help with pointers and

Hello!

I am using Qt4.2.3.

Please help me with pointers and correct this piece of code. And if possible, put some explanation on why I enounter errors such as "functional cast expression list treated as compound expression" and "no matching call' errors. Thanks in advance

Code:

---

void MainWinow::doFunction1()
 {
 	QImage *image = new QImage(QSize(100,100), QImage::Format_RGB32);
 
 	int x = 0;
 	int y = 0;
 	for (x= 0; x < image->width(); x++){
 		for (y = 0; y < image->height(); y++){
 			image->setPixel(x, y, QRgb(255,0,0));
 		}
 	}
 
 	QGraphicsScene *scene = new QGraphicsScene;
	QGraphicsPixmapItem *item;
	item->setShapeMode(QGraphicsPixmapItem::BoundingRectShape);
 	item->setFlag(QGraphicsItem::ItemIsMovable);
 	scene->addPixmap(QPixmap::fromImage(&image));
 
//graphicsViewVis is globally declared
 	graphicsViewVis->setScene(scene);
	graphicsViewVis->show();
 
 }

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Quote:

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Originally Posted by sincnarf

Hello!

I am using Qt4.2.3.

Please help me with pointers and correct this piece of code. And if possible, put some explanation on why I enounter errors such as "functional cast expression list treated as compound expression" and "no matching call' errors. Thanks in advance

Code:

---

scene->addPixmap(QPixmap::fromImage(&image));

---

---

Change it to

Code:

---

scene->addPixmap(QPixmap::fromImage(*image));

---

You are trying to pass QImage** to a function which takes const QImage& as parameter.

Side notes: there is no need to allocate image on the heap and item is never initialized.

Thanks for the help! I changed the lines 5 to 11 into

Code:

---

int x = 0;
int y = 0;
for (x= 0; x < image.width(); x++){
    for (y = 0; y < image.height(); y++){
 	image.setPixel(x, y, QRgb(255,0,0));
    }
}

---

and it produces the error

mainwindow.cpp:139: error: functional cast expression list treated as compound expression
mainwindow.cpp:139: warning: left-hand operand of comma has no effect
mainwindow.cpp:139: warning: right-hand operand of comma has no effect

Change line no 3 in your first snippet to

Code:

---

QImage image(QSize(100,100), QImage::Format_RGB32);

---

This is my code

Code:

---

void MainWindow::doFunction1()
 {
 	QImage image(QSize(100,100), QImage::Format_RGB32);
 
 	int x = 0;
 	int y = 0;
 	for (x= 0; x < image.width(); x++){
 		for (y = 0; y < image.height(); y++){
 			image.setPixel(x, y, QRgb(255,0,0));
 		}
 	}
 
 	QGraphicsScene *scene = new QGraphicsScene;
	QGraphicsPixmapItem *item;
	item->setShapeMode(QGraphicsPixmapItem::BoundingRectShape);
 	item->setFlag(QGraphicsItem::ItemIsMovable);
 	scene->addPixmap(QPixmap::fromImage(image));
 
 	graphicsViewVis->setScene(scene);
	graphicsViewVis->show();
 
 }

---

on compilation, there are errors and warnings :
error: functional cast expression list treated as compound expression
warning: left-hand operand of comma has no effect
warning: right-hand operand of comma has no effect

it is noted that the line image.setPixel(x, y, QRgb(255,0,0)); is underlined in red. this is where the error is. Thanks in advance to those who can explain to me how to solve the error functional cast expression list treated as compound expression.

It should be "qRgb(255,0,0)". Notice comments in earlier posts; variable "QGraphicsPixmapItem *item" is still used as uninitialized so a crash will follow.