summaryrefslogtreecommitdiffstats
path: root/src/declarative/graphicsitems/qdeclarativeloader.cpp
blob: 2b2e00b3c40118652f6f0ca02384fe09e3fb82f6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtQuick1 module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia.  For licensing terms and
** conditions see http://qt.digia.com/licensing.  For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights.  These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "private/qdeclarativeloader_p_p.h"

#include <qdeclarativeinfo.h>
#include <private/qdeclarativeengine_p.h>
#include <private/qdeclarativeglobal_p.h>

QT_BEGIN_NAMESPACE

QDeclarativeLoaderPrivate::QDeclarativeLoaderPrivate()
    : item(0), component(0), ownComponent(false), updatingSize(false),
      itemWidthValid(false), itemHeightValid(false)
{
}

QDeclarativeLoaderPrivate::~QDeclarativeLoaderPrivate()
{
}

void QDeclarativeLoaderPrivate::itemGeometryChanged(QDeclarativeItem *resizeItem, const QRectF &newGeometry, const QRectF &oldGeometry)
{
    if (resizeItem == item) {
        if (!updatingSize && newGeometry.width() != oldGeometry.width())
            itemWidthValid = true;
        if (!updatingSize && newGeometry.height() != oldGeometry.height())
            itemHeightValid = true;
        _q_updateSize(false);
    }
    QDeclarativeItemChangeListener::itemGeometryChanged(resizeItem, newGeometry, oldGeometry);
}

void QDeclarativeLoaderPrivate::clear()
{
    if (ownComponent) {
        component->deleteLater();
        component = 0;
        ownComponent = false;
    }
    source = QUrl();

    if (item) {
        if (QDeclarativeItem *qmlItem = qobject_cast<QDeclarativeItem*>(item)) {
            QDeclarativeItemPrivate *p =
                    static_cast<QDeclarativeItemPrivate *>(QGraphicsItemPrivate::get(qmlItem));
            p->removeItemChangeListener(this, QDeclarativeItemPrivate::Geometry);
        }

        // We can't delete immediately because our item may have triggered
        // the Loader to load a different item.
        if (item->scene()) {
            item->scene()->removeItem(item);
        } else {
            item->setParentItem(0);
            item->setVisible(false);
        }
        item->deleteLater();
        item = 0;
    }
}

void QDeclarativeLoaderPrivate::initResize()
{
    Q_Q(QDeclarativeLoader);
    if (QDeclarativeItem *qmlItem = qobject_cast<QDeclarativeItem*>(item)) {
        QDeclarativeItemPrivate *p =
                static_cast<QDeclarativeItemPrivate *>(QGraphicsItemPrivate::get(qmlItem));
        p->addItemChangeListener(this, QDeclarativeItemPrivate::Geometry);
        // We may override the item's size, so we need to remember
        // whether the item provided its own valid size.
        itemWidthValid = p->widthValid;
        itemHeightValid = p->heightValid;
    } else if (item && item->isWidget()) {
        QGraphicsWidget *widget = static_cast<QGraphicsWidget*>(item);
        widget->installEventFilter(q);
    }
    _q_updateSize();
}

/*!
    \qmltype Loader
    \instantiates QDeclarativeLoader
    \ingroup qml-utility-elements
    \since 4.7
    \inherits Item

    \brief The Loader item allows dynamically loading an Item-based
    subtree from a URL or Component.

    Loader is used to dynamically load visual QML components. It can load a
    QML file (using the \l source property) or a \l Component object (using 
    the \l sourceComponent property). It is useful for delaying the creation 
    of a component until it is required: for example, when a component should 
    be created on demand, or when a component should not be created 
    unnecessarily for performance reasons.

    Here is a Loader that loads "Page1.qml" as a component when the 
    \l MouseArea is clicked:

    \snippet doc/src/snippets/declarative/loader/simple.qml 0

    The loaded item can be accessed using the \l item property.

    If the \l source or \l sourceComponent changes, any previously instantiated
    items are destroyed. Setting \l source to an empty string or setting
    \l sourceComponent to \c undefined destroys the currently loaded item,
    freeing resources and leaving the Loader empty.

    \section2 Loader sizing behavior

    Loader is like any other visual item and must be positioned and sized
    accordingly to become visible.

