------------
#
# Python modules
#
#------------------------------------------------------------------------
from gettext import gettext as _

#------------------------------------------------------------------------
#
# Gramps modules
#
#------------------------------------------------------------------------
import BaseDoc
from PluginUtils import register_text_doc, register_draw_doc, register_book_doc
import Errors

#------------------------------------------------------------------------
#
# Set up logging
#
#------------------------------------------------------------------------
import logging
log = logging.getLogger(".GtkDoc")

#-------------------------------------------------------------------------
#
# GTK modules
#
#-------------------------------------------------------------------------
import gtk
import cairo
import pango
import pangocairo

if gtk.pygtk_version < (2,10,0):
    raise Errors.UnavailableError(
        _("Cannot be loaded because PyGtk 2.10 or later is not installed"))

###------------------------------------------------------------------------
###
### PreviewCanvas and PreviewWindow
###
### These classes provide a simple print preview functionality.
### They do not actually render anything themselves, they rely
### upon the Print opertaion to do the rendering.
###
###------------------------------------------------------------------------
##class PreviewCanvas(gtk.DrawingArea):
    ##"""Provide a simple widget for displaying a
    ##cairo rendering used to show print preview windows.
    ##"""
    
    ##def __init__(self,
                 ##operation,
                 ##preview_operation,
                 ##print_context):
        ##gtk.DrawingArea.__init__(self)
        ##self._operation = operation
        ##self._preview_operation = preview_operation
        ##self._print_context = print_context

        ##self.connect("expose_event",self.expose)
        ##self.connect("realize",self.realize)
        
        ##self._page_no = 1 # always start on page 1


    ##def set_page(self,page):
        ##"""Change which page is displayed"""
        ##if page > 0:
            ##self._page_no = page
            ##self.queue_draw()
        
    ##def realize(self, dummy=None):
        ##"""Generate the cairo context for this drawing area
        ##and pass it to the print context."""
        ##gtk.DrawingArea.realize(self)
        ##self._context = self.window.cairo_create()
        ##self._print_context.set_cairo_context(self._context,72,72)

    ##def expose(self, widget, event):
        ##"""Ask the print operation to actually draw the page."""
        ##self.window.clear()
        ##self._preview_operation.render_page(self._page_no)

        ### need to calculate how large the widget now is and
        ### set it so that the scrollbars are updated.
        ### I can't work out how to do this.
        ###self.set_size_request(200, 300)

    
##class PreviewWindow(gtk.Window):
    ##"""A dialog to show a print preview."""
    
    ##def __init__(self,
                 ##operation,
                 ##preview_operation,
                 ##print_context,
                 ##parent):
        ##gtk.Window.__init__(self)
        ##self.set_default_size(640, 480)

        ##self._operation = operation
        ##self._preview_operation = preview_operation

        ##self.connect("delete_event", self.delete_event)

        ##self.set_title("Print Preview")
        ##self.set_transient_for(parent)

        ### Setup widgets
        ##self._vbox = gtk.VBox()
        ##self.add(self._vbox)
        ##self._spin = gtk.SpinButton()
        ##self._spin.set_value(1)
        
        ##self._close_bt = gtk.Button(stock=gtk.STOCK_CLOSE)
        ##self._close_bt.connect("clicked",self.close)
                               
        ##self._hbox = gtk.HBox()
        ##self._hbox.pack_start(self._spin)
        ##self._hbox.pack_start(self._close_bt,expand=False)
        ##self._vbox.pack_start(self._hbox,expand=False)


        ##self._scroll = gtk.ScrolledWindow(None,None)
        ##self._canvas = PreviewCanvas(operation,preview_operation,print_context)
        ##self._scroll.add_with_viewport(self._canvas)
        ##self._vbox.pack_start(self._scroll,expand=True,fill=True)

        ### The print operation does not know how many pages there are until
        ### after the first expose event, so we use the expose event to
        ### trigger an update of the spin box.
        ### This still does not work properly, sometimes the first expose event
        ### happends before this gets connected and the spin box does not get
        ### updated, I am probably just not doing it very cleverly.
        ##self._change_n_pages_connect_id = self._canvas.connect("expose_event", self.change_n_pages)
        ##self._spin.connect("value-changed",
                           ##lambda spinbutton: self._canvas.set_page(spinbutton.get_value_as_int()))
        
        ##self._canvas.set_double_buffered(False)

        ##self.show_all()



