qgraphicsanchorlayout.cpp

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33 -

34 /*! -

35 \class QGraphicsAnchorLayout -

36 \brief The QGraphicsAnchorLayout class provides a layout where one can anchor widgets -

37 together in Graphics View. -

38 \since 4.6 -

39 \ingroup appearance -

40 \ingroup geomanagement -

41 \ingroup graphicsview-api -

42 \inmodule QtWidgets -

43 -

44 The anchor layout allows developers to specify how widgets should be placed relative to -

45 each other, and to the layout itself. The specification is made by adding anchors to the -

46 layout by calling addAnchor(), addAnchors() or addCornerAnchors(). -

47 -

48 Existing anchors in the layout can be accessed with the anchor() function. -

49 Items that are anchored are automatically added to the layout, and if items -

50 are removed, all their anchors will be automatically removed. -

51 -

52 \div {class="float-left"} -

53 \inlineimage simpleanchorlayout-example.png Using an anchor layout to align simple colored widgets. -

54 \enddiv -

55 -

56 Anchors are always set up between edges of an item, where the "center" is also considered to -

57 be an edge. Consider the following example: -

58 -

59 \snippet graphicsview/simpleanchorlayout/main.cpp adding anchors -

60 -

61 Here, the right edge of item \c a is anchored to the left edge of item \c b and the bottom -

62 edge of item \c a is anchored to the top edge of item \c b, with the result that -

63 item \c b will be placed diagonally to the right and below item \c b. -

64 -

65 The addCornerAnchors() function provides a simpler way of anchoring the corners -

66 of two widgets than the two individual calls to addAnchor() shown in the code -

67 above. Here, we see how a widget can be anchored to the top-left corner of the enclosing -

68 layout: -

69 -

70 \snippet graphicsview/simpleanchorlayout/main.cpp adding a corner anchor -

71 -

72 In cases where anchors are used to match the widths or heights of widgets, it is -

73 convenient to use the addAnchors() function. As with the other functions for specifying -

74 anchors, it can also be used to anchor a widget to a layout. -

75 -

76 \section1 Size Hints and Size Policies in an Anchor Layout -

77 -

78 QGraphicsAnchorLayout respects each item's size hints and size policies. -

79 Note that there are some properties of QSizePolicy that are \l{Known issues}{not respected}. -

80 -

81 \section1 Spacing within an Anchor Layout -

82 -

83 The layout may distribute some space between the items. If the spacing has not been -

84 explicitly specified, the actual amount of space will usually be 0. -

85 -

86 However, if the first edge is the \e opposite of the second edge (e.g., the right edge -

87 of the first widget is anchored to the left edge of the second widget), the size of the -

88 anchor will be queried from the style through a pixel metric: -

89 \l{QStyle::}{PM_LayoutHorizontalSpacing} for horizontal anchors and -

90 \l{QStyle::}{PM_LayoutVerticalSpacing} for vertical anchors. -

91 -

92 If the spacing is negative, the items will overlap to some extent. -

93 -

94 -

95 \section1 Known Issues -

96 There are some features that QGraphicsAnchorLayout currently does not support. -

97 This might change in the future, so avoid using these features if you want to -

98 avoid any future regressions in behaviour: -

99 \list -

100 -

101 \li Stretch factors are not respected. -

102 -

103 \li QSizePolicy::ExpandFlag is not respected. -

104 -

105 \li Height for width is not respected. -

106 -

107 \endlist -

108 -

109 \sa QGraphicsLinearLayout, QGraphicsGridLayout, QGraphicsLayout -

110 */ -

111 -

112 /*! -

113 \class QGraphicsAnchor -

114 \brief The QGraphicsAnchor class represents an anchor between two items in a -

