Add code to get metrics from fonts, convert QRawFont to an Sfnt and fix curve drawing

src/calibre/ebooks/pdf/render/engine.py

@@ -10,15 +10,16 @@ __docformat__ = 'restructuredtext en'
 import sys, traceback
 from math import sqrt
 from collections import namedtuple
-from future_builtins import map
 from functools import wraps
 
 from PyQt4.Qt import (QPaintEngine, QPaintDevice, Qt, QApplication, QPainter,
-                      QTransform, QPainterPath, QFontMetricsF)
+                      QTransform, QPainterPath, QRawFont)
 
 from calibre.constants import DEBUG
 from calibre.ebooks.pdf.render.serialize import (Color, PDFStream, Path, Text)
 from calibre.ebooks.pdf.render.common import inch, A4
+from calibre.utils.fonts.sfnt.container import Sfnt
+from calibre.utils.fonts.sfnt.metrics import FontMetrics
 
 XDPI = 1200
 YDPI = 1200
@@ -309,11 +310,16 @@ class PdfEngine(QPaintEngine):
             elif elem.isLineTo():
                 p.line_to(*em)
             elif elem.isCurveTo():
+                added = False
                 if path.elementCount() > i+1:
-                    c1, c2 = map(lambda j:(
-                        path.elementAt(j).x, path.elementAt(j).y), (i, i+1))
+                    c1, c2 = path.elementAt(i), path.elementAt(i+1)
+                    if (c1.type == path.CurveToDataElement and c2.type ==
+                        path.CurveToDataElement):
                         i += 2
-                    p.curve_to(*(c1 + c2 + em))
+                        p.curve_to(em[0], em[1], c1.x, c1.y, c2.x, c2.y)
+                        added = True
+                if not added:
+                    raise ValueError('Invalid curve to operation')
         return p
 
     @store_error
@@ -355,15 +361,8 @@ class PdfEngine(QPaintEngine):
         else:
             sz = px
 
-        q = self.qt_system
-        if not q.isIdentity() and q.type() > q.TxShear:
-            # We cant map this transform to a PDF text transform operator
-            f, s = self.do_fill, self.do_stroke
-            self.do_fill, self.do_stroke = True, False
-            super(PdfEngine, self).drawTextItem(point, text_item)
-            self.do_fill, self.do_stroke = f, s
-            return
-
+        r = QRawFont.fromFont(f)
+        metrics = FontMetrics(Sfnt(r))
         to = Text()
         to.size = sz
         to.set_transform(1, 0, 0, -1, point.x(), point.y())
@@ -375,43 +374,24 @@ class PdfEngine(QPaintEngine):
             to.word_spacing = ws
         spacing = f.letterSpacing()
         st = f.letterSpacingType()
+        text = type(u'')(text_item.text())
         if st == f.AbsoluteSpacing and spacing != 0:
             to.char_space = spacing/self.scale
         if st == f.PercentageSpacing and spacing not in {100, 0}:
-            # TODO: Implement this with the TJ operator
-            avg_char_width = QFontMetricsF(f).averageCharWidth()
-            to.char_space = (spacing - 100) * avg_char_width / 100
-        text = type(u'')(text_item.text())
+            # TODO: Figure out why the results from uncommenting the super
+            # class call above differ. The advance widths are the same as those
+            # reported by QRawfont, so presumably, Qt use some other
+            # algorithm, I can't be bothered to track it down. This behavior is
+            # correct as per the Qt docs' description of PercentageSpacing
+            widths = [w*-1 for w in metrics.advance_widths(text,
+                                            sz, f.stretch()/100.)]
+            to.glyph_adjust = ((spacing-100)/100., widths)
         to.text = text
         with self:
             self.graphics_state.apply_fill(self.graphics_state.current_state['stroke'],
                                            self, self.pdf)
             self.pdf.draw_text(to)
 
