QtRotateImage

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ID	...	Creation date	June 18, 2009
Platform	S60 3rd Edition, FP1, FP2 S60 5th Edition	Tested on devices
Category	Qt for Symbian	Subcategory	UI

Keywords (APIs, classes, methods, functions): QPixmap, QSignalMapper, QFileDialog::getOpenFileName, QFileDialog::getSaveFileName

Overview

This code example shows how to work with QPixmap class. User can load any image, rotate it and then save it with a new name.

This snippet can be self-signed. As it does not use any API which require developer/certified signing.

Preconditions

Download and Install latest version Qt for Symbian - Installation packages which has links on how to install the latest version

Images

Source

QtRotateImage.zip

#include <QtGui/QApplication>
#include "mainwindow.h"
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QtGui/QMainWindow>
#include <QSignalMapper>
#include <QPixmap>
 
namespace Ui
{
    class MainWindow;
}
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();
 
private slots:
    void loadImage();
    void saveImage();
    void rotateImage(int angle);
 
private:
    Ui::MainWindow *ui;
    QSignalMapper *rotateMapper;
    QPixmap pixmap;
};
 
#endif // MAINWINDOW_H

#include <QFileDialog>
#include <QPixmap>
 
#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent), ui(new Ui::MainWindow)
{
    ui->setupUi(this);
 
    rotateMapper = new QSignalMapper(this);
 
    connect(ui->actionLoad, SIGNAL(triggered()), this, SLOT(loadImage()));
    connect(ui->actionSave, SIGNAL(triggered()), this, SLOT(saveImage()));
 
    connect(ui->actionRotate_90, SIGNAL(triggered()), rotateMapper, SLOT(map()));
    connect(ui->actionRotate_180, SIGNAL(triggered()), rotateMapper, SLOT(map()));
    connect(ui->actionRotate_270, SIGNAL(triggered()), rotateMapper, SLOT(map()));
 
    rotateMapper->setMapping(ui->actionRotate_90, 90);
    rotateMapper->setMapping(ui->actionRotate_180, 180);
    rotateMapper->setMapping(ui->actionRotate_270, 270);
 
    connect(rotateMapper, SIGNAL(mapped(int)), this, SLOT(rotateImage(int)));
}

MainWindow::~MainWindow()
{
    if(rotateMapper)
    {
         delete rotateMapper;
    }
    delete ui;
}

void MainWindow::loadImage()
{
    QString fileName = QFileDialog::getOpenFileName(this, 
        tr("Open Image"), "/", tr("Image Files (*.png *.jpg *.bmp)"));
    if ( fileName.isNull() == false )
    {
        if ( pixmap.load(fileName) == true )
        {
            ui->label->setPixmap(pixmap);
        }
    }
}

void MainWindow::saveImage()
{
    if ( pixmap.isNull() == false )
    {
        QString fileName = QFileDialog::getSaveFileName(this, 
            tr("Save Image"), "/", tr("Image Files (*.png *.jpg *.bmp)"));
        if ( fileName.isNull() == false )
        {
            pixmap.save(fileName);
        }
    }
}

void MainWindow::rotateImage(int angle)
{
    int h = pixmap.height();
    int w = pixmap.width();
 
    QPixmap p = pixmap.transformed(
        QTransform().translate(w/2, h/2).rotate(angle).translate(-w/2, -h/2));
    ui->label->setPixmap(p);
    pixmap=p;
}

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