115 QGraphicsAnchorLayout. -

116 \since 4.6 -

117 \ingroup appearance -

118 \ingroup geomanagement -

119 \ingroup graphicsview-api -

120 \inmodule QtWidgets -

121 -

122 The graphics anchor provides an API that enables you to query and manipulate the -

123 properties an anchor has. When an anchor is added to the layout with -

124 QGraphicsAnchorLayout::addAnchor(), a QGraphicsAnchor instance is returned where the properties -

125 are initialized to their default values. The properties can then be further changed, and they -

126 will be picked up the next time the layout is activated. -

127 -

128 \sa QGraphicsAnchorLayout::anchor() -

129 -

130 */ -

131 #include "qgraphicsanchorlayout_p.h" -

132 #ifndef QT_NO_GRAPHICSVIEW -

133 QT_BEGIN_NAMESPACE -

134 -

135 QGraphicsAnchor::QGraphicsAnchor(QGraphicsAnchorLayout *parentLayout) -

136 : QObject(*(new QGraphicsAnchorPrivate)) -

137 { -

138 Q_D(QGraphicsAnchor); -

139 Q_ASSERT(parentLayout); -

140 d->layoutPrivate = parentLayout->d_func(); -

141

}

never executed: end of block

142 -

143 /*! -

144 Removes the QGraphicsAnchor object from the layout and destroys it. -

145 */ -

146 QGraphicsAnchor::~QGraphicsAnchor() -

147 { -

148 } -

149 -

150 /*! -

151 \property QGraphicsAnchor::sizePolicy -

152 \brief the size policy for the QGraphicsAnchor. -

153 -

154 By setting the size policy on an anchor you can configure how the anchor can resize itself -

155 from its preferred spacing. For instance, if the anchor has the size policy -

156 QSizePolicy::Minimum, the spacing is the minimum size of the anchor. However, its size -

157 can grow up to the anchors maximum size. If the default size policy is QSizePolicy::Fixed, -

158 the anchor can neither grow or shrink, which means that the only size the anchor can have -

159 is the spacing. QSizePolicy::Fixed is the default size policy. -

160 QGraphicsAnchor always has a minimum spacing of 0 and a very large maximum spacing. -

161 -

162 \sa QGraphicsAnchor::spacing -

163 */ -

164 -

165 void QGraphicsAnchor::setSizePolicy(QSizePolicy::Policy policy) -

166 { -

167 Q_D(QGraphicsAnchor); -

168 d->setSizePolicy(policy); -

169

}

never executed: end of block

170 -

171 QSizePolicy::Policy QGraphicsAnchor::sizePolicy() const -

172 { -

173 Q_D(const QGraphicsAnchor); -

174

return d->sizePolicy;

never executed: return d->sizePolicy;

175 } -

176 -

177 /*! -

178 \property QGraphicsAnchor::spacing -

179 \brief the preferred space between items in the QGraphicsAnchorLayout. -

180 -

181 Depending on the anchor type, the default spacing is either -

182 0 or a value returned from the style. -

183 -

184 \sa QGraphicsAnchorLayout::addAnchor() -

185 */ -

186 void QGraphicsAnchor::setSpacing(qreal spacing) -

187 { -

188 Q_D(QGraphicsAnchor); -

189 d->setSpacing(spacing); -

190

}

never executed: end of block

191 -

192 qreal QGraphicsAnchor::spacing() const -

193 { -

194 Q_D(const QGraphicsAnchor); -

195

return d->spacing();

never executed: return d->spacing();

