electrum/plugins/revealer/qt.py

'''

Revealer 
So you have something to hide?

plug-in for the electrum wallet.

Features:
    - Deep Cold multi-factor backup solution
    - Safety - One time pad security
    - Redundancy - Trustless printing & distribution
    - Encrypt your seedphrase or any secret you want for your revealer
    - Based on crypto by legendary cryptographers Naor and Shamir  

Tiago Romagnani Silveira, 2017

'''

import os
import random
import qrcode
import traceback
from hashlib import sha256
from decimal import Decimal

from PyQt5.QtPrintSupport import QPrinter

from electrum.plugins import BasePlugin, hook
from electrum.i18n import _
from electrum_gui.qt.util import *
from electrum_gui.qt.qrtextedit import ScanQRTextEdit
from electrum.util import to_bytes, make_dir


class Plugin(BasePlugin):

    def __init__(self, parent, config, name):
        BasePlugin.__init__(self, parent, config, name)
        self.base_dir = config.electrum_path()+'/revealer/'

        if self.config.get('calibration_h') == None:
            self.config.set_key('calibration_h', 0)
        if self.config.get('calibration_v') == None:
            self.config.set_key('calibration_v', 0)

        self.calibration_h = self.config.get('calibration_h')
        self.calibration_v = self.config.get('calibration_v')

        self.version = '0'
        self.size = (159, 97)
        self.f_size = QSize(1014*2, 642*2)
        self.abstand_h = 21
        self.abstand_v = 34
        self.calibration_noise = int('10' * 128)
        self.rawnoise = False
        make_dir(self.base_dir)

    @hook
    def set_seed(self, seed, parent):
        self.cseed = seed.upper()
        parent.addButton(':icons/revealer.png', partial(self.setup_dialog, parent), "Revealer"+_(" secret backup utility"))

    def requires_settings(self):
        return True

    def settings_widget(self, window):
        return EnterButton(_('Printer Calibration'), partial(self.calibration_dialog, window))

    def setup_dialog(self, window):
        self.update_wallet_name(window.parent().parent().wallet)
        self.user_input = False
        self.noise_seed = False
        self.d = WindowModalDialog(window, "Revealer")
        self.d.setMinimumWidth(420)
        vbox = QVBoxLayout(self.d)
        vbox.addSpacing(21)
        logo = QLabel()
        vbox.addWidget(logo)
        logo.setPixmap(QPixmap(':icons/revealer.png'))
        logo.setAlignment(Qt.AlignCenter)
        vbox.addSpacing(42)

        self.load_noise = ScanQRTextEdit()
        self.load_noise.setTabChangesFocus(True)
        self.load_noise.textChanged.connect(self.on_edit)
        self.load_noise.setMaximumHeight(33)

        vbox.addWidget(WWLabel("<b>"+_("Enter your physical revealer code:")+"<b>"))
        vbox.addWidget(self.load_noise)
        vbox.addSpacing(11)

        self.next_button = QPushButton(_("Next"), self.d)
        self.next_button.setDefault(True)
        self.next_button.setEnabled(False)
        vbox.addLayout(Buttons(self.next_button))
        self.next_button.clicked.connect(self.d.close)
        self.next_button.clicked.connect(partial(self.cypherseed_dialog, window))
        vbox.addSpacing(21)

        vbox.addWidget(WWLabel(_("or, alternatively: ")))
        bcreate = QPushButton(_("Create a digital Revealer"))

        def mk_digital():
            try:
                self.make_digital(self.d)
            except Exception:
                traceback.print_exc(file=sys.stdout)
            else:
                self.cypherseed_dialog(window)

        bcreate.clicked.connect(mk_digital)

        vbox.addWidget(bcreate)
        vbox.addSpacing(11)
        vbox.addWidget(QLabel(''.join([ "<b>"+_("WARNING")+ "</b>:" + _("Printing a revealer and encrypted seed"), '<br/>',
                                       _("on the same printer is not trustless towards the printer."), '<br/>',
                                       ])))
        vbox.addSpacing(11)
        vbox.addLayout(Buttons(CloseButton(self.d)))

        return bool(self.d.exec_())

    def get_noise(self):
        text = self.load_noise.text()
        return ''.join(text.split()).lower()

    def on_edit(self):
        s = self.get_noise()
        b = self.is_noise(s)
        if b:
            self.noise_seed = s[:-3]
            self.user_input = True
        self.next_button.setEnabled(b)

