covers.py

#!/usr/bin/env python


__license__ = 'GPL v3'
__copyright__ = '2014, Kovid Goyal <kovid at kovidgoyal.net>'

import numbers
import random
import re
import unicodedata
from collections import namedtuple
from contextlib import contextmanager
from itertools import chain
from math import atan2, ceil, cos, sin, sqrt

from qt.core import (
    QBrush,
    QColor,
    QFont,
    QFontMetrics,
    QImage,
    QLinearGradient,
    QPainter,
    QPainterPath,
    QPen,
    QPointF,
    QRadialGradient,
    QRect,
    QRectF,
    Qt,
    QTextCharFormat,
    QTextLayout,
    QTextOption,
    QTransform,
)

from calibre import fit_image, force_unicode
from calibre.constants import __appname__, __version__
from calibre.ebooks.metadata import fmt_sidx
from calibre.ebooks.metadata.book.base import Metadata
from calibre.ebooks.metadata.book.formatter import SafeFormat
from calibre.gui2 import config, ensure_app, load_builtin_fonts, pixmap_to_data
from calibre.utils.cleantext import clean_ascii_chars, clean_xml_chars
from calibre.utils.config import JSONConfig
from calibre.utils.resources import get_image_path as I
from polyglot.builtins import iteritems, itervalues, string_or_bytes

# Default settings {{{
cprefs = JSONConfig('cover_generation')
cprefs.defaults['title_font_size'] = 120  # px
cprefs.defaults['subtitle_font_size'] = 80  # px
cprefs.defaults['footer_font_size'] = 80  # px
cprefs.defaults['cover_width'] = 1200  # px
cprefs.defaults['cover_height'] = 1600  # px
cprefs.defaults['title_font_family'] = None
cprefs.defaults['subtitle_font_family'] = None
cprefs.defaults['footer_font_family'] = None
cprefs.defaults['color_themes'] = {}
cprefs.defaults['disabled_color_themes'] = []
cprefs.defaults['disabled_styles'] = []
cprefs.defaults['title_template'] = '<b>{title}'
cprefs.defaults['subtitle_template'] = '''{series:'test($, strcat("<i>", $, "</i> - ", raw_field("formatted_series_index")), "")'}'''
cprefs.defaults['footer_template'] = r'''program:
# Show at most two authors, on separate lines.
authors = field('authors');
num = count(authors, ' &amp; ');
authors = sublist(authors, 0, 2, ' &amp; ');
authors = list_re(authors, ' &amp; ', '(.+)', '<b>\1');
authors = re(authors, ' &amp; ', '<br>');
re(authors, '&amp;&amp;', '&amp;')
'''
Prefs = namedtuple('Prefs', ' '.join(sorted(cprefs.defaults)))

_use_roman = None


def get_use_roman():
    global _use_roman
    if _use_roman is None:
        return config['use_roman_numerals_for_series_number']
    return _use_roman


def set_use_roman(val):
    global _use_roman
    _use_roman = bool(val)

# }}}


# Draw text {{{
Point = namedtuple('Point', 'x y')


def parse_text_formatting(text):
    pos = 0
    tokens = []
    for m in re.finditer(r'</?([a-zA-Z1-6]+)/?>', text):
        q = text[pos:m.start()]
        if q:
            tokens.append((False, q))
        tokens.append((True, (m.group(1).lower(), '/' in m.group()[:2])))
        pos = m.end()
    if tokens:
        if text[pos:]:
            tokens.append((False, text[pos:]))
    else:
        tokens = [(False, text)]

    ranges, open_ranges, text = [], [], []
    offset = 0
    for is_tag, tok in tokens:
        if is_tag:
            tag, closing = tok
            if closing:
                if open_ranges:
                    r = open_ranges.pop()
                    r[-1] = offset - r[-2]
                    if r[-1] > 0:
                        ranges.append(r)
            else:
                if tag in {'b', 'strong', 'i', 'em'}:
                    open_ranges.append([tag, offset, -1])
        else:
            offset += len(tok.replace('&amp;', '&'))
            text.append(tok)
    text = ''.join(text)
    formats = []
    for tag, start, length in chain(ranges, open_ranges):
        fmt = QTextCharFormat()
        if tag in {'b', 'strong'}:
            fmt.setFontWeight(QFont.Weight.Bold)
        elif tag in {'i', 'em'}:
            fmt.setFontItalic(True)
        else:
            continue
        if length == -1:
            length = len(text) - start
        if length > 0:
            r = QTextLayout.FormatRange()
            r.format = fmt
            r.start, r.length = start, length
            formats.append(r)
    return text, formats


