重新实现paintEvent()函数。

效果如下：

 效果为蓝色区域，背景是vs接面，代码直接复制可用，留给有需要的人。

#ifndef CircleWidget_h__
#define CircleWidget_h__

#include <QWidget>

class CCircleWidget : public QWidget
{
	Q_OBJECT

public:

	explicit CCircleWidget(QWidget* parent = 0); // explicit 避免歧义

	CCircleWidget(const QString& strImagePath, int nRadius, QWidget* parent = 0);

public:

	void SetNormalOutLineColor(QColor color);

	void SetHoverOutLineColor(QColor color);

	void SetPressedOutLineColor(QColor color);

	void SetOutLineWidth(int nWidth);

	void SetImagePath(const QString& strImagePath);

	void SetHovered(bool bHovered);

	void SetPressed(bool bPressed);

protected: // override

	void Init();

	void paintEvent(QPaintEvent*) override;                // 绘图事件，调用update()时触发

	void mousePressEvent(QMouseEvent* e) override;          // 鼠标按下事件

	void mouseReleaseEvent(QMouseEvent* e) override;        // 鼠标释放事件

	void enterEvent(QEvent*) override;                     // 鼠标进入事件

	void leaveEvent(QEvent*) override;                     // 鼠标离开事件

signals:

	void SigClicked(); // 点击信号

private:

	QString m_strImagePath; // 图片路径
	QColor m_normalColor;
	QColor m_hoverColor;
	QColor m_pressedColor;
	int m_nWidth;
	int m_nRadius;        // 圆形半径
	bool m_bPressed;      // 左键单击控制
	bool m_bHovered;      // 鼠标悬停控制
};

#endif // CircleWidget_h__

#include "CircleWidget.h"
#include <QPainter>
#include <QMouseEvent>

CCircleWidget::CCircleWidget(QWidget* parent)
	: QWidget(parent)
	, m_strImagePath(":/dotnetIcon.png")
	, m_normalColor("#58a3ef")
	, m_hoverColor("#6eb8f5")
	, m_pressedColor("#417cac")
	, m_nWidth(4)
	, m_nRadius(46)
	, m_bPressed(false)
	, m_bHovered(false)
{
	Init();
}

CCircleWidget::CCircleWidget(const QString& strImagePath, int nRadius, QWidget* parent)
	: QWidget(parent)
	, m_strImagePath(strImagePath)
	, m_normalColor("#58a3ef")
	, m_hoverColor("#6eb8f5")
	, m_pressedColor("#417cac")
	, m_nWidth(4)
	, m_nRadius(nRadius)
	, m_bPressed(false)
	, m_bHovered(false)
{
	Init();
}

void CCircleWidget::SetNormalOutLineColor(QColor color)
{
	m_normalColor = color;
}

void CCircleWidget::SetHoverOutLineColor(QColor color)
{
	m_hoverColor = color;
}

void CCircleWidget::SetPressedOutLineColor(QColor color)
{
	m_pressedColor = color;
}

void CCircleWidget::SetOutLineWidth(int nWidth)
{
	m_nWidth = nWidth;
}

void CCircleWidget::SetImagePath(const QString& strImagePath)
{
	m_strImagePath = strImagePath;
}

void CCircleWidget::SetHovered(bool bHovered)
{
	m_bHovered = bHovered;
	update();
}

void CCircleWidget::SetPressed(bool bPressed)
{
	m_bPressed = bPressed;
	update();
}

void CCircleWidget::Init()
{
	// 无边框
	setWindowFlags(Qt::FramelessWindowHint);
	// 窗口背景透明
	setAttribute(Qt::WA_TranslucentBackground, true);
}

void CCircleWidget::paintEvent(QPaintEvent*)
{
	QPainter p(this);
	p.setRenderHint(QPainter::Antialiasing);

	QPen pen;
	pen.setWidth(m_nWidth);

	if (m_bPressed)
	{
		pen.setColor("#417cac"); // 按下时的边框颜色
	}
	else if (m_bHovered)
	{
		pen.setColor("#6eb8f5"); // 悬停时的边框颜色
	}
	else
	{
		pen.setColor("#58a3ef"); // 正常状态的边框颜色
	}

	p.setPen(pen);
	p.setBrush(Qt::NoBrush);

	// 设置圆心为圆的半径，以确保圆形完整显示
	//QPoint center(m_nRadius + m_nWidth / 2, m_nRadius + m_nWidth / 2);
	QPoint center(rect().center());

	// 绘制背景圆形
	p.drawEllipse(center, m_nRadius, m_nRadius);

	// 绘制图片
	QPixmap pixmap(m_strImagePath);
	QRect imageRect(0, 0, 2 * m_nRadius, 2 * m_nRadius); // 计算图片绘制区域
	QPainterPath clipPath;
	clipPath.addEllipse(center, m_nRadius, m_nRadius);

	p.setClipPath(clipPath);
	p.drawPixmap(center.x() - m_nRadius, center.y() - m_nRadius, imageRect.width(), imageRect.height(), pixmap);
}


void CCircleWidget::mousePressEvent(QMouseEvent* e)
{
	m_bPressed = true;
	update();
}

void CCircleWidget::mouseReleaseEvent(QMouseEvent* e)
{
	m_bPressed = false;
	update();
}

void CCircleWidget::enterEvent(QEvent*)
{
	m_bHovered = true;
	update();
}

void CCircleWidget::leaveEvent(QEvent*)
{
	m_bHovered = false;
	update();
}