Display images from source directory selected by user - c++

Question

I have a Qt application where user selects source directory which has images (.pgm files) (any number). In the UI,
I have created a display area (QGroupBox) which has 2 QGraphicsview which displays 2 images at a time.
UI image:
Going ahead,
I want to create QGraphicsViews Widget for all the images and display 2 of them at a time. There will be a scroll bar to the right.
When user drags the scroll bar down other QGraphicsView Widgets
should be visible to the user with different images. How can i do this using Qt in C++?
PS: I am able to display two images in the display area using QGraphicsView Widget when the load images button is clicked.
#include "ui_DataViewerPage.h"
#include <iostream>
#include <QGraphicsScene>
#include <QPixmap>
#include <QThread>
#include <QSettings>
#include "DataWorker.h"
namespace Ui
{
class DataViewerPage;
}
// This is the main UI thread header and cpp file
class DataViewerPage : public QWidget
{
Q_OBJECT
public:
DataViewerPage(QWidget* parent = nullptr);
virtual ~DataViewerPage();
public slots:
void on_loadButton_clicked();
void startWorker();
void stopWorker();
void displayImage(QString fileName);
signals:
void startLoadingImages();
private:
Ui::DataViewerPage* ui;
DataWorker* worker;
QSettings settings;
// Worker thread handles data processing away from ui thread
QThread workerThread;
QSharedPointer<QGraphicsScene> ptr_scene;
QSharedPointer<QGraphicsScene> ptr_scene2;
int currentDisplayNum;
};
#include "DataViewerPage.h"
DataViewerPage::DataViewerPage(QWidget* parent)
: QWidget(parent), worker(nullptr), ui(new Ui::DataViewerPage)
{
ui->setupUi(this);
ui->Display->setVisible(true);
ptr_scene = QSharedPointer<QGraphicsScene>(new QGraphicsScene(this));
ptr_scene2 = QSharedPointer<QGraphicsScene>(new QGraphicsScene(this));
}
DataViewerPage::~DataViewerPage()
{
workerThread.quit();
workerThread.wait();
workerThread.terminate();
if (worker)
{
delete worker;
}
delete ui;
}
void DataViewerPage::on_loadButton_clicked()
{
ui->Display->setVisible(true);
ui->loadButton->setDisabled(true);
emit startLoadingImages();
}
void DataViewerPage::stopWorker()
{
workerThread.quit();
workerThread.wait();
workerThread.terminate();
if (worker)
{
delete worker;
worker = nullptr;
}
}
void DataViewerPage::startWorker()
{
stopWorker();
worker = new DataWorker();
worker->moveToThread(&workerThread);
connect(this, &DataViewerPage::startLoadingImages, worker, &DataWorker::startLoadingImages);
connect(worker, &DataWorker::displayImage, this, &DataViewerPage::displayImage);
workerThread.start();
currentDisplayNum = 0;
}
void DataViewerPage::displayImage(QString fileName)
{
QPixmap pixelMap(fileName.toStdString().c_str()); // <- path to image file
switch (currentDisplayNum)
{
case 0:
ptr_scene->addPixmap(pixelMap);
ui->img1->setScene(ptr_scene.get());
break;
case 1:
ptr_scene2->addPixmap(pixelMap);
ui->img2->setScene(ptr_scene2.get());
break;
default:
break;
}
currentDisplayNum++;
}
// This is the worker thread header and cpp file.
#pragma once
#include <QThread>
#include <QSettings>
#include <filesystem>
class DataWorker : public QObject
{
Q_OBJECT
public:
DataWorker();
~DataWorker();
public slots:
void startLoadingImages();
signals:
void displayImage(QString fileName);
private:
QSettings settings;
std::string path;
};
#include "DataWorker.h"
#include <iostream>
#include <QImage>
DataWorker::DataWorker()
{
path = settings.value("dataDir").toString().toStdString();
}
DataWorker::~DataWorker()
{
}
void DataWorker::startLoadingImages()
{
std::cout << "startloadingImages called..." << std::endl;
int iCount = 0;
for (const auto& entry : std::filesystem::directory_iterator(path))
{
QString imgPath = QString::fromStdString(entry.path().string());
emit displayImage(imgPath);
iCount++;
if(iCount > 1)
break; // Right now do it for two only.......
}
}