| liudianwu |
2020-05-21 08:59 |
Qt开源作品16-通用无边框拖动拉伸
## 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：
1. 可以指定需要无边框的widget
2. 边框四周八个方位都可以自由拉伸
3. 可设置对应位置的边距,以便识别更大区域
4. 可设置是否允许拖动
5. 可设置是否允许拉伸
## 二、代码思路
```c++
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
[attachment=21592]
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老刘我有个建议。