class Block:

    def __init__(self, text='', width=0, font=None, img=None, max_height=100, align=Qt.AlignmentFlag.AlignCenter):
        self.layouts = []
        self._position = Point(0, 0)
        self.leading = self.line_spacing = 0
        if font is not None:
            fm = QFontMetrics(font, img)
            self.leading = fm.leading()
            self.line_spacing = fm.lineSpacing()
        for text in text.split('<br>') if text else ():
            text, formats = parse_text_formatting(sanitize(text))
            l = QTextLayout(unescape_formatting(text), font, img)
            l.setFormats(formats)
            to = QTextOption(align)
            to.setWrapMode(QTextOption.WrapMode.WrapAtWordBoundaryOrAnywhere)
            l.setTextOption(to)

            l.beginLayout()
            height = 0
            while height + 3*self.leading < max_height:
                line = l.createLine()
                if not line.isValid():
                    break
                line.setLineWidth(width)
                height += self.leading
                line.setPosition(QPointF(0, height))
                height += line.height()
            max_height -= height
            l.endLayout()
            if self.layouts:
                self.layouts.append(self.leading)
            else:
                self._position = Point(l.position().x(), l.position().y())
            self.layouts.append(l)
        if self.layouts:
            self.layouts.append(self.leading)

    @property
    def height(self):
        return int(ceil(sum(l if isinstance(l, numbers.Number) else l.boundingRect().height() for l in self.layouts)))

    @property
    def position(self):
        return self._position

    @position.setter
    def position(self, new_pos):
        (x, y) = new_pos
        self._position = Point(x, y)
        if self.layouts:
            self.layouts[0].setPosition(QPointF(x, y))
            y += self.layouts[0].boundingRect().height()
            for l in self.layouts[1:]:
                if isinstance(l, numbers.Number):
                    y += l
                else:
                    l.setPosition(QPointF(x, y))
                    y += l.boundingRect().height()

    def draw(self, painter):
        for l in self.layouts:
            if hasattr(l, 'draw'):
                # Etch effect for the text
                painter.save()
                painter.setRenderHints(QPainter.RenderHint.TextAntialiasing | QPainter.RenderHint.Antialiasing)
                painter.save()
                painter.setPen(QColor(255, 255, 255, 125))
                l.draw(painter, QPointF(1, 1))
                painter.restore()
                l.draw(painter, QPointF())
                painter.restore()


def layout_text(prefs, img, title, subtitle, footer, max_height, style):
    width = img.width() - 2 * style.hmargin
    title, subtitle, footer = title, subtitle, footer
    title_font = QFont(prefs.title_font_family or 'Liberation Serif')
    title_font.setPixelSize(prefs.title_font_size)
    title_font.setStyleStrategy(QFont.StyleStrategy.PreferAntialias)
    title_block = Block(title, width, title_font, img, max_height, style.TITLE_ALIGN)
    title_block.position = style.hmargin, style.vmargin
    subtitle_block = Block()
    if subtitle:
        subtitle_font = QFont(prefs.subtitle_font_family or 'Liberation Sans')
        subtitle_font.setPixelSize(prefs.subtitle_font_size)
        subtitle_font.setStyleStrategy(QFont.StyleStrategy.PreferAntialias)
        gap = 2 * title_block.leading
        mh = max_height - title_block.height - gap
        subtitle_block = Block(subtitle, width, subtitle_font, img, mh, style.SUBTITLE_ALIGN)
        subtitle_block.position = style.hmargin, title_block.position.y + title_block.height + gap

    footer_font = QFont(prefs.footer_font_family or 'Liberation Serif')
    footer_font.setStyleStrategy(QFont.StyleStrategy.PreferAntialias)
    footer_font.setPixelSize(prefs.footer_font_size)
    footer_block = Block(footer, width, footer_font, img, max_height, style.FOOTER_ALIGN)
    footer_block.position = style.hmargin, img.height() - style.vmargin - footer_block.height

    return title_block, subtitle_block, footer_block

# }}}

# Format text using templates {{{


def sanitize(s):
    return unicodedata.normalize('NFC', clean_xml_chars(clean_ascii_chars(force_unicode(s or ''))))


