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The QRubberBand class provides a rectangle or line that can indicate a selection or a boundary. More...
#include <QRubberBand>
Inherits QWidget.
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.
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.
| Constant | Value | Description |
|---|---|---|
| QRubberBand::Line | 0 | A 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::Rectangle | 1 | A QRubberBand can represent a rectangle. Some styles will interpret this as a filled (often semi-transparent) rectangle, or a rectangular outline. |
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 Mac OS X) will change this and call QWidget::setWindowOpacity() to make a semi-transparent filled selection rectangle.
Destructor.
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.
See also QStyleOption::initFrom().
Moves the rubberband to point (x, y).
See also resize().
This is an overloaded member function, provided for convenience.
Moves the rubberband to point p.
See also resize().
Resizes the rubberband so that its width is width, and its height is height.
See also move().
This is an overloaded member function, provided for convenience.
Resizes the rubberband so that its new size is size.
See also move().
Sets the geometry of the rubber band to rect, specified in the coordinate system of its parent widget.
See also QWidget::geometry.
This is an overloaded member function, provided for convenience.
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.
Returns the shape of this rubber band. The shape can only be set upon construction.
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