QButton and QIcon don't work well together (?)

[oin-oin]

I took the calculator example app direct from Qt examples. I'm using Qt Creator 7.0.2 (Based on Qt 6.2.3 (Clang 13.0 (Apple), 64 bit), Built on May 23 2022 01:27:08, From revision ac1e86fe74).

I want to customize Buttons with specific images, but it seems that Buttons won't accept just any image. I have a png file, which is 300 pixels by 98 pixels that I wish to use. In spite of my specifying the size of the Icon, I can't get it to display on the button (all else seems to work).

Here's the code mostly taken from the calculator app example, leaving only the essential code:

First, the header files:
button.h:

#ifndef BUTTON_H
#define BUTTON_H

#include <QToolButton>

//! [0]
class Button : public QToolButton {
   Q_OBJECT

public:
   explicit Button(const QString &text, QWidget *parent = nullptr);

   QSize sizeHint() const override;
};
//! [0]


#endif

calculator.h:

#ifndef CALCULATOR_H
#define CALCULATOR_H

#include <QWidget>

QT_BEGIN_NAMESPACE
class QLineEdit;
QT_END_NAMESPACE
class Button;

//! [0]
class Calculator : public QWidget {
   Q_OBJECT

public:
   Calculator(QWidget *parent = nullptr);

private slots:
   //! [0]
   void gotAClick();
   //! [1]
private:
   //! [1] //! [2]A
   Button *createButton(const QString &text, std::string path, const char *member);

   //! [9]
   QLineEdit *display;
   //! [9] //! [10]

};
//! [10]

#endif

button.cpp:

#include "button.h"

//! [0]
Button::Button(const QString &text, QWidget *parent)
   : QToolButton(parent)
{
   setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Preferred);
   setText(text);
}

//! [0]

//! [1]
QSize Button::sizeHint() const
//! [1] //! [2]
{
   QSize size = QToolButton::sizeHint();
   size.rheight() += 20;
   size.rwidth() = qMax(size.width(), size.height());
   return size;
}
//! [2]

calculator:cpp

#include "calculator.h"
#include "button.h"

#include <QGridLayout>
#include <QLineEdit>
#include <QtMath>
#include <QRawFont>
#include <string>

//! [0]
Calculator::Calculator(QWidget *parent) : QWidget(parent) {
   //! [0]

   //! [1]
   display = new QLineEdit("0");
   //! [1] //! [2]
   display->setReadOnly(true);
   display->setAlignment(Qt::AlignRight);
   display->setMaxLength(15);

   Button *onOffButton = createButton("188", "./x000y000_x299y097.png", SLOT(gotAClick()));
   //! [5]
   QGridLayout *mainLayout = new QGridLayout;
   //! [5] //! [6]
   mainLayout->setSizeConstraint(QLayout::SetFixedSize);
   mainLayout->setHorizontalSpacing(0);
   mainLayout->setVerticalSpacing(0);
   mainLayout->addWidget(display, 0, 0, 1, 6, Qt::AlignCenter);
   mainLayout->addWidget(onOffButton, 1, 0, 1, 2); //, Qt::AlignCenter);
   setLayout(mainLayout);

   setWindowTitle(tr("Button Icons DFW"));
}
//! [6]

//! [34]
Button *Calculator::createButton(const QString &qtext, std::string path, const char *member) {
   int xpos = path.rfind("/")+2;
   int ypos = xpos + 4;
   int x = std::atoi(path.substr(xpos, 3).c_str());
   int y = std::atoi(path.substr(ypos, 3).c_str());
   int w, h;

   xpos = ypos + 5;
   ypos = xpos + 4;

   w = std::atoi(path.substr(xpos, 3).c_str()) - x + 1;
   h = std::atoi(path.substr(ypos, 3).c_str()) - y + 1;

   Button *button = new Button(qtext);
   QIcon eq;
   QSize qs;

   qs.setWidth(w);
   qs.setHeight(h);

   eq.addFile(path.c_str(), qs, QIcon::Normal);
   button->setIcon(eq);
   button->setIconSize(qs);
   button->setFixedSize(qs);
   button->setContentsMargins(0, 0, 0, 0);
   connect(button, SIGNAL(clicked()), this, member);
   return button;
}
void Calculator::gotAClick() {
   Button *clickedButton = qobject_cast<Button *>(sender());
   int digitValue = clickedButton->text().toInt();
   printf("gotAClick, digitValue = %d\n", digitValue);
   fflush(stdout);
}
//! [38]

finally, main.cpp:

#include <QApplication>

#include "calculator.h"

int main(int argc, char *argv[]) {
   QApplication app(argc, argv);
   Calculator calc;
   calc.show();
   return app.exec();
}

All I get is the following:

Note that if my images are more "squarish", then I do get an icon.

Can Icons be "any" size ?

[jsulm]

@oin-oin said in QButton and QIcon don't work well together (?):

Button *onOffButton = createButton("188", "./x000y000_x299y097.png", SLOT(gotAClick()));

You're using relative path to the icon. Most probably the file is not found at runtime. Usually you pack all the icons into a resource file and reference them from there.

[oin-oin]

@jsulm Thanks for the suggestion, but that's not the problem. Of course I checked, and the image file is right where it is supposed to be. In fact, I put in many debugging statements (not shown) to confirm the opening of the file.

[Christian Ehrlicher]

@oin-oin said in QButton and QIcon don't work well together (?):

o confirm the opening of the file.

Your code does not open a file, it just passes the filename to QIcon.
Please show the code - I'm pretty sure the path is wrong.

[JonB]

@oin-oin

qDebug() << QFile::exists("./x000y000_x299y097.png");
Button *onOffButton = createButton("188", "./x000y000_x299y097.png", SLOT(gotAClick()));

[oin-oin]

@Christian-Ehrlicher Thank you for your help.

The code is there already, in calculator.cpp, function createButton.

But, (blushing and wiping the egg off my face), I somehow changed the full pathname between projects, and the file was not being opened.

Thank you for your help.

[oin-oin]

@JonB Thank you for your help. Indeed, as in a previous post, to my great shame going between projects I hadn't noticed that during cutting and pasting I changed the full pathname, and was debugging the wrong project !