    ##def change_n_pages(self, widget, event ):
        ##"""Update the spin box to have the correct number of pages for the
        ##print operation"""
        ##n_pages = self._preview_operation.get_property("n_pages")
        
        ##if n_pages != -1:
            ### As soon as we have a valid number of pages we no
            ### longer need this call back so we can disconnect it.
            ##self._canvas.disconnect(self._change_n_pages_connect_id)
            
        ##value = int(self._spin.get_value())
        ##if value == -1: value = 1
        ##self._spin.configure(gtk.Adjustment(value,1,
                                            ##n_pages,
                                            ##1,1,1),1,0)

    ##def end_preview(self):
        ##self._operation.end_preview()
        
    ##def delete_event(self, widget, event, data=None):
        ##self.end_preview()
        ##return False

    ##def close(self,btn):
        ##self.end_preview()
        ##self.destroy()

        ### I am not sure that this is the correct way to do this
        ### but I expect the print dialog to reappear after I
        ### close the print preview button.
        ##self._operation.do_print()
        ##return False       

def paperstyle_to_pagesetup(paper_style):
    """Convert a BaseDoc.PaperStyle instance into a gtk.PageSetup instance.
    
    @param paper_style: Gramps paper style object to convert
    @param type: BaseDoc.PaperStyle
    @return: page_setup
    @rtype: gtk.PageSetup
    """
    gramps_to_gtk = {
        "Letter": "na_letter",
        "Legal": "na_legal",
        "A0": "iso_a0",
        "A1": "iso_a1",
        "A2": "iso_a2",
        "A3": "iso_a3",
        "A4": "iso_a4",
        "A5": "iso_a5",
        "B0": "iso_b0",
        "B1": "iso_b1",
        "B2": "iso_b2",
        "B3": "iso_b3",
        "B4": "iso_b4",
        "B5": "iso_b5",
        "B6": "iso_b6",
        "B": "iso_b",
        "C": "iso_c",
        "D": "iso_d",
        "E": "iso_e",
    }

    # First set the paper size
    gramps_paper_size = paper_style.get_size()
    gramps_paper_name = gramps_paper_size.get_name()
    
    if gramps_to_gtk.has_key(gramps_paper_name):
        paper_size = gtk.PaperSize(gramps_to_gtk[gramps_paper_name])
    elif gramps_paper_name == "Custom Size":
        paper_width = gramps_paper_size.get_width() * 10
        paper_height = gramps_paper_size.get_height() * 10
        paper_size = gtk.paper_size_new_custom("custom",
                                               "Custom Size",
                                               paper_width,
                                               paper_height,
                                               gtk.UNIT_MM)
    else:
        def_paper_size_name = gtk.paper_size_get_default()
        paper_size = gtk.PaperSize(def_paper_size_name)
        log.debug("Unknown paper size, falling back to the default: %s" %
                  def_paper_size_name)
        
    page_setup = gtk.PageSetup()
    page_setup.set_paper_size(paper_size)
    
    # Set paper orientation
    if paper_style.get_orientation() == BaseDoc.PAPER_PORTRAIT:
        page_setup.set_orientation(gtk.PAGE_ORIENTATION_PORTRAIT)
    else:
        page_setup.set_orientation(gtk.PAGE_ORIENTATION_LANDSCAPE)

    # gtk.PageSize provides default margins for the standard papers.
    # Anyhow, we overwrite those with the settings from Gramps,
    # though at the moment all of them are fixed at 1 inch.
    page_setup.set_top_margin(paper_style.get_top_margin() * 10,
                              gtk.UNIT_MM)
    page_setup.set_bottom_margin(paper_style.get_bottom_margin() * 10,
                                 gtk.UNIT_MM)
    page_setup.set_left_margin(paper_style.get_left_margin() * 10,
                               gtk.UNIT_MM)
    page_setup.set_right_margin(paper_style.get_right_margin() * 10,
                                gtk.UNIT_MM)
    
    return page_setup

def fontstyle_to_fontdescription(font_style):
    """Convert a BaseDoc.FontStyle instance to a pango.FontDescription one.
    
    Font color and underline is not implemented in pango.FontDescription,
    and has to be set with pango.Layout.set_attributes(attrlist) method.
    
