Dynamically resizing two QLabel implementations - c++

Question

I'm trying to create a simple frame in Qt with a tick and some text. I made two new label implementations because I wanted the labels to dynamically fill all the available space but when I resize the window the sizes are off, as shown by the qDebug output, which represents the size of the image label:
Resized: 244 , 244 <-- Window first created
Resized: 305 , 305 <-- Window maximized
Resized: 135 , 135 <-- Window restored to original size
As you can see, when the window is restored to its original size the image is not. The last size should be 244, 244.
The code which describes the behaviour of the two widgets is the following:
"widgets.h":
/*
* This file includes many custom widgets.
*/
#ifndef APOCRYPHA_WIDGETS
#define APOCRYPHA_WIDGETS
#include <QWidget>
#include <QLabel>
#include <QTimer>
#include <QPixmap>
#include <QResizeEvent>
#include <QPaintEvent>
class AutoTextLabel : public QLabel {
Q_OBJECT
public:
explicit AutoTextLabel(QWidget* parent);
AutoTextLabel(QWidget* parent, QString text);
protected:
void resizeEvent(QResizeEvent* event) override;
private:
QTimer* resizeTimer;
private slots:
void onResizeEnd();
};
class AutoImageLabel : public QLabel {
Q_OBJECT
public:
explicit AutoImageLabel(QWidget* parent);
AutoImageLabel(QWidget* parent, const QPixmap& pixmap);
void setFillOrientation(int orientation);
QSize sizeHint() const override;
public slots:
void setPixmap(const QPixmap &newPix);
void resizeEvent(QResizeEvent* event) override;
protected:
// void paintEvent(QPaintEvent* event) override;
private:
int fillOrientation;
int widthForHeight(int h) const;
int heightForWidth(int w) const override;
QPixmap scaledPixmap() const;
QPixmap labelPixmap;
};
#endif //APOCRYPHA_WIDGETS
"widgets.cpp":
/*
* This file includes many custom widgets.
*/
#include "widgets.h"
#include <QPainter>
#include <QDebug>
AutoTextLabel::AutoTextLabel(QWidget *parent, QString text) : QLabel(text, parent){
// Enable antialiasing
QFont aaFont(font());
aaFont.setStyleStrategy(QFont::PreferAntialias);
setFont(aaFont);
// This timer is used to fire a slot when a window is resized
resizeTimer = new QTimer();
resizeTimer->setSingleShot(true);
connect(resizeTimer, SIGNAL(timeout()), SLOT(onResizeEnd()));
}
AutoTextLabel::AutoTextLabel(QWidget *parent) : AutoTextLabel(parent, "") {}
void AutoTextLabel::resizeEvent(QResizeEvent *event) {
QWidget::resizeEvent(event);
// Only fire when 25ms have passed since the last resize.
resizeTimer->start(25);
}
void AutoTextLabel::onResizeEnd() {
QFont updatedFont(font());
// Resize Text
if (!text().isEmpty()){
int fontSize = 1;
updatedFont.setPixelSize(fontSize);
QRect boundingRectangle;
// Update bounding rectangle
if (wordWrap())
boundingRectangle = QFontMetrics(updatedFont).boundingRect(contentsRect(), Qt::TextWordWrap, text());
else
boundingRectangle = QFontMetrics(updatedFont).boundingRect(text());
while (boundingRectangle.height() <= contentsRect().height()) {
fontSize++;
updatedFont.setPixelSize(fontSize);
// Update bounding rectangle
if (wordWrap())
boundingRectangle = QFontMetrics(updatedFont).boundingRect(contentsRect(), Qt::TextWordWrap, text());
else
boundingRectangle = QFontMetrics(updatedFont).boundingRect(text());
}
updatedFont.setPixelSize(fontSize - 1);
setFont(updatedFont);
}
}
/* Auto Image Label */
AutoImageLabel::AutoImageLabel(QWidget *parent, const QPixmap &pixmap) : QLabel(parent) {
setMinimumSize(1, 1);
setScaledContents(false);
setPixmap(pixmap);
}
AutoImageLabel::AutoImageLabel(QWidget *parent) : QLabel(parent) {
setScaledContents(false);
}
void AutoImageLabel::resizeEvent(QResizeEvent *event) {
QWidget::resizeEvent(event);
if(!labelPixmap.isNull())
QLabel::setPixmap(scaledPixmap());
qDebug() << "Resized: " << scaledPixmap().width() << ", " << scaledPixmap().height();
}
int AutoImageLabel::widthForHeight(int h) const {
return labelPixmap.isNull() ? width() : (labelPixmap.width() * h) / labelPixmap.height();
}
int AutoImageLabel::heightForWidth(int w) const {
return labelPixmap.isNull() ? height() : (labelPixmap.height() * w) / labelPixmap.width();
}
void AutoImageLabel::setFillOrientation(int orientation) {
this->fillOrientation = orientation;
}
QSize AutoImageLabel::sizeHint() const {
if (fillOrientation == Qt::Horizontal)
return QSize(width(), heightForWidth(width()));
else
return QSize(widthForHeight(height()), height());
}
QPixmap AutoImageLabel::scaledPixmap() const {
return labelPixmap.scaled(sizeHint(), Qt::KeepAspectRatio, Qt::SmoothTransformation);
}
void AutoImageLabel::setPixmap(const QPixmap &newPix) {
labelPixmap = newPix;
QLabel::setPixmap(scaledPixmap());
}
"other_frames.h":
//
// Created by Riccardo on 18/09/2017.
//
#ifndef APOCRYPHA_OTHER_FRAMES_H
#define APOCRYPHA_OTHER_FRAMES_H
#include <QFrame>
#include <QLabel>
