Qt无边框MainWindow如何拖动四周改变大小

原来还有winEvent(), x11Event() and macEvent() 这些东西。。。不过貌似还需要找更好的办法，否则就无法跨平台了。

你需要重新处理部分窗体事件，以下代码适用于Windows平台，仅供参考！

bool MainWindow::winEvent(MSG *msg, long *result)
{
switch (msg->message)
{
case WM_NCHITTEST:
{
*result = 0;
const LONG border_width = 8; //in pixels
RECT winrect;
GetWindowRect(winId(), &winrect);

long x = GET_X_LPARAM(msg->lParam);
long y = GET_Y_LPARAM(msg->lParam);

bool resizeWidth = minimumWidth() != maximumWidth();
bool resizeHeight = minimumHeight() != maximumHeight();
if(resizeWidth)
{
//left border
if (x >= winrect.left && x < winrect.left + border_width)
{
*result = HTLEFT;
}
//right border
if (x < winrect.right && x >= winrect.right - border_width)
{
*result = HTRIGHT;
}
}
if(resizeHeight)
{
//bottom border
if (y < winrect.bottom && y >= winrect.bottom - border_width)
{
*result = HTBOTTOM;
}
//top border
if (y >= winrect.top && y < winrect.top + border_width)
{
*result = HTTOP;
}
}
if(resizeWidth && resizeHeight)
{
//bottom left corner
if (x >= winrect.left && x < winrect.left + border_width &&
y < winrect.bottom && y >= winrect.bottom - border_width)
{
*result = HTBOTTOMLEFT;
}
//bottom right corner
if (x < winrect.right && x >= winrect.right - border_width &&
y < winrect.bottom && y >= winrect.bottom - border_width)
{
*result = HTBOTTOMRIGHT;
}
//top left corner
if (x >= winrect.left && x < winrect.left + border_width &&
y >= winrect.top && y < winrect.top + border_width)
{
*result = HTTOPLEFT;
}
//top right corner
if (x < winrect.right && x >= winrect.right - border_width &&
y >= winrect.top && y < winrect.top + border_width)
{
*result = HTTOPRIGHT;
}
}

if(*result == 0)
return  QWidget::winEvent(msg,result);

return true;
break;
} //end case WM_NCHITTEST
default:
return QWidget::winEvent(msg,result);
}
}

参考：https://forum.qt.io/topic/29398/%E5%B7%B2%E8%A7%A3%E5%86%B3-qt%E6%97%A0%E8%BE%B9%E6%A1%86mainwindow%E5%A6%82%E4%BD%95%E6%8B%96%E5%8A%A8%E5%9B%9B%E5%91%A8%E6%94%B9%E5%8F%98%E5%A4%A7%E5%B0%8F/5
http://blog.csdn.net/kfbyj/article/details/9284923