    """
    if font_style.face == BaseDoc.FONT_SERIF:
        f_family = 'serif'
    elif font_style.face == BaseDoc.FONT_SANS_SERIF:
        f_family = 'sans serif'
    else:
        f_family = 'monospace'
    
    if font_style.get_bold():
        f_weight = pango.WEIGHT_BOLD
    else:
        f_weight = pango.WEIGHT_NORMAL
        
    if font_style.get_italic():
        f_style = pango.STYLE_ITALIC
    else:
        f_style = pango.STYLE_NORMAL
        
    font_description = pango.FontDescription(f_family)
    font_description.set_size(font_style.get_size() * pango.SCALE)
    font_description.set_weight(f_weight)
    font_description.set_style(f_style)
    
    return font_description

##class PrintFacade(gtk.PrintOperation):
    ##"""Provide the main print operation functions."""
    
    ##def __init__(self, renderer, page_setup):
        ##"""
        ##@param renderer: the renderer object
        ##@param type: an object like:
            ##class renderer:
                ##def render(operation, context, page_nr)
                ### renders the page_nr page onto the provided context.
                ##def get_n_pages(operation, context)
                ### returns the number of pages that would be needed
                ### to render onto the given context.
        
        ##@param page_setup: to be used as default page setup
        ##@param type: gtk.PageSetup
        ##"""
        ##gtk.PrintOperation.__init__(self)

        ##self._renderer = renderer
        
        ##self.set_default_page_setup(page_setup)
        
        ##self.connect("begin_print", self.on_begin_print)
        ##self.connect("draw_page", self.on_draw_page)
        ##self.connect("paginate", self.on_paginate)
        ###self.connect("preview", self.on_preview)        

        ##self._settings = None
        ##self._print_op = None
        
    ##def on_begin_print(self, operation, context):
        ##"""
        
        ##The "begin-print" signal is emitted after the user has finished
        ##changing print settings in the dialog, before the actual rendering
        ##starts.

        ##A typical use for this signal is to use the parameters from the
        ##gtk.PrintContext and paginate the document accordingly, and then set
        ##the number of pages with gtk.PrintOperation.set_n_pages().
        
        ##"""
        ##operation.set_n_pages(self._renderer.get_n_pages(operation, context))

    ##def on_paginate(self, operation, context):
        ##"""
        
        ##The "paginate" signal is emitted after the "begin-print" signal,
        ##but before the actual rendering starts. It keeps getting emitted until
        ##it returns False.

        ##This signal is intended to be used for paginating the document in
        ##small chunks, to avoid blocking the user interface for a long time.
        ##The signal handler should update the number of pages using the
        ##gtk.PrintOperation.set_n_pages() method, and return True if the
        ##document has been completely paginated.

        ##If you don't need to do pagination in chunks, you can simply do it all
        ##in the "begin-print" handler, and set the number of pages from there.
        
        ##"""
        ##return True

    ##def on_draw_page(self,operation, context, page_nr):
        ##"""
        
        ##The "draw-page" signal is emitted for every page that is printed.
        ##The signal handler must render the page_nr's page onto the cairo
        ##context obtained from context using
        ##gtk.PrintContext.get_cairo_context().
        
        ##Use the gtk.PrintOperation.set_use_full_page() and
        ##gtk.PrintOperation.set_unit()  methods before starting the print
        ##operation to set up the transformation of the cairo context according
        ##to your needs.
        
        ##"""
        ##self._renderer.render(operation, context, page_nr)
        
    ###def on_preview(self, operation, preview, context, parent, dummy=None):
        ###"""
        
        ###The "preview" signal is emitted when a preview is requested from the
        ###native dialog. If you handle this you must set the cairo context on
        ###the printing context.

        ###If you don't override this, a default implementation using an external
        ###viewer will be used.
        
        ###"""
        ###preview = PreviewWindow(self, preview, context, parent)
        ###return True
        
    ##def do_print(self, widget=None, data=None):
        ##"""This is the method that actually runs the Gtk Print operation."""

        ### We need to store the settings somewhere so that they are remembered
        ### each time the dialog is restarted.
        ##if self._settings != None:
            ##self.set_print_settings(self._settings)

        ##res = self.run(gtk.PRINT_OPERATION_ACTION_PRINT_DIALOG, None)
        
        ##if res == gtk.PRINT_OPERATION_RESULT_APPLY:
            ##self._settings = self.get_print_settings()

#------------------------------------------------------------------------
#
# Document element classes
#
#------------------------------------------------------------------------
        
class GtkDocBaseElement(object):
    """Base of all document elements.
    
    Support document element structuring and can render itself onto
    a Cairo surface.
    