196 } -

197 -

198 void QGraphicsAnchor::unsetSpacing() -

199 { -

200 Q_D(QGraphicsAnchor); -

201 d->unsetSpacing(); -

202

}

never executed: end of block

203 -

204 /*! -

205 Constructs a QGraphicsAnchorLayout instance. \a parent is passed to -

206 QGraphicsLayout's constructor. -

207 */ -

208 QGraphicsAnchorLayout::QGraphicsAnchorLayout(QGraphicsLayoutItem *parent) -

209 : QGraphicsLayout(*new QGraphicsAnchorLayoutPrivate(), parent) -

210 { -

211 Q_D(QGraphicsAnchorLayout); -

212 d->createLayoutEdges(); -

213

}

never executed: end of block

214 -

215 /*! -

216 Destroys the QGraphicsAnchorLayout object. -

217 */ -

218 QGraphicsAnchorLayout::~QGraphicsAnchorLayout() -

219 { -

220 Q_D(QGraphicsAnchorLayout); -

221 -

222

for (int i = count() - 1; i >= 0; --i) {

i >= 0	Description
TRUE	never evaluated
FALSE	never evaluated

223 QGraphicsLayoutItem *item = d->items.at(i); -

224 removeAt(i); -

225

if (item) {

item	Description
TRUE	never evaluated
FALSE	never evaluated

226

if (item->ownedByLayout())

item->ownedByLayout()	Description
TRUE	never evaluated
FALSE	never evaluated

227

delete item;

never executed: delete item;

228

}

never executed: end of block

229

}

never executed: end of block

230 -

231 d->removeCenterConstraints(this, QGraphicsAnchorLayoutPrivate::Horizontal); -

232 d->removeCenterConstraints(this, QGraphicsAnchorLayoutPrivate::Vertical); -

233 d->deleteLayoutEdges(); -

234 -

235 Q_ASSERT(d->itemCenterConstraints[0].isEmpty()); -

236 Q_ASSERT(d->itemCenterConstraints[1].isEmpty()); -

237 Q_ASSERT(d->items.isEmpty()); -

238 Q_ASSERT(d->m_vertexList.isEmpty()); -

239

}

never executed: end of block

240 -

241 /*! -

242 Creates an anchor between the edge \a firstEdge of item \a firstItem and the edge \a secondEdge -

243 of item \a secondItem. The spacing of the anchor is picked up from the style. Anchors -

244 between a layout edge and an item edge will have a size of 0. -

245 If there is already an anchor between the edges, the new anchor will replace the old one. -

246 -

247 \a firstItem and \a secondItem are automatically added to the layout if they are not part -

248 of the layout. This means that count() can increase by up to 2. -

249 -

250 The spacing an anchor will get depends on the type of anchor. For instance, anchors from the -

251 Right edge of one item to the Left edge of another (or vice versa) will use the default -

252 horizontal spacing. The same behaviour applies to Bottom to Top anchors, (but they will use -

253 the default vertical spacing). For all other anchor combinations, the spacing will be 0. -

254 All anchoring functions will follow this rule. -

255 -

256 The spacing can also be set manually by using QGraphicsAnchor::setSpacing() method. -

257 -

258 Calling this function where \a firstItem or \a secondItem are ancestors of the layout have -

259 undefined behaviour. -

260 -

261 \sa addAnchors(), addCornerAnchors() -

262 */ -

263 QGraphicsAnchor * -

264 QGraphicsAnchorLayout::addAnchor(QGraphicsLayoutItem *firstItem, Qt::AnchorPoint firstEdge, -

265 QGraphicsLayoutItem *secondItem, Qt::AnchorPoint secondEdge) -

266 { -

267 Q_D(QGraphicsAnchorLayout); -

268 QGraphicsAnchor *a = d->addAnchor(firstItem, firstEdge, secondItem, secondEdge); -

269 invalidate(); -

270

return a;

never executed: return a;

271 } -

272 -

273 /*! -

274 Returns the anchor between the anchor points defined by \a firstItem and \a firstEdge and -

275 \a secondItem and \a secondEdge. If there is no such anchor, the function will return 0. -

276 */ -

277 QGraphicsAnchor * -

278 QGraphicsAnchorLayout::anchor(QGraphicsLayoutItem *firstItem, Qt::AnchorPoint firstEdge, -

279 QGraphicsLayoutItem *secondItem, Qt::AnchorPoint secondEdge) -

280 { -

281 Q_D(QGraphicsAnchorLayout); -

282

return d->getAnchor(firstItem, firstEdge, secondItem, secondEdge);

never executed: return d->getAnchor(firstItem, firstEdge, secondItem, secondEdge);

