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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Getting Input for a Macro</title><meta name="generator" content="DocBook XSL Stylesh input in a Java program. Nevertheless, it can be too lengthy or tedious for someone trying to write a macro quickly. Not every macro needs a user interface specified in such detail; some macros require only a single keystroke or no input at all. In this section we outline some other techniques for obtaining input that will help you write macros quickly.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="macr the method <code class="function">Macros.input()</code> offers a convenient way to obtain a single line of text input. Here is an example that inserts a pair of HTML markup tags specified by the user.</p><div class="informalexample"><pre cl void insertTag() { caret = textArea.getCaretPosition(); tag = Macros.input(view, <span class="quote">“<span class="quote">Enter name of tag:</span>”</spa if( tag == null || tag.length() == 0) return; text = textArea.getSelectedText(); if(text == null) text = <span class="quote">“<span class="quote"></span>”</span>; sb = new StringBuffer(); sb.append(<span class="quote">“<span class="quote"><</span>”</span>).append(tag).append(<span c sb.append(text); sb.append(<span class="quote">“<span class="quote"></</span>”</span>).append(tag).append(<span textArea.setSelectedText(sb.toString()); if(text.length() == 0) textArea.setCaretPosition(caret + tag.length() + 2); } insertTag(); // end Insert_Tag.bsh</pre></div><p>Here the call to <code class="function">Macros.input()</code> name of the markup tag. This method sets the message box title to a fixed string, <span class="quote">“<span class="quote">Macro input</span>”</span>, but the specifi <span class="guilabel"><strong>Enter name of tag</strong></span> provides all the information necessary. The return value <code class="varname">tag</code> must be tested to see if it is null. This would occur if the user presses the <span class="guilabel"><strong>Cancel</strong></span> button or closes the dialog window displayed by <code class="function">Macros.input()</code>.</p></div><div class="section"><div cl calls to <code class="function">Macros.input()</code> is a possible, but awkward approach, because it would not be possible to correct early input after the corresponding message box is dismissed. Where more is required, but a full dialog layout is either unnecessary or too much work, the Java method <code class="function">JOptionPane.showConfirmDialog()</code> is available. The version to use has the following prototype:</p><div class="itemizedlist"><ul class="itemiz <b class="fsfunc">showConfirmDialog</b>(</code></td><td>Component <var class="pdparam">parentComponent</var>, </td></tr><tr><td> </td><td>Object <var class="pdparam">message</var>, </td></tr><tr><td> </td><td>String <var class="pdparam">title</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">optionType</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">messageType</var><code>)</code>;</td></tr></table><div class="funcprototype- <code class="varname">message</code> parameter can be an object of any Java class (since all classes are derived from <code class="classname">Object</code>), or any array of objects. The following example shows how this feature can be used.</p><div class="informalexample"><pre clas title = <span class="quote">“<span class="quote">Write file header</span>”</span>; currentName = buffer.getName(); nameField = new JTextField(currentName); authorField = new JTextField(<span class="quote">“<span class="quote">Your name here</span>”</sp descField = new JTextField(<span class="quote">“<span class="quote"></span>”</span>, 25); namePanel = new JPanel(new GridLayout(1, 2)); nameLabel = new JLabel(<span class="quote">“<span class="quote">Name of file:</span>”</span>, Swin saveField = new JCheckBox(<span class="quote">“<span class="quote">Save file when done</span>”</s !buffer.isNewFile()); namePanel.add(nameLabel); namePanel.add(saveField); message = new Object[9]; message[0] = namePanel; message[1] = nameField; message[2] = Box.createVerticalStrut(10); message[3] = <span class="quote">“<span class="quote">Author's name:” message[4] = authorField; message[5] = Box.createVerticalStrut(10); message[6] = <span class="quote">“<span class="quote">Enter description:</span>”</span>; message[7] = descField; message[8] = Box.createVerticalStrut(5); if( JOptionPane.OK_OPTION != JOptionPane.showConfirmDialog(view, message, title, JOptionPane.OK_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE)) return null; // *****remainder of macro script omitted***** // end excerpt from Write_File_Header.bsh</pre></div><p>This macro takes several items of user in formatted file header at the beginning of the buffer. The full macro is included in the set of macros installed by jEdit. There are a number of input features of this excerpt worth noting.</p><div class="itemizedlist"><ul class=" Two of them are created behind the scenes by <code class="function">showConfirmDialog()</code>, the rest are made by the macro. To arrange them, the script creates an array of <code class="classname">Object</code> objects and assigns components to each location in the array. This translates to a fixed, top-to-bottom arrangement in the message box created by <code class="function">showConfirmDialog()</code>.</p></li><li class="listitem"><p>Th objects to obtain most of the input data. The fields <code class="varname">nameField</code> and <code class="varname">authorField</code> are created with constructors that take the initial, default text to be displayed in the field as a parameter. When the message box is displayed, the default text will appear and can be altered or deleted by the user.