_formatter = None
_template_cache = {}


def escape_formatting(val):
    return val.replace('&', '&amp;').replace('<', '&lt;').replace('>', '&gt;')


def unescape_formatting(val):
    return val.replace('&lt;', '<').replace('&gt;', '>').replace('&amp;', '&')


class Formatter(SafeFormat):

    def get_value(self, orig_key, args, kwargs):
        ans = SafeFormat.get_value(self, orig_key, args, kwargs)
        return escape_formatting(ans)


def formatter():
    global _formatter
    if _formatter is None:
        _formatter = Formatter()
    return _formatter


def format_fields(mi, prefs):
    f = formatter()

    def safe_format(field):
        return f.safe_format(
            getattr(prefs, field), mi, _('Template error'), mi, template_cache=_template_cache
        )
    return map(safe_format, ('title_template', 'subtitle_template', 'footer_template'))


@contextmanager
def preserve_fields(obj, fields):
    if isinstance(fields, string_or_bytes):
        fields = fields.split()
    null = object()
    mem = {f:getattr(obj, f, null) for f in fields}
    try:
        yield
    finally:
        for f, val in iteritems(mem):
            if val is null:
                delattr(obj, f)
            else:
                setattr(obj, f, val)


def format_text(mi, prefs):
    with preserve_fields(mi, 'authors formatted_series_index'):
        mi.authors = [a for a in mi.authors if a != _('Unknown')]
        mi.formatted_series_index = fmt_sidx(mi.series_index or 0, use_roman=get_use_roman())
        return tuple(format_fields(mi, prefs))
# }}}


# Colors {{{
ColorTheme = namedtuple('ColorTheme', 'color1 color2 contrast_color1 contrast_color2')


def to_theme(x):
    return {k:v for k, v in zip(ColorTheme._fields[:4], x.split())}


fallback_colors = to_theme('ffffff 000000 000000 ffffff')

default_color_themes = {
    'Earth' : to_theme('e8d9ac c7b07b 564628 382d1a'),
    'Grass' : to_theme('d8edb5 abc8a4 375d3b 183128'),
    'Water' : to_theme('d3dcf2 829fe4 00448d 00305a'),
    'Silver': to_theme('e6f1f5 aab3b6 6e7476 3b3e40'),
}


def theme_to_colors(theme):
    colors = {k:QColor('#' + theme[k]) for k in ColorTheme._fields}
    return ColorTheme(**colors)


def load_color_themes(prefs):
    t = default_color_themes.copy()
    t.update(prefs.color_themes)
    disabled = frozenset(prefs.disabled_color_themes)
    ans = [theme_to_colors(v) for k, v in iteritems(t) if k not in disabled]
    if not ans:
        # Ignore disabled and return only the builtin color themes
        ans = [theme_to_colors(v) for k, v in iteritems(default_color_themes)]
    return ans


def color(color_theme, name):
    ans = getattr(color_theme, name)
    if not ans.isValid():
        ans = QColor('#' + fallback_colors[name])
    return ans

# }}}

# Styles {{{


class Style:

    TITLE_ALIGN = SUBTITLE_ALIGN = FOOTER_ALIGN = Qt.AlignmentFlag.AlignHCenter | Qt.AlignmentFlag.AlignTop

    def __init__(self, color_theme, prefs):
        self.load_colors(color_theme)
        self.calculate_margins(prefs)

    def calculate_margins(self, prefs):
        self.hmargin = int((50 / 600) * prefs.cover_width)
        self.vmargin = int((50 / 800) * prefs.cover_height)

    def load_colors(self, color_theme):
        self.color1 = color(color_theme, 'color1')
        self.color2 = color(color_theme, 'color2')
        self.ccolor1 = color(color_theme, 'contrast_color1')
        self.ccolor2 = color(color_theme, 'contrast_color2')


class Cross(Style):

    NAME = 'The Cross'
    GUI_NAME = _('The Cross')

    def __call__(self, painter, rect, color_theme, title_block, subtitle_block, footer_block):
        painter.fillRect(rect, self.color1)
        r = QRect(0, int(title_block.position.y), rect.width(),
                  title_block.height + subtitle_block.height + subtitle_block.line_spacing // 2 + title_block.leading)
        painter.save()
        p = QPainterPath()
        p.addRoundedRect(QRectF(r), 10, 10 * r.width()/r.height(), Qt.SizeMode.RelativeSize)
        painter.setClipPath(p)
        painter.setRenderHint(QPainter.RenderHint.Antialiasing)
        painter.fillRect(r, self.color2)
        painter.restore()
        r = QRect(0, 0, int(title_block.position.x), rect.height())
        painter.fillRect(r, self.color2)
        return self.ccolor2, self.ccolor2, self.ccolor1


class Half(Style):

