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39
40#include <private/qtquickglobal_p.h>
41#include "qquickitemgrabresult.h"
42
43#include "qquickrendercontrol.h"
44#include "qquickwindow.h"
45#include "qquickitem.h"
46#if QT_CONFIG(quick_shadereffect)
47#include "qquickshadereffectsource_p.h"
48#endif
49
50#include <QtQml/QQmlEngine>
51#include <QtQml/QQmlInfo>
52
53#include <private/qquickpixmapcache_p.h>
54#include <private/qquickitem_p.h>
55#include <private/qsgcontext_p.h>
56#include <private/qsgadaptationlayer_p.h>
57
58QT_BEGIN_NAMESPACE
59
60const QEvent::Type Event_Grab_Completed = static_cast<QEvent::Type>(QEvent::User + 1);
61
62class QQuickItemGrabResultPrivate : public QObjectPrivate
63{
64public:
65 QQuickItemGrabResultPrivate()
66 : cacheEntry(nullptr)
67 , qmlEngine(nullptr)
68 , texture(nullptr)
69 {
70 }
71
72 ~QQuickItemGrabResultPrivate()
73 {
74 delete cacheEntry;
75 }
76
77 void ensureImageInCache() const {
78 if (url.isEmpty() && !image.isNull()) {
79 url.setScheme(QQuickPixmap::itemGrabberScheme);
80 url.setPath(path: QVariant::fromValue(value: item.data()).toString());
81 static uint counter = 0;
82 url.setFragment(fragment: QString::number(++counter));
83 cacheEntry = new QQuickPixmap(url, image);
84 }
85 }
86
87 static QQuickItemGrabResult *create(QQuickItem *item, const QSize &size);
88
89 QImage image;
90
91 mutable QUrl url;
92 mutable QQuickPixmap *cacheEntry;
93
94 QQmlEngine *qmlEngine;
95 QJSValue callback;
96
97 QPointer<QQuickItem> item;
98 QPointer<QQuickWindow> window;
99 QSGLayer *texture;
100 QSizeF itemSize;
101 QSize textureSize;
102};
103
104/*!
105 * \qmlproperty url QtQuick::ItemGrabResult::url
106 *
107 * This property holds a URL which can be used in conjunction with
108 * URL based image consumers, such as the QtQuick::Image type.
109 *
110 * The URL is valid while there is a reference in QML or JavaScript
111 * to the ItemGrabResult or while the image the URL references is
112 * actively used.
113 *
114 * The URL does not represent a valid file or location to read it from, it
115 * is primarily a key to access images through Qt Quick's image-based types.
116 */
117
118/*!
119 * \property QQuickItemGrabResult::url
120 *
121 * This property holds a URL which can be used in conjunction with
122 * URL based image consumers, such as the QtQuick::Image type.
123 *
124 * The URL is valid until the QQuickItemGrabResult object is deleted.
125 *
126 * The URL does not represent a valid file or location to read it from, it
127 * is primarily a key to access images through Qt Quick's image-based types.
128 */
129
130/*!
131 * \qmlproperty variant QtQuick::ItemGrabResult::image
132 *
133 * This property holds the pixel results from a grab in the
134 * form of a QImage.
135 */
136
137/*!
138 * \property QQuickItemGrabResult::image
139 *
140 * This property holds the pixel results from a grab.
141 *
142 * If the grab is not yet complete or if it failed,
143 * a null image is returned (\c {image.isNull()} will return \c true).
144 */
145
146/*!
147 \class QQuickItemGrabResult
148 \inmodule QtQuick
149 \brief The QQuickItemGrabResult contains the result from QQuickItem::grabToImage().
150
151 \sa QQuickItem::grabToImage()
152 */
153
154/*!
155 * \fn void QQuickItemGrabResult::ready()
156 *
157 * This signal is emitted when the grab has completed.
158 */
159
160/*!
161 * \qmltype ItemGrabResult
162 * \instantiates QQuickItemGrabResult
163 * \inherits QtObject
164 * \inqmlmodule QtQuick
165 * \ingroup qtquick-visual
166 * \brief Contains the results from a call to Item::grabToImage().
167 *
168 * The ItemGrabResult is a small container used to encapsulate
169 * the results from Item::grabToImage().
170 *
171 * \sa Item::grabToImage()
172 */
173
174QQuickItemGrabResult::QQuickItemGrabResult(QObject *parent)
175 : QObject(*new QQuickItemGrabResultPrivate, parent)
176{
177}
178
179/*!
180 * \qmlmethod bool QtQuick::ItemGrabResult::saveToFile(fileName)
181 *
182 * Saves the grab result as an image to \a fileName. Returns true
183 * if successful; otherwise returns false.
184 */
185
186/*!
187 * Saves the grab result as an image to \a fileName. Returns true
188 * if successful; otherwise returns false.
