Last modified by cds on 2025/01/30 12:03
<
From version < 18.1 >
edited by cds
on 2012/10/24 13:12
To version < 20.1 >
edited by cds
on 2012/10/24 13:32
>
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125 125  The next task consists of creating a view that is able to display the state of a Turing Machine. We will do this using a table with one column, where each row represents an entry on the tape of the Turing Machine. The tape shall be infinite to one side, and the position of the read/write head shall be movable by two buttons. The content of the tape shall be determined by the currently active instance of our simple text editor.
126 126  
127 127  {{info title="Hint"}}
128 -In this tutorial, we will be making use of the Standard Widget Toolkit (SWT) and JFace to build a user interface. It might be a good idea now to search for an introduction to SWT and JFace concepts on the Internet before you proceed.
128 +In the following, we will be making use of the Standard Widget Toolkit (SWT) and JFace to build a user interface. It might be a good idea now to search for an introduction to SWT and JFace concepts on the Internet before you proceed.
129 129  {{/info}}
130 130  
131 131  == Creating the View Class ==
... ... @@ -137,7 +137,7 @@
137 137  1. (((
138 138  Your {{code language="none"}}TableViewPart{{/code}} contains a still empty method {{code language="none"}}createPartControl{{/code}}. This method will be responsible for creating the user interface components of your view. Add the following code to create the table we want to display:
139 139  
140 -{{code title="createPartControl(...)" language="java"}}
140 +{{code language="java"}}
141 141  Table table = new Table(parent, SWT.BORDER);
142 142  TableColumn column = new TableColumn(table, SWT.NONE);
143 143  column.setWidth(80);
... ... @@ -147,7 +147,7 @@
147 147  1. (((
148 148  The {{code language="none"}}setFocus{{/code}} method controls what happens when your part gets the focus. Make sure the focus will then automatically be set to the table by adding the following code:
149 149  
150 -{{code title="setFocus(...)"}}
150 +{{code}}
151 151  tableViewer.getControl().setFocus();
152 152  {{/code}}
153 153  )))
... ... @@ -172,7 +172,7 @@
172 172  1. (((
173 173  Create a class {{code language="none"}}TuringTape{{/code}} in a new package {{code language="none"}}de.cau.cs.rtprak.login.simple.model{{/code}} with the following fields:
174 174  
175 -{{code title="Fields" language="java"}}
175 +{{code language="java"}}
176 176  private int headPosition = 1;
177 177  private StringBuffer text = new StringBuffer();
178 178  {{/code}}
... ... @@ -182,7 +182,7 @@
182 182  1. (((
183 183  Add two constants to the class:
184 184  
185 -{{code title="Constants" language="java"}}
185 +{{code language="java"}}
186 186  public static final char START_CHAR = '\u25b7';
187 187  public static final char BLANK_CHAR = '\u25fb';
188 188  {{/code}}
... ... @@ -198,7 +198,7 @@
198 198  1*. The method {{code language="none"}}getElements(){{/code}} must return an array of objects, where each object must contain all necessary data to be displayed in a single row of the table. The number of returned objects corresponds to the number of rows.
199 199  1*. Suppose the input element is an instance of {{code language="none"}}TuringTape{{/code}}. The result of {{code language="none"}}getElements(){{/code}} shall be an array of {{code language="none"}}TapeData{{/code}} elements. The size of the array shall be one more than the maximum of the tape head position and the length of the tape text. The index and character of each tape data element shall be filled with {{code language="none"}}i{{/code}} and the result of {{code language="none"}}turingTape.getCharacter(i){{/code}}, respectively, where {{code language="none"}}i{{/code}} is the array index of the element.
200 200  1. Create a class {{code language="none"}}TapeLabelProvider{{/code}} in the {{code language="none"}}de.cau.cs.rtprak.login.simple.views{{/code}} package that extends [[BaseLabelProvider>>url:http://help.eclipse.org/juno/topic/org.eclipse.platform.doc.isv/reference/api/org/eclipse/jface/viewers/BaseLabelProvider.html||shape="rect"]] and implements [[ITableLabelProvider>>url:http://help.eclipse.org/juno/topic/org.eclipse.platform.doc.isv/reference/api/org/eclipse/jface/viewers/ITableLabelProvider.html||shape="rect"]].\\
201 -1*. Add a private field tape of type {{code language="none"}}TuringTape{{/code}} that is initialized from the constructor.