    NAME = 'Half and Half'
    GUI_NAME = _('Half and half')

    def __call__(self, painter, rect, color_theme, title_block, subtitle_block, footer_block):
        g = QLinearGradient(QPointF(0, 0), QPointF(0, rect.height()))
        g.setStops([(0, self.color1), (0.7, self.color2), (1, self.color1)])
        painter.fillRect(rect, QBrush(g))
        return self.ccolor1, self.ccolor1, self.ccolor1


def rotate_vector(angle, x, y):
    return x * cos(angle) - y * sin(angle), x * sin(angle) + y * cos(angle)


def draw_curved_line(painter_path, dx, dy, c1_frac, c1_amp, c2_frac, c2_amp):
    length = sqrt(dx * dx + dy * dy)
    angle = atan2(dy, dx)
    c1 = QPointF(*rotate_vector(angle, c1_frac * length, c1_amp * length))
    c2 = QPointF(*rotate_vector(angle, c2_frac * length, c2_amp * length))
    pos = painter_path.currentPosition()
    painter_path.cubicTo(pos + c1, pos + c2, pos + QPointF(dx, dy))


class Banner(Style):

    NAME = 'Banner'
    GUI_NAME = _('Banner')
    GRADE = 0.07

    def calculate_margins(self, prefs):
        Style.calculate_margins(self, prefs)
        self.hmargin = int(0.15 * prefs.cover_width)
        self.fold_width = int(0.1 * prefs.cover_width)

    def __call__(self, painter, rect, color_theme, title_block, subtitle_block, footer_block):
        painter.fillRect(rect, self.color1)
        top = title_block.position.y + 2
        extra_spacing = subtitle_block.line_spacing // 2 if subtitle_block.line_spacing else title_block.line_spacing // 3
        height = title_block.height + subtitle_block.height + extra_spacing + title_block.leading
        right = rect.right() - self.hmargin
        width = right - self.hmargin

        # Draw main banner
        p = main = QPainterPath(QPointF(self.hmargin, top))
        draw_curved_line(p, rect.width() - 2 * self.hmargin, 0, 0.1, -0.1, 0.9, -0.1)
        deltax = self.GRADE * height
        p.lineTo(right + deltax, top + height)
        right_corner = p.currentPosition()
        draw_curved_line(p, - width - 2 * deltax, 0, 0.1, 0.05, 0.9, 0.05)
        left_corner = p.currentPosition()
        p.closeSubpath()

        # Draw fold rectangles
        rwidth = self.fold_width
        yfrac = 0.1
        width23 = int(0.67 * rwidth)
        rtop = top + height * yfrac

        def draw_fold(x, m=1, corner=left_corner):
            ans = p = QPainterPath(QPointF(x, rtop))
            draw_curved_line(p, rwidth*m, 0, 0.1, 0.1*m, 0.5, -0.2*m)
            fold_upper = p.currentPosition()
            p.lineTo(p.currentPosition() + QPointF(-deltax*m, height))
            fold_corner = p.currentPosition()
            draw_curved_line(p, -rwidth*m, 0, 0.2, -0.1*m, 0.8, -0.1*m)
            draw_curved_line(p, deltax*m, -height, 0.2, 0.1*m, 0.8, 0.1*m)
            p = inner_fold = QPainterPath(corner)
            dp = fold_corner - p.currentPosition()
            draw_curved_line(p, dp.x(), dp.y(), 0.5, 0.3*m, 1, 0*m)
            p.lineTo(fold_upper), p.closeSubpath()
            return ans, inner_fold

        left_fold, left_inner = draw_fold(self.hmargin - width23)
        right_fold, right_inner = draw_fold(right + width23, m=-1, corner=right_corner)

        painter.save()
        painter.setRenderHint(QPainter.RenderHint.Antialiasing)
        pen = QPen(self.ccolor2)
        pen.setWidth(3)
        pen.setJoinStyle(Qt.PenJoinStyle.RoundJoin)
        painter.setPen(pen)
        for r in (left_fold, right_fold):
            painter.fillPath(r, QBrush(self.color2))
            painter.drawPath(r)
        for r in (left_inner, right_inner):
            painter.fillPath(r, QBrush(self.color2.darker()))
            painter.drawPath(r)
        painter.fillPath(main, QBrush(self.color2))
        painter.drawPath(main)
        painter.restore()
        return self.ccolor2, self.ccolor2, self.ccolor1


class Ornamental(Style):