</p></li><li class="listitem"><p>The text field <code class="varname">descField</code> use empty string for its initial value. The second parameter in its constructor sets the width of the text field component, expressed as the number of characters of <span class="quote">“<span class="quote">average</span>”</span> width. When <code class="function">showConfirmDialog()</code> prepares the layout of the message box, it sets the width wide enough to accommodate the designated with of <code class="varname">descField</code>. This technique produces a message box and input text fields that are wide enough for your data with one line of code.</p></li><li class="listitem"><p>The displayed message box includes <code class="classname">JCheckBox</code> component that determines whether the buffer will be saved to disk immediately after the file header is written. To conserve space in the message box, we want to display the check box to the right of the label <span class="guilabel"><strong>Name of file:</strong></span>. To do that, we create a <code class="classname">JPanel</code> object and populate it with the label and the checkbox in a left-to-right <code class="classname">GridLayout</code>. The <code class="classname">JPanel</code> containing the two components is then added to the beginning of <code class="varname">message</code> array.</p></li><li class="listitem"><p>The two visible components created by <code class="function">showConfirmDialog()</code> appear at positions 3 and 6 of the <code class="varname">message</code> array. Only the text is required; they are rendered as text labels.</p></li><li class="listitem"><p>There are three <code class="function">showConfirmDialog()</code>. Each of them involves a call to <code class="function">Box.createVerticalStrut()</code>. The <code class="classname">Box</code> class is a sophisticated layout class that gives the user great flexibility in sizing and positioning components. Here we use a <code class="function">static</code> method of the <code class="classname">Box</code> class that produces a vertical <em class="glossterm">strut</em>. This is a transparent component whose width expands to fill its parent component (in this case, the message box). The single parameter indicates the height of the strut in pixels. The last call to <code class="function">createVerticalStrut()</code> separates the description text field from the <span class="guilabel"><strong>OK</strong></span> and <span class="guilabel"><strong>Cancel</strong></span> buttons that are automatically added by <code class="function">showConfirmDialog()</code>.</p></li><li class="listitem"><p>Fina <code class="function">showConfirmDialog()</code> uses defined constants for the option type and the message type. The constants are the same as those used with the <code class="function">Macros.confirm()</code> method; see <a class="xref" href="helpful-me use of <span class="guilabel"><strong>OK</strong></span> and <span class="guilabel"><strong>Cancel</strong></span> buttons. The <code class="constant">QUERY_MESSAGE</code> message type causes the message box to display a question mark icon.</p><p>The return value of the method is tested against value <code class="constant">OK_OPTION</code>. If the return value is something else (because the <span class="guilabel"><strong>Cancel</strong></span> button was pressed or because the message box window was closed without a button press), a <code class="constant">null</code> value is returned to a calling function, signaling that the user canceled macro execution. If the return value is <code class="constant">OK_OPTION</code>, each of the input components can yield their contents for further processing by calls to <code class="function">JTextField.getText()</code> (or, in the case of the check box, <code class="function">JCheckBox.isSelected()</code>).</p></li></ul></div></div><div class="secti combo box containing a number of pre-set options. If this is the only input required, one of the versions of <code class="function">showInputDialog()</code> in the <code class="classname">JOptionPane</code> class provides a shortcut. Here is its prototype:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style- <b class="fsfunc">showInputDialog</b>(</code></td><td>Component <var class="pdparam">parentComponent</var>, </td></tr><tr><td> </td><td>Object <var class="pdparam">message</var>, </td></tr><tr><td> </td><td>String <var class="pdparam">title</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">messageType</var>, </td></tr><tr><td> </td><td>Icon <var class="pdparam">icon</var>, < <var class="pdparam">selectionValues</var>, </td></tr><tr><td> </td><td>Object <var class="pdparam">initialSelectionValue</var><code>)</code>;</td></tr></table><div class="func of the options specified in the method's parameters, along with <span class="guilabel"><strong>OK</strong></span> and <span class="guilabel"><strong>Cancel</stro Compared to <code class="function">showConfirmDialog()</code>, this method lacks an <code class="varname">optionType</code> parameter and has three additional parameters: an <code class="varname">icon</code> to display in the dialog (which can be set to <code class="constant">null</code>), an array of <code class="varname">selectionValues</code> objects, and a reference to one of the options as the <code class="varname">initialSelectionValue</code> to be displayed. In addition, instead of returning an <code class="classname">int</code> representing the user's action, <code class="function">showInputDialog()</code> returns the <code class="classname">Object</code> corresponding to the user's selection, or <code class="constant">null</code> if the selection is canceled.