    \list
    \li If an explicit size is not specified for the Loader, the Loader
    is automatically resized to the size of the loaded item once the
    component is loaded.
    \li If the size of the Loader is specified explicitly by setting
    the width, height or by anchoring, the loaded item will be resized
    to the size of the Loader.
    \endlist

    In both scenarios the size of the item and the Loader are identical.
    This ensures that anchoring to the Loader is equivalent to anchoring
    to the loaded item.

    \table
    \row
    \li sizeloader.qml
    \li sizeitem.qml
    \row
    \li \snippet doc/src/snippets/declarative/loader/sizeloader.qml 0
    \li \snippet doc/src/snippets/declarative/loader/sizeitem.qml 0
    \row
    \li The red rectangle will be sized to the size of the root item.
    \li The red rectangle will be 50x50, centered in the root item.
    \endtable


    \section2 Receiving signals from loaded items

    Any signals emitted from the loaded item can be received using the 
    \l Connections element. For example, the following \c application.qml
    loads \c MyItem.qml, and is able to receive the \c message signal from
    the loaded item through a \l Connections object:

    \table
    \row 
    \li application.qml
    \li MyItem.qml
    \row
    \li \snippet doc/src/snippets/declarative/loader/connections.qml 0
    \li \snippet doc/src/snippets/declarative/loader/MyItem.qml 0
    \endtable

    Alternatively, since \c MyItem.qml is loaded within the scope of the
    Loader, it could also directly call any function defined in the Loader or
    its parent \l Item.


    \section2 Focus and key events

    Loader is a focus scope. Its \l {Item::}{focus} property must be set to 
    \c true for any of its children to get the \e {active focus}. (See 
    \l{qmlfocus#Acquiring Focus and Focus Scopes}{the focus documentation page} 
    for more details.) Any key events received in the loaded item should likely
    also be \l {KeyEvent::}{accepted} so they are not propagated to the Loader.

    For example, the following \c application.qml loads \c KeyReader.qml when
    the \l MouseArea is clicked.  Notice the \l {Item::}{focus} property is 
    set to \c true for the Loader as well as the \l Item in the dynamically 
    loaded object:

    \table
    \row 
    \li application.qml
    \li KeyReader.qml
    \row
    \li \snippet doc/src/snippets/declarative/loader/focus.qml 0
    \li \snippet doc/src/snippets/declarative/loader/KeyReader.qml 0
    \endtable

    Once \c KeyReader.qml is loaded, it accepts key events and sets 
    \c event.accepted to \c true so that the event is not propagated to the
    parent \l Rectangle.

    \sa {dynamic-object-creation}{Dynamic Object Creation}
*/

QDeclarativeLoader::QDeclarativeLoader(QDeclarativeItem *parent)
  : QDeclarativeImplicitSizeItem(*(new QDeclarativeLoaderPrivate), parent)
{
    Q_D(QDeclarativeLoader);
    d->flags |= QGraphicsItem::ItemIsFocusScope;
}

QDeclarativeLoader::~QDeclarativeLoader()
{
    Q_D(QDeclarativeLoader);
    if (d->item) {
        if (QDeclarativeItem *qmlItem = qobject_cast<QDeclarativeItem*>(d->item)) {
            QDeclarativeItemPrivate *p =
                    static_cast<QDeclarativeItemPrivate *>(QGraphicsItemPrivate::get(qmlItem));
            p->removeItemChangeListener(d, QDeclarativeItemPrivate::Geometry);
        }
    }
}

/*!
    \qmlproperty url Loader::source
    This property holds the URL of the QML component to instantiate.

    Note the QML component must be an \l{Item}-based component. The loader
    cannot load non-visual components.

    To unload the currently loaded item, set this property to an empty string,
    or set \l sourceComponent to \c undefined. Setting \c source to a
    new URL will also cause the item created by the previous URL to be unloaded.

    \sa sourceComponent, status, progress
*/
QUrl QDeclarativeLoader::source() const
{
    Q_D(const QDeclarativeLoader);
    return d->source;
}

void QDeclarativeLoader::setSource(const QUrl &url)
{
    Q_D(QDeclarativeLoader);
    if (d->source == url)
        return;

    d->clear();

    d->source = url;

    if (d->source.isEmpty()) {
        emit sourceChanged();
        emit statusChanged();
        emit progressChanged();
        emit itemChanged();
        return;
    }

    d->component = new QDeclarativeComponent(qmlEngine(this), d->source, this);
    d->ownComponent = true;

    if (isComponentComplete())
        d->load();
}

/*!
    \qmlproperty Component Loader::sourceComponent
    This property holds the \l{Component} to instantiate.