    NAME = 'Ornamental'
    GUI_NAME = _('Ornamental')

    # SVG vectors {{{
    CORNER_VECTOR = "m 67.791903,64.260958 c -4.308097,-2.07925 -4.086719,-8.29575 0.334943,-9.40552 4.119758,-1.03399 8.732363,5.05239 5.393055,7.1162 -0.55,0.33992 -1,1.04147 -1,1.55902 0,1.59332 2.597425,1.04548 5.365141,-1.1316 1.999416,-1.57274 2.634859,-2.96609 2.634859,-5.7775 0,-9.55787 -9.827495,-13.42961 -24.43221,-9.62556 -3.218823,0.83839 -5.905663,1.40089 -5.970755,1.25 -0.06509,-0.1509 -0.887601,-1.19493 -1.827799,-2.32007 -1.672708,-2.00174 -1.636693,-2.03722 1.675668,-1.65052 1.861815,0.21736 6.685863,-0.35719 10.720107,-1.27678 12.280767,-2.79934 20.195487,-0.0248 22.846932,8.0092 3.187273,9.65753 -6.423297,17.7497 -15.739941,13.25313 z m 49.881417,-20.53932 c -3.19204,-2.701 -3.72967,-6.67376 -1.24009,-9.16334 2.48236,-2.48236 5.35141,-2.67905 7.51523,-0.51523 1.85966,1.85966 2.07045,6.52954 0.37143,8.22857 -2.04025,2.04024 3.28436,1.44595 6.92316,-0.77272 9.66959,-5.89579 0.88581,-18.22422 -13.0777,-18.35516 -5.28594,-0.0496 -10.31098,1.88721 -14.26764,5.4991 -1.98835,1.81509 -2.16454,1.82692 -2.7936,0.18763 -0.40973,-1.06774 0.12141,-2.82197 1.3628,-4.50104 2.46349,-3.33205 1.67564,-4.01299 -2.891784,-2.49938 -2.85998,0.94777 -3.81038,2.05378 -5.59837,6.51495 -1.184469,2.95536 -3.346819,6.86882 -4.805219,8.69657 -1.4584,1.82776 -2.65164,4.02223 -2.65164,4.87662 0,3.24694 -4.442667,0.59094 -5.872557,-3.51085 -1.361274,-3.90495 0.408198,-8.63869 4.404043,-11.78183 5.155844,-4.05558 1.612374,-3.42079 -9.235926,1.65457 -12.882907,6.02725 -16.864953,7.18038 -24.795556,7.18038 -8.471637,0 -13.38802,-1.64157 -17.634617,-5.88816 -2.832233,-2.83224 -3.849773,-4.81378 -4.418121,-8.6038 -1.946289,-12.9787795 8.03227,-20.91713135 19.767685,-15.7259993 5.547225,2.4538018 6.993631,6.1265383 3.999564,10.1557393 -5.468513,7.35914 -15.917883,-0.19431 -10.657807,-7.7041155 1.486298,-2.1219878 1.441784,-2.2225068 -0.984223,-2.2225068 -1.397511,0 -4.010527,1.3130878 -5.806704,2.9179718 -2.773359,2.4779995 -3.265777,3.5977995 -3.265777,7.4266705 0,5.10943 2.254112,8.84197 7.492986,12.40748 8.921325,6.07175 19.286666,5.61396 37.12088,-1.63946 15.35037,-6.24321 21.294999,-7.42408 34.886123,-6.92999 11.77046,0.4279 19.35803,3.05537 24.34054,8.42878 4.97758,5.3681 2.53939,13.58271 -4.86733,16.39873 -4.17361,1.58681 -11.00702,1.19681 -13.31978,-0.76018 z m 26.50156,-0.0787 c -2.26347,-2.50111 -2.07852,-7.36311 0.39995,-10.51398 2.68134,-3.40877 10.49035,-5.69409 18.87656,-5.52426 l 6.5685,0.13301 -7.84029,0.82767 c -8.47925,0.89511 -12.76997,2.82233 -16.03465,7.20213 -1.92294,2.57976 -1.96722,3.00481 -0.57298,5.5 1.00296,1.79495 2.50427,2.81821 4.46514,3.04333 2.92852,0.33623 2.93789,0.32121 1.08045,-1.73124 -1.53602,-1.69728 -1.64654,-2.34411 -0.61324,-3.58916 2.84565,-3.4288 7.14497,-0.49759 5.03976,3.43603 -1.86726,3.48903 -8.65528,4.21532 -11.3692,1.21647 z m -4.17462,-14.20302 c -0.38836,-0.62838 -0.23556,-1.61305 0.33954,-2.18816 1.3439,-1.34389 4.47714,-0.17168 3.93038,1.47045 -0.5566,1.67168 -3.38637,2.14732 -4.26992,0.71771 z m -8.48037,-9.1829 c -12.462,-4.1101 -12.53952,-4.12156 -25.49998,-3.7694 -24.020921,0.65269 -32.338219,0.31756 -37.082166,-1.49417 -5.113999,-1.95305 -8.192504,-6.3647405 -6.485463,-9.2940713 0.566827,-0.972691 1.020091,-1.181447 1.037211,-0.477701 0.01685,0.692606 1.268676,1.2499998 2.807321,1.2499998 1.685814,0 4.868609,1.571672 8.10041,4.0000015 4.221481,3.171961 6.182506,3.999221 9.473089,3.996261 l 4.149585,-0.004 -3.249996,-1.98156 c -3.056252,-1.863441 -4.051566,-3.8760635 -2.623216,-5.3044145 0.794,-0.794 6.188222,1.901516 9.064482,4.5295635 1.858669,1.698271 3.461409,1.980521 10.559493,1.859621 11.30984,-0.19266 20.89052,1.29095 31.97905,4.95208 7.63881,2.52213 11.51931,3.16471 22.05074,3.65141 7.02931,0.32486 13.01836,0.97543 13.30902,1.44571 0.29065,0.47029 -5.2356,0.83436 -12.28056,0.80906 -12.25942,-0.044 -13.34537,-0.2229 -25.30902,-4.16865 z"  # noqa
    # }}}
    PATH_CACHE = {}
    VIEWPORT = (400, 500)