201 +1*. Add a private field {{code language="none"}}tape{{/code}} of type {{code language="none"}}TuringTape{{/code}} that is initialized from the constructor.
202 202  1*. Add fields {{code language="none"}}presentImage{{/code}} and {{code language="none"}}absentImage{{/code}} of type [[Image>>url:http://help.eclipse.org/juno/topic/org.eclipse.platform.doc.isv/reference/api/org/eclipse/swt/graphics/Image.html||shape="rect"]].
203 203  1*. (((
204 204  Initialize each image using the following code, where {{code language="none"}}path_to_image{{/code}} is {{code language="none"}}icons/head_present.gif{{/code}} and {{code language="none"}}icons/head_absent.gif{{/code}}, respectively:
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207 207  image = Activator.imageDescriptorFromPlugin(Activator.PLUGIN_ID, "path_to_image").createImage();
208 208  {{/code}}
209 209  )))
210 -1*. Override the implementation of {{code language="none"}}dispose(){{/code}} in {{code language="none"}}TapeLabelProvider{{/code}} to dispose both images after calling {{code language="none"}}super.dispose(){{/code}}.
210 +1*. Override the implementation of {{code language="none"}}dispose(){{/code}} in {{code language="none"}}TapeLabelProvider{{/code}} to dispose both images after calling {{code language="none"}}super.dispose(){{/code}}. (Right-click in the source-code and click //Source// -> //Override/Implement Methods//.)
211 211  1*. In {{code language="none"}}getColumnImage(){{/code}} and {{code language="none"}}getColumnText(){{/code}}, first check whether the element is an instance of {{code language="none"}}TapeData{{/code}} and the column index is 0, and return {{code language="none"}}null{{/code}} otherwise. If the check passes, return the following:\\
212 212  1**. {{code language="none"}}getColumnImage(){{/code}}: {{code language="none"}}presentImage{{/code}} if the index given by the tape data element equals the current value of {{code language="none"}}tape.getHeadPosition(){{/code}}, {{code language="none"}}absentImage{{/code}} otherwise.
213 213  1**. {{code language="none"}}getColumnText(){{/code}}: a {{code language="none"}}String{{/code}} containing the character of the tape data element.
... ... @@ -221,8 +221,123 @@
221 221  {{/code}}
222 222  )))
223 223  
224 -
224 +== Use Simple Text Editor as Tape View Input ==
225 225  
226 +We will now add code to make the Tape view display the content of a currently active Simple Text Editor.
227 +
228 +1. (((
229 +Add the following methods to {{code language="none"}}SimpleEditorPart{{/code}}:
230 +
231 +{{code language="java"}}
232 +/*
233 + * Returns the text that is currently displayed in the editor.
234 + * @return the currently displayed text
235 + */
236 +public String getText() {
237 + return getDocumentProvider().getDocument(getEditorInput()).get();
238 +}
239 +/** The listener that is currently registered for this editor. */
240 +private IDocumentListener registeredListener;
241 +/**
242 + * Registers the given runnable as listener for changes to the text
243 + * of this editor.
244 + * @param runnable a runnable to register as text listener
245 + */
246 +public void registerTextListener(final Runnable runnable) {
247 + registeredListener = new IDocumentListener() {
248 + public void documentAboutToBeChanged(DocumentEvent event) {}
249 + public void documentChanged(DocumentEvent event) {
250 + runnable.run();
251 + }
252 + };
253 + getDocumentProvider().getDocument(getEditorInput())
254 + .addDocumentListener(registeredListener);
255 +}
256 +/**
257 + * Removes the last registered text listener.