189 *
190 * \note In Qt versions prior to 5.9, this function is marked as non-\c{const}.
191 */
192bool QQuickItemGrabResult::saveToFile(const QString &fileName) const
193{
194 Q_D(const QQuickItemGrabResult);
195 return d->image.save(fileName);
196}
197
198#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
199#if QT_DEPRECATED_SINCE(5, 15)
200/*!
201 * \overload
202 * \internal
203 */
204bool QQuickItemGrabResult::saveToFile(const QString &fileName)
205{
206 return qAsConst(t&: *this).saveToFile(fileName);
207}
208#endif
209#endif // < Qt 6
210
211QUrl QQuickItemGrabResult::url() const
212{
213 Q_D(const QQuickItemGrabResult);
214 d->ensureImageInCache();
215 return d->url;
216}
217
218QImage QQuickItemGrabResult::image() const
219{
220 Q_D(const QQuickItemGrabResult);
221 return d->image;
222}
223
224/*!
225 * \internal
226 */
227bool QQuickItemGrabResult::event(QEvent *e)
228{
229 Q_D(QQuickItemGrabResult);
230 if (e->type() == Event_Grab_Completed) {
231 // JS callback
232 if (d->qmlEngine && d->callback.isCallable()) {
233 d->callback.call(args: QJSValueList() << d->qmlEngine->newQObject(object: this));
234 deleteLater();
235 } else {
236 Q_EMIT ready();
237 }
238 return true;
239 }
240 return QObject::event(event: e);
241}
242
243void QQuickItemGrabResult::setup()
244{
245 Q_D(QQuickItemGrabResult);
246 if (!d->item) {
247 disconnect(sender: d->window.data(), signal: &QQuickWindow::beforeSynchronizing, receiver: this, slot: &QQuickItemGrabResult::setup);
248 disconnect(sender: d->window.data(), signal: &QQuickWindow::afterRendering, receiver: this, slot: &QQuickItemGrabResult::render);
249 QCoreApplication::postEvent(receiver: this, event: new QEvent(Event_Grab_Completed));
250 return;
251 }
252
253 QSGRenderContext *rc = QQuickWindowPrivate::get(c: d->window.data())->context;
254 d->texture = rc->sceneGraphContext()->createLayer(renderContext: rc);
255 d->texture->setItem(QQuickItemPrivate::get(item: d->item)->itemNode());
256 d->itemSize = QSizeF(d->item->width(), d->item->height());
257}
258
259void QQuickItemGrabResult::render()
260{
261 Q_D(QQuickItemGrabResult);
262 if (!d->texture)
263 return;
264
265 d->texture->setRect(QRectF(0, d->itemSize.height(), d->itemSize.width(), -d->itemSize.height()));
266 const QSize minSize = QQuickWindowPrivate::get(c: d->window.data())->context->sceneGraphContext()->minimumFBOSize();
267 d->texture->setSize(QSize(qMax(a: minSize.width(), b: d->textureSize.width()),
268 qMax(a: minSize.height(), b: d->textureSize.height())));
269 d->texture->scheduleUpdate();
270 d->texture->updateTexture();
271 d->image = d->texture->toImage();
272
273 delete d->texture;
274 d->texture = nullptr;
275
276 disconnect(sender: d->window.data(), signal: &QQuickWindow::beforeSynchronizing, receiver: this, slot: &QQuickItemGrabResult::setup);
277 disconnect(sender: d->window.data(), signal: &QQuickWindow::afterRendering, receiver: this, slot: &QQuickItemGrabResult::render);
278 QCoreApplication::postEvent(receiver: this, event: new QEvent(Event_Grab_Completed));
279}
280
281QQuickItemGrabResult *QQuickItemGrabResultPrivate::create(QQuickItem *item, const QSize &targetSize)
282{
283 QSize size = targetSize;
284 if (size.isEmpty())
285 size = QSize(item->width(), item->height());
286
287 if (size.width() < 1 || size.height() < 1) {
288 qmlWarning(me: item) << "grabToImage: item has invalid dimensions";
289 return nullptr;
290 }
291
292 if (!item->window()) {
293 qmlWarning(me: item) << "grabToImage: item is not attached to a window";
294 return nullptr;
295 }
296
297 QWindow *effectiveWindow = item->window();
298 if (QWindow *renderWindow = QQuickRenderControl::renderWindowFor(win: item->window()))
299 effectiveWindow = renderWindow;
300
301 if (!effectiveWindow->isVisible()) {
302 qmlWarning(me: item) << "grabToImage: item's window is not visible";
303 return nullptr;
304 }
305
306 QQuickItemGrabResult *result = new QQuickItemGrabResult();
307 QQuickItemGrabResultPrivate *d = result->d_func();
308 d->item = item;
309 d->window = item->window();
310 d->textureSize = size;
311
312 QQuickItemPrivate::get(item)->refFromEffectItem(hide: false);
313
314 // trigger sync & render
315 item->window()->update();
316
317 return result;
318}
319
320/*!