    def code_hashid(self, txt):
        x = to_bytes(txt, 'utf8')
        hash = sha256(x).hexdigest()
        return hash[-3:].upper()

    def is_noise(self, txt):
        if (len(txt) >= 34):
            try:
                int(txt, 16)
            except:
                self.user_input = False
                return False
            else:
                id = self.code_hashid(txt[:-3])
                if (txt[-3:].upper() == id.upper()):
                    self.code_id = id
                    self.user_input = True
                    return True
                else:
                    return False
        else:
            self.user_input = False
            return False

    def make_digital(self, dialog):
        self.make_rawnoise(True)
        self.bdone(dialog)
        self.d.close()

    def bcrypt(self, dialog):
        self.rawnoise = False
        dialog.show_message(''.join([_("{} encrypted for Revealer {}_{} saved as PNG and PDF at:").format(self.was, self.version, self.code_id),
                                     "<br/>","<b>", self.base_dir+ self.filename+self.version+"_"+self.code_id,"</b>"]))
        dialog.close()

    def bdone(self, dialog):
        dialog.show_message(''.join([_("Digital Revealer ({}_{}) saved as PNG and PDF at:").format(self.version, self.code_id),
                                     "<br/>","<b>", self.base_dir + 'revealer_' +self.version + '_'+ self.code_id, '</b>']))


    def customtxt_limits(self):
        txt = self.text.text()
        self.max_chars.setVisible(False)
        self.char_count.setText("("+str(len(txt))+"/216)")
        if len(txt)>0:
            self.ctext.setEnabled(True)
        if len(txt) > 216:
            self.text.setPlainText(self.text.toPlainText()[:216])
            self.max_chars.setVisible(True)

    def t(self):
        self.txt = self.text.text()
        self.seed_img(is_seed=False)

    def cypherseed_dialog(self, window):

        d = WindowModalDialog(window, "Revealer")
        d.setMinimumWidth(420)

        self.c_dialog = d

        self.vbox = QVBoxLayout(d)
        self.vbox.addSpacing(21)

        logo = QLabel()
        self.vbox.addWidget(logo)
        logo.setPixmap(QPixmap(':icons/revealer.png'))
        logo.setAlignment(Qt.AlignCenter)
        self.vbox.addSpacing(42)

        grid = QGridLayout()
        self.vbox.addLayout(grid)

        cprint = QPushButton(_("Generate encrypted seed PDF"))
        cprint.clicked.connect(partial(self.seed_img, True))
        self.vbox.addWidget(cprint)
        self.vbox.addSpacing(14)

        self.vbox.addWidget(WWLabel(_("and/or type any secret below:")))
        self.text = ScanQRTextEdit()
        self.text.setTabChangesFocus(True)
        self.text.setMaximumHeight(70)
        self.text.textChanged.connect(self.customtxt_limits)
        self.vbox.addWidget(self.text)

        self.char_count = WWLabel("")
        self.char_count.setAlignment(Qt.AlignRight)
        self.vbox.addWidget(self.char_count)

        self.max_chars = WWLabel("<font color='red'>" + _("This version supports a maximum of 216 characters.")+"</font>")
        self.vbox.addWidget(self.max_chars)
        self.max_chars.setVisible(False)

        self.ctext = QPushButton(_("Generate custom secret encrypted PDF"))
        self.ctext.clicked.connect(self.t)

        self.vbox.addWidget(self.ctext)
        self.ctext.setEnabled(False)

        self.vbox.addSpacing(21)
        self.vbox.addLayout(Buttons(CloseButton(d)))
        return bool(d.exec_())


    def update_wallet_name (self, name):
        self.wallet_name = str(name)
        self.base_name = self.base_dir + self.wallet_name
        
    def seed_img(self, is_seed = True):
      
        if not self.cseed and self.txt == False:
            return
        
        if is_seed:
            txt = self.cseed
        else:
            txt = self.txt.upper()

        img = QImage(self.size[0],self.size[1], QImage.Format_Mono)
        bitmap = QBitmap.fromImage(img, Qt.MonoOnly)
        bitmap.fill(Qt.white)
        painter = QPainter()
        painter.begin(bitmap)
        QFontDatabase.addApplicationFont(os.path.join(os.path.dirname(__file__), 'SourceSansPro-Bold.otf') )
        if len(txt) < 102 :
            fontsize = 12
            linespace = 15
            max_letters = 17
            max_lines = 6
            max_words = 3
        if len(txt) > 102:
            fontsize = 9
            linespace = 10
            max_letters = 24
            max_lines = 9
            max_words = int(max_letters/4)