    def calculate_margins(self, prefs):
        self.hmargin = int((51 / self.VIEWPORT[0]) * prefs.cover_width)
        self.vmargin = int((83 / self.VIEWPORT[1]) * prefs.cover_height)

    def __call__(self, painter, rect, color_theme, title_block, subtitle_block, footer_block):
        if not self.PATH_CACHE:
            from calibre.utils.speedups import svg_path_to_painter_path
            try:
                self.__class__.PATH_CACHE['corner'] = svg_path_to_painter_path(self.CORNER_VECTOR)
            except Exception:
                import traceback
                traceback.print_exc()
        p = painter
        painter.setRenderHint(QPainter.RenderHint.Antialiasing)
        g = QRadialGradient(QPointF(rect.center()), rect.width())
        g.setColorAt(0, self.color1), g.setColorAt(1, self.color2)
        painter.fillRect(rect, QBrush(g))
        painter.save()
        painter.setWindow(0, 0, *self.VIEWPORT)
        try:
            path = self.PATH_CACHE['corner']
        except KeyError:
            path = QPainterPath()
        pen = p.pen()
        pen.setColor(self.ccolor1)
        p.setPen(pen)

        def corner():
            b = QBrush(self.ccolor1)
            p.fillPath(path, b)
            p.rotate(90), p.translate(100, -100), p.scale(1, -1), p.translate(-103, -97)
            p.fillPath(path, b)
            p.setWorldTransform(QTransform())
        # Top-left corner
        corner()
        # Top right corner
        p.scale(-1, 1), p.translate(-400, 0), corner()
        # Bottom left corner
        p.scale(1, -1), p.translate(0, -500), corner()
        # Bottom right corner
        p.scale(-1, -1), p.translate(-400, -500), corner()
        for y in (28.4, 471.7):
            p.drawLine(QPointF(160, y), QPointF(240, y))
        for x in (31.3, 368.7):
            p.drawLine(QPointF(x, 155), QPointF(x, 345))
        pen.setWidthF(1.8)
        p.setPen(pen)
        for y in (23.8, 476.7):
            p.drawLine(QPointF(160, y), QPointF(240, y))
        for x in (26.3, 373.7):
            p.drawLine(QPointF(x, 155), QPointF(x, 345))
        painter.restore()

        return self.ccolor2, self.ccolor2, self.ccolor1


class Blocks(Style):

