NAME¶
Selection - maintains a list of selected graphical component views
SYNOPSIS¶
#include <Unidraw/selection.h>
DESCRIPTION¶
A Selection manages a set of distinguished graphical component views, usually
those in which the user has expressed interest by selecting them with a tool
or command. Each selection object maintains a list of graphical component
views and provides operations for iterating through and manipulating the list.
Components, commands, tools, and editors often rely on one or more selection
objects to supply the components on which they operate.
PUBLIC OPERATIONS¶
- Selection(Selection* = nil)
- Create a new selection object, optionally containing references to the
same views as the given selection object.
- virtual ~Selection()
- Destroy a selection instance. Deleting the selection does not in
turn delete the view instances it maintains.
- void Show(Viewer* = nil)
- void Update(Viewer* = nil)
- void Hide(Viewer* = nil)
- void Init(Viewer* = nil)
- These operations affect how the selection is represented visually in the
viewer. Show instructs the views to initialize and draw their handles to
highlight themselves, thus indicating that they are selected. To do so, it
calls RedrawHandles on each view. Update makes handles of newly-selected,
unhighlighted views appear by calling DrawHandles on all its views. Hide
unhighlights the views