        font = QFont('Source Sans Pro', fontsize, QFont.Bold)
        font.setLetterSpacing(QFont.PercentageSpacing, 100)
        painter.setFont(font)
        seed_array = txt.split(' ')

        for n in range(max_lines):
            nwords = max_words
            temp_seed = seed_array[:nwords]
            while len(' '.join(map(str, temp_seed))) > max_letters:
               nwords = nwords - 1
               temp_seed = seed_array[:nwords]
            painter.drawText(QRect(0, linespace*n , self.size[0], self.size[1]), Qt.AlignHCenter, ' '.join(map(str, temp_seed)))
            del seed_array[:nwords]

        painter.end()
        img = bitmap.toImage()
        if (self.rawnoise == False):
            self.make_rawnoise()

        self.make_cypherseed(img, self.rawnoise, False, is_seed)
        return img

    def make_rawnoise(self, create_revealer=False):
        w = self.size[0]
        h = self.size[1]
        rawnoise = QImage(w, h, QImage.Format_Mono)

        if(self.noise_seed == False):
            self.noise_seed = random.SystemRandom().getrandbits(128)
            self.hex_noise = format(self.noise_seed, '02x')
            self.hex_noise = self.version + str(self.hex_noise)

        if (self.user_input == True):
            self.noise_seed = int(self.noise_seed, 16)
            self.hex_noise = self.version + str(format(self.noise_seed, '02x'))


        self.code_id = self.code_hashid(self.hex_noise)
        self.hex_noise = ' '.join(self.hex_noise[i:i+4] for i in range(0,len(self.hex_noise),4))
        random.seed(self.noise_seed)

        for x in range(w):
            for y in range(h):
                rawnoise.setPixel(x,y,random.randint(0, 1))

        self.rawnoise = rawnoise
        if create_revealer==True:
            self.make_revealer()
        self.noise_seed = False

    def make_calnoise(self):
        random.seed(self.calibration_noise)
        w = self.size[0]
        h = self.size[1]
        rawnoise = QImage(w, h, QImage.Format_Mono)
        for x in range(w):
            for y in range(h):
                rawnoise.setPixel(x,y,random.randint(0, 1))
        self.calnoise = self.pixelcode_2x2(rawnoise)

    def make_revealer(self):
        revealer = self.pixelcode_2x2(self.rawnoise)
        revealer.invertPixels()
        revealer = QBitmap.fromImage(revealer)
        revealer = self.overlay_marks(revealer)
        revealer = revealer.scaled(1014, 642)
        self.filename = 'Revealer - '
        revealer.save(self.base_dir + self.filename + self.version+'_'+self.code_id + '.png')
        self.toPdf(QImage(revealer))
        QDesktopServices.openUrl(QUrl.fromLocalFile(os.path.abspath(self.base_dir + self.filename + self.version+'_'+ self.code_id + '.pdf')))

    def make_cypherseed(self, img, rawnoise, calibration=False, is_seed = True):
        img = img.convertToFormat(QImage.Format_Mono)
        p = QPainter()
        p.begin(img)
        p.setCompositionMode(26) #xor
        p.drawImage(0, 0, rawnoise)
        p.end()
        cypherseed = self.pixelcode_2x2(img)
        cypherseed = QBitmap.fromImage(cypherseed)
        cypherseed = cypherseed.scaled(self.f_size, Qt.KeepAspectRatio)
        cypherseed = self.overlay_marks(cypherseed, True, calibration)

        if not is_seed:
            self.filename = _('custom_secret')+'_'
            self.was = _('Custom secret')
        else:
            self.filename = self.wallet_name+'_'+ _('seed')+'_'
            self.was = self.wallet_name +' ' + _('seed')

        if not calibration:
            self.toPdf(QImage(cypherseed))
            QDesktopServices.openUrl (QUrl.fromLocalFile(os.path.abspath(self.base_dir+self.filename+self.version+'_'+self.code_id+'.pdf')))
            cypherseed.save(self.base_dir + self.filename +self.version + '_'+ self.code_id + '.png')
            self.bcrypt(self.c_dialog)
        return cypherseed