-        def draw_line(kind='underline'):
-            m = QFontMetricsF(f)
-            tw = m.width(text)
-            p = Path()
-            if kind == 'underline':
-                dy = m.underlinePos()
-            elif kind == 'overline':
-                dy = -m.overlinePos()
-            elif kind == 'strikeout':
-                dy = -m.strikeOutPos()
-            p.move_to(point.x(), point.y()+dy)
-            p.line_to(point.x()+tw, point.y()+dy)
-            with self:
-                self.graphics_state.apply_line_width(m.lineWidth(),
-                        self, self.pdf)
-                self.pdf.draw_path(p, stroke=True, fill=False)
-
-        if f.underline():
-            draw_line()
-        if f.overline():
-            draw_line('overline')
-        if f.strikeOut():
-            draw_line('strikeout')
-
     @store_error
     def drawPolygon(self, points, mode):
         if not points: return
@@ -419,8 +399,7 @@ class PdfEngine(QPaintEngine):
         p.move_to(points[0].x(), points[0].y())
         for point in points[1:]:
             p.line_to(point.x(), point.y())
-        if points[-1] != points[0]:
-            p.line_to(points[0].x(), points[0].y())
+        p.close()
         fill_rule = {self.OddEvenMode:'evenodd',
                     self.WindingMode:'winding'}.get(mode, 'evenodd')
         self.pdf.draw_path(p, stroke=True, fill_rule=fill_rule,
@@ -504,13 +483,16 @@ if __name__ == '__main__':
             p.restore()
 
             f = p.font()
-            f.setPointSize(24)
-            f.setUnderline(True)
+            f.setPointSize(48)
+            f.setLetterSpacing(f.PercentageSpacing, 200)
+            # f.setUnderline(True)
+            # f.setOverline(True)
+            # f.setStrikeOut(True)
             f.setFamily('Times New Roman')
             p.setFont(f)
             # p.scale(2, 2)
-            p.rotate(45)
-            p.setPen(QColor(0, 255, 0))
+            # p.rotate(45)
+            p.setPen(QColor(0, 0, 255))
             p.drawText(QPoint(100, 300), 'Some text')
         finally:
             p.end()

src/calibre/ebooks/pdf/render/serialize.py

@@ -9,6 +9,7 @@ __docformat__ = 'restructuredtext en'
 
 import hashlib
 from future_builtins import map
+from itertools import izip
 from collections import namedtuple
 
 from calibre.constants import (__appname__, __version__)
@@ -137,6 +138,9 @@ class Path(object):
     def curve_to(self, x1, y1, x2, y2, x, y):
         self.ops.append((x1, y1, x2, y2, x, y, 'c'))
 
+    def close(self):
+        self.ops.append(('h',))
+
 class Text(object):
 
     def __init__(self):
@@ -146,6 +150,7 @@ class Text(object):
         self.horizontal_scale = self.default_horizontal_scale = 100
         self.word_spacing = self.default_word_spacing = 0
         self.char_space = self.default_char_space = 0
+        self.glyph_adjust = self.default_glyph_adjust = None
         self.size = 12
         self.text = ''
 
@@ -170,8 +175,17 @@ class Text(object):
         if self.char_space != self.default_char_space:
             stream.write('%g Tc '%self.char_space)
         stream.write_line()
+        if self.glyph_adjust is self.default_glyph_adjust:
             serialize(String(self.text), stream)
             stream.write(' Tj ')
+        else:
+            chars = Array()
+            frac, widths = self.glyph_adjust
+            for c, width in izip(self.text, widths):
+                chars.append(String(c))
+                chars.append(int(width * frac))
+            serialize(chars, stream)
+            stream.write(' TJ ')
         stream.write_line('ET')
 
 

src/calibre/utils/fonts/sfnt/container.py

@@ -16,7 +16,8 @@ from calibre.utils.fonts.utils import (get_tables, checksum_of_block,
 from calibre.utils.fonts.sfnt import align_block, UnknownTable, max_power_of_two
 from calibre.utils.fonts.sfnt.errors import UnsupportedFont
 