    """
    _type = 'BASE'
    _allowed_children = None
    
    def __init__(self):
        self._parent = None
        self._children = []
        self._style = None
    
    def get_type(self):
        """Get the type of this element.
        """
        return self._type
    
    def set_parent(self, parent):
        """Set the parent element of this element.
        """
        self._parent = parent
        
    def get_parent(self):
        """Get the parent element of this element.
        """
        return self._parent
    
    def add_child(self, element):
        """Add a child element.
        
        Returns False if the child cannot be added (e.g. not an allowed type),
        or True otherwise.
        
        """
        # check if it is an allowed child for this type
        if element.get_type() not in self._allowed_children:
            log.debug("%r is not an allowed child for %r" %
                      (element.__class__, self.__class__))
            return False
        
        # append the child and set it's parent
        self._children.append(element)
        element.set_parent(self)
        return True
        
    def get_children(self):
        """Get the list if children fo this element.
        """
        return self._children
    
    def divide(self, layout, width, height):
        """Divide the element into two depending on available space.
        
        @param layout: pango layout to write on
        @param type: pango.Layout
        @param width: width of available space for this element
        @param type: device points
        @param height: height of available space for this element
        @param type: device points
        
        @return: the divided element, and the height of the first part
        @rtype: (GtkDocXXX-1, GtkDocXXX-2), device points
        
        """
        raise NotImplementedError
    
    def draw(self, width, height):
        """Draw itself onto a cairo surface with the given size.
        
        @param width: width of available space for this element
        @param type: device points
        @param height: height of available space for this element
        @param type: device points
        
        @return: drawing of this element on a cairo surface
        @rtype: cairo.ImageSurface
        
        """
        raise NotImplementedError
    
class GtkDocDocument(GtkDocBaseElement):
    """The whole document or a page.
    """
    _type = 'DOCUMENT'
    _allowed_children = ['PARAGRAPH', 'PAGEBREAK', 'TABLE', 'MEDIA']
    
    def draw(self, width, height):
        surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
        cr = cairo.Context(surface)

        x = y = 0
        
        for elem in self._children:
            elem_surface, elem_height = elem.draw(width, height)
            cr.set_source_surface(elem_surface, x, y)
            cr.rectangle(x, y, x + width, y + elem_height)
            cr.fill()
            
            y += elem_height
            
        return surface, y
    
class GtkDocPagebreak(GtkDocBaseElement):
    """Implement a page break.
    """
    _type = 'PAGEBREAK'
    _allowed_children = None
    
    def divide(self, layout, width, height):
        return (None, None), 0
    
class GtkDocParagraph(GtkDocBaseElement):
    """Paragraph.
    """
    _type = 'PARAGRAPH'
    _allowed_children = None
    
    spacing = 2.0
    
    def __init__(self, style, text):
        GtkDocBaseElement.__init__(self)
        self._style = style
        self._text = text
        if self._text:
            self._text = self._text + ' '
        
    def add_text(self, text):
        self._text = self._text + text
        
    def divide(self, layout, width, height):
        # calculate real width (margins, padding cm->pango)
        text_width = width
        layout.set_width(text_width * pango.SCALE)
        
        # set paragraph properties
        layout.set_wrap(pango.WRAP_WORD_CHAR)
        layout.set_spacing(self.spacing * pango.SCALE)
        font_style = self._style.get_font()
        layout.set_font_description(fontstyle_to_fontdescription(font_style))
        # FIXME set alignment and first indent too
        
        # calculate the height of one line
        layout.set_text('Test')
        layout_width, layout_height = layout.get_size()
        line_height = layout_height / pango.SCALE + self.spacing
        # and the number of lines fit on the available height
        line_per_height = height / line_height
        
        # if nothing fits
        if line_per_height < 1:
            return (None, self), 0
        
        # calculate where to cut the paragraph
        layout.set_markup(self._text)
        layout_width, layout_height = layout.get_size()
        line_count = layout.get_line_count()
        
        if line_count <= line_per_height:
            # FIXME return proper paragraph height
            return (self, None), layout_height / pango.SCALE
        
        # get index of first character which doesn't fit on available height
        layout_line = layout.get_line(line_per_height)
        index = layout_line.start_index
        # and divide the text
        # FIXME new paragraph's style has to be modified
        new_paragraph = GtkDocParagraph(self._style)
        new_paragraph.add_text(self._text[index:])
        # FIXME own style should be modified to
        self._text = self._text[:index]
        
        # FIXME return proper paragraph height
        return (self, new_paragraph), line_height * line_count
    
    def draw(self, width, height):
        surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
        cr = pangocairo.CairoContext(cairo.Context(surface))
        layout = cr.create_layout()