283 } -

284 -

285 /*! -

286 Creates two anchors between \a firstItem and \a secondItem specified by the corners, -

287 \a firstCorner and \a secondCorner, where one is for the horizontal edge and another -

288 one for the vertical edge. -

289 -

290 This is a convenience function, since anchoring corners can be expressed as anchoring -

291 two edges. For instance: -

292 -

293 \snippet graphicsview/simpleanchorlayout/main.cpp adding a corner anchor in two steps -

294 -

295 This can also be achieved with the following line of code: -

296 -

297 \snippet graphicsview/simpleanchorlayout/main.cpp adding a corner anchor -

298 -

299 If there is already an anchor between the edge pairs, it will be replaced by the anchors that -

300 this function specifies. -

301 -

302 \a firstItem and \a secondItem are automatically added to the layout if they are not part of the -

303 layout. This means that count() can increase by up to 2. -

304 -

305 \sa addAnchor(), addAnchors() -

306 */ -

307 void QGraphicsAnchorLayout::addCornerAnchors(QGraphicsLayoutItem *firstItem, -

308 Qt::Corner firstCorner, -

309 QGraphicsLayoutItem *secondItem, -

310 Qt::Corner secondCorner) -

311 { -

312 Q_D(QGraphicsAnchorLayout); -

313 -

314 // Horizontal anchor -

315

Qt::AnchorPoint firstEdge = (firstCorner & 1 ? Qt::AnchorRight: Qt::AnchorLeft);

firstCorner & 1	Description
TRUE	never evaluated
FALSE	never evaluated

316

Qt::AnchorPoint secondEdge = (secondCorner & 1 ? Qt::AnchorRight: Qt::AnchorLeft);

secondCorner & 1	Description
TRUE	never evaluated
FALSE	never evaluated

317

if (d->addAnchor(firstItem, firstEdge, secondItem, secondEdge)) {

d->addAnchor(f...m, secondEdge)	Description
TRUE	never evaluated
FALSE	never evaluated

318 // Vertical anchor -

319

firstEdge = (firstCorner & 2 ? Qt::AnchorBottom: Qt::AnchorTop);

firstCorner & 2	Description
TRUE	never evaluated
FALSE	never evaluated

320

secondEdge = (secondCorner & 2 ? Qt::AnchorBottom: Qt::AnchorTop);

secondCorner & 2	Description
TRUE	never evaluated
FALSE	never evaluated

321 d->addAnchor(firstItem, firstEdge, secondItem, secondEdge); -

322 -

323 invalidate(); -

324

}

never executed: end of block

325

}

never executed: end of block

326 -

327 /*! -

328 Anchors two or four edges of \a firstItem with the corresponding -

329 edges of \a secondItem, so that \a firstItem has the same size as -

330 \a secondItem in the dimensions specified by \a orientations. -

331 -

332 For example, the following example anchors the left and right edges of two items -

333 to match their widths: -

334 -

335 \snippet graphicsview/simpleanchorlayout/main.cpp adding anchors to match sizes in two steps -

336 -

337 This can also be achieved using the following line of code: -

338 -

339 \snippet graphicsview/simpleanchorlayout/main.cpp adding anchors to match sizes -

340 -

341 \sa addAnchor(), addCornerAnchors() -

342 */ -

343 void QGraphicsAnchorLayout::addAnchors(QGraphicsLayoutItem *firstItem, -

344 QGraphicsLayoutItem *secondItem, -

345 Qt::Orientations orientations) -

346 { -

347 bool ok = true; -

348

if (orientations & Qt::Horizontal) {

orientations & Qt::Horizontal	Description
TRUE	never evaluated
FALSE	never evaluated

349 // Currently, if the first is ok, then the rest of the calls should be ok -

350 ok = addAnchor(secondItem, Qt::AnchorLeft, firstItem, Qt::AnchorLeft) != 0; -