#include <QGridLayout>
#include <QWidget>
#include <QResizeEvent>
#include <QPixmap>
#include <QTimer>
#include "widgets.h"
class ConfirmationFrame : public QFrame {
Q_OBJECT
public:
explicit ConfirmationFrame(QWidget* parent);
ConfirmationFrame(QWidget* parent, const QString& text);
private:
QGridLayout* layout;
AutoImageLabel* imageLabel;
AutoTextLabel* textLabel;
};
#endif //APOCRYPHA_OTHER_FRAMES_H
"other_frames.cpp":
//
// Created by Riccardo on 18/09/2017.
//
#include "other_frames.h"
#include <QDebug>
ConfirmationFrame::ConfirmationFrame(QWidget* parent, const QString &text) : QFrame(parent) {
textLabel = new AutoTextLabel(this, text);
QPixmap pix(":/images/check-tick.png");
imageLabel = new AutoImageLabel(this, pix);
textLabel->setAlignment(Qt::AlignCenter);
imageLabel->setAlignment(Qt::AlignCenter);
textLabel->setWordWrap(true);
// Green Background
setStyleSheet("background-color: rgba(106, 242, 94, 1);");
layout = new QGridLayout();
layout->setSpacing(0);
layout->setContentsMargins(32, 32, 32, 32);
layout->setRowStretch(0, 1);
layout->setRowStretch(1, 1);
layout->addWidget(imageLabel, 0, 1);
layout->addWidget(textLabel, 1, 1);
setLayout(layout);
}
ConfirmationFrame::ConfirmationFrame(QWidget *parent) : ConfirmationFrame(parent, "") {
}
"window_main.h":
#ifndef WINDOW_MAIN_H
#define WINDOW_MAIN_H
#include <QMainWindow>
#include <QMenuBar>
#include <QMenu>
#include <QGridLayout>
#include <QFrame>
#include <QScreen>
class MainWindow : public QMainWindow {
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = nullptr);
QFrame *mainFrame;
void center(QScreen* screen);
void autoSetSize(QScreen* screen);
private:
void createMenu();
// Components
QGridLayout *mainLayout;
QMenuBar *menuBar;
QMenu *fileMenu;
};
#endif // WINDOW_MAIN
"window_main.cpp":
#include "window_main.h"
MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) {
mainFrame = new QFrame();
mainLayout = new QGridLayout();
mainLayout->setSpacing(0);
mainLayout->setContentsMargins(0, 0, 0, 0);
createMenu();
mainFrame->setStyleSheet("background-color: red;");
mainFrame->setLayout(mainLayout);
setCentralWidget(mainFrame);
}
void MainWindow::createMenu(){
menuBar = new QMenuBar;
fileMenu = new QMenu(tr("&File"), this);
menuBar->addMenu(fileMenu);
setMenuBar(menuBar);
}
void MainWindow::center(QScreen *screen) {
QSize size = screen->availableSize();
int x = size.width() / 2 - width() / 2;
int y = size.height() / 2 - height() / 2;
move(x, y);
}
void MainWindow::autoSetSize(QScreen *screen) {
QSize screenSize = screen->availableSize();
// TODO Math.round
setMinimumSize(QSize((int)(screenSize.width() / 1.25), (int)(screenSize.height() / 1.25)));
}
"main.cpp":
#include <QApplication>
#include <iostream>
#include <QFile>
#include "quiz/choice.h"
#include "quiz/question.h"
#include "quiz/quizmaker.h"
#include <QSettings>
#include <QStandardPaths>
#include <QDebug>
#include <src/user_interface/other_frames.h>
#include "user_interface/window_main.h"
#include <QScreen>
#include <QFontDatabase>
int main(int argc, char *argv[]) {
QApplication a(argc, argv);
// Set Application Parameters
QCoreApplication::setOrganizationName("Riccardo Fagiolo");
QCoreApplication::setOrganizationDomain("kopharex.me");
QCoreApplication::setApplicationName("Apocrypha");
// Set application font
const int id = QFontDatabase::addApplicationFont(":/fonts/montserrat/Montserrat-Regular.otf");
QString family = QFontDatabase::applicationFontFamilies(id).at(0);
QFont font(family);
font.setStyleStrategy(QFont::PreferAntialias);
a.setFont(font);
// App Settings
QSettings settings;
settings.setValue("data_dir", QStandardPaths::writableLocation(QStandardPaths::AppDataLocation));
// Create UI
auto* window = new MainWindow();
ConfirmationFrame* cframe = new ConfirmationFrame(window, "But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects, dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?");
window->mainFrame->layout()->addWidget(cframe);
window->autoSetSize(a.primaryScreen());
//cframe->updateTextLabel();
window->show();
window->center(a.primaryScreen());
// [...] - Nothing related to user interface.
return a.exec();
}
Here is a screenshot of the current MainWindow and ConfirmationFrame to give you an idea of what i'm trying to accomplish:
Window Screenshot
All comments regarding the code are welcome.
Thanks for any help,
Riccardo

Answer 1

Hello I tried to fix the resizing issue with an hack.
Before starting the timer to resize the text, just reduce its font to a 1 pixel font:
void AutoTextLabel::resizeEvent(QResizeEvent *event) {
QWidget::resizeEvent(event);
// set a very small font, then start the timer
QFont updatedFont(font());
updatedFont.setPixelSize(1);
setFont(updatedFont);
// Only fire when 25ms have passed since the last resize.
resizeTimer->start(25);
}
Can the effect be acceptable in your opinion?