mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    canDraw = false;
    pix = new QPixmap;
}

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

void MainWindow::paintEvent(QPaintEvent *event)
{
    if (canDraw)
    {
        paintImage("", ui->productImage->pos().x(), ui->productImage->pos().y());
    }
}

void MainWindow::paintImage(QString fileName, int x, int y)
{
    QPainter painter;
    QImage saveImage(150, 150, QImage::Format_RGB16);

    if (fileName != "")
    {
        painter.begin(&saveImage);
    }
    else
    {
        painter.begin(this);
    }

    if (!pix->isNull())
    {
        painter.setClipRect(x, y, 150, 150);
        painter.fillRect(QRect(x, y, 150, 150), Qt::SolidPattern);
        painter.drawPixmap(x - drawPos.x(), y - drawPos.y(), drawSize.width(), drawSize.height(), *pix);
    }

    painter.end();

    if (fileName != "")
    {
        saveImage.save(fileName);
        QMessageBox::information(this, "Success", "Image has been successfully saved!");
    }
}

void MainWindow::on_browseButton_clicked()
{
    QString fileName = QFileDialog::getOpenFileName(this, tr("Open Image"), QDir::currentPath(), tr("Image Files (*.jpg *.jpeg)"));

    if (fileName != "")
    {
        QPixmap* newPix = new QPixmap(fileName);

        if (!newPix->isNull())
        {
            if (newPix->width() < 150 || newPix->height() < 150)
            {
                QMessageBox::warning(this, tr("Invalid Size"), tr("Image size too small. Please use an image larger than 150x150."));
                return;
            }

            pix = newPix;
            imageSize = pix->size();
            drawSize = pix->size();

            canDraw = true;
        }
        else
        {
            canDraw = false;

            QMessageBox::warning(this, tr("Invalid Image"), tr("Invalid or corrupted file. Please try again with another image file."));
        }
    }
}

void MainWindow::on_scaleSlider_valueChanged(int value)
{
    drawSize = imageSize * value / 100;
    update();
}

void MainWindow::on_leftSlider_valueChanged(int value)
{
    drawPos.setX(value * drawSize.width() / 100 * 0.5);
    update();
}

void MainWindow::on_topSlider_valueChanged(int value)
{
    drawPos.setY(value * drawSize.height() / 100 * 0.5);
    update();
}

void MainWindow::on_saveButton_clicked()
{
    if (canDraw)
    {
        if (!pix->isNull())
        {
            // Save new pic from painter
            paintImage(QCoreApplication::applicationDirPath() + "/image.jpg", 0, 0);
        }
    }
}