        # calculate real width (margins, padding cm->pango)
        text_width = width
        layout.set_width(text_width * pango.SCALE)
        
        # set paragraph properties
        layout.set_wrap(pango.WRAP_WORD_CHAR)
        layout.set_spacing(self.spacing * pango.SCALE)
        font_style = self._style.get_font()
        layout.set_font_description(fontstyle_to_fontdescription(font_style))
        # FIXME set alignment and first indent too
        layout.set_markup(self._text)
        layout_width, layout_height = layout.get_size()
        
        # FIXME move to the proper position (margin, padding)
        cr.move_to(0, 0)
        cr.show_layout(layout)
        
        # draw the borders
        if self._style.get_top_border():
            cr.move_to(0, 0)
            cr.line(width, 0)
        if self._style.get_right_border():
            cr.move_to(width, 0)
            cr.line(width, height)
        if self._style.get_bottom_border():
            cr.move_to(0, height)
            cr.line(width, height)
        if self._style.get_left_border():
            cr.move_to(0, 0)
            cr.line(0, height)

        cr.set_line_width(0.1)
        cr.set_source_rgb(0, 0, 0)
        cr.stroke()
        
        
        return surface, layout_height / pango.SCALE
        
    
#------------------------------------------------------------------------
#
# CairoDoc and GtkPrint class
#
#------------------------------------------------------------------------
class CairoDoc(BaseDoc.BaseDoc, BaseDoc.TextDoc, BaseDoc.DrawDoc):
    """Act as an abstract document that can render onto a cairo context.
    
    Maintains an abstract model of the document. The root of this abstract
    document is self._doc. The model is build via the subclassed BaseDoc, and
    the implemented TextDoc, DrawDoc interface methods.
    
    It can render the model onto cairo context pages, according to the received
    page style.
        
    """
    
    # BaseDoc implementation
    
    def open(self, filename):
        self._doc = GtkDocDocument()
        self._active_element = self._doc
        self._pages = []
    
    def close(self):
        raise NotImplementedError
    
    # TextDoc implementation
    
    def page_break(self):
        self._active_element.add_child(GtkDocPagebreak())

    def start_bold(self):
        self.write_text('<b>')
    
    def end_bold(self):
        self.write_text('</b>')
    
    def start_superscript(self):
        self.write_text('<sup>')
    
    def end_superscript(self):
        self.write_text('</sup>')
    
    def start_paragraph(self, style_name, leader=''):
        style_sheet = self.get_style_sheet()
        style = style_sheet.get_paragraph_style(style_name)
        
        new_paragraph = GtkDocParagraph(style, leader)
        self._active_element.add_child(new_paragraph)
        
        self._active_element = new_paragraph
    
    def end_paragraph(self):
        self._active_element = self._active_element.get_parent()
    
    def start_table(self, name, style_name):
        pass
    
    def end_table(self):
        pass
    
    def start_row(self):
        pass
    
    def end_row(self):
        pass
    
    def start_cell(self, style_name, span=1):
        pass
    
    def end_cell(self):
        pass
    
    def write_note(self, text, format, style_name):
        log.debug("write_note: %s" % text)

        if format == 1:
            for line in text.split('\n'):
                self.start_paragraph(style_name)
                self.write_text(line)
                self.end_paragraph()
        elif format == 0:
            for line in text.split('\n\n'):
                self.start_paragraph(style_name)
                line = line.replace('\n',' ')
                line = ' '.join(line.split())
                self.write_text(line)
                self.end_paragraph()

    def write_text(self, text, mark=None):
        log.debug("write_text: %s" % text)
        self._active_element.add_text(text)
    
    def add_media_object(self, name, pos, x_cm, y_cm):
        pass

    # DrawDoc implementation
    
    def start_page(self):
        pass
    
    def end_page(self):
        pass
    
    def draw_path(self, style, path):
        pass
        
    def draw_box(self, style, text, x, y, w, h):
        pass
    
    def draw_text(self, style, text, x, y):
        pass
    
    def center_text(self, style, text, x, y):
        pass
    
    def draw_line(self, style, x1, y1, x2, y2):
        pass

    def rotate_text(self, style, text, x, y, angle):
        pass
    
class GtkPrint(CairoDoc):
    
    def close(self):
        page_setup = paperstyle_to_pagesetup(self.paper)
        
        print_operation = gtk.PrintOperation()
        print_operation.set_default_page_setup(page_setup)
        print_operation.connect("begin_print", self.on_begin_print)
        print_operation.connect("draw_page", self.on_draw_page)
        print_operation.connect("paginate", self.on_paginate)
        #print_operation.run(gtk.PRINT_OPERATION_ACTION_PRINT_DIALOG, None)
        self.print_settings = None
        self.do_print(print_operation)

    def do_print(self, operation):
        """Run the Gtk Print operation.
        """
        # set print settings if it was stored previously
        if self.print_settings is not None:
            operation.set_print_settings(self.print_settings)

