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comparison: Documentation/Source/eric4.Graphics.AssociationItem.html

Documentation/Source/eric4.Graphics.AssociationItem.html

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4 <html><head>
5 <title>eric4.Graphics.AssociationItem</title>
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22 <body><a NAME="top" ID="top"></a>
23 <h1>eric4.Graphics.AssociationItem</h1>
24 <p>
25 Module implementing a graphics item for an association between two items.
26 </p>
27 <h3>Global Attributes</h3>
28 <table>
29 <tr><td>Center</td></tr><tr><td>East</td></tr><tr><td>Generalisation</td></tr><tr><td>Imports</td></tr><tr><td>NoRegion</td></tr><tr><td>Normal</td></tr><tr><td>North</td></tr><tr><td>NorthEast</td></tr><tr><td>NorthWest</td></tr><tr><td>South</td></tr><tr><td>SouthEast</td></tr><tr><td>SouthWest</td></tr><tr><td>West</td></tr>
30 </table>
31 <h3>Classes</h3>
32 <table>
33 <tr>
34 <td><a href="#AssociationItem">AssociationItem</a></td>
35 <td>Class implementing a graphics item for an association between two items.</td>
36 </tr>
37 </table>
38 <h3>Functions</h3>
39 <table>
40 <tr><td>None</td></tr>
41 </table>
42 <hr /><hr />
43 <a NAME="AssociationItem" ID="AssociationItem"></a>
44 <h2>AssociationItem</h2>
45 <p>
46 Class implementing a graphics item for an association between two items.
47 </p><p>
48 The association is drawn as an arrow starting at the first items and
49 ending at the second.
50 </p>
51 <h3>Derived from</h3>
52 E4ArrowItem
53 <h3>Class Attributes</h3>
54 <table>
55 <tr><td>None</td></tr>
56 </table>
57 <h3>Methods</h3>
58 <table>
59 <tr>
60 <td><a href="#AssociationItem.__init__">AssociationItem</a></td>
61 <td>Constructor</td>
62 </tr><tr>
63 <td><a href="#AssociationItem.__calculateEndingPoints_center">__calculateEndingPoints_center</a></td>
64 <td>Private method to calculate the ending points of the association item.</td>
65 </tr><tr>
66 <td><a href="#AssociationItem.__calculateEndingPoints_rectangle">__calculateEndingPoints_rectangle</a></td>
67 <td>Private method to calculate the ending points of the association item.</td>
68 </tr><tr>
69 <td><a href="#AssociationItem.__findIntersection">__findIntersection</a></td>
70 <td>Method to calculate the intersection point of two lines.</td>
71 </tr><tr>
72 <td><a href="#AssociationItem.__findPointRegion">__findPointRegion</a></td>
73 <td>Private method to find out, which region of rectangle rect contains the point (PosX, PosY) and returns the region number.</td>
74 </tr><tr>
75 <td><a href="#AssociationItem.__findRectIntersectionPoint">__findRectIntersectionPoint</a></td>
76 <td>Private method to find the intersetion point of a line with a rectangle.</td>
77 </tr><tr>
78 <td><a href="#AssociationItem.__mapRectFromItem">__mapRectFromItem</a></td>
79 <td>Private method to map item's rectangle to this item's coordinate system.</td>
80 </tr><tr>
81 <td><a href="#AssociationItem.__updateEndPoint">__updateEndPoint</a></td>
82 <td>Private method to update an endpoint.</td>
83 </tr><tr>
84 <td><a href="#AssociationItem.unassociate">unassociate</a></td>
85 <td>Public method to unassociate from the widgets.</td>
86 </tr><tr>
87 <td><a href="#AssociationItem.widgetMoved">widgetMoved</a></td>
88 <td>Public method to recalculate the association after a widget was moved.</td>
89 </tr>
90 </table>
91 <a NAME="AssociationItem.__init__" ID="AssociationItem.__init__"></a>
92 <h4>AssociationItem (Constructor)</h4>
93 <b>AssociationItem</b>(<i>itemA, itemB, type = Normal, parent = None</i>)
94 <p>
95 Constructor
96 </p><dl>
97 <dt><i>itemA</i></dt>
98 <dd>
99 first widget of the association
100 </dd><dt><i>itemB</i></dt>
101 <dd>
102 second widget of the association
103 </dd><dt><i>type</i></dt>
104 <dd>
105 type of the association. This must be one of
106 <ul>
107 <li>Normal (default)</li>
108 <li>Generalisation</li>
109 <li>Imports</li>
110 </ul>
111 </dd><dt><i>parent=</i></dt>
112 <dd>
113 reference to the parent object (QGraphicsItem)
114 </dd>
115 </dl><a NAME="AssociationItem.__calculateEndingPoints_center" ID="AssociationItem.__calculateEndingPoints_center"></a>
116 <h4>AssociationItem.__calculateEndingPoints_center</h4>
117 <b>__calculateEndingPoints_center</b>(<i></i>)