    def calibration(self):
        img = QImage(self.size[0],self.size[1], QImage.Format_Mono)
        bitmap = QBitmap.fromImage(img, Qt.MonoOnly)
        bitmap.fill(Qt.black)
        self.make_calnoise()
        img = self.overlay_marks(self.calnoise.scaledToHeight(self.f_size.height()), False, True)
        self.calibration_pdf(img)
        QDesktopServices.openUrl (QUrl.fromLocalFile(os.path.abspath(self.base_dir+_('calibration')+'.pdf')))
        return img        
    
    def toPdf(self, image):
        printer = QPrinter()
        printer.setPaperSize(QSizeF(210, 297), QPrinter.Millimeter)
        printer.setResolution(600)
        printer.setOutputFormat(QPrinter.PdfFormat)
        printer.setOutputFileName(self.base_dir+self.filename+self.version + '_'+self.code_id+'.pdf')
        printer.setPageMargins(0,0,0,0,6)
        painter = QPainter()
        painter.begin(printer)
  
        delta_h = round(image.width()/self.abstand_v)
        delta_v = round(image.height()/self.abstand_h) 

        size_h = 2028+((int(self.calibration_h)*2028/(2028-(delta_h*2)+int(self.calibration_h)))/2)
        size_v = 1284+((int(self.calibration_v)*1284/(1284-(delta_v*2)+int(self.calibration_v)))/2)
        
        image =  image.scaled(size_h, size_v)

        painter.drawImage(553,533, image)
        wpath = QPainterPath()
        wpath.addRoundedRect(QRectF(553,533, size_h, size_v), 19, 19)
        painter.setPen(QPen(Qt.black, 1))
        painter.drawPath(wpath)
        painter.end()
    
    def calibration_pdf(self, image):
        printer = QPrinter()
        printer.setPaperSize(QSizeF(210, 297), QPrinter.Millimeter)
        printer.setResolution(600)
        printer.setOutputFormat(QPrinter.PdfFormat)
        printer.setOutputFileName(self.base_dir+_('calibration')+'.pdf')
        printer.setPageMargins(0,0,0,0,6)

        painter = QPainter()
        painter.begin(printer)
        painter.drawImage(553,533, image)
        font = QFont('Source Sans Pro', 10, QFont.Bold)
        painter.setFont(font)
        painter.drawText(254,277, _("Calibration sheet"))
        font = QFont('Source Sans Pro', 7, QFont.Bold)
        painter.setFont(font)
        painter.drawText(600,2077, _("Instructions:"))
        font = QFont('Source Sans Pro', 7, QFont.Normal)
        painter.setFont(font)
        painter.drawText(700, 2177, _("1. Place this paper on a flat and well iluminated surface."))
        painter.drawText(700, 2277, _("2. Align your Revealer borderlines to the dashed lines on the top and left."))
        painter.drawText(700, 2377, _("3. Press slightly the Revealer against the paper and read the numbers that best "
                                      "match on the opposite sides. "))
        painter.drawText(700, 2477, _("4. Type the numbers in the software"))
        painter.end()
                            
    def pixelcode_2x2(self, img):
        result = QImage(img.width()*2, img.height()*2, QImage.Format_ARGB32 )
        white = qRgba(255,255,255,0)
        black = qRgba(0,0,0,255)

        for x in range(img.width()):
            for y in range(img.height()):
                c = img.pixel(QPoint(x,y))
                colors = QColor(c).getRgbF()
                if colors[0]:
                    result.setPixel(x*2+1,y*2+1, black)
                    result.setPixel(x*2,y*2+1, white)
                    result.setPixel(x*2+1,y*2, white)
                    result.setPixel(x*2, y*2, black)
                    
                else:
                    result.setPixel(x*2+1,y*2+1, white)
                    result.setPixel(x*2,y*2+1, black)
                    result.setPixel(x*2+1,y*2, black)
                    result.setPixel(x*2, y*2, white)
        return result

    def overlay_marks(self, img, is_cseed=False, calibration_sheet=False):
        border_color = Qt.white
        base_img = QImage(self.f_size.width(),self.f_size.height(), QImage.Format_ARGB32)
        base_img.fill(border_color)
        img = QImage(img)

        painter = QPainter()
        painter.begin(base_img)

        total_distance_h = round(base_img.width() / self.abstand_v)
        dist_v = round(total_distance_h) / 2
        dist_h = round(total_distance_h) / 2

        img = img.scaledToWidth(base_img.width() - (2 * (total_distance_h)))
        painter.drawImage(total_distance_h,
                          total_distance_h,
                          img)