    NAME = 'Blocks'
    GUI_NAME = _('Blocks')
    FOOTER_ALIGN = Qt.AlignmentFlag.AlignRight | Qt.AlignmentFlag.AlignTop

    def __call__(self, painter, rect, color_theme, title_block, subtitle_block, footer_block):
        painter.fillRect(rect, self.color1)
        y = rect.height() - rect.height() // 3
        r = QRect(rect)
        r.setBottom(y)
        painter.fillRect(rect, self.color1)
        r = QRect(rect)
        r.setTop(y)
        painter.fillRect(r, self.color2)
        return self.ccolor1, self.ccolor1, self.ccolor2


def all_styles():
    return {
        x.NAME for x in itervalues(globals()) if
        isinstance(x, type) and issubclass(x, Style) and x is not Style
    }


def load_styles(prefs, respect_disabled=True):
    disabled = frozenset(prefs.disabled_styles) if respect_disabled else ()
    ans = tuple(x for x in itervalues(globals()) if
            isinstance(x, type) and issubclass(x, Style) and x is not Style and x.NAME not in disabled)
    if not ans and disabled:
        # If all styles have been disabled, ignore the disabling and return all
        # the styles
        ans = load_styles(prefs, respect_disabled=False)
    return ans

# }}}


def init_environment():
    ensure_app()
    load_builtin_fonts()


def generate_cover(mi, prefs=None, as_qimage=False):
    init_environment()
    prefs = prefs or cprefs
    prefs = {k:prefs.get(k) for k in cprefs.defaults}
    prefs = Prefs(**prefs)
    color_theme = random.choice(load_color_themes(prefs))
    style = random.choice(load_styles(prefs))(color_theme, prefs)
    title, subtitle, footer = format_text(mi, prefs)
    img = QImage(prefs.cover_width, prefs.cover_height, QImage.Format.Format_ARGB32)
    title_block, subtitle_block, footer_block = layout_text(
        prefs, img, title, subtitle, footer, img.height() // 3, style)
    p = QPainter(img)
    rect = QRect(0, 0, img.width(), img.height())
    colors = style(p, rect, color_theme, title_block, subtitle_block, footer_block)
    for block, color in zip((title_block, subtitle_block, footer_block), colors):
        p.setPen(color)
        block.draw(p)
    p.end()
    img.setText('Generated cover', f'{__appname__} {__version__}')
    if as_qimage:
        return img
    return pixmap_to_data(img)


def override_prefs(base_prefs, **overrides):
    ans = {k:overrides.get(k, base_prefs[k]) for k in cprefs.defaults}
    override_color_theme = overrides.get('override_color_theme')
    if override_color_theme is not None:
        all_themes = set(default_color_themes) | set(ans['color_themes'])
        if override_color_theme in all_themes:
            all_themes.discard(override_color_theme)
            ans['disabled_color_themes'] = all_themes
    override_style = overrides.get('override_style')
    if override_style is not None:
        styles = all_styles()
        if override_style in styles:
            styles.discard(override_style)
            ans['disabled_styles'] = styles

    return ans


def create_cover(title, authors, series=None, series_index=1, prefs=None, as_qimage=False):
    ' Create a cover from the specified title, author and series. Any user set'
    ' templates are ignored, to ensure that the specified metadata is used. '
    mi = Metadata(title, authors)
    if series:
        mi.series, mi.series_index = series, series_index
    d = cprefs.defaults
    prefs = override_prefs(
        prefs or cprefs, title_template=d['title_template'], subtitle_template=d['subtitle_template'], footer_template=d['footer_template'])
    return generate_cover(mi, prefs=prefs, as_qimage=as_qimage)


def calibre_cover2(title, author_string='', series_string='', prefs=None, as_qimage=False, logo_path=None):
    init_environment()
    title, subtitle, footer = '<b>' + escape_formatting(title), '<i>' + escape_formatting(series_string), '<b>' + escape_formatting(author_string)
    prefs = prefs or cprefs
    prefs = {k:prefs.get(k) for k in cprefs.defaults}
    scale = 800. / prefs['cover_height']
    scale_cover(prefs, scale)
    prefs = Prefs(**prefs)
    img = QImage(prefs.cover_width, prefs.cover_height, QImage.Format.Format_ARGB32)
    img.fill(Qt.GlobalColor.white)
    # colors = to_theme('ffffff ffffff 000000 000000')
    color_theme = theme_to_colors(fallback_colors)

    class CalibeLogoStyle(Style):
        NAME = GUI_NAME = 'calibre'

