QRubberBand Class

The QRubberBand class provides a rectangle or line that can indicate a selection or a boundary. 更多...

头文件: #include <QRubberBand>
qmake: QT += widgets
基类: QWidget

公有类型

enum Shape { Line, Rectangle }

公有函数

QRubberBand(Shape s, QWidget *p = Q_NULLPTR)
~QRubberBand()
void move(int x, int y)
void move(const QPoint &p)
void resize(int width, int height)
void resize(const QSize &size)
void setGeometry(const QRect &rect)
void setGeometry(int x, int y, int width, int height)
Shape shape() const

受保护的函数

void initStyleOption(QStyleOptionRubberBand *option) const

重新实现的受保护函数

virtual void changeEvent(QEvent *e)
virtual bool event(QEvent *e)
virtual void moveEvent(QMoveEvent *)
virtual void paintEvent(QPaintEvent *)
virtual void resizeEvent(QResizeEvent *)
virtual void showEvent(QShowEvent *e)
  • 35 个受保护的函数继承自 QWidget
  • 9 个受保护的函数继承自 QObject
  • 1 个受保护的函数继承自 QPaintDevice

其他继承的成员

详细描述

The QRubberBand class provides a rectangle or line that can indicate a selection or a boundary.

A rubber band is often used to show a new bounding area (as in a QSplitter or a QDockWidget that is undocking). Historically this has been implemented using a QPainter and XOR, but this approach doesn't always work properly since rendering can happen in the window below the rubber band, but before the rubber band has been "erased".

You can create a QRubberBand whenever you need to render a rubber band around a given area (or to represent a single line), then call setGeometry(), move() or resize() to position and size it. A common pattern is to do this in conjunction with mouse events. For example:

  void Widget::mousePressEvent(QMouseEvent *event)
  {
      origin = event->pos();
      if (!rubberBand)
          rubberBand = new QRubberBand(QRubberBand::Rectangle, this);
      rubberBand->setGeometry(QRect(origin, QSize()));
      rubberBand->show();
  }

  void Widget::mouseMoveEvent(QMouseEvent *event)
  {
      rubberBand->setGeometry(QRect(origin, event->pos()).normalized());
  }

  void Widget::mouseReleaseEvent(QMouseEvent *event)
  {
      rubberBand->hide();
      // determine selection, for example using QRect::intersects()
      // and QRect::contains().
  }

If you pass a parent to QRubberBand's constructor, the rubber band will display only inside its parent, but stays on top of other child widgets. If no parent is passed, QRubberBand will act as a top-level widget.

Call show() to make the rubber band visible; also when the rubber band is not a top-level. Hiding or destroying the widget will make the rubber band disappear. The rubber band can be a Rectangle or a Line (vertical or horizontal), depending on the shape() it was given when constructed.

成员类型

enum QRubberBand::Shape

This enum specifies what shape a QRubberBand should have. This is a drawing hint that is passed down to the style system, and can be interpreted by each QStyle.

ConstantValueDescription
QRubberBand::Line0A QRubberBand can represent a vertical or horizontal line. Geometry is still given in rect() and the line will fill the given geometry on most styles.
QRubberBand::Rectangle1A QRubberBand can represent a rectangle. Some styles will interpret this as a filled (often semi-transparent) rectangle, or a rectangular outline.

成员函数

QRubberBand::QRubberBand(Shape s, QWidget *p = Q_NULLPTR)

Constructs a rubber band of shape s, with parent p.

By default a rectangular rubber band (s is Rectangle) will use a mask, so that a small border of the rectangle is all that is visible. Some styles (e.g., native macOS) will change this and call QWidget::setWindowOpacity() to make a semi-transparent filled selection rectangle.

QRubberBand::~QRubberBand()

Destructor.

[virtual protected] void QRubberBand::changeEvent(QEvent *e)

重新实现 QWidget::changeEvent().

[virtual protected] bool QRubberBand::event(QEvent *e)

重新实现 QObject::event().

[protected] void QRubberBand::initStyleOption(QStyleOptionRubberBand *option) const

Initialize option with the values from this QRubberBand. This method is useful for subclasses when they need a QStyleOptionRubberBand, but don't want to fill in all the information themselves.

参见 QStyleOption::initFrom().

void QRubberBand::move(int x, int y)

Moves the rubberband to point (x, y).

参见 resize().

void QRubberBand::move(const QPoint &p)

This is an overloaded function.

Moves the rubberband to point p.

参见 resize().

[virtual protected] void QRubberBand::moveEvent(QMoveEvent *)

重新实现 QWidget::moveEvent().

[virtual protected] void QRubberBand::paintEvent(QPaintEvent *)

重新实现 QWidget::paintEvent().

void QRubberBand::resize(int width, int height)

Resizes the rubberband so that its width is width, and its height is height.

参见 move().

void QRubberBand::resize(const QSize &size)

This is an overloaded function.

Resizes the rubberband so that its new size is size.

参见 move().

[virtual protected] void QRubberBand::resizeEvent(QResizeEvent *)

重新实现 QWidget::resizeEvent().

void QRubberBand::setGeometry(const QRect &rect)

Sets the geometry of the rubber band to rect, specified in the coordinate system of its parent widget.

参见 QWidget::geometry.

void QRubberBand::setGeometry(int x, int y, int width, int height)

This is an overloaded function.

Sets the geometry of the rubberband to the rectangle whose top-left corner lies at the point (x, y), and with dimensions specified by width and height. The geometry is specified in the parent widget's coordinate system.

Shape QRubberBand::shape() const

Returns the shape of this rubber band. The shape can only be set upon construction.

[virtual protected] void QRubberBand::showEvent(QShowEvent *e)

重新实现 QWidget::showEvent().