118 <p>
119 Private method to calculate the ending points of the association item.
120 </p><p>
121 The ending points are calculated from the centers of the
122 two associated items.
123 </p><a NAME="AssociationItem.__calculateEndingPoints_rectangle" ID="AssociationItem.__calculateEndingPoints_rectangle"></a>
124 <h4>AssociationItem.__calculateEndingPoints_rectangle</h4>
125 <b>__calculateEndingPoints_rectangle</b>(<i></i>)
126 <p>
127 Private method to calculate the ending points of the association item.
128 </p><p>
129 The ending points are calculated by the following method.
130 </p><p>
131 For each item the diagram is divided in four Regions by its diagonals
132 as indicated below
133 <pre>
134 \ Region 2 /
135 \ /
136 |--------|
137 | \ / |
138 | \ / |
139 | \/ |
140 Region 1 | /\ | Region 3
141 | / \ |
142 | / \ |
143 |--------|
144 / \
145 / Region 4 \
146 </pre>
147 </p><p>
148 Each diagonal is defined by two corners of the bounding rectangle
149 </p><p>
150 To calculate the start point we have to find out in which
151 region (defined by itemA's diagonals) is itemB's TopLeft corner
152 (lets call it region M). After that the start point will be
153 the middle point of rectangle's side contained in region M.
154 </p><p>
155 To calculate the end point we repeat the above but in the opposite direction
156 (from itemB to itemA)
157 </p><a NAME="AssociationItem.__findIntersection" ID="AssociationItem.__findIntersection"></a>
158 <h4>AssociationItem.__findIntersection</h4>
159 <b>__findIntersection</b>(<i>p1, p2, p3, p4</i>)
160 <p>
161 Method to calculate the intersection point of two lines.
162 </p><p>
163 The first line is determined by the points p1 and p2, the second
164 line by p3 and p4. If the intersection point is not contained in
165 the segment p1p2, then it returns (-1.0, -1.0).
166 </p><p>
167 For the function's internal calculations remember:<br />
168 QT coordinates start with the point (0,0) as the topleft corner
169 and x-values increase from left to right and y-values increase
170 from top to bottom; it means the visible area is quadrant I in
171 the regular XY coordinate system
172 </p><p>
173 <pre>
174 Quadrant II | Quadrant I
175 -----------------|-----------------
176 Quadrant III | Quadrant IV
177 </pre>
178 </p><p>
179 In order for the linear function calculations to work in this method
180 we must switch x and y values (x values become y values and viceversa)
181 </p><dl>
182 <dt><i>p1</i></dt>
183 <dd>
184 first point of first line (QPointF)
185 </dd><dt><i>p2</i></dt>
186 <dd>
187 second point of first line (QPointF)
188 </dd><dt><i>p3</i></dt>
189 <dd>
190 first point of second line (QPointF)
191 </dd><dt><i>p4</i></dt>
192 <dd>
193 second point of second line (QPointF)
194 </dd>
195 </dl><dl>
196 <dt>Returns:</dt>
197 <dd>
198 the intersection point (QPointF)
199 </dd>
200 </dl><a NAME="AssociationItem.__findPointRegion" ID="AssociationItem.__findPointRegion"></a>
201 <h4>AssociationItem.__findPointRegion</h4>
202 <b>__findPointRegion</b>(<i>rect, posX, posY</i>)
203 <p>
204 Private method to find out, which region of rectangle rect contains the point
205 (PosX, PosY) and returns the region number.
