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| 55 | <H2><A NAME="SECTION0014130000000000000000"></A><A NAME="writer-interface"></A> |
| 56 | <BR> |
| 57 | 12.1.3 The Writer Interface |
| 58 | </H2> |
| 59 | |
| 60 | <P> |
| 61 | Interfaces to create writers are dependent on the specific writer |
| 62 | class being instantiated. The interfaces described below are the |
| 63 | required interfaces which all writers must support once initialized. |
| 64 | Note that while most applications can use the |
| 65 | <tt class="class">AbstractFormatter</tt> class as a formatter, the writer must |
| 66 | typically be provided by the application. |
| 67 | |
| 68 | <P> |
| 69 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 70 | <td><nobr><b><tt id='l2h-3812' xml:id='l2h-3812' class="method">flush</tt></b>(</nobr></td> |
| 71 | <td><var></var>)</td></tr></table></dt> |
| 72 | <dd> |
| 73 | Flush any buffered output or device control events. |
| 74 | </dl> |
| 75 | |
| 76 | <P> |
| 77 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 78 | <td><nobr><b><tt id='l2h-3813' xml:id='l2h-3813' class="method">new_alignment</tt></b>(</nobr></td> |
| 79 | <td><var>align</var>)</td></tr></table></dt> |
| 80 | <dd> |
| 81 | Set the alignment style. The <var>align</var> value can be any object, |
| 82 | but by convention is a string or <code>None</code>, where <code>None</code> |
| 83 | indicates that the writer's ``preferred'' alignment should be used. |
| 84 | Conventional <var>align</var> values are <code>'left'</code>, <code>'center'</code>, |
| 85 | <code>'right'</code>, and <code>'justify'</code>. |
| 86 | </dl> |
| 87 | |
| 88 | <P> |
| 89 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 90 | <td><nobr><b><tt id='l2h-3814' xml:id='l2h-3814' class="method">new_font</tt></b>(</nobr></td> |
| 91 | <td><var>font</var>)</td></tr></table></dt> |
| 92 | <dd> |
| 93 | Set the font style. The value of <var>font</var> will be <code>None</code>, |
| 94 | indicating that the device's default font should be used, or a tuple |
| 95 | of the form <code>(</code><var>size</var>, <var>italic</var>, <var>bold</var>, |
| 96 | <var>teletype</var><code>)</code>. Size will be a string indicating the size of |
| 97 | font that should be used; specific strings and their interpretation |
| 98 | must be defined by the application. The <var>italic</var>, <var>bold</var>, and |
| 99 | <var>teletype</var> values are Boolean values specifying which of those |
| 100 | font attributes should be used. |
| 101 | </dl> |
| 102 | |
| 103 | <P> |
| 104 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 105 | <td><nobr><b><tt id='l2h-3815' xml:id='l2h-3815' class="method">new_margin</tt></b>(</nobr></td> |
| 106 | <td><var>margin, level</var>)</td></tr></table></dt> |
| 107 | <dd> |
| 108 | Set the margin level to the integer <var>level</var> and the logical tag |
| 109 | to <var>margin</var>. Interpretation of the logical tag is at the |
| 110 | writer's discretion; the only restriction on the value of the logical |
| 111 | tag is that it not be a false value for non-zero values of |
| 112 | <var>level</var>. |
| 113 | </dl> |
| 114 | |
| 115 | <P> |
| 116 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 117 | <td><nobr><b><tt id='l2h-3816' xml:id='l2h-3816' class="method">new_spacing</tt></b>(</nobr></td> |
| 118 | <td><var>spacing</var>)</td></tr></table></dt> |
| 119 | <dd> |
| 120 | Set the spacing style to <var>spacing</var>. |
| 121 | </dl> |
| 122 | |
| 123 | <P> |
| 124 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 125 | <td><nobr><b><tt id='l2h-3817' xml:id='l2h-3817' class="method">new_styles</tt></b>(</nobr></td> |
| 126 | <td><var>styles</var>)</td></tr></table></dt> |
| 127 | <dd> |
| 128 | Set additional styles. The <var>styles</var> value is a tuple of |
