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comparison dwt/layout/FormAttachment.d @ 50:d48f7334742c

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FormLayout, FormData, FormAttachment
author Frank Benoit <benoit@tionex.de>
date Fri, 11 Jan 2008 10:44:12 +0100
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49:a67796650ad4 50:d48f7334742c
1 /*******************************************************************************
2 * Copyright (c) 2000, 2006 IBM Corporation and others.
3 * All rights reserved. This program and the accompanying materials
4 * are made available under the terms of the Eclipse Public License v1.0
5 * which accompanies this distribution, and is available at
6 * http://www.eclipse.org/legal/epl-v10.html
7 *
8 * Contributors:
9 * IBM Corporation - initial API and implementation
10 *******************************************************************************/
11 module dwt.layout.FormAttachment;
12
13 import dwt.SWT;
14 import dwt.widgets.Control;
15 import dwt.layout.FormLayout;
16 import dwt.layout.FormData;
17
18 import tango.text.convert.Format;
19
20 /**
21 * Instances of this class are used to define the edges of a control
22 * within a <code>FormLayout</code>.
23 * <p>
24 * <code>FormAttachments</code> are set into the top, bottom, left,
25 * and right fields of the <code>FormData</code> for a control.
26 * For example:
27 * <pre>
28 * FormData data = new FormData();
29 * data.top = new FormAttachment(0,5);
30 * data.bottom = new FormAttachment(100,-5);
31 * data.left = new FormAttachment(0,5);
32 * data.right = new FormAttachment(100,-5);
33 * button.setLayoutData(data);
34 * </pre>
35 * </p>
36 * <p>
37 * A <code>FormAttachment</code> defines where to attach the side of
38 * a control by using the equation, y = ax + b. The "a" term represents
39 * a fraction of the parent composite's width (from the left) or height
40 * (from the top). It can be defined using a numerator and denominator,
41 * or just a percentage value. If a percentage is used, the denominator
42 * is set to 100. The "b" term in the equation represents an offset, in
43 * pixels, from the attachment position. For example:
44 * <pre>
45 * FormAttachment attach = new FormAttachment (20, -5);
46 * </pre>
47 * specifies that the side to which the <code>FormAttachment</code>
48 * object belongs will lie at 20% of the parent composite, minus 5 pixels.
49 * </p>
50 * <p>
51 * Control sides can also be attached to another control.
52 * For example:
53 * <pre>
54 * FormAttachment attach = new FormAttachment (button, 10);
55 * </pre>
56 * specifies that the side to which the <code>FormAttachment</code>
57 * object belongs will lie in the same position as the adjacent side of
58 * the <code>button</code> control, plus 10 pixels. The control side can
59 * also be attached to the opposite side of the specified control.
60 * For example:
61 * <pre>
62 * FormData data = new FormData ();
63 * data.left = new FormAttachment (button, 0, SWT.LEFT);
64 * </pre>
65 * specifies that the left side of the control will lie in the same position
66 * as the left side of the <code>button</code> control. The control can also
67 * be attached in a position that will center the control on the specified
68 * control. For example:
69 * <pre>
70 * data.left = new FormAttachment (button, 0, SWT.CENTER);
71 * </pre>
72 * specifies that the left side of the control will be positioned so that it is
73 * centered between the left and right sides of the <code>button</code> control.
74 * If the alignment is not specified, the default is to attach to the adjacent side.
75 * </p>
76 *
77 * @see FormLayout
78 * @see FormData
79 *
80 * @since 2.0
81 */
82 public final class FormAttachment {
83 /**
84 * numerator specifies the numerator of the "a" term in the
85 * equation, y = ax + b, which defines the attachment.
86 */
87 public int numerator;
88
89 /**
90 * denominator specifies the denominator of the "a" term in the
91 * equation, y = ax + b, which defines the attachment.
92 *
93 * The default value is 100.
94 */
95 public int denominator = 100;
96
97 /**
98 * offset specifies the offset, in pixels, of the control side
99 * from the attachment position.
100 * If the offset is positive, then the control side is offset
101 * to the right of or below the attachment position. If it is
102 * negative, then the control side is offset to the left of or
103 * above the attachment position.
104 *
105 * This is equivalent to the "b" term in the equation y = ax + b.
106 * The default value is 0.
107 */
108 public int offset;
109
110 /**
111 * control specifies the control to which the control side is
112 * attached.
113 */
114 public Control control;
115
116 /**
117 * alignment specifies the alignment of the control side that is
118 * attached to a control.
119 * <p>
120 * For top and bottom attachments, TOP, BOTTOM and CENTER are used. For left
121 * and right attachments, LEFT, RIGHT and CENTER are used. If any other case
122 * occurs, the default will be used instead.
123 * </p>
124 *
125 * <br>Possible values are: <ul>
126 * <li>TOP: Attach the side to the top side of the specified control.</li>
127 * <li>BOTTOM : Attach the side to the bottom side of the specified control.</li>
128 * <li>LEFT: Attach the side to the left side of the specified control.</li>
129 * <li>RIGHT: Attach the side to the right side of the specified control.</li>
130 * <li>CENTER: Attach the side at a position which will center the control on the specified control.</li>
131 * <li>DEFAULT: Attach the side to the adjacent side of the specified control.</li>
132 * </ul>
133 */
134 public int alignment;
135
136 /**
137 * Constructs a new instance of this class.