206 </p><dl>
207 <dt><i>rect</i></dt>
208 <dd>
209 rectangle to calculate the region for (QRectF)
210 </dd><dt><i>posX</i></dt>
211 <dd>
212 x position of point (float)
213 </dd><dt><i>posY</i></dt>
214 <dd>
215 y position of point (float)
216 </dd>
217 </dl><dl>
218 <dt>Returns:</dt>
219 <dd>
220 the calculated region number<br />
221 West = Region 1<br />
222 North = Region 2<br />
223 East = Region 3<br />
224 South = Region 4<br />
225 NorthWest = On diagonal 2 between Region 1 and 2<br />
226 NorthEast = On diagonal 1 between Region 2 and 3<br />
227 SouthEast = On diagonal 2 between Region 3 and 4<br />
228 SouthWest = On diagonal 1 between Region4 and 1<br />
229 Center = On diagonal 1 and On diagonal 2 (the center)<br />
230 </dd>
231 </dl><a NAME="AssociationItem.__findRectIntersectionPoint" ID="AssociationItem.__findRectIntersectionPoint"></a>
232 <h4>AssociationItem.__findRectIntersectionPoint</h4>
233 <b>__findRectIntersectionPoint</b>(<i>item, p1, p2</i>)
234 <p>
235 Private method to find the intersetion point of a line with a rectangle.
236 </p><dl>
237 <dt><i>item</i></dt>
238 <dd>
239 item to check against
240 </dd><dt><i>p1</i></dt>
241 <dd>
242 first point of the line (QPointF)
243 </dd><dt><i>p2</i></dt>
244 <dd>
245 second point of the line (QPointF)
246 </dd>
247 </dl><dl>
248 <dt>Returns:</dt>
249 <dd>
250 the intersection point (QPointF)
251 </dd>
252 </dl><a NAME="AssociationItem.__mapRectFromItem" ID="AssociationItem.__mapRectFromItem"></a>
253 <h4>AssociationItem.__mapRectFromItem</h4>
254 <b>__mapRectFromItem</b>(<i>item</i>)
255 <p>
256 Private method to map item's rectangle to this item's coordinate system.
257 </p><dl>
258 <dt><i>item</i></dt>
259 <dd>
260 reference to the item to be mapped (QGraphicsRectItem)
261 </dd>
262 </dl><dl>
263 <dt>Returns:</dt>
264 <dd>
265 item's rectangle in local coordinates (QRectF)
266 </dd>
267 </dl><a NAME="AssociationItem.__updateEndPoint" ID="AssociationItem.__updateEndPoint"></a>
268 <h4>AssociationItem.__updateEndPoint</h4>
269 <b>__updateEndPoint</b>(<i>region, isWidgetA</i>)
270 <p>
271 Private method to update an endpoint.
272 </p><dl>
273 <dt><i>region</i></dt>
274 <dd>
275 the region for the endpoint (integer)
276 </dd><dt><i>isWidgetA</i></dt>
277 <dd>
278 flag indicating update for itemA is done (boolean)
279 </dd>
280 </dl><a NAME="AssociationItem.unassociate" ID="AssociationItem.unassociate"></a>
281 <h4>AssociationItem.unassociate</h4>
282 <b>unassociate</b>(<i></i>)
283 <p>
284 Public method to unassociate from the widgets.
285 </p><a NAME="AssociationItem.widgetMoved" ID="AssociationItem.widgetMoved"></a>
286 <h4>AssociationItem.widgetMoved</h4>
287 <b>widgetMoved</b>(<i></i>)
288 <p>
289 Public method to recalculate the association after a widget was moved.
290 </p>
291 <div align="right"><a href="#top">Up</a></div>
292 <hr />
293 </body></html>

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