一、前言
相信各位CS结构开发的程序员，多多少少都遇到过需要美化界面的事情，一般都不会采用系统的标题栏，这样就需要无边框标题栏窗体，默认的话无边框的标题栏都不支持拉伸和拖动的，毕竟去掉了标题栏则意味着失去了系统的窗体的属性，拉伸和拖动都需要自己写代码去实现，网上有很多类似的开源的方案，我也看过不少，总体来说复杂了些，对于初学者来说有可能看的云里雾里的，比如边框四周八个方位都可以自由拉伸这块，我的思路是针对设定的八个方位的区域进行识别鼠标是否按下，按下的哪个部位则执行什么拉伸策略，鼠标移到哪个位置则对应改变鼠标指针形状，更浅显易懂一些，至于拖动移动，还可以设置拖动的标题栏的高度等。
主要功能： 可以指定需要无边框的widget 边框四周八个方位都可以自由拉伸 可设置对应位置的边距,以便识别更大区域 可设置是否允许拖动 可设置是否允许拉伸
二、代码思路 bool FramelessWidget::eventFilter(QObject *watched, QEvent *event) { if (widget != 0 && watched == widget) { if (event->type() == QEvent::Resize) { //重新计算八个描点的区域,描点区域的作用还有就是计算鼠标坐标是否在某一个区域内 int width = widget->width(); int height = widget->height(); //左侧描点区域 rectLeft = QRect(0, padding, padding, height - padding * 2); //上侧描点区域 rectTop = QRect(padding, 0, width - padding * 2, padding); //右侧描点区域 rectRight = QRect(width - padding, padding, padding, height - padding * 2); //下侧描点区域 rectBottom = QRect(padding, height - padding, width - padding * 2, padding); //左上角描点区域 rectLeftTop = QRect(0, 0, padding, padding); //右上角描点区域 rectRightTop = QRect(width - padding, 0, padding, padding); //左下角描点区域 rectLeftBottom = QRect(0, height - padding, padding, padding); //右下角描点区域 rectRightBottom = QRect(width - padding, height - padding, padding, padding); } else if (event->type() == QEvent::HoverMove) { //设置对应鼠标形状,这个必须放在这里而不是下面,因为可以在鼠标没有按下的时候识别 QHoverEvent *hoverEvent = (QHoverEvent *)event; QPoint point = hoverEvent->pos(); if (resizeEnable) { if (rectLeft.contains(point)) { widget->setCursor(Qt::SizeHorCursor); } else if (rectRight.contains(point)) { widget->setCursor(Qt::SizeHorCursor); } else if (rectTop.contains(point)) { widget->setCursor(Qt::SizeVerCursor); } else if (rectBottom.contains(point)) { widget->setCursor(Qt::SizeVerCursor); } else if (rectLeftTop.contains(point)) { widget->setCursor(Qt::SizeFDiagCursor); } else if (rectRightTop.contains(point)) { widget->setCursor(Qt::SizeBDiagCursor); } else if (rectLeftBottom.contains(point)) { widget->setCursor(Qt::SizeBDiagCursor); } else if (rectRightBottom.contains(point)) { widget->setCursor(Qt::SizeFDiagCursor); } else { widget->setCursor(Qt::ArrowCursor); } } //根据当前鼠标位置,计算XY轴移动了多少 int offsetX = point.x() - lastPos.x(); int offsetY = point.y() - lastPos.y(); //根据按下处的位置判断是否是移动控件还是拉伸控件 if (moveEnable) { if (pressed) { widget->move(widget->x() + offsetX, widget->y() + offsetY); } } if (resizeEnable) { if (pressedLeft) { int resizeW = widget->width() - offsetX; if (widget->minimumWidth() <= resizeW) { widget->setGeometry(widget->x() + offsetX, rectY, resizeW, rectH); } } else if (pressedRight) { widget->setGeometry(rectX, rectY, rectW + offsetX, rectH); } else if (pressedTop) { int resizeH = widget->height() - offsetY; if (widget->minimumHeight() <= resizeH) { widget->setGeometry(rectX, widget->y() + offsetY, rectW, resizeH); } } else if (pressedBottom) { widget->setGeometry(rectX, rectY, rectW, rectH + offsetY); } else if (pressedLeftTop) { int resizeW = widget->width() - offsetX; int resizeH = widget->height() - offsetY; if (widget->minimumWidth() <= resizeW) { widget->setGeometry(widget->x() + offsetX, widget->y(), resizeW, resizeH); } if (widget->minimumHeight() <= resizeH) { widget->setGeometry(widget->x(), widget->y() + offsetY, resizeW, resizeH); } } else if (pressedRightTop) { int resizeW = rectW + offsetX; int resizeH = widget->height() - offsetY; if (widget->minimumHeight() <= resizeH) { widget->setGeometry(widget->x(), widget->y() + offsetY, resizeW, resizeH); } } else if (pressedLeftBottom) { int resizeW = widget->width() - offsetX; int resizeH = rectH + offsetY; if (widget->minimumWidth() <= resizeW) { widget->setGeometry(widget->x() + offsetX, widget->y(), resizeW, resizeH); } if (widget->minimumHeight() <= resizeH) { widget->setGeometry(widget->x(), widget->y(), resizeW, resizeH); } } else if (pressedRightBottom) { int resizeW = rectW + offsetX; int resizeH = rectH + offsetY; widget->setGeometry(widget->x(), widget->y(), resizeW, resizeH); } } } else if (event->type() == QEvent::MouseButtonPress) { //记住当前控件坐标和宽高以及鼠标按下的坐标 QMouseEvent *mouseEvent = (QMouseEvent *)event; rectX = widget->x(); rectY = widget->y(); rectW = widget->width(); rectH = widget->height(); lastPos = mouseEvent->pos(); //判断按下的手柄的区域位置 if (rectLeft.contains(lastPos)) { pressedLeft = true; } else if (rectRight.contains(lastPos)) { pressedRight = true; } else if (rectTop.contains(lastPos)) { pressedTop = true; } else if (rectBottom.contains(lastPos)) { pressedBottom = true; } else if (rectLeftTop.contains(lastPos)) { pressedLeftTop = true; } else if (rectRightTop.contains(lastPos)) { pressedRightTop = true; } else if (rectLeftBottom.contains(lastPos)) { pressedLeftBottom = true; } else if (rectRightBottom.contains(lastPos)) { pressedRightBottom = true; } else { pressed = true; } } else if (event->type() == QEvent::MouseMove) { //改成用HoverMove识别 } else if (event->type() == QEvent::MouseButtonRelease) { //恢复所有 pressed = false; pressedLeft = false; pressedRight = false; pressedTop = false; pressedBottom = false; pressedLeftTop = false; pressedRightTop = false; pressedLeftBottom = false; pressedRightBottom = false; widget->setCursor(Qt::ArrowCursor); } } return QObject::eventFilter(watched, event); }
三、效果图

四、开源主页
以上作品完整源码下载都在开源主页，会持续不断更新作品数量和质量，欢迎各位关注。 国内站点： https://gitee.com/feiyangqingyun/QWidgetDemo 国际站点： https://github.com/feiyangqingyun/QWidgetDemo 个人主页： https://blog.csdn.net/feiyangqingyun 知乎主页： https://www.zhihu.com/people/feiyangqingyun/