        # run print dialog
        res = operation.run(gtk.PRINT_OPERATION_ACTION_PRINT_DIALOG, None)
        
        # store print settings if printing was successful
        if res == gtk.PRINT_OPERATION_RESULT_APPLY:
            self.print_settings = operation.get_print_settings()

    def on_begin_print(self, operation, context):
        """Handler for 'begin-print' signal.
        
        The "begin-print" signal is emitted after the user has finished
        changing print settings in the dialog, before the actual rendering
        starts.

        A typical use for this signal is to use the parameters from the
        gtk.PrintContext and paginate the document accordingly, and then set
        the number of pages with gtk.PrintOperation.set_n_pages().
        
        """
        # set context parameters to pages
        self.page_width = context.get_width()
        self.page_height = context.get_height()
        
        self.elements_to_paginate = self._doc.get_children()
        self._pages.append(GtkDocDocument())
        self.available_height = self.page_height
       
    def on_paginate(self, operation, context):
        """Handler for 'paginate' signal.
        
        The "paginate" signal is emitted after the "begin-print" signal,
        but before the actual rendering starts. It keeps getting emitted until
        it returns False.

        This signal is intended to be used for paginating the document in
        small chunks, to avoid blocking the user interface for a long time.
        The signal handler should update the number of pages using the
        gtk.PrintOperation.set_n_pages() method, and return True if the
        document has been completely paginated.

        If you don't need to do pagination in chunks, you can simply do it all
        in the "begin-print" handler, and set the number of pages from there.
        
        """
        layout = context.create_pango_layout()
        
        # try to fit the next element to current page, divide it if needed
        elem = self.elements_to_paginate.pop(0)
        (e1, e2), e1_h = elem.divide(layout,
                                     self.page_width,
                                     self.available_height)

        # if (part of) it fits on current page add it
        if e1 is not None:
            self._pages[len(self._pages) - 1].add_child(e1)

        # if elem was divided remember the second half to be processed
        if e2 is not None:
            self.elements_to_paginate.insert(0, e2)

        # calculate how much space left on current page
        self.available_height -= e1_h

        # start new page if needed
        if (e1 is None) or (e2 is not None):
            self._pages.append(GtkDocDocument())
            self.available_height = self.page_height
            
        # update page number
        operation.set_n_pages(len(self._pages))
        
        # tell operation whether we finished or not
        finished = len(self.elements_to_paginate) == 0
        return finished

    def on_draw_page(self,operation, context, page_nr):
        """
        
        The "draw-page" signal is emitted for every page that is printed.
        The signal handler must render the page_nr's page onto the cairo
        context obtained from context using
        gtk.PrintContext.get_cairo_context().
        
        Use the gtk.PrintOperation.set_use_full_page() and
        gtk.PrintOperation.set_unit()  methods before starting the print
        operation to set up the transformation of the cairo context according
        to your needs.
        
        """
        page_surface, real_height = self._pages[page_nr].draw(self.page_width,
                                                              self.page_height)
        cr = context.get_cairo_context()
        cr.set_source_surface(page_surface, 0, 0)
        cr.rectangle(0, 0, self.page_width, real_height)
        cr.fill()
        
    #def on_preview(self, operation, preview, context, parent, dummy=None):
        #"""
        
        #The "preview" signal is emitted when a preview is requested from the
        #native dialog. If you handle this you must set the cairo context on
        #the printing context.

        #If you don't override this, a default implementation using an external
        #viewer will be used.
        
        #"""
        #preview = PreviewWindow(self, preview, context, parent)
        #return True
        

#------------------------------------------------------------------------
#
# Register the document generator with the GRAMPS plugin system
#
#------------------------------------------------------------------------
raise Errors.UnavailableError("Work in progress...")
register_text_doc(_('Print... (Gtk+)'), GtkPrint, 1, 1, 1, "", None)
##register_draw_doc(_('GtkPrint'), GtkPrint, 1, 1, "", None)
##register_book_doc(_("GtkPrint"), GtkPrint, 1, 1, 1, "", None)