-from calibre.utils.fonts.sfnt.head import HeadTable
+from calibre.utils.fonts.sfnt.head import (HeadTable, HorizontalHeader,
+                                           OS2Table, PostTable)
 from calibre.utils.fonts.sfnt.maxp import MaxpTable
 from calibre.utils.fonts.sfnt.loca import LocaTable
 from calibre.utils.fonts.sfnt.glyf import GlyfTable
@@ -29,18 +30,9 @@ from calibre.utils.fonts.sfnt.cff.table import CFFTable
 
 class Sfnt(object):
 
-    def __init__(self, raw):
-        self.sfnt_version = raw[:4]
-        if self.sfnt_version not in {b'\x00\x01\x00\x00', b'OTTO', b'true',
-                b'type1'}:
-            raise UnsupportedFont('Font has unknown sfnt version: %r'%self.sfnt_version)
-        self.read_tables(raw)
-
-    def read_tables(self, raw):
-        self.tables = {}
-        for table_tag, table, table_index, table_offset, table_checksum in get_tables(raw):
-            self.tables[table_tag] = {
+    TABLE_MAP = {
         b'head' : HeadTable,
+        b'hhea' : HorizontalHeader,
         b'maxp' : MaxpTable,
         b'loca' : LocaTable,
         b'glyf' : GlyfTable,
@@ -48,7 +40,32 @@ class Sfnt(object):
         b'CFF ' : CFFTable,
         b'kern' : KernTable,
         b'GSUB' : GSUBTable,
-                    }.get(table_tag, UnknownTable)(table)
+        b'OS/2' : OS2Table,
+        b'post' : PostTable,
+    }
+
+    def __init__(self, raw_or_qrawfont):
+        self.tables = {}
+        if isinstance(raw_or_qrawfont, bytes):
+            raw = raw_or_qrawfont
+            self.sfnt_version = raw[:4]
+            if self.sfnt_version not in {b'\x00\x01\x00\x00', b'OTTO', b'true',
+                    b'type1'}:
+                raise UnsupportedFont('Font has unknown sfnt version: %r'%self.sfnt_version)
+            for table_tag, table, table_index, table_offset, table_checksum in get_tables(raw):
+                self.tables[table_tag] = self.TABLE_MAP.get(
+                    table_tag, UnknownTable)(table)
+        else:
+            for table_tag in {
+                b'cmap', b'hhea', b'head', b'hmtx', b'maxp', b'name', b'OS/2',
+                b'post', b'cvt ', b'fpgm', b'glyf', b'loca', b'prep', b'CFF ',
+                b'VORG', b'EBDT', b'EBLC', b'EBSC', b'BASE', b'GSUB', b'GPOS',
+                b'GDEF', b'JSTF', b'gasp', b'hdmx', b'kern', b'LTSH', b'PCLT',
+                b'VDMX', b'vhea', b'vmtx', b'MATH'}:
+                table = bytes(raw_or_qrawfont.fontTable(table_tag))
+                if table:
+                    self.tables[table_tag] = self.TABLE_MAP.get(
+                        table_tag, UnknownTable)(table)
 
     def __getitem__(self, key):
         return self.tables[key]
@@ -140,7 +157,8 @@ def test_roundtrip(ff=None):
     if data[:12] != rd[:12]:
         raise ValueError('Roundtripping failed, font header not the same')
     if len(data) != len(rd):
-        raise ValueError('Roundtripping failed, size different')
+        raise ValueError('Roundtripping failed, size different (%d vs. %d)'%
+                         (len(data), len(rd)))
 
 if __name__ == '__main__':
     import sys

src/calibre/utils/fonts/sfnt/head.py

@@ -11,6 +11,7 @@ from itertools import izip
 from struct import unpack_from, pack
 
 from calibre.utils.fonts.sfnt import UnknownTable, DateTimeProperty, FixedProperty
+from calibre.utils.fonts.sfnt.errors import UnsupportedFont
 
 class HeadTable(UnknownTable):
 