        def __call__(self, painter, rect, color_theme, title_block, subtitle_block, footer_block):
            top = title_block.position.y + 10
            extra_spacing = subtitle_block.line_spacing // 2 if subtitle_block.line_spacing else title_block.line_spacing // 3
            height = title_block.height + subtitle_block.height + extra_spacing + title_block.leading
            top += height + 25
            bottom = footer_block.position.y - 50
            logo = QImage(logo_path or I('library.png'))
            pwidth, pheight = rect.width(), bottom - top
            scaled, width, height = fit_image(logo.width(), logo.height(), pwidth, pheight)
            x, y = (pwidth - width) // 2, (pheight - height) // 2
            rect = QRect(x, top + y, width, height)
            painter.setRenderHint(QPainter.RenderHint.SmoothPixmapTransform)
            painter.drawImage(rect, logo)
            return self.ccolor1, self.ccolor1, self.ccolor1
    style = CalibeLogoStyle(color_theme, prefs)
    title_block, subtitle_block, footer_block = layout_text(
        prefs, img, title, subtitle, footer, img.height() // 3, style)
    p = QPainter(img)
    rect = QRect(0, 0, img.width(), img.height())
    colors = style(p, rect, color_theme, title_block, subtitle_block, footer_block)
    for block, color in zip((title_block, subtitle_block, footer_block), colors):
        p.setPen(color)
        block.draw(p)
    p.end()
    img.setText('Generated cover', f'{__appname__} {__version__}')
    if as_qimage:
        return img
    return pixmap_to_data(img)


def message_image(text, width=500, height=400, font_size=20):
    init_environment()
    img = QImage(width, height, QImage.Format.Format_ARGB32)
    img.fill(Qt.GlobalColor.white)
    p = QPainter(img)
    f = QFont()
    f.setPixelSize(font_size)
    p.setFont(f)
    r = img.rect().adjusted(10, 10, -10, -10)
    p.drawText(r, Qt.AlignmentFlag.AlignJustify | Qt.AlignmentFlag.AlignVCenter | Qt.TextFlag.TextWordWrap, text)
    p.end()
    return pixmap_to_data(img)


def scale_cover(prefs, scale):
    for x in ('cover_width', 'cover_height', 'title_font_size', 'subtitle_font_size', 'footer_font_size'):
        prefs[x] = int(scale * prefs[x])


def generate_masthead(title, output_path=None, width=600, height=60, as_qimage=False, font_family=None):
    init_environment()
    font_family = font_family or cprefs['title_font_family'] or 'Liberation Serif'
    img = QImage(width, height, QImage.Format.Format_ARGB32)
    img.fill(Qt.GlobalColor.white)
    p = QPainter(img)
    p.setRenderHints(QPainter.RenderHint.Antialiasing | QPainter.RenderHint.TextAntialiasing)
    f = QFont(font_family)
    f.setStyleStrategy(QFont.StyleStrategy.PreferAntialias)
    f.setPixelSize((height * 3) // 4), f.setBold(True)
    p.setFont(f)
    p.drawText(img.rect(), Qt.AlignmentFlag.AlignLeft | Qt.AlignmentFlag.AlignVCenter, sanitize(title))
    p.end()
    if as_qimage:
        return img
    data = pixmap_to_data(img)
    if output_path is None:
        return data
    with open(output_path, 'wb') as f:
        f.write(data)


def test(scale=0.25):
    from qt.core import QGridLayout, QLabel, QMainWindow, QPixmap, QScrollArea, QWidget

    from calibre.gui2 import Application
    app = Application([])
    mi = Metadata('Unknown', ['Kovid Goyal', 'John & Doe', 'Author'])
    mi.series = 'A series & styles'
    m = QMainWindow()
    sa = QScrollArea(m)
    w = QWidget(m)
    sa.setWidget(w)
    l = QGridLayout(w)
    w.setLayout(l), l.setSpacing(30)
    scale *= w.devicePixelRatioF()
    labels = []
    for r, color in enumerate(sorted(default_color_themes)):
        for c, style in enumerate(sorted(all_styles())):
            mi.series_index = c + 1
            mi.title = 'An algorithmic cover [%s]' % color
            prefs = override_prefs(cprefs, override_color_theme=color, override_style=style)
            scale_cover(prefs, scale)
            img = generate_cover(mi, prefs=prefs, as_qimage=True)
            img.setDevicePixelRatio(w.devicePixelRatioF())
            la = QLabel()
            la.setPixmap(QPixmap.fromImage(img))
            l.addWidget(la, r, c)
            labels.append(la)
    m.setCentralWidget(sa)
    w.resize(w.sizeHint())
    m.show()
    app.exec()


if __name__ == '__main__':
    test()