How to retrieve the icon FROM a QPushButton? - c++

Question

QT 5.8.0, OSX 10.12.6
I need to retrieve the image on a QButton in a window. Here's where I'm at:
I have a number of QPushButtons in a window. These all have been set to have images in QtDesigner by selecting the images from resources assigned to the project. Which works fine.
My (admittedly vague) understanding is that when the window initializes the ui...
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
...the images are applied to the button. When the window opens, they are there, and I didn't do anything else, so that's my guess.
What I need to do now is access the images in the buttons, by which I mean I need to make local copies of them for modification and use later. QAbstractButton has an icon() function, which says it returns the "icon property", so within MainWindow(), I attempted to get the icon from the entire button as follows...
{
QIcon xx;
xx = ui->entire->icon();
}
...which promptly crashes with:
Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Codes:
KERN_INVALID_ADDRESS at 0x00000023000004b8 Exception Note:
EXC_CORPSE_NOTIFY
So I'm doing it wrong, or perhaps it can't be done. TIA for any insight on this one.

Answer 1

There is likely an error somewhere else in your code. I'm using Qt 5.13.0 and the following code works without problems. I suggest, that you might try it in your environment.
#include <QFrame>
#include <QHBoxLayout>
#include <QPushButton>
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
auto frame = new QFrame;
frame->setLayout(new QHBoxLayout);
auto btn = new QPushButton("Test");
btn->setIcon(QIcon("./data/icon.png"));
frame->layout()->addWidget(btn);
QObject::connect(btn, &QPushButton::clicked, [btn]() {
auto icon = btn->icon();
auto pixmap=icon.pixmap(16,16,QIcon::Mode::Normal, QIcon::State::On);
pixmap.save("savedIcon.png");
});
frame->show();
return a.exec();
}