Qt实现可拉伸和可移动无边框的Widget

使用FramelessWindowHint设置之后Widget不能移动和拉伸，需要自己实现

setWindowFlags(Qt::FramelessWindowHint);

.h文件

#pragma once
#include <QWidget>

class FramelessWidget : public QWidget {
  Q_OBJECT
 public:
  FramelessWidget(QWidget* Parent = Q_NULLPTR);
  void set_boundary(int32_t Boundary, int32_t MoveHeight);

 protected:
  bool nativeEvent(const QByteArray& EventType, void* pMessage,
                   long* pResult) override;

 private:
  int32_t m_Boundary;    //调整拉伸生效的范围
  int32_t m_MoveHeight;  //调整拖动生效的范围
};

.cpp文件

默认4边4角都可拉伸，整个窗体不可移动，要减少拉伸边数直接注释即可

#include <windows.h>
#include <windowsx.h>

#include "ui_frameless_widget.h"

FramelessWidget::FramelessWidget(QWidget* parent)
    : QWidget(parent),
      m_Boundary(0),
      m_MoveHeight(0)  //默认无法拖动和拉伸
{
  // setAttribute(Qt::WA_TranslucentBackground, true);
  setWindowFlags(Qt::Window | Qt::FramelessWindowHint);  //设置为无边框窗口
}

void FramelessWidget::set_boundary(int32_t Boundary, int32_t MoveHeight) {
  m_Boundary = Boundary;
  m_MoveHeight = MoveHeight;
}

bool FramelessWidget::nativeEvent(const QByteArray& EventType, void* pMessage,
                                  long* pResult) {
  MSG* pMsg = (MSG*)pMessage;
  switch (pMsg->message) {
    case WM_NCHITTEST:
      int PosX = GET_X_LPARAM(pMsg->lParam) - this->frameGeometry().x();
      int PosY = GET_Y_LPARAM(pMsg->lParam) - this->frameGeometry().y();
      if (childAt(PosX, PosY) == 0) {
        //拖拽生效区域
        if (PosY <= m_MoveHeight) {
          *pResult = HTCAPTION;
        }
      } else {
        return false;
      }
      if (PosX < m_Boundary && PosY > (height() - m_Boundary) &&
          PosY < height())
        *pResult = HTBOTTOMLEFT;  //左下
      else if (PosX > (width() - m_Boundary) && PosX < width() &&
               PosY > (height() - m_Boundary) && PosY < height())
        *pResult = HTBOTTOMRIGHT;  //右下
      else if (PosX < m_Boundary && PosY < m_Boundary)
        *pResult = HTTOPLEFT;  //左上
      else if (PosX > (width() - m_Boundary) && PosX < width() &&
               PosY < m_Boundary)
        *pResult = HTTOPRIGHT;  //右上
      else if (PosX < m_Boundary)
        *pResult = HTLEFT;  //左
      else if (PosX > (width() - m_Boundary) && PosX < width())
        *pResult = HTRIGHT;  //右
      else if (PosY < m_Boundary)
        *pResult = HTTOP;  //上
      else if (PosY > (height() - m_Boundary) && PosY < height())
        *pResult = HTBOTTOM;  //下
      return true;
  }
  return false;
}

参考链接