351

if (ok)

ok	Description
TRUE	never evaluated
FALSE	never evaluated

352

addAnchor(firstItem, Qt::AnchorRight, secondItem, Qt::AnchorRight);

never executed: addAnchor(firstItem, Qt::AnchorRight, secondItem, Qt::AnchorRight);

353

}

never executed: end of block

354

if (orientations & Qt::Vertical && ok) {

orientations & Qt::Vertical	Description
TRUE	never evaluated
FALSE	never evaluated

ok	Description
TRUE	never evaluated
FALSE	never evaluated

355 addAnchor(secondItem, Qt::AnchorTop, firstItem, Qt::AnchorTop); -

356 addAnchor(firstItem, Qt::AnchorBottom, secondItem, Qt::AnchorBottom); -

357

}

never executed: end of block

358

}

never executed: end of block

359 -

360 /*! -

361 Sets the default horizontal spacing for the anchor layout to \a spacing. -

362 -

363 \sa horizontalSpacing(), setVerticalSpacing(), setSpacing() -

364 */ -

365 void QGraphicsAnchorLayout::setHorizontalSpacing(qreal spacing) -

366 { -

367 Q_D(QGraphicsAnchorLayout); -

368 -

369 d->spacings[0] = spacing; -

370 invalidate(); -

371

}

never executed: end of block

372 -

373 /*! -

374 Sets the default vertical spacing for the anchor layout to \a spacing. -

375 -

376 \sa verticalSpacing(), setHorizontalSpacing(), setSpacing() -

377 */ -

378 void QGraphicsAnchorLayout::setVerticalSpacing(qreal spacing) -

379 { -

380 Q_D(QGraphicsAnchorLayout); -

381 -

382 d->spacings[1] = spacing; -

383 invalidate(); -

384

}

never executed: end of block

385 -

386 /*! -

387 Sets the default horizontal and the default vertical spacing for the anchor layout to \a spacing. -

388 -

389 If an item is anchored with no spacing associated with the anchor, it will use the default -

390 spacing. -

391 -

392 QGraphicsAnchorLayout does not support negative spacings. Setting a negative value will unset the -

393 previous spacing and make the layout use the spacing provided by the current widget style. -

394 -

395 \sa setHorizontalSpacing(), setVerticalSpacing() -

396 */ -

397 void QGraphicsAnchorLayout::setSpacing(qreal spacing) -

398 { -

399 Q_D(QGraphicsAnchorLayout); -

400 -

401 d->spacings[0] = d->spacings[1] = spacing; -

402 invalidate(); -

403

}

never executed: end of block

404 -

405 /*! -

406 Returns the default horizontal spacing for the anchor layout. -

407 -

408 \sa verticalSpacing(), setHorizontalSpacing() -

409 */ -

410 qreal QGraphicsAnchorLayout::horizontalSpacing() const -

411 { -

412 Q_D(const QGraphicsAnchorLayout); -

413

return d->styleInfo().defaultSpacing(Qt::Horizontal);

never executed: return d->styleInfo().defaultSpacing(Qt::Horizontal);

414 } -

415 -

416 /*! -

417 Returns the default vertical spacing for the anchor layout. -

418 -

419 \sa horizontalSpacing(), setVerticalSpacing() -

420 */ -

421 qreal QGraphicsAnchorLayout::verticalSpacing() const -

422 { -

423 Q_D(const QGraphicsAnchorLayout); -

424

return d->styleInfo().defaultSpacing(Qt::Vertical);

never executed: return d->styleInfo().defaultSpacing(Qt::Vertical);