321 * Grabs the item into an in-memory image.
322 *
323 * The grab happens asynchronously and the signal QQuickItemGrabResult::ready()
324 * is emitted when the grab has been completed.
325 *
326 * Use \a targetSize to specify the size of the target image. By default, the
327 * result will have the same size as item.
328 *
329 * If the grab could not be initiated, the function returns \c null.
330 *
331 * \note This function will render the item to an offscreen surface and
332 * copy that surface from the GPU's memory into the CPU's memory, which can
333 * be quite costly. For "live" preview, use \l {QtQuick::Item::layer.enabled} {layers}
334 * or ShaderEffectSource.
335 *
336 * \sa QQuickWindow::grabWindow()
337 */
338QSharedPointer<QQuickItemGrabResult> QQuickItem::grabToImage(const QSize &targetSize)
339{
340 QQuickItemGrabResult *result = QQuickItemGrabResultPrivate::create(item: this, targetSize);
341 if (!result)
342 return QSharedPointer<QQuickItemGrabResult>();
343
344 connect(sender: window(), signal: &QQuickWindow::beforeSynchronizing, receiver: result, slot: &QQuickItemGrabResult::setup, type: Qt::DirectConnection);
345 connect(sender: window(), signal: &QQuickWindow::afterRendering, receiver: result, slot: &QQuickItemGrabResult::render, type: Qt::DirectConnection);
346
347 return QSharedPointer<QQuickItemGrabResult>(result);
348}
349
350/*!
351 * \qmlmethod bool QtQuick::Item::grabToImage(callback, targetSize)
352 *
353 * Grabs the item into an in-memory image.
354 *
355 * The grab happens asynchronously and the JavaScript function \a callback is
356 * invoked when the grab is completed. The callback takes one argument, which
357 * is the result of the grab operation; an \l ItemGrabResult object.
358 *
359 * Use \a targetSize to specify the size of the target image. By default, the result
360 * will have the same size as the item.
361 *
362 * If the grab could not be initiated, the function returns \c false.
363 *
364 * The following snippet shows how to grab an item and store the results to
365 * a file.
366 *
367 * \snippet qml/itemGrab.qml grab-source
368 * \snippet qml/itemGrab.qml grab-to-file
369 *
370 * The following snippet shows how to grab an item and use the results in
371 * another image element.
372 *
373 * \snippet qml/itemGrab.qml grab-image-target
374 * \snippet qml/itemGrab.qml grab-to-cache
375 *
376 * \note This function will render the item to an offscreen surface and
377 * copy that surface from the GPU's memory into the CPU's memory, which can
378 * be quite costly. For "live" preview, use \l {QtQuick::Item::layer.enabled} {layers}
379 * or ShaderEffectSource.
380 */
381
382/*!
383 * \internal
384 * Only visible from QML.
385 */
386bool QQuickItem::grabToImage(const QJSValue &callback, const QSize &targetSize)
387{
388 QQmlEngine *engine = qmlEngine(this);
389 if (!engine) {
390 qmlWarning(me: this) << "grabToImage: item has no QML engine";
391 return false;
392 }
393
394 if (!callback.isCallable()) {
395 qmlWarning(me: this) << "grabToImage: 'callback' is not a function";
396 return false;
397 }
398
399 QSize size = targetSize;
400 if (size.isEmpty())
401 size = QSize(width(), height());
402
403 if (size.width() < 1 || size.height() < 1) {
404 qmlWarning(me: this) << "grabToImage: item has invalid dimensions";
405 return false;
406 }
407
408 if (!window()) {
409 qmlWarning(me: this) << "grabToImage: item is not attached to a window";
410 return false;
411 }
412
413 QQuickItemGrabResult *result = QQuickItemGrabResultPrivate::create(item: this, targetSize: size);
414 if (!result)
415 return false;
416
417 connect(sender: window(), signal: &QQuickWindow::beforeSynchronizing, receiver: result, slot: &QQuickItemGrabResult::setup, type: Qt::DirectConnection);
418 connect(sender: window(), signal: &QQuickWindow::afterRendering, receiver: result, slot: &QQuickItemGrabResult::render, type: Qt::DirectConnection);
419
420 QQuickItemGrabResultPrivate *d = result->d_func();
421 d->qmlEngine = engine;
422 d->callback = callback;
423 return true;
424}
425
426QT_END_NAMESPACE
427
428#include "moc_qquickitemgrabresult.cpp"
429

source code of qtdeclarative/src/quick/items/qquickitemgrabresult.cpp