Drag and drop with darkened area on qt (c++)

form.cpp

#include "form.h"
#include "ui_form.h"

#include <QDragEnterEvent>
#include <QDragMoveEvent>
#include <QDragLeaveEvent>
#include <QDropEvent>
#include <QMimeData>
#include <QUrl>
#include <QFile>
#include <QXmlStreamReader>
#include <QPainter>

Form::Form(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Form)
{
    ui->setupUi(this);
    setAcceptDrops(true);
    setAutoFillBackground(true);

//          // Set the background color to a dark shade
//          QPalette palette = this->palette();
//          palette.setColor(QPalette::Window, QColor(30, 30, 30));
//          setPalette(palette);

}

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


void Form::dragEnterEvent(QDragEnterEvent *event)
{
    if (event->mimeData()->hasUrls()) {
                // Check if any of the dropped URLs have XML file extension
                for (const QUrl& url : event->mimeData()->urls()) {
                    if (url.isLocalFile() && url.toLocalFile().endsWith(".xml")) {
                        event->acceptProposedAction();
                        return;
                    }
                }
            }
}

void Form::dropEvent(QDropEvent *event)
{
    if (event->mimeData()->hasUrls()) {
               QStringList xmlFiles;
               // Extract the dropped XML file paths
               for (const QUrl& url : event->mimeData()->urls()) {
                   if (url.isLocalFile() && url.toLocalFile().endsWith(".xml"))
                       xmlFiles.append(url.toLocalFile());
               }

               // Process the XML files (e.g., parse and display in QPlainTextEdit)
               for (const QString& file : xmlFiles) {
                   parseXmlFile(file);
               }

               event->acceptProposedAction();
           }
}

void Form::dragMoveEvent(QDragMoveEvent* event)  {
     if (event->mimeData()->hasUrls())
         event->acceptProposedAction();
 }
void Form::dragLeaveEvent(QDragLeaveEvent* event)  {
      event->accept();
      update();
  }


void Form::parseXmlFile(const QString& filePath) {
       QFile file(filePath);
       if (!file.open(QIODevice::ReadOnly | QIODevice::Text)) {
           qDebug() << "Failed to open file: " << file.errorString();
return;
       }

       QXmlStreamReader xmlReader(&file);

       while (!xmlReader.atEnd() && !xmlReader.hasError()) {
           QXmlStreamReader::TokenType token = xmlReader.readNext();

           if (token == QXmlStreamReader::StartElement) {
               xmlContent.append("<" + xmlReader.name().toString() + ">\n");
           } else if (token == QXmlStreamReader::EndElement) {
               xmlContent.append("</" + xmlReader.name().toString() + ">\n");
           } else if (token == QXmlStreamReader::Characters) {
               QString text = xmlReader.text().toString().trimmed();
               if (!text.isEmpty())
                   xmlContent.append(text + "\n");
           }
       }

       if (xmlReader.hasError()) {
           qDebug() << "XML parsing error: " << xmlReader.errorString();
return;
       }
        emit textsignal(xmlContent);
       file.close();

   }
void Form::paintEvent(QPaintEvent* event)
{
    QWidget::paintEvent(event);

    // Adjust the background color and transparency based on hover state
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing);
    QPalette appPalette = QApplication::palette();

       // Retrieve the color you're interested in
       QColor appColor = appPalette.color(QPalette::Window);

    if (underMouse())
        painter.fillRect(rect(), QColor(30, 30, 30, 150)); // Darkened color with transparency
    else
        painter.fillRect(rect(), appColor); // Default darkened color

    // Draw a message text in the center of the darkened area
    painter.setPen(Qt::black);
    painter.setFont(QFont("Arial", 14, QFont::Bold));

    QRectF textRect = rect().adjusted(10, 10, -10, -10);
    painter.drawText(textRect, Qt::AlignCenter, "Drag and Drop Files Here");
}

bool Form::isHovered(const QPoint& pos) const {
    return rect().contains(pos);
}

form.h

#ifndef FORM_H
#define FORM_H

#include <QWidget>

namespace Ui {
class Form;
}

class Form : public QWidget
{
    Q_OBJECT

public:
    explicit Form(QWidget *parent = nullptr);
    ~Form();

signals:
    QString textsignal(const QString& str);


private:

    Ui::Form *ui;
    QString xmlContent;
    void parseXmlFile(const QString& filePath);
    bool isHovered(const QPoint& pos) const;

protected:
    void dragEnterEvent(QDragEnterEvent *event) override;
    void dropEvent(QDropEvent *event) override;
    void dragMoveEvent(QDragMoveEvent* event) override;
    void paintEvent(QPaintEvent* event) override;
    void dragLeaveEvent(QDragLeaveEvent* event) override ;
};

#endif // FORM_H

main.cpp

#include "mainwindow.h"

#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

MainWindow.cpp

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

#include "form.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    Form *w = new Form(ui->widget);
    QObject::connect(w, &Form::textsignal, [this](QString str) {ui->plainTextEdit->appendPlainText(str);});



}

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

MainWindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QListWidget>
#include <QPlainTextEdit>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private:
    Ui::MainWindow *ui;


private:
};
#endif // MAINWINDOW_H