        #frame around image
        pen = QPen(Qt.black, 2)
        painter.setPen(pen)

        #horz
        painter.drawLine(0, total_distance_h, base_img.width(), total_distance_h)
        painter.drawLine(0, base_img.height()-(total_distance_h), base_img.width(), base_img.height()-(total_distance_h))
        #vert
        painter.drawLine(total_distance_h, 0,  total_distance_h, base_img.height())
        painter.drawLine(base_img.width()-(total_distance_h), 0,  base_img.width()-(total_distance_h), base_img.height())

        #border around img
        border_thick = 6
        Rpath = QPainterPath()
        Rpath.addRect(QRectF((total_distance_h)+(border_thick/2), 
                             (total_distance_h)+(border_thick/2), 
                             base_img.width()-((total_distance_h)*2)-((border_thick)-1),
                             (base_img.height()-((total_distance_h))*2)-((border_thick)-1)))
        pen = QPen(Qt.black, border_thick)
        pen.setJoinStyle (Qt.MiterJoin)
        
        painter.setPen(pen)
        painter.drawPath(Rpath)

        Bpath = QPainterPath()
        Bpath.addRect(QRectF((total_distance_h), (total_distance_h),
                             base_img.width()-((total_distance_h)*2), (base_img.height()-((total_distance_h))*2)))
        pen = QPen(Qt.black, 1)
        painter.setPen(pen)
        painter.drawPath(Bpath)
        
        pen = QPen(Qt.black, 1)
        painter.setPen(pen)
        painter.drawLine(0, base_img.height()/2, total_distance_h, base_img.height()/2)
        painter.drawLine(base_img.width()/2, 0, base_img.width()/2, total_distance_h)
        
        painter.drawLine(base_img.width()-total_distance_h, base_img.height()/2, base_img.width(), base_img.height()/2)
        painter.drawLine(base_img.width()/2, base_img.height(), base_img.width()/2, base_img.height() - total_distance_h)

        #print code
        f_size = 37
        QFontDatabase.addApplicationFont(os.path.join(os.path.dirname(__file__), 'DejaVuSansMono-Bold.ttf'))
        font = QFont("DejaVu Sans Mono", f_size-11, QFont.Bold)
        painter.setFont(font)

        if not calibration_sheet:
            if is_cseed: #its a secret
                painter.setPen(QPen(Qt.black, 1, Qt.DashDotDotLine))
                painter.drawLine(0, dist_v, base_img.width(), dist_v)
                painter.drawLine(dist_h, 0,  dist_h, base_img.height())
                painter.drawLine(0, base_img.height()-dist_v, base_img.width(), base_img.height()-(dist_v))
                painter.drawLine(base_img.width()-(dist_h), 0,  base_img.width()-(dist_h), base_img.height())

                painter.drawImage(((total_distance_h))+11, ((total_distance_h))+11,
                                  QImage(':icons/electrumb.png').scaledToWidth(2.1*(total_distance_h), Qt.SmoothTransformation))

                painter.setPen(QPen(Qt.white, border_thick*8))
                painter.drawLine(base_img.width()-((total_distance_h))-(border_thick*8)/2-(border_thick/2)-2, 
                                (base_img.height()-((total_distance_h)))-((border_thick*8)/2)-(border_thick/2)-2, 
                                base_img.width()-((total_distance_h))-(border_thick*8)/2-(border_thick/2)-2 - 77,
                                (base_img.height()-((total_distance_h)))-((border_thick*8)/2)-(border_thick/2)-2)
                painter.setPen(QColor(0,0,0,255))
                painter.drawText(QRect(0, base_img.height()-107, base_img.width()-total_distance_h - border_thick - 11,
                                       base_img.height()-total_distance_h - border_thick), Qt.AlignRight, self.version + '_'+self.code_id)
                painter.end()
                    
            else: # revealer

                painter.setPen(QPen(border_color, 17))
                painter.drawLine(0, dist_v, base_img.width(), dist_v)
                painter.drawLine(dist_h, 0,  dist_h, base_img.height())
                painter.drawLine(0, base_img.height()-dist_v, base_img.width(), base_img.height()-(dist_v))
                painter.drawLine(base_img.width()-(dist_h), 0,  base_img.width()-(dist_h), base_img.height())

                painter.setPen(QPen(Qt.black, 2))
                painter.drawLine(0, dist_v, base_img.width(), dist_v)
                painter.drawLine(dist_h, 0,  dist_h, base_img.height())
                painter.drawLine(0, base_img.height()-dist_v, base_img.width(), base_img.height()-(dist_v))
                painter.drawLine(base_img.width()-(dist_h), 0,  base_img.width()-(dist_h), base_img.height())
                logo = QImage(':icons/revealer_c.png').scaledToWidth(1.3*(total_distance_h))
                painter.drawImage((total_distance_h)+ (border_thick), ((total_distance_h))+ (border_thick), logo, Qt.SmoothTransformation)