</p><p>The following macro frag method.</p><div class="informalexample"><pre class="programlisting">// fragment illustrati options = new Object[5]; options[0] = "JLabel"; options[1] = "JTextField"; options[2] = "JCheckBox"; options[3] = "HistoryTextField"; options[4} = "-- other --"; result = JOptionPane.showInputDialog(view, "Choose component class", "Select class for input component", JOptionPane.QUESTION_MESSAGE, null, options, options[0]);</pre></div><p>The return value <code class="varname">result</code> wi the <code class="classname">String</code> object representing the selected text item or <code class="constant">null</code> representing no selection. Any further use of this fragment would have to test the value of <code class="varname">result</code> and likely exit from the macro if the value equaled <code class="constant">null</code>.</p><p>A set of options can be similarly placed in <code class="classname">JComboBox</code> component created as part of a larger dialog or <code class="function">showMessageDialog()</code> layout. Here are some code fragments showing this approach:</p><div class="informalexample"><pre class // import statements and other code omitted // from main routine, this method call returns an array // of Strings representing the names of abbreviation sets abbrevSets = getActiveSets(); ... // from showAbbrevs() method combo = new JComboBox(abbrevSets); // set width to uniform size regardless of combobox contents Dimension dim = combo.getPreferredSize(); dim.width = Math.max(dim.width, 120); combo.setPreferredSize(dim); combo.setSelectedItem(STARTING_SET); // defined as "global" // end fragments</pre></div></div><div class="section"><div class="titlepage"><div><div><h3 class="t text editors such as <span class="application">emacs</span> or <span class="application">vi</span>. They will require only a single keypress as input that would be handled by the macro but not displayed on the screen. If the keypress corresponds to a character value, jEdit can pass that value as a parameter to a BeanShell script.</p><p>The jEdit class <a class="ulink" href="../api/org/gjt/sp/jedit/gui/InputHand is an abstract class that that manages associations between keyboard input and editing actions, along with the recording of macros. Keyboard input in jEdit is normally managed by the derived class <a class="ulink" href="../api/org/gjt/sp/jedit/gui/DefaultInputHandler.html" target= One of the methods in the <a class="ulink" href="../api/org/gjt/sp/jedit/gui/InputHandler class handles input from a single keypress:</p><div class="itemizedlist"><ul class="itemizedl <b class="fsfunc">readNextChar</b>(</code></td><td>String <var class="pdparam">prompt</var>, </td></tr><tr><td> </td><td>String <var class="pdparam">code</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> < <code class="varname">prompt</code> parameter is shown in the view's status bar. The method then waits for a key press, after which the contents of the <code class="varname">code</code> parameter will be run as a BeanShell script, with one important modification. Each time the string <code class="varname">__char__</code> appears in the parameter script, it will be substituted by the character pressed. The key press is <span class="quote">“<span class="quote">consumed</span>”</span> by <code class="function">readNe will not be displayed on the screen or otherwise processed by jEdit.</p><p>Using <code class="function">readNextChar()</code> requires a macro within the macro, formatted as a single, potentially lengthy string literal. The following macro illustrates this technique. It selects a line of text from the current caret position to the first occurrence of the character next typed by the user. If the character does not appear on the line, no new selection occurs and the display remains unchanged.</p><div class="informalexample"><pre class="programlisting">// Next_Cha script = new StringBuffer(512); script.append( "start = textArea.getCaretPosition();" ); script.append( "line = textArea.getCaretLine();" ); script.append( "end = textArea.getLineEndOffset(line) + 1;" ); script.append( "text = buffer.getText(start, end - start);" ); script.append( "match = text.indexOf(__char__, 1);" ); script.append( "if(match != -1) {" ); script.append( "if(__char__ != '\\n') ++match;" ); script.append( "textArea.select(start, start + match - 1);" ); script.append( "}" ); view.getInputHandler().readNextChar("Enter a character", script.toString()); // end Next_Char.bsh</pre></div><p>Once again, here are a few comments on the macro's design.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: di for efficiency; it obviates multiple creation of fixed-length <code class="classname">String</code> objects. The parameter to the constructor of <code class="varname">script</code> specifies the initial size of the buffer that will receive the contents of the child script.</p></li><li class="listitem"><p>Besides the quoting of the script of the macro is entirely optional but (hopefully) makes it easier to read.</p></li><li class="listitem"><p>It is important that the child script be self-contained. It does not run in the same namespace as the <span class="quote">“<span class="quote">parent</span>”</span> macro <code class="filename">Next_Char.bsh</code> and therefore does not share variables, methods, or scripted objects defined in the parent macro.</p></li><li class="listitem"><p>Finally, access to the <a class="ulink" href="../ap object used by jEdit is available by calling <code class="function">getInputHandler()</code> on the current view.</p></li></ul></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigat ¤ Dauer der Verarbeitung: 0.25 Sekunden (vorverarbeitet) ¤ |
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