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#ifndef MULTI_GEOMETRY_WIDGET_HPP__
#define MULTI_GEOMETRY_WIDGET_HPP__
#include <cstddef>
#include <utility>
#include <array>
#include <QWidget>
#include <QByteArray>
#include <QEvent>
//
// Class MultiGeometryWidget<N, Widget> - Decorate a QWidget type with
// switchable geometries
//
// The abstract base class imbues a Qt Widget type with N alternative
// geometries. Sub-classes can initialise the currently selected
// geometry and the initial geometries using geometries. To switch
// geometry call select_geometry(n) which saves the current geometry
// and switches to the n'th saved geometry.
//
template<std::size_t N, typename Widget=QWidget>
class MultiGeometryWidget
: public Widget
{
public:
template<typename... Args>
explicit MultiGeometryWidget (Args&&... args)
: Widget {std::forward<Args> (args)...}
, current_geometry_ {0}
{
}
void geometries (std::size_t current
, std::array<QByteArray, N> const& the_geometries = std::array<QByteArray, N> {})
{
Q_ASSERT (current < the_geometries.size ());
saved_geometries_ = the_geometries;
current_geometry_ = current;
Widget::restoreGeometry (saved_geometries_[current_geometry_]);
}
std::array<QByteArray, N> const& geometries () const {return saved_geometries_;}
std::size_t current () {return current_geometry_;}
// Call this to select a new geometry denoted by the 'n' argument,
// any actual layout changes should be made in the implementation of
// the change_layout operation below.
void select_geometry (std::size_t n)
{
Q_ASSERT (n < N);
auto geometry = Widget::saveGeometry ();
change_layout (n);
saved_geometries_[current_geometry_] = geometry;
current_geometry_ = n;
// Defer restoration of the window geometry until the layour
// request event has been processed, this is necessary otherwise
// the final geometry may be affected by widgets not shown in the
// new layout.
desired_geometry_ = saved_geometries_[n];
}
protected:
virtual ~MultiGeometryWidget () {}
private:
// Override this operation to implement any layout changes for the
// geometry specified by the argument 'n'.
virtual void change_layout (std::size_t n) = 0;
bool event (QEvent * e) override
{
auto ret = Widget::event (e);
if (QEvent::LayoutRequest == e->type ()
&& desired_geometry_.size ())
{
// Restore the new desired geometry and flag that we have done
// so by clearing the desired_geometry_ member variable.
QByteArray geometry;
std::swap (geometry, desired_geometry_);
Widget::restoreGeometry (geometry);
}
return ret;
}
std::size_t current_geometry_;
std::array<QByteArray, N> saved_geometries_;
QByteArray desired_geometry_;
};
#endif
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