                #frame around logo
                painter.setPen(QPen(Qt.black, border_thick))                
                painter.drawLine(total_distance_h+border_thick, total_distance_h+logo.height()+3*(border_thick/2),
                                 total_distance_h+logo.width()+border_thick, total_distance_h+logo.height()+3*(border_thick/2))
                painter.drawLine(logo.width()+total_distance_h+3*(border_thick/2), total_distance_h+(border_thick),
                                 total_distance_h+logo.width()+3*(border_thick/2), total_distance_h+logo.height()+(border_thick))

                #frame around code/qr
                qr_size = 179

                painter.drawLine((base_img.width()-((total_distance_h))-(border_thick/2)-2)-qr_size,
                                (base_img.height()-((total_distance_h)))-((border_thick*8))-(border_thick/2)-2,
                                 (base_img.width()/2+(total_distance_h/2)-border_thick-(border_thick*8)/2)-qr_size,
                                (base_img.height()-((total_distance_h)))-((border_thick*8))-(border_thick/2)-2)

                painter.drawLine((base_img.width()/2+(total_distance_h/2)-border_thick-(border_thick*8)/2)-qr_size,
                                (base_img.height()-((total_distance_h)))-((border_thick*8))-(border_thick/2)-2,
                                 base_img.width()/2 + (total_distance_h/2)-border_thick-(border_thick*8)/2-qr_size,
                                 ((base_img.height()-((total_distance_h)))-(border_thick/2)-2))

                painter.setPen(QPen(Qt.white, border_thick * 8))
                painter.drawLine(
                    base_img.width() - ((total_distance_h)) - (border_thick * 8) / 2 - (border_thick / 2) - 2,
                    (base_img.height() - ((total_distance_h))) - ((border_thick * 8) / 2) - (border_thick / 2) - 2,
                    base_img.width() / 2 + (total_distance_h / 2) - border_thick - qr_size,
                    (base_img.height() - ((total_distance_h))) - ((border_thick * 8) / 2) - (border_thick / 2) - 2)

                painter.setPen(QColor(0,0,0,255))
                painter.drawText(QRect(((base_img.width()/2) +21)-qr_size, base_img.height()-107,
                                       base_img.width()-total_distance_h - border_thick -93,
                                       base_img.height()-total_distance_h - border_thick), Qt.AlignLeft, self.hex_noise.upper())
                painter.drawText(QRect(0, base_img.height()-107, base_img.width()-total_distance_h - border_thick -3 -qr_size,
                                       base_img.height()-total_distance_h - border_thick), Qt.AlignRight, self.code_id)

                # draw qr code
                qr_qt = self.paintQR(self.hex_noise.upper() +self.code_id)
                target = QRectF(base_img.width()-65-qr_size,
                                base_img.height()-65-qr_size,
                                qr_size, qr_size );
                painter.drawImage(target, qr_qt);
                painter.setPen(QPen(Qt.black, 4))
                painter.drawLine(base_img.width()-65-qr_size,
                                base_img.height()-65-qr_size,
                                 base_img.width() - 65 - qr_size,
                                (base_img.height() - ((total_distance_h))) - ((border_thick * 8)) - (border_thick / 2) - 4
                                 )
                painter.drawLine(base_img.width()-65-qr_size,
                                base_img.height()-65-qr_size,
                                 base_img.width() - 65,
                                base_img.height()-65-qr_size
                                 )
                painter.end()

        else: # calibration only
            painter.end()
            cal_img = QImage(self.f_size.width() + 100, self.f_size.height() + 100,
                              QImage.Format_ARGB32)
            cal_img.fill(Qt.white)
            
            cal_painter = QPainter()
            cal_painter.begin(cal_img)
            cal_painter.drawImage(0,0, base_img)

