Window Structure Analysis

Creating miniature widgets like those found in trading platforms requires understanding three core components:

• Window Frame: The outer boundary that enables resizing functionality
• Title Bar: Custom implementation replacing native Windows title bar
• Client Area: The content region where custom widget are displayed

Interactive Window Resizing

The key to creating resizable mini-widgets lies in overriding mouse event handlers to detect edge interactions and modify window dimensions accordingly.

class ResizableWidget : public QWidget {
protected:
    void mousePressEvent(QMouseEvent* event) override;
    void mouseMoveEvent(QMouseEvent* event) override;
    void mouseReleaseEvent(QMouseEvent* event) override;
};

Cursor State Management

Determining weather the cursor is positioned over a resizeable edge requires checking boundary conditions:

void CustomWidget::updateEdgeDetection(const QPoint& mousePos) {
    QRect widgetRect = rect();
    int edgeThreshold = 5;
    
    bool atLeft = mousePos.x() <= edgeThreshold;
    bool atRight = mousePos.x() >= widgetRect.width() - edgeThreshold;
    bool atTop = mousePos.y() <= edgeThreshold;
    bool atBottom = mousePos.y() >= widgetRect.height() - edgeThreshold;
    
    // Corner detection combinations
    topLeftCorner = atTop && atLeft;
    topRightCorner = atTop && atRight;
    bottomLeftCorner = atBottom && atLeft;
    bottomRightCorner = atBottom && atRight;
    
    canResize = atLeft || atRight || atTop || atBottom;
}

Dynamic Cursor Appearance

Based on edge detection results, the cursor appearance changes to indicate available resize directions:

void CustomWidget::adjustCursor(const QPoint& position) {
    updateEdgeDetection(position);
    
    if (topLeftCorner || bottomRightCorner) {
        setCursor(Qt::SizeFDiagCursor);
    } else if (topRightCorner || bottomLeftCorner) {
        setCursor(Qt::SizeBDiagCursor);
    } else if (atLeft || atRight) {
        setCursor(Qt::SizeHorCursor);
    } else if (atTop || atBottom) {
        setCursor(Qt::SizeVerCursor);
    } else {
        unsetCursor();
    }
}

Window Dimension Adjustment

Resizing calculations use the initial press position as reference point to maintain consistent behavior:

void CustomWidget::handleResize(QMouseEvent* event) {
    QPoint currentGlobal = event->globalPos();
    QPoint offset = currentGlobal - pressStartPosition;
    
    QRect newGeometry = initialGeometry;
    
    if (atLeft) newGeometry.setLeft(newGeometry.left() + offset.x());
    if (atRight) newGeometry.setRight(newGeometry.right() + offset.x());
    if (atTop) newGeometry.setTop(newGeometry.top() + offset.y());
    if (atBottom) newGeometry.setBottom(newGeometry.bottom() + offset.y());
    
    setGeometry(newGeometry);
}

Clock Display Implementation

The clock widget features dynamic text scaling based on window size using QPainter transformations.

Layout Structure

A simple vertical arrangement contains the time display and date information:

// Create separator line
QFrame* separator = new QFrame();
separator->setFrameShape(QFrame::HLine);
separator->setStyleSheet("color: #474F57;");

// Setup layout
QVBoxLayout* layout = new QVBoxLayout();
layout->addWidget(timeDisplay);
layout->addWidget(separator);
layout->addWidget(dateDisplay);
setLayout(layout);

Scalable Text Rendering

The core innovation uses scene transformation to achieve smooth font scaling:

void ScalableTextLabel::paintEvent(QPaintEvent* event) {
    QWidget::paintEvent(event);
    
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing, true);
    
    QFont font = painter.font();
    font.setPixelSize(14);
    painter.setFont(font);
    
    // Calculate optimal scale factor
    double scaleFactor = qMin(width(), height()) / 100.0;
    
    // Center and scale drawing area
    painter.translate(width() / 2, height() / 2);
    painter.scale(scaleFactor, scaleFactor);
    
    // Measure text dimensions
    int textWidth = painter.fontMetrics().horizontalAdvance(displayText);
    int textHeight = painter.fontMetrics().height();
    
    // Draw centered text
    QRect textRect(-textWidth/2, -textHeight/2, textWidth, textHeight);
    painter.drawText(textRect, displayText);
}

Real-time Updates

A timer updates the display every second with current time information:

// Initialize update timer
QTimer* updateTimer = new QTimer(this);
connect(updateTimer, &QTimer::timeout, this, &ClockWidget::refreshTime);
updateTimer->start(1000);

void ClockWidget::refreshTime() {
    QDateTime currentTime = QDateTime::currentDateTime();
    
    // Update time display
    timeLabel->setText(currentTime.toString("HH:mm:ss"));
    
    // Update date display  
    QString dateString = QString("Beijing(CN) %1")
                        .arg(currentTime.toString("yyyy/MM/dd"));
    dateLabel->setText(dateString);
    
    // Trigger repaint
    update();
}