    \qml
    Item {
        Component {
            id: redSquare
            Rectangle { color: "red"; width: 10; height: 10 }
        }

        Loader { sourceComponent: redSquare }
        Loader { sourceComponent: redSquare; x: 10 }
    }
    \endqml

    To unload the currently loaded item, set this property to an empty string
    or \c undefined.

    \sa source, progress
*/

QDeclarativeComponent *QDeclarativeLoader::sourceComponent() const
{
    Q_D(const QDeclarativeLoader);
    return d->component;
}

void QDeclarativeLoader::setSourceComponent(QDeclarativeComponent *comp)
{
    Q_D(QDeclarativeLoader);
    if (comp == d->component)
        return;

    d->clear();

    d->component = comp;
    d->ownComponent = false;

    if (!d->component) {
        emit sourceChanged();
        emit statusChanged();
        emit progressChanged();
        emit itemChanged();
        return;
    }

    if (isComponentComplete())
        d->load();
}

void QDeclarativeLoader::resetSourceComponent()
{
    setSourceComponent(0);
}

void QDeclarativeLoaderPrivate::load()
{
    Q_Q(QDeclarativeLoader);

    if (!q->isComponentComplete() || !component)
        return;

    if (!component->isLoading()) {
        _q_sourceLoaded();
    } else {
        QObject::connect(component, SIGNAL(statusChanged(QDeclarativeComponent::Status)),
                q, SLOT(_q_sourceLoaded()));
        QObject::connect(component, SIGNAL(progressChanged(qreal)),
                q, SIGNAL(progressChanged()));
        emit q->statusChanged();
        emit q->progressChanged();
        emit q->sourceChanged();
        emit q->itemChanged();
    }
}

void QDeclarativeLoaderPrivate::_q_sourceLoaded()
{
    Q_Q(QDeclarativeLoader);

    if (component) {
        if (!component->errors().isEmpty()) {
            QDeclarativeEnginePrivate::warning(qmlEngine(q), component->errors());
            emit q->sourceChanged();
            emit q->statusChanged();
            emit q->progressChanged();
            return;
        }

        QDeclarativeContext *creationContext = component->creationContext();
        if (!creationContext) creationContext = qmlContext(q);
        QDeclarativeContext *ctxt = new QDeclarativeContext(creationContext);
        ctxt->setContextObject(q);

        QDeclarativeGuard<QDeclarativeComponent> c = component;
        QObject *obj = component->beginCreate(ctxt);
        if (component != c) {
            // component->create could trigger a change in source that causes
            // component to be set to something else. In that case we just
            // need to cleanup.
            if (c)
                c->completeCreate();
            delete obj;
            delete ctxt;
            return;
        }
        if (obj) {
            item = qobject_cast<QGraphicsObject *>(obj);
            if (item) {
                QDeclarative_setParent_noEvent(ctxt, obj);
                QDeclarative_setParent_noEvent(item, q);
                item->setParentItem(q);
//                item->setFocus(true);
                initResize();
            } else {
                qmlInfo(q) << QDeclarativeLoader::tr("Loader does not support loading non-visual elements.");
                delete obj;
                delete ctxt;
            }
        } else {
            if (!component->errors().isEmpty())
                QDeclarativeEnginePrivate::warning(qmlEngine(q), component->errors());
            delete obj;
            delete ctxt;
            source = QUrl();
        }
        component->completeCreate();
        emit q->sourceChanged();
        emit q->statusChanged();
        emit q->progressChanged();
        emit q->itemChanged();
        emit q->loaded();
    }
}

/*!
    \qmlproperty enumeration Loader::status

    This property holds the status of QML loading.  It can be one of:
    \list
    \li Loader.Null - no QML source has been set
    \li Loader.Ready - the QML source has been loaded
    \li Loader.Loading - the QML source is currently being loaded
    \li Loader.Error - an error occurred while loading the QML source
    \endlist

    Use this status to provide an update or respond to the status change in some way.
    For example, you could:

    \list
    \li Trigger a state change:
    \qml
        State { name: 'loaded'; when: loader.status == Loader.Ready }
    \endqml

    \li Implement an \c onStatusChanged signal handler:
    \qml
        Loader {
            id: loader
            onStatusChanged: if (loader.status == Loader.Ready) console.log('Loaded')
        }
    \endqml

    \li Bind to the status value:
    \qml
        Text { text: loader.status == Loader.Ready ? 'Loaded' : 'Not loaded' }
    \endqml
    \endlist

    Note that if the source is a local file, the status will initially be Ready (or Error). While
    there will be no onStatusChanged signal in that case, the onLoaded will still be invoked.