138 * Since no numerator, denominator or offset is specified,
139 * the attachment is treated as a percentage of the form.
140 * The numerator is zero, the denominator is 100 and the
141 * offset is zero.
142 *
143 * @since 3.2
144 */
145 public this () {
146 }
147
148 /**
149 * Constructs a new instance of this class given a numerator
150 * Since no denominator or offset is specified, the default
151 * is to treat the numerator as a percentage of the form, with a
152 * denominator of 100. The offset is zero.
153 *
154 * @param numerator the percentage of the position
155 *
156 * @since 3.0
157 */
158 public this (int numerator) {
159 this (numerator, 100, 0);
160 }
161
162 /**
163 * Constructs a new instance of this class given a numerator
164 * and an offset. Since no denominator is specified, the default
165 * is to treat the numerator as a percentage of the form, with a
166 * denominator of 100.
167 *
168 * @param numerator the percentage of the position
169 * @param offset the offset of the side from the position
170 */
171 public this (int numerator, int offset) {
172 this (numerator, 100, offset);
173 }
174
175 /**
176 * Constructs a new instance of this class given a numerator
177 * and denominator and an offset. The position of the side is
178 * given by the fraction of the form defined by the numerator
179 * and denominator.
180 *
181 * @param numerator the numerator of the position
182 * @param denominator the denominator of the position
183 * @param offset the offset of the side from the position
184 */
185 public this (int numerator, int denominator, int offset) {
186 if (denominator == 0) SWT.error (SWT.ERROR_CANNOT_BE_ZERO);
187 this.numerator = numerator;
188 this.denominator = denominator;
189 this.offset = offset;
190 }
191
192 /**
193 * Constructs a new instance of this class given a control.
194 * Since no alignment is specified, the default alignment is
195 * to attach the side to the adjacent side of the specified
196 * control. Since no offset is specified, an offset of 0 is
197 * used.
198 *
199 * @param control the control the side is attached to
200 */
201 public this (Control control) {
202 this (control, 0, SWT.DEFAULT);
203 }
204
205 /**
206 * Constructs a new instance of this class given a control
207 * and an offset. Since no alignment is specified, the default
208 * alignment is to attach the side to the adjacent side of the
209 * specified control.
210 *
211 * @param control the control the side is attached to
212 * @param offset the offset of the side from the control
213 */
214 public this (Control control, int offset) {
215 this (control, offset, SWT.DEFAULT);
216 }
217
218 /**
219 * Constructs a new instance of this class given a control,
220 * an offset and an alignment.
221 *
222 * @param control the control the side is attached to
223 * @param offset the offset of the side from the control
224 * @param alignment the alignment of the side to the control it is attached to
225 */
226 public this (Control control, int offset, int alignment) {
227 this.control = control;
228 this.offset = offset;
229 this.alignment = alignment;
230 }
231
232 FormAttachment divide (int value) {
233 return new FormAttachment (numerator, denominator * value, offset / value);
234 }
235
236 int gcd (int m, int n) {
237 int temp;
238 m = Math.abs (m);
239 n = Math.abs (n);
240 if (m < n) {
241 temp = m;
242 m = n;
243 n = temp;
244 }
245 while (n != 0){
246 temp = m;
247 m = n;
248 n = temp % n;
249 }
250 return m;
251 }
252
253 FormAttachment minus (FormAttachment attachment) {
254 FormAttachment solution = new FormAttachment ();
255 solution.numerator = numerator * attachment.denominator - denominator * attachment.numerator;
256 solution.denominator = denominator * attachment.denominator;
257 int gcd = gcd (solution.denominator, solution.numerator);
258 solution.numerator = solution.numerator / gcd;
259 solution.denominator = solution.denominator / gcd;
260 solution.offset = offset - attachment.offset;
261 return solution;
262 }
263
264 FormAttachment minus (int value) {
265 return new FormAttachment (numerator, denominator, offset - value);
266 }
267
268 FormAttachment plus (FormAttachment attachment) {
269 FormAttachment solution = new FormAttachment ();
270 solution.numerator = numerator * attachment.denominator + denominator * attachment.numerator;
271 solution.denominator = denominator * attachment.denominator;
272 int gcd = gcd (solution.denominator, solution.numerator);
273 solution.numerator = solution.numerator / gcd;
274 solution.denominator = solution.denominator / gcd;
275 solution.offset = offset + attachment.offset;
276 return solution;
277 }
278
279 FormAttachment plus (int value) {
280 return new FormAttachment (numerator, denominator, offset + value);
281 }
282
283 int solveX (int value) {
284 if (denominator == 0) SWT.error (SWT.ERROR_CANNOT_BE_ZERO);
285 return ((numerator * value) / denominator) + offset;
286 }
287
288 int solveY (int value) {
289 if (numerator == 0) SWT.error (SWT.ERROR_CANNOT_BE_ZERO);
290 return (value - offset) * denominator / numerator;
291 }
292
293 /**
294 * Returns a string containing a concise, human-readable
295 * description of the receiver.
296 *
297 * @return a string representation of the FormAttachment
298 */
299 public char[] toString () {
300 char[] string = control != null ? control.toString () : Format( "{}/{}", numerator, denominator );
301 return Format("{{y = ({})x + {}}", string, ( offset >= 0 ? Format(")x + {}", offset ) : Format( ")x - {}", -offset)));
302 }
303
304 }