set size text box and button in Qt Widget Application - c++

Question

I developed iPhone application in Qt Widget on MAC, but problem with size of screen and all elements, I set all elements and screen for iPhone 4s. When this application run on iPhone 5, then all things look very smaller. So I want to set size of screen and all elements so It looks better in all type of phones and screen.
In widget application I cannot add directly in .qml file, I can change by drag and drop only.
Thanks in advanace.

Answer 1

You could set the screen size dynamically by querying it from QDesktopWidget.
QRect r = QApplication::desktop()->screenGeometry();
int h = r.height();
int w = r.width();
The Qt layout system provides a simple and powerful way of automatically arranging child widgets within a widget to ensure that they make good use of the available space.
See the example code below which takes the full screen and splits that space for text label and button. You can resize the window until the widgets' minimum sizes limit.
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
};
#endif // MAINWINDOW_H
mainwindow.cpp
#include "mainwindow.h"
#include <QVBoxLayout>
#include <QPushButton>
#include <QLabel>
#include <QApplication>
#include <QDesktopWidget>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent)
{
QWidget *central_widget = new QWidget;
QVBoxLayout *layout = new QVBoxLayout(central_widget);
QPushButton *button1 = new QPushButton("Button1");
layout->addWidget(button1);
QLabel *label1 = new QLabel();
label1->setText("Label1");
label1->setAlignment(Qt::AlignCenter);
layout->addWidget(label1);
setCentralWidget(central_widget);
QRect r = QApplication::desktop()->screenGeometry();
int h = r.height();
int w = r.width();
button1->setMinimumHeight(h/4);
button1->setMaximumHeight(h/2);
button1->setMinimumWidth(w/2);
button1->setMaximumWidth(w);
label1->setMinimumHeight(h/4);
label1->setMaximumHeight(h/2);
label1->setMinimumWidth(w/2);
label1->setMaximumWidth(w);
resize(w, h);
}
MainWindow::~MainWindow()
{
}