    \sa progress
*/

QDeclarativeLoader::Status QDeclarativeLoader::status() const
{
    Q_D(const QDeclarativeLoader);

    if (d->component)
        return static_cast<QDeclarativeLoader::Status>(d->component->status());

    if (d->item)
        return Ready;

    return d->source.isEmpty() ? Null : Error;
}

void QDeclarativeLoader::componentComplete()
{
    Q_D(QDeclarativeLoader);

    QDeclarativeItem::componentComplete();
    d->load();
}


/*!
    \qmlsignal Loader::onLoaded()

    This handler is called when the \l status becomes \c Loader.Ready, or on successful
    initial load.
*/


/*!
\qmlproperty real Loader::progress

This property holds the progress of loading QML data from the network, from
0.0 (nothing loaded) to 1.0 (finished).  Most QML files are quite small, so
this value will rapidly change from 0 to 1.

\sa status
*/
qreal QDeclarativeLoader::progress() const
{
    Q_D(const QDeclarativeLoader);

    if (d->item)
        return 1.0;

    if (d->component)
        return d->component->progress();

    return 0.0;
}

void QDeclarativeLoaderPrivate::_q_updateSize(bool loaderGeometryChanged)
{
    Q_Q(QDeclarativeLoader);
    if (!item || updatingSize)
        return;

    updatingSize = true;
    if (QDeclarativeItem *qmlItem = qobject_cast<QDeclarativeItem*>(item)) {
        if (!itemWidthValid)
            q->setImplicitWidth(qmlItem->implicitWidth());
        else
            q->setImplicitWidth(qmlItem->width());
        if (loaderGeometryChanged && q->widthValid())
            qmlItem->setWidth(q->width());
        if (!itemHeightValid)
            q->setImplicitHeight(qmlItem->implicitHeight());
        else
            q->setImplicitHeight(qmlItem->height());
        if (loaderGeometryChanged && q->heightValid())
            qmlItem->setHeight(q->height());
    } else if (item && item->isWidget()) {
        QGraphicsWidget *widget = static_cast<QGraphicsWidget*>(item);
        QSizeF widgetSize = widget->size();
        q->setImplicitWidth(widgetSize.width());
        if (loaderGeometryChanged && q->widthValid())
            widgetSize.setWidth(q->width());
        q->setImplicitHeight(widgetSize.height());
        if (loaderGeometryChanged && q->heightValid())
            widgetSize.setHeight(q->height());
        if (widget->size() != widgetSize)
            widget->resize(widgetSize);
    }
    updatingSize = false;
}

/*!
    \qmlproperty Item Loader::item
    This property holds the top-level item that is currently loaded.
*/
QGraphicsObject *QDeclarativeLoader::item() const
{
    Q_D(const QDeclarativeLoader);
    return d->item;
}

void QDeclarativeLoader::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
{
    Q_D(QDeclarativeLoader);
    if (newGeometry != oldGeometry) {
        d->_q_updateSize();
    }
    QDeclarativeItem::geometryChanged(newGeometry, oldGeometry);
}

QVariant QDeclarativeLoader::itemChange(GraphicsItemChange change, const QVariant &value)
{
    Q_D(QDeclarativeLoader);
    if (change == ItemSceneHasChanged) {
        if (d->item && d->item->isWidget()) {
            d->item->removeEventFilter(this);
            d->item->installEventFilter(this);
        }
    }
    return QDeclarativeItem::itemChange(change, value);
}

bool QDeclarativeLoader::eventFilter(QObject *watched, QEvent *e)
{
    Q_D(QDeclarativeLoader);
    if (watched == d->item && e->type() == QEvent::GraphicsSceneResize) {
        if (d->item && d->item->isWidget())
            d->_q_updateSize(false);
    }
    return QDeclarativeItem::eventFilter(watched, e);
}

#include <moc_qdeclarativeloader_p.cpp>

QT_END_NAMESPACE