            #black lines in the middle of border top left only        
            cal_painter.setPen(QPen(Qt.black, 1, Qt.DashDotDotLine))
            cal_painter.drawLine(0, dist_v, base_img.width(), dist_v)
            cal_painter.drawLine(dist_h, 0,  dist_h, base_img.height())

            pen = QPen(Qt.black, 2, Qt.DashDotDotLine)
            cal_painter.setPen(pen)
            n=15

            cal_painter.setFont(QFont("DejaVu Sans Mono", 21, QFont.Bold))
            for x in range(-n,n):
                #lines on bottom (vertical calibration)
                cal_painter.drawLine((((base_img.width())/(n*2)) *(x))+ (base_img.width()/2)-13,
                                 x+2+base_img.height()-(dist_v),
                                 (((base_img.width())/(n*2)) *(x))+ (base_img.width()/2)+13,
                                 x+2+base_img.height()-(dist_v))

                num_pos = 9
                if x > 9 : num_pos = 17
                if x < 0 : num_pos = 20
                if x < -9: num_pos = 27

                cal_painter.drawText((((base_img.width())/(n*2)) *(x))+ (base_img.width()/2)-num_pos,
                                 50+base_img.height()-(dist_v),
                                  str(x))

                #lines on the right (horizontal calibrations)

                cal_painter.drawLine(x+2+(base_img.width()-(dist_h)),
                                 ((base_img.height()/(2*n)) *(x))+ (base_img.height()/n)+(base_img.height()/2)-13,
                                 x+2+(base_img.width()-(dist_h)),
                                 ((base_img.height()/(2*n)) *(x))+ (base_img.height()/n)+(base_img.height()/2)+13)


                cal_painter.drawText(30+(base_img.width()-(dist_h)),
                                ((base_img.height()/(2*n)) *(x))+ (base_img.height()/2)+13, str(x))

            cal_painter.end()
            base_img = cal_img

        return base_img

    def paintQR(self, data):
        if not data:
            return
        qr = qrcode.QRCode()
        qr.add_data(data)
        matrix = qr.get_matrix()
        k = len(matrix)
        border_color = Qt.white
        base_img = QImage(k * 5, k * 5, QImage.Format_ARGB32)
        base_img.fill(border_color)
        qrpainter = QPainter()
        qrpainter.begin(base_img)
        boxsize = 5
        size = k * boxsize
        left = (base_img.width() - size)/2
        top = (base_img.height() - size)/2
        qrpainter.setBrush(Qt.black)
        qrpainter.setPen(Qt.black)

        for r in range(k):
            for c in range(k):
                if matrix[r][c]:
                    qrpainter.drawRect(left+c*boxsize, top+r*boxsize, boxsize - 1, boxsize - 1)
        qrpainter.end()
        return base_img

    def calibration_dialog(self, window):
        d = WindowModalDialog(window, _("Revealer - Printer calibration settings"))
        
        d.setMinimumSize(100, 200)

        vbox = QVBoxLayout(d)
        vbox.addWidget(QLabel(''.join(["<br/>", _("If you have an old printer, or want optimal precision"),"<br/>",
                                       _("print the calibration pdf and follow the instructions "), "<br/>","<br/>",
                                    ])))
        self.calibration_h = self.config.get('calibration_h')
        self.calibration_v = self.config.get('calibration_v')
        cprint = QPushButton(_("Open calibration pdf"))
        cprint.clicked.connect(self.calibration)
        vbox.addWidget(cprint)

        vbox.addWidget(QLabel(_('Calibration values:')))
        grid = QGridLayout()
        vbox.addLayout(grid)
        grid.addWidget(QLabel(_('Right side')), 0, 0)
        horizontal = QLineEdit()
        horizontal.setText(str(self.calibration_h))
        grid.addWidget(horizontal, 0, 1)

        grid.addWidget(QLabel(_('Bottom')), 1, 0)
        vertical = QLineEdit()
        vertical.setText(str(self.calibration_v))
        grid.addWidget(vertical, 1, 1)

        vbox.addStretch()
        vbox.addSpacing(13)   
        vbox.addLayout(Buttons(CloseButton(d), OkButton(d)))

        if not d.exec_():
            return

        self.calibration_h = int(Decimal(horizontal.text()))
        self.config.set_key('calibration_h', self.calibration_h)
        self.calibration_v = int(Decimal(vertical.text()))
        self.config.set_key('calibration_v', self.calibration_v)