258 + */
259 +public void disposeTextListener() {
260 + if (registeredListener != null) {
261 + if (getDocumentProvider() != null) {
262 + getDocumentProvider().getDocument(getEditorInput())
263 + .removeDocumentListener(registeredListener);
264 + }
265 + registeredListener = null;
266 + }
267 +}
268 +{{/code}}
269 +)))
270 +1. (((
271 +Add the following code to {{code language="none"}}TapeViewPart{{/code}}:
272 +
273 +{{code language="java"}}
274 +/** The editor part that is currently set as input for the viewer. */
275 +private SimpleEditorPart currentInput;
276 +/**
277 + * Sets the displayed text of the given editor part as input of the
278 + * viewer, if the editor part is a SimpleEditorPart.
279 + * @param part workbench part to set as input
280 + */
281 +private void setInput(final IWorkbenchPart part) {
282 + if (part instanceof SimpleEditorPart && part != currentInput) {
283 + if (currentInput != null) {
284 + currentInput.disposeTextListener();
285 + }
286 + currentInput = (SimpleEditorPart) part;
287 + Runnable runnable = new Runnable() {
288 + public void run() {
289 + tape.setText(new StringBuffer(currentInput.getText()));
290 + tableViewer.refresh();
291 + }
292 + };
293 + runnable.run();
294 + currentInput.registerTextListener(runnable);
295 + }
296 +}
297 +{{/code}}
298 +)))
299 +1. (((
300 +Add the following code to {{code language="none"}}createPartControl(){{/code}}:
301 +
302 +{{code language="java"}}
303 +IWorkbenchWindow workbenchWindow = getSite().getWorkbenchWindow();
304 +IWorkbenchPage activePage = workbenchWindow.getActivePage();
305 +if (activePage != null) {
306 + setInput(activePage.getActivePart());
307 +}
308 +workbenchWindow.getPartService().addPartListener(new IPartListener() {
309 + public void partActivated(final IWorkbenchPart part) {
310 + setInput(part);
311 + }
312 + public void partDeactivated(final IWorkbenchPart part) {}
313 + public void partBroughtToTop(final IWorkbenchPart part) {}
314 + public void partClosed(final IWorkbenchPart part) {}
315 + public void partOpened(final IWorkbenchPart part) {}
316 +});
317 +{{/code}}
318 +)))
319 +
320 +== Create Actions to Move the Tape Head ==
321 +
322 +If we want to add buttons to the view's tool bar, we will have to ask its [[IToolbarManager>>url:http://help.eclipse.org/juno/topic/org.eclipse.platform.doc.isv/reference/api/org/eclipse/jface/action/IToolBarManager.html||shape="rect"]] to do that for us:
323 +
324 +1. (((
325 +Get the tool bar manager using the following code:
326 +
327 +{{code language="java"}}
328 +IToolBarManager toolBarManager = getViewSite().getActionBars().getToolBarManager();
329 +{{/code}}
330 +)))
331 +1. Add two actions to the toolbar manager by extending the class [[Action>>url:http://help.eclipse.org/juno/topic/org.eclipse.platform.doc.isv/reference/api/org/eclipse/jface/action/Action.html||shape="rect"]] and implementing the {{code language="none"}}run(){{/code}}method.
332 +1*. It is convenient to add actions as anonymous nested classes.
333 +1*. The first action shall have the text "L". When it is run, it shall move the head to the left (to the top in the table viewer), if the head is not already at position 0.
334 +1*. The second action shall have the text "R". When it is run, it shall move the head to the right.
335 +1*. You should call {{code language="none"}}tableViewer.refresh(){{/code}} after any change to the {{code language="none"}}tape.headPosition{{/code}} variable.
336 +
337 +== Test the View ==
338 +
339 +If you open an instance of the simple text editor and open the Tape view, the view should correctly display the editor's text on a tape, and the L and R buttons should move the tape head.
340 +
226 226  = Creating an Extension Point =
227 227  
228 228  WRITE THIS SECTION
Confluence.Code.ConfluencePageClass[0]
Id
... ... @@ -1,1 +1,1 @@
1 -2982293
1 +2982296
URL
... ... @@ -1,1 +1,1 @@
1 -https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/WS12EclPract/pages/2982293/The Plug-in Architecture of Eclipse
1 +https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/WS12EclPract/pages/2982296/The Plug-in Architecture of Eclipse

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