I. Introduction
I believe that programmers have more or less encountered things that need to beautify the interface. Generally, the title bar of the system will not be used, so a borderless title bar form is required. By default, the borderless title bar does not support stretching And dragging, after all, removing the title bar means losing the properties of the system's form. Stretching and dragging need to write code to achieve it. There are many similar open source solutions on the Internet, and I have seen many , generally speaking, it is a bit more complicated. For beginners, it is possible to see it in the clouds. For example, the eight directions around the frame can be stretched freely. My idea is to target the set eight directions. Identify whether the mouse is pressed, which part of the press will execute the stretching strategy, and which position the mouse moves to will change the shape of the mouse pointer, which is easier to understand. As for dragging and moving, you can also set the title bar of the drag height etc.
The main function:
- You can specify a widget that requires no borders
- The eight directions around the border can be stretched freely
- The margin of the corresponding position can be set to identify a larger area
- Can set whether to allow dragging
- Can set whether to allow stretching
2. Code idea
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);
}3. Rendering
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