| 129 | arbitrary values; the value <tt class="constant">AS_IS</tt> should be ignored. The |
| 130 | <var>styles</var> tuple may be interpreted either as a set or as a stack |
| 131 | depending on the requirements of the application and writer |
| 132 | implementation. |
| 133 | </dl> |
| 134 | |
| 135 | <P> |
| 136 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 137 | <td><nobr><b><tt id='l2h-3818' xml:id='l2h-3818' class="method">send_line_break</tt></b>(</nobr></td> |
| 138 | <td><var></var>)</td></tr></table></dt> |
| 139 | <dd> |
| 140 | Break the current line. |
| 141 | </dl> |
| 142 | |
| 143 | <P> |
| 144 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 145 | <td><nobr><b><tt id='l2h-3819' xml:id='l2h-3819' class="method">send_paragraph</tt></b>(</nobr></td> |
| 146 | <td><var>blankline</var>)</td></tr></table></dt> |
| 147 | <dd> |
| 148 | Produce a paragraph separation of at least <var>blankline</var> blank |
| 149 | lines, or the equivalent. The <var>blankline</var> value will be an |
| 150 | integer. Note that the implementation will receive a call to |
| 151 | <tt class="method">send_line_break()</tt> before this call if a line break is needed; |
| 152 | this method should not include ending the last line of the paragraph. |
| 153 | It is only responsible for vertical spacing between paragraphs. |
| 154 | </dl> |
| 155 | |
| 156 | <P> |
| 157 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 158 | <td><nobr><b><tt id='l2h-3820' xml:id='l2h-3820' class="method">send_hor_rule</tt></b>(</nobr></td> |
| 159 | <td><var>*args, **kw</var>)</td></tr></table></dt> |
| 160 | <dd> |
| 161 | Display a horizontal rule on the output device. The arguments to this |
| 162 | method are entirely application- and writer-specific, and should be |
| 163 | interpreted with care. The method implementation may assume that a |
| 164 | line break has already been issued via <tt class="method">send_line_break()</tt>. |
| 165 | </dl> |
| 166 | |
| 167 | <P> |
| 168 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 169 | <td><nobr><b><tt id='l2h-3821' xml:id='l2h-3821' class="method">send_flowing_data</tt></b>(</nobr></td> |
| 170 | <td><var>data</var>)</td></tr></table></dt> |
| 171 | <dd> |
| 172 | Output character data which may be word-wrapped and re-flowed as |
| 173 | needed. Within any sequence of calls to this method, the writer may |
| 174 | assume that spans of multiple whitespace characters have been |
| 175 | collapsed to single space characters. |
| 176 | </dl> |
| 177 | |
| 178 | <P> |
| 179 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 180 | <td><nobr><b><tt id='l2h-3822' xml:id='l2h-3822' class="method">send_literal_data</tt></b>(</nobr></td> |
| 181 | <td><var>data</var>)</td></tr></table></dt> |
| 182 | <dd> |
| 183 | Output character data which has already been formatted |
| 184 | for display. Generally, this should be interpreted to mean that line |
| 185 | breaks indicated by newline characters should be preserved and no new |
| 186 | line breaks should be introduced. The data may contain embedded |
| 187 | newline and tab characters, unlike data provided to the |
| 188 | <tt class="method">send_formatted_data()</tt> interface. |
| 189 | </dl> |
| 190 | |
| 191 | <P> |
| 192 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 193 | <td><nobr><b><tt id='l2h-3823' xml:id='l2h-3823' class="method">send_label_data</tt></b>(</nobr></td> |
| 194 | <td><var>data</var>)</td></tr></table></dt> |
| 195 | <dd> |
| 196 | Set <var>data</var> to the left of the current left margin, if possible. |
| 197 | The value of <var>data</var> is not restricted; treatment of non-string |
| 198 | values is entirely application- and writer-dependent. This method |
| 199 | will only be called at the beginning of a line. |
| 200 | </dl> |
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