Add support for changing font sizes in generated EPUB files. Also make all font sizes relative, to work around Adobe DE refusing to resize text in a HTML file with absolute font sizes. Fixes #1095 (lit to epub not resizing)

src/calibre/ebooks/epub/__init__.py

@@ -14,13 +14,15 @@ from calibre.ebooks.html import config as common_config, tostring
 
 class DefaultProfile(object):
     
-    flow_size = sys.maxint
+    flow_size   = sys.maxint
     screen_size = None
+    dpi         = 100
     
 class PRS505(DefaultProfile):
     
     flow_size   = 300000
     screen_size = (600, 775)
+    dpi         = 166
         
 
 PROFILES = {
@@ -105,6 +107,8 @@ to auto-generate a Table of Contents.
            help=_('Set the left margin in pts. Default is %default'))
     layout('margin_right', ['--margin-right'], default=5.0, 
            help=_('Set the right margin in pts. Default is %default'))
+    layout('base_font_size', ['--base-font-size'], default=100.0,
+           help=_('The base font size as a percentage. Default is %default. Changing this should allow you to control overall base font sizes, except for input HTML files that use absolute font sizes for their text tags.'))
     
     c.add_opt('show_opf', ['--show-opf'], default=False, group='debug',
               help=_('Print generated OPF file to stdout'))

src/calibre/ebooks/epub/from_html.py

@@ -64,6 +64,7 @@ class HTMLProcessor(Processor):
         
         
         self.extract_css()
+        self.relativize_font_sizes()
         if opts.verbose > 2:
             self.debug_tree('nocss')
             

src/calibre/ebooks/html.py

@@ -623,9 +623,45 @@ class Processor(Parser):
             self.css += '\n\n'+self.opts.override_css
         self.do_layout()
         # TODO: Figure out what to do about CSS imports from linked stylesheets
+    
+    def relativize_font_sizes(self, dpi=100, base=16):
+        '''
+        Convert all absolute font sizes to percentages of ``base`` using ``dpi``
+        to convert from screen to paper units.
+        :param base: Base size in pixels. Adobe DE seems to need base size to be 16
+        irrespective of the unit of the length being converted
+        :param dpi: Dots per inch used to convert pixels to absolute lengths. Since
+        most HTML files are created on computers with monitors of DPI ~ 100, we use
+        100 by default.
+        '''
+        size_value_pat = re.compile(r'(?<!/)(?P<num>[0-9.]+)(?P<unit>cm|mm|in|pt|pc|px)', re.I)
         
+        # points per unit
+        ptu = { # Convert to pt
+                  'px' : 72./dpi,
+                  'pt' : 1.0,
+                  'pc' : 1/12.,
+                  'in' : 72.,
+                  'cm' : 72/2.54,
+                  'mm' : 72/25.4,
+                  }
+        
+        def relativize(match):
+            val  = float(match.group('num'))
+            unit = match.group('unit').lower()
+            val  *= ptu[unit]
+            return '%.1f%%'%((val/base) * 100)
+             
+        
+        def sub(match):
+            rule = match.group(1)
+            value = size_value_pat.sub(relativize, match.group(2))
+            return '%s : %s'%(rule, value)
+        
+        self.css = re.compile(r'(font|font-size)\s*:\s*([^;]+)', re.I).sub(sub, self.css)
+    
     def do_layout(self):
-        self.css += '\nbody {margin-top: 0pt; margin-bottom: 0pt; margin-left: 0pt; margin-right: 0pt}\n'
+        self.css += '\nbody {margin-top: 0pt; margin-bottom: 0pt; margin-left: 0pt; margin-right: 0pt; font-size: %f%%}\n'%self.opts.base_font_size
         self.css += '@page {margin-top: %fpt; margin-bottom: %fpt; margin-left: %fpt; margin-right: %fpt}\n'%(self.opts.margin_top, self.opts.margin_bottom, self.opts.margin_left, self.opts.margin_right)
 