425 } -

426 -

427 /*! -

428 \reimp -

429 */ -

430 void QGraphicsAnchorLayout::setGeometry(const QRectF &geom) -

431 { -

432 Q_D(QGraphicsAnchorLayout); -

433 -

434 QGraphicsLayout::setGeometry(geom); -

435 d->calculateVertexPositions(QGraphicsAnchorLayoutPrivate::Horizontal); -

436 d->calculateVertexPositions(QGraphicsAnchorLayoutPrivate::Vertical); -

437 d->setItemsGeometries(geom); -

438

}

never executed: end of block

439 -

440 /*! -

441 Removes the layout item at \a index without destroying it. Ownership of -

442 the item is transferred to the caller. -

443 -

444 Removing an item will also remove any of the anchors associated with it. -

445 -

446 \sa itemAt(), count() -

447 */ -

448 void QGraphicsAnchorLayout::removeAt(int index) -

449 { -

450 Q_D(QGraphicsAnchorLayout); -

451 QGraphicsLayoutItem *item = d->items.value(index); -

452 -

453

if (!item)

!item	Description
TRUE	never evaluated
FALSE	never evaluated

454

return;

never executed: return;

455 -

456 // Removing an item affects both horizontal and vertical graphs -

457 d->removeCenterConstraints(item, QGraphicsAnchorLayoutPrivate::Horizontal); -

458 d->removeCenterConstraints(item, QGraphicsAnchorLayoutPrivate::Vertical); -

459 d->removeAnchors(item); -

460 d->items.remove(index); -

461 -

462 item->setParentLayoutItem(0); -

463 invalidate(); -

464

}

never executed: end of block

465 -

466 /*! -

467 \reimp -

468 */ -

469 int QGraphicsAnchorLayout::count() const -

470 { -

471 Q_D(const QGraphicsAnchorLayout); -

472

return d->items.size();

never executed: return d->items.size();

473 } -

474 -

475 /*! -

476 \reimp -

477 */ -

478 QGraphicsLayoutItem *QGraphicsAnchorLayout::itemAt(int index) const -

479 { -

480 Q_D(const QGraphicsAnchorLayout); -

481

return d->items.value(index);

never executed: return d->items.value(index);

482 } -

483 -

484 /*! -

485 \reimp -

486 */ -

487 void QGraphicsAnchorLayout::invalidate() -

488 { -

489 Q_D(QGraphicsAnchorLayout); -

490 QGraphicsLayout::invalidate(); -

491 d->calculateGraphCacheDirty = true; -

492 d->styleInfoDirty = true; -

493

}

never executed: end of block

494 -

495 /*! -

496 \reimp -

497 */ -

498 QSizeF QGraphicsAnchorLayout::sizeHint(Qt::SizeHint which, const QSizeF &constraint) const -

499 { -

500 Q_UNUSED(constraint); -

501 Q_D(const QGraphicsAnchorLayout); -

502 -

503 // Some setup calculations are delayed until the information is -

504 // actually needed, avoiding unnecessary recalculations when -

505 // adding multiple anchors. -

506 -

507 // sizeHint() / effectiveSizeHint() already have a cache -

508 // mechanism, using invalidate() to force recalculation. However -

509 // sizeHint() is called three times after invalidation (for max, -

510 // min and pref), but we just need do our setup once. -

511 -

512 const_cast<QGraphicsAnchorLayoutPrivate *>(d)->calculateGraphs(); -

513 -

514 // ### apply constraint! -

515 QSizeF engineSizeHint( -

516 d->sizeHints[QGraphicsAnchorLayoutPrivate::Horizontal][which], -

517 d->sizeHints[QGraphicsAnchorLayoutPrivate::Vertical][which]); -

518 -

519 qreal left, top, right, bottom; -

520 getContentsMargins(&left, &top, &right, &bottom); -

521 -

522

return engineSizeHint + QSizeF(left + right, top + bottom);

never executed: return engineSizeHint + QSizeF(left + right, top + bottom);

523 } -

524 -

525 QT_END_NAMESPACE -

526 -

527 #include "moc_qgraphicsanchorlayout.cpp" -

528 -

529 #endif //QT_NO_GRAPHICSVIEW -

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