[UI] Add rounded corner widget

FinalProject/roundedcornerwidget.cpp

@@ -0,0 +1,98 @@
+#include <qpainterpath.h>
+#include <qregularexpression.h>
+
+#include "roundedcornerwidget.h"
+
+RoundedCornerWidget::RoundedCornerWidget(QWidget* parent) : QWidget(parent) {
+    // Create main layout and main widget
+    _mainLayout = new QVBoxLayout(this);
+    _mainLayout->setContentsMargins(0, 1, 1, 1);
+    _mainLayout->setSpacing(0);
+    _mainWidget = new QWidget(this);
+    _mainWidget->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
+    _mainLayout->addWidget(_mainWidget);
+    _mainWidget->show();
+    setLayout(_mainLayout);
+}
+
+RoundedCornerWidget::~RoundedCornerWidget() {
+}
+
+void RoundedCornerWidget::showEvent(QShowEvent* event) {
+    // Call parent show event
+    QWidget::showEvent(event);
+
+    // Initialize widget UI
+    initializeWidgetUI();
+
+    // Set initialized state
+    _initialized = true;
+}
+
+void RoundedCornerWidget::initializeWidgetUI() {
+    // Set up border widget
+    _borderWidget = new QWidget(this);
+    _borderWidget->setObjectName("borderWidget");
+    QString borderWidgetStyleSheet =
+        "QWidget#borderWidget{background-color:#00FFFFFF;border:2px solid " + _borderColor.name() + ";"
+        "border-radius:" + QString::number(_cornerRadius) + "px;}";
+    _borderWidget->setStyleSheet(borderWidgetStyleSheet);
+    _borderWidget->setAttribute(Qt::WA_TransparentForMouseEvents);
+    _borderWidget->move(0, 0);
+    _borderWidget->resize(width(), height());
+    _borderWidget->show();
+
+    // Create a round cornered mask
+    QPainterPath path;
+    path.addRoundedRect(_mainWidget->rect(), _cornerRadius, _cornerRadius);
+    QRegion region(path.toFillPolygon().toPolygon());
+    _mainWidget->setMask(region);
+}
+
+void RoundedCornerWidget::resizeEvent(QResizeEvent* event) {
+    // Resize widget border
+    if (_borderWidget != nullptr) {
+        _borderWidget->move(0, 0);
+        _borderWidget->resize(width(), height());
+    }
+    
+    // Resize window mask
+    if (_mainWidget != nullptr) {
+        QPainterPath path;
+        path.addRoundedRect(_mainWidget->rect(), _cornerRadius, _cornerRadius);
+        QRegion region(path.toFillPolygon().toPolygon());
+        _mainWidget->setMask(region);
+    }
+}
+
+void RoundedCornerWidget::setCornerRadius(int radius) {
+    // Set corner radius
+    _cornerRadius = radius;
+
+    // Modify the corner radius in the current style sheet of the border widget
+    QString styleSheet = _borderWidget->styleSheet();
+    styleSheet.replace(QRegularExpression("border-radius:\\d+px;"),
+        QString("border-radius:%1px;").arg(_cornerRadius));
+    _borderWidget->setStyleSheet(styleSheet);
+    
+    // Reset the mask of the main widget
+    QPainterPath path;
+    path.addRoundedRect(_mainWidget->rect(), _cornerRadius, _cornerRadius);
+    QRegion region(path.toFillPolygon().toPolygon());
+    _mainWidget->setMask(region);
+}
+
+void RoundedCornerWidget::setBorderColor(QColor color) {
+    // Set color
+    _borderColor = color;
+
+    // Modify the border color in the current style sheet of the border widget
+    QString styleSheet = _borderWidget->styleSheet();
+    styleSheet.replace(QRegularExpression("border:2px solid #\\w+;"),
+        QString("border:2px solid %1;").arg(_borderColor.name()));
+    _borderWidget->setStyleSheet(styleSheet);
+}
+
+QWidget* RoundedCornerWidget::mainWidget() const {
+    return _mainWidget;
+}

FinalProject/roundedcornerwidget.h

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+#pragma once
+
+#include <qwidget.h>
+#include <qevent.h>
+#include <qboxlayout.h>
+
+class RoundedCornerWidget : public QWidget {
+    
+    Q_OBJECT
+
+public:
+    RoundedCornerWidget(QWidget* parent = 0);
+    ~RoundedCornerWidget();
+
+protected:
+    // UI settings
+    int _cornerRadius = 15;
+    QColor _borderColor = QColor(255, 255, 255);
+
+    // UI elements
+    QWidget* _mainWidget = nullptr;
+    QVBoxLayout* _mainLayout = nullptr;
+    QWidget* _borderWidget = nullptr;
+    
+    // Initialization mark
+    bool _initialized = false;
+    void initializeWidgetUI();
+
+    // UI events
+    virtual void showEvent(QShowEvent* event) override;
+    virtual void resizeEvent(QResizeEvent* event) override;
+
+public:
+    // Public APIs
+    void setCornerRadius(int radius);
+    void setBorderColor(QColor color);
+    QWidget* mainWidget() const;
+};