@@ -52,4 +53,75 @@ class HeadTable(UnknownTable):
         vals = [getattr(self, f) for f in self._fields]
         self.raw = pack(self._fmt, *vals)
 
+class HorizontalHeader(UnknownTable):
+
+    version_number = FixedProperty('_version_number')
+
+    def read_data(self, hmtx):
+        if hasattr(self, 'ascender'): return
+        field_types = (
+            '_version_number' , 'l',
+            'ascender', 'h',
+            'descender', 'h',
+            'line_gap', 'h',
+            'advance_width_max', 'H',
+            'min_left_size_bearing', 'h',
+            'min_right_side_bearing', 'h',
+            'x_max_extent', 'h',
+            'caret_slope_rise', 'h',
+            'caret_slop_run', 'h',
+            'caret_offset', 'h',
+            'r1', 'h',
+            'r2', 'h',
+            'r3', 'h',
+            'r4', 'h',
+            'metric_data_format', 'h',
+            'number_of_h_metrics', 'H',
+        )
+
+        self._fmt = ('>%s'%(''.join(field_types[1::2]))).encode('ascii')
+        self._fields = field_types[0::2]
+
+        for f, val in izip(self._fields, unpack_from(self._fmt, self.raw)):
+            setattr(self, f, val)
+
+        raw = hmtx.raw
+        num = self.number_of_h_metrics
+        if len(raw) < 4*num:
+            raise UnsupportedFont('The hmtx table has insufficient data')
+        long_hor_metric = raw[:4*num]
+        fmt = '>%dH'%(2*num)
+        entries = unpack_from(fmt.encode('ascii'), long_hor_metric)
+        self.advance_widths = entries[0::2]
+        fmt = '>%dh'%(2*num)
+        entries = unpack_from(fmt.encode('ascii'), long_hor_metric)
+        self.left_side_bearings = entries[1::2]
+
+class OS2Table(UnknownTable):
+
+    version_number = FixedProperty('_version')
+
+    def read_data(self):
+        if hasattr(self, 'char_width'): return
+        from calibre.utils.fonts.utils import get_font_characteristics
+        vals = get_font_characteristics(self.raw, raw_is_table=True,
+                                        return_all=True)
+        for i, attr in enumerate((
+            '_version', 'char_width', 'weight', 'width', 'fs_type',
+            'subscript_x_size', 'subscript_y_size', 'subscript_x_offset',
+            'subscript_y_offset', 'superscript_x_size', 'superscript_y_size',
+            'superscript_x_offset', 'superscript_y_offset', 'strikeout_size',
+            'strikeout_position', 'family_class', 'panose', 'selection',
+            'is_italic', 'is_bold', 'is_regular')):
+            setattr(self, attr, vals[i])
+
+class PostTable(UnknownTable):
+
+    version_number = FixedProperty('_version')
+    italic_angle = FixedProperty('_italic_angle')
+
+    def read_data(self):
+        if hasattr(self, 'underline_position'): return
+        (self._version, self._italic_angle, self.underline_position,
+         self.underline_thickness) = unpack_from(b'>llhh', self.raw)
 

