QPixmap or QImage exchange the buffers

[heatblazer]

Hello, I am interested in the following topic: Can I exchange the QPixmap/QImage buffers or source file? Consider this small code:
@
static inline void CellOnPaint(QPainter* qp,
const QStyleOptionGraphicsItem* qsi,
QWidget* wd, QGraphicsItem* ari ) {
MY_UNUSED(qp,qsi,wd,ari)
QRectF rec = ((ActionItem*)ari)->boundingRect();
QPixmap door = ((ActionItem)ari)->getMyPixmap();
QImage eframe = door->toImage();
qp->drawImage(rec, eframe);
wd->update(); //needed
}
@

WHere:

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getMyPixmap()
@

is rturning a private member from my custom ActionItem class. The member is set in the construction, kind of

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ActionItem* a1 = new ActionItem(QPixmap(":/res/p1.png"...));
@

@
a1->setNewPixmap(":/res/p2.png");
@

Now the call to CellOnPaint will display "p2.png". BUt how to exchange the buffers?

[ckakman]

Hi,

I didn't understand what you meant by exchanging buffers. Where is a buffer in the code you have provided?

[heatblazer]

Maybe I post it bad. Consider the CellOnPaint. See line 6. It assigns per call the ref from ActionItems private pixmap, which is set in the constructor and is known. I want to just exchange the pixmap. Ive wrote setNewQPix(QPix...) but on the call the program fails.

[ckakman]

Check out the QPixmap constructors. If you want to pass in a file path, use the constructor that accepts a QString. Note there is another constructor that accepts const char* but that one expects data not a path.

Try a1->setNewQPixmap( QPixmap(QString( ":/...png") ) ).

[heatblazer]

Let me show you the full code of the setQpix...
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static inline void SwapOn(QGraphicsSceneMouseEvent* me,
QGraphicsItem* ari) {
((ActionItem*)ari)->setMyPixmap(
MainWindow::getActionItemByName("Wolf1")->getPixmapRes()
);
}
@
Sorry, its a bit hard to read, I suppose, but the idea is qute, simple, take the QGaraphics item clicked, and set its pixmap to another QGraphics derivate found by name from a heap simulation list of items. I`ll give a try to your suggestion.

[ckakman]

I am sorry but you are not showing me anything here:

• What do you pass in to that function? What does getPixmapRes() mean? get Pixmap Resolution? What does it return?
• How is the setNewPixmap() or setMyPixmap() or setQpix... is implemented?
• What does it mean that the program fails? Does it crash? Does it fail to compile? Does it fail to link?

Here is how a QPixmap is "updated":http://doc.qt.io/qt-5/qpixmap.html#QPixmap-6:
@
QPixmap a;
QPixmap b;
b = a;
@

[heatblazer]

Sorry I kind of suck at forums :)
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void ActionItem::setMyPixmap(QString s) {
pixmap = new QPixmap(s);
}

QPixmap* ActionItem::getMyPixmap()
{
return pixmap;
}
@
Let me give a try to your suggestion and I`ll write back. Probably your help was enough. Hope so. :)

[quote author="ckakman" date="1421180662"]I am sorry but you are not showing me anything here:

• What do you pass in to that function? What does getPixmapRes() mean? get Pixmap Resolution? What does it return?
• How is the setNewPixmap() or setMyPixmap() or setQpix... is implemented?
• What does it mean that the program fails? Does it crash? Does it fail to compile? Does it fail to link?

Here is how a QPixmap is "updated":http://doc.qt.io/qt-5/qpixmap.html#QPixmap-6:
@
QPixmap a;
QPixmap b;
b = a;
@[/quote]

[ckakman]

You don't need a pointer to QPixmap as member variable. QPixmap is implicitly shared.

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private:
QPixmap pixmap;
@

If you somehow have to use a pointer, than you have a memory leak there. Delete the pixmap before assigning a new one.