实现QT无边框窗口的拖动，尺寸改变。需要的时候从该类继承，派生类需要定义为QWidget。

头文件：

#ifndef SIZEABLEWIDGET_H
#define SIZEABLEWIDGET_H#include <QWidget>class SizeableWidget : public QWidget
{Q_OBJECT
public:SizeableWidget(QWidget *parent = 0);//允许或禁止移动bool isMoveable()const;void setMoveable(bool moveable);//允许或禁止改变大小bool isSizeable()const;void setSizeable(bool sizeable);private:void mousePressEvent (QMouseEvent* event);void mouseReleaseEvent(QMouseEvent* event);void mouseMoveEvent(QMouseEvent* event);int calcPosition(const QPoint& pt);void setCursorType(int value);private:bool    m_bMoveable;bool    m_bSizeable;bool    m_bLeftMouseButtonPressed;int     m_lastPosition;QPoint  m_ptLast;Qt::CursorShape m_currentCursor;
};#endif // SIZEABLEWIDGET_H

源文件：

#include "sizeablewidget.h"
#include <QPainter>
#include <QMouseEvent>namespace
{const int g_padding = 4;int helperCalcPosition(int pos, int range){return (pos < g_padding) ? 0 : ((pos > (range - g_padding)) ? 2 : 1);}
}SizeableWidget::SizeableWidget(QWidget *parent) :QWidget(parent) ,m_bMoveable(true) ,m_bSizeable(true) ,m_bLeftMouseButtonPressed(false) ,m_lastPosition(11) ,m_currentCursor(Qt::ArrowCursor)
{setCursor(m_currentCursor);setMinimumSize(QSize(32, 32));
}bool SizeableWidget::isMoveable()const
{return m_bMoveable;
}void SizeableWidget::setMoveable(bool moveable)
{m_bMoveable = moveable;
}bool SizeableWidget::isSizeable()const
{return m_bSizeable;
}void SizeableWidget::setSizeable(bool sizeable)
{m_bSizeable = sizeable;
}int SizeableWidget::calcPosition(const QPoint& pt)
{int row = helperCalcPosition(pt.y(), rect().height());int col = helperCalcPosition(pt.x(), rect().width());return row * 10 + col;
}void SizeableWidget::mousePressEvent(QMouseEvent* event)
{m_bLeftMouseButtonPressed = true;m_ptLast = event->globalPos();m_lastPosition = calcPosition(event->pos());QWidget::mousePressEvent(event);
}void SizeableWidget::mouseReleaseEvent(QMouseEvent* event)
{m_bLeftMouseButtonPressed = false;QWidget::mouseReleaseEvent(event);
}void SizeableWidget::mouseMoveEvent(QMouseEvent* event)
{if(m_bLeftMouseButtonPressed){QPoint ptNew = event->globalPos();ptNew -= m_ptLast;if(11 == m_lastPosition)    //拖动{if (m_bMoveable){ptNew += pos();move(ptNew);}}else    //调整大小{if (m_bSizeable){QRect rectWindow = geometry();switch(m_lastPosition){case 00:rectWindow.setTopLeft(rectWindow.topLeft() + ptNew);break;case 02:rectWindow.setTopRight(rectWindow.topRight() + ptNew);break;case 20:rectWindow.setBottomLeft(rectWindow.bottomLeft() + ptNew);break;case 22:rectWindow.setBottomRight(rectWindow.bottomRight() + ptNew);break;case 10:rectWindow.setLeft(rectWindow.left() + ptNew.x());break;case 12:rectWindow.setRight(rectWindow.right() + ptNew.x());break;case 01:rectWindow.setTop(rectWindow.top() + ptNew.y());break;case 21:rectWindow.setBottom(rectWindow.bottom() + ptNew.y());break;default:Q_ASSERT(0);}setGeometry(rectWindow);}}m_ptLast  = event->globalPos();}else{if (m_bSizeable)setCursorType(calcPosition(event->pos()));}QWidget::mouseMoveEvent(event);
}void SizeableWidget::setCursorType(int value)
{Qt::CursorShape cursor;switch(value){case 00:case 22:cursor = Qt::SizeFDiagCursor;break;case 02:case 20:cursor = Qt::SizeBDiagCursor;break;case 10:case 12:cursor = Qt::SizeHorCursor;break;case 01:case 21:cursor = Qt::SizeVerCursor;break;case 11:cursor = Qt::ArrowCursor;break;default:Q_ASSERT(0);break;}if(cursor != m_currentCursor){m_currentCursor = cursor;setCursor(m_currentCursor);}
}