src/calibre/utils/fonts/sfnt/metrics.py

@@ -0,0 +1,86 @@
+#!/usr/bin/env python
+# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:fdm=marker:ai
+from __future__ import (unicode_literals, division, absolute_import,
+                        print_function)
+
+__license__   = 'GPL v3'
+__copyright__ = '2012, Kovid Goyal <kovid at kovidgoyal.net>'
+__docformat__ = 'restructuredtext en'
+
+from future_builtins import map
+
+class FontMetrics(object):
+
+    '''
+    Get various metrics for the specified sfnt. All the metrics are returned in
+    units of pixels. To calculate a metric you have to specify the font size
+    (in pixels) and the horizontal stretch factor (between 0.0 and 1.0).
+    '''
+
+    def __init__(self, sfnt):
+        self.sfnt = sfnt
+
+        hhea = self.sfnt[b'hhea']
+        hhea.read_data(self.sfnt[b'hmtx'])
+        self.ascent = hhea.ascender
+        self.descent = hhea.descender
+        self._advance_widths = hhea.advance_widths
+        self.cmap = self.sfnt[b'cmap']
+        self.head = self.sfnt[b'head']
+        self.units_per_em = self.head.units_per_em
+        self.os2 = self.sfnt[b'OS/2']
+        self.os2.read_data()
+        self.post = self.sfnt[b'post']
+        self.post.read_data()
+
+    def underline_thickness(self, pixel_size=12.0):
+        'Thickness for lines (in pixels) at the specified size'
+        yscale = pixel_size / self.units_per_em
+        return self.post.underline_thickness * yscale
+
+    def underline_position(self, pixel_size=12.0):
+        yscale = pixel_size / self.units_per_em
+        return self.post.underline_position * yscale
+
+    def overline_position(self, pixel_size=12.0):
+        yscale = pixel_size / self.units_per_em
+        return (self.ascent + 2) * yscale
+
+    def strikeout_size(self, pixel_size=12.0):
+        'The width of the strikeout line, in pixels'
+        yscale = pixel_size / self.units_per_em
+        return yscale * self.os2.strikeout_size
+
+    def strikeout_position(self, pixel_size=12.0):
+        'The displacement from the baseline to top of the strikeout line, in pixels'
+        yscale = pixel_size / self.units_per_em
+        return yscale * self.os2.strikeout_position
+
+    def advance_widths(self, string, pixel_size=12.0, stretch=1.0):
+        '''
+        Return the advance widths (in pixels) for all glyphs corresponding to
+        the characters in string at the specified pixel_size and stretch factor.
+        '''
+        if not isinstance(string, type(u'')):
+            raise ValueError('Must supply a unicode object')
+        chars = tuple(map(ord, string))
+        cmap = self.cmap.get_character_map(chars)
+        glyph_ids = (cmap[c] for c in chars)
+        last = len(self._advance_widths)
+        pixel_size_x = stretch * pixel_size
+        xscale = pixel_size_x / self.units_per_em
+        return tuple(self._advance_widths[i if i < last else -1]*xscale for i in glyph_ids)
+
+    def width(self, string, pixel_size=12.0, stretch=1.0):
+        'The width of the string at the specified pixel size and stretch, in pixels'
+        return sum(self.advance_widths(string, pixel_size, stretch))
+
+if __name__ == '__main__':
+    import sys
+    from calibre.utils.fonts.sfnt.container import Sfnt
+    with open(sys.argv[-2], 'rb') as f:
+        raw = f.read()
+    sfnt = Sfnt(raw)
+    m = FontMetrics(sfnt)
+    print (m.advance_widths(sys.argv[-1]))
+

src/calibre/utils/fonts/utils.py

@@ -41,7 +41,7 @@ def get_table(raw, name):
             return table, table_index, table_offset, table_checksum
     return None, None, None, None
 
-def get_font_characteristics(raw, raw_is_table=False):
+def get_font_characteristics(raw, raw_is_table=False, return_all=False):
     '''
     Return (weight, is_italic, is_bold, is_regular, fs_type, panose, width,
     is_oblique, is_wws). These
@@ -79,6 +79,13 @@ def get_font_characteristics(raw, raw_is_table=False):
     is_regular = (selection & (1 << 6)) != 0
     is_wws = (selection & (1 << 8)) != 0
     is_oblique = (selection & (1 << 9)) != 0
+    if return_all:
+        return (version, char_width, weight, width, fs_type, subscript_x_size,
+            subscript_y_size, subscript_x_offset, subscript_y_offset,
+            superscript_x_size, superscript_y_size, superscript_x_offset,
+            superscript_y_offset, strikeout_size, strikeout_position,
+            family_class, panose, selection, is_italic, is_bold, is_regular)
+
     return weight, is_italic, is_bold, is_regular, fs_type, panose, width, is_oblique, is_wws, version
 
 def panose_to_css_generic_family(panose):