 def config(defaults=None, config_name='html',

src/calibre/gui2/dialogs/epub.ui

@@ -77,7 +77,7 @@
      <item>
       <widget class="QStackedWidget" name="stack" >
        <property name="currentIndex" >
-        <number>3</number>
+        <number>1</number>
        </property>
        <widget class="QWidget" name="metadata_page" >
         <layout class="QGridLayout" name="gridLayout_4" >
@@ -89,6 +89,36 @@
               <string>Book Cover</string>
              </property>
              <layout class="QGridLayout" name="_2" >
+              <item row="0" column="0" >
+               <layout class="QHBoxLayout" name="_3" >
+                <item>
+                 <widget class="ImageView" name="cover" >
+                  <property name="text" >
+                   <string/>
+                  </property>
+                  <property name="pixmap" >
+                   <pixmap resource="../images.qrc" >:/images/book.svg</pixmap>
+                  </property>
+                  <property name="scaledContents" >
+                   <bool>true</bool>
+                  </property>
+                  <property name="alignment" >
+                   <set>Qt::AlignCenter</set>
+                  </property>
+                 </widget>
+                </item>
+               </layout>
+              </item>
+              <item row="2" column="0" >
+               <widget class="QCheckBox" name="opt_prefer_metadata_cover" >
+                <property name="text" >
+                 <string>Use cover from &amp;source file</string>
+                </property>
+                <property name="checked" >
+                 <bool>true</bool>
+                </property>
+               </widget>
+              </item>
               <item row="1" column="0" >
                <layout class="QVBoxLayout" name="_4" >
                 <property name="spacing" >
@@ -140,36 +170,6 @@
                 </item>
                </layout>
               </item>
-              <item row="2" column="0" >
-               <widget class="QCheckBox" name="opt_prefer_metadata_cover" >
-                <property name="text" >
-                 <string>Use cover from &amp;source file</string>
-                </property>
-                <property name="checked" >
-                 <bool>true</bool>
-                </property>
-               </widget>
-              </item>
-              <item row="0" column="0" >
-               <layout class="QHBoxLayout" name="_3" >
-                <item>
-                 <widget class="ImageView" name="cover" >
-                  <property name="text" >
-                   <string/>
-                  </property>
-                  <property name="pixmap" >
-                   <pixmap resource="../images.qrc" >:/images/book.svg</pixmap>
-                  </property>
-                  <property name="scaledContents" >
-                   <bool>true</bool>
-                  </property>
-                  <property name="alignment" >
-                   <set>Qt::AlignCenter</set>
-                  </property>
-                 </widget>
-                </item>
-               </layout>
-              </item>
              </layout>
              <zorder>opt_prefer_metadata_cover</zorder>
              <zorder></zorder>
@@ -396,17 +396,53 @@
        <widget class="QWidget" name="lookandfeel_page" >
         <layout class="QVBoxLayout" name="verticalLayout" >
          <item>
-          <widget class="QLabel" name="label_26" >
+          <layout class="QGridLayout" name="gridLayout_6" >
-           <property name="text" >
+           <item row="0" column="0" >
-            <string>Source en&amp;coding:</string>
+            <widget class="QLabel" name="label_26" >
-           </property>
+             <property name="text" >
-           <property name="buddy" >
+              <string>Source en&amp;coding:</string>
-            <cstring>opt_encoding</cstring>
+             </property>
-           </property>
+             <property name="buddy" >
-          </widget>
+              <cstring>opt_encoding</cstring>
-         </item>
+             </property>
-         <item>
+            </widget>
-          <widget class="QLineEdit" name="opt_encoding" />
+           </item>
+           <item row="0" column="1" colspan="2" >
+            <widget class="QLineEdit" name="opt_encoding" />
+           </item>
+           <item row="1" column="0" colspan="2" >
+            <widget class="QLabel" name="label_18" >
+             <property name="text" >
+              <string>Base &amp;font size:</string>
+             </property>
+             <property name="buddy" >
+              <cstring>opt_base_font_size</cstring>
+             </property>
+            </widget>
+           </item>
+           <item row="1" column="2" >
+            <widget class="QDoubleSpinBox" name="opt_base_font_size" >
+             <property name="suffix" >
+              <string> %</string>
+             </property>
+             <property name="decimals" >
+              <number>0</number>
+             </property>
+             <property name="minimum" >
+              <double>10.000000000000000</double>
+             </property>
+             <property name="maximum" >
+              <double>500.000000000000000</double>
+             </property>
+             <property name="singleStep" >
+              <double>5.000000000000000</double>
+             </property>
+             <property name="value" >
+              <double>100.000000000000000</double>
+             </property>
+            </widget>
+           </item>
+          </layout>
          </item>
          <item>
           <widget class="QGroupBox" name="groupBox" >