Improvements on coloring: add an in_list formatter function. Add more documentation in the preference screen. Add a scroll bar to the doc in the preferences screen.

src/calibre/gui2/preferences/look_feel.py

@@ -159,7 +159,6 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         self.df_up_button.clicked.connect(self.move_df_up)
         self.df_down_button.clicked.connect(self.move_df_down)
 
-        self.color_help_text.setWordWrap(True)
         self.color_help_text.setText('<p>' +
                 _('Here you can specify coloring rules for fields shown in the '
                   'library view. Choose the field you wish to color, then '
@@ -169,14 +168,25 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
                   'below. You can use any legal template expression. '
                   'For example, you can set the title to always display in '
                   'green using the template "green" (without the quotes). '
-                  'To show the title in blue if the book has the tag "Science '
-                  'Fiction", red if the book has the tag "Mystery", or black if '
-                  'the book has neither tag, use '
-                  '"{tags:switch(Science Fiction,blue,Mystery,red,)}" '
+                  'To show the title in the color named in the custom column '
+                  '#column, use "{#column}". To show the title in blue if the '
+                  'custom column #column contains the value "foo", in red if the '
+                  'column contains the value "bar", otherwise in black, use '
+                  '<pre>{#column:switch(foo,blue,bar,red,black)}</pre>'
+                  'To show the title in blue if the book has the exact tag '
+                  '"Science Fiction", red if the book has the exact tag '
+                  '"Mystery", or black if the book has neither tag, use'
+                  "<pre>program: \n"
+                  "    t = field('tags'); \n"
+                  "    first_non_empty(\n"
+                  "        in_list(t, ',', '^Science Fiction$', 'blue', ''), \n"
+                  "        in_list(t, ',', '^Mystery$', 'red', 'black'))</pre>"
                   'To show the title in green if it has one format, blue if it '
-                  'two formats, and red if more, use '
-                  "\"program:cmp(count(field('formats'),','), 2, 'green', 'blue', 'red')\"") +
+                  'two formats, and red if more, use'
+                  "<pre>program:cmp(count(field('formats'),','), 2, 'green', 'blue', 'red')</pre>") +
                                '</p><p>' +
+                _('You can access a multi-line template editor from the '
+                  'context menu (right-click).') + '</p><p>' +
                 _('Note: if you want to color a "custom column with a fixed set '
                   'of values", it is possible and often easier to specify the '
                   'colors in the column definition dialog. There you can '

src/calibre/gui2/preferences/look_feel.ui

@@ -424,7 +424,12 @@ then the tags will be displayed each on their own line.</string>
         </widget>
        </item>
        <item row="0" column="0" colspan="2">
-        <widget class="QLabel" name="color_help_text">
+        <widget class="QTextEdit" name="color_help_text">
+         <property name="readOnly">
+          <bool>true</bool>
+         </property>
+         <sizepolicy vsizetype="Minimum" hsizetype="Expanding">
+         </sizepolicy>
         </widget>
        </item>
        <item row="1" column="1">
@@ -483,6 +488,9 @@ then the tags will be displayed each on their own line.</string>
        </item>
        <item row="21" column="0" colspan="2">
         <widget class="QTextEdit" name="colors_box">
+         <property name="readOnly">
+          <bool>true</bool>
+         </property>
          <property name="sizePolicy">
           <sizepolicy vsizetype="Expanding" hsizetype="Expanding">
            <horstretch>0</horstretch>

src/calibre/utils/formatter_functions.py

@@ -327,6 +327,22 @@ class BuiltinSwitch(BuiltinFormatterFunction):
                 return args[i+1]
             i += 2
 
+class BuiltinInList(BuiltinFormatterFunction):
+    name = 'in_list'
+    arg_count = 5
+    doc = _('in_list(val, separator, pattern, found_val, not_found_val) -- '
+            'treat val as a list of items separated by separator, '
+            'comparing the pattern against each value in the list. If the '
+            'pattern matches a value, return found_val, otherwise return '
+            'not_found_val.')
+
+    def evaluate(self, formatter, kwargs, mi, locals, val, sep, pat, fv, nfv):
+        l = [v.strip() for v in val.split(sep) if v.strip()]
+        for v in l:
+            if re.search(pat, v):
+                return fv
+        return nfv
+
 class BuiltinRe(BuiltinFormatterFunction):
     name = 're'
     arg_count = 3
@@ -591,6 +607,7 @@ builtin_first_non_empty = BuiltinFirstNonEmpty()
 builtin_field       = BuiltinField()
 builtin_format_date = BuiltinFormat_date()
 builtin_ifempty     = BuiltinIfempty()
+builtin_in_list     = BuiltinInList()
 builtin_list_item   = BuiltinListitem()
 builtin_lookup      = BuiltinLookup()
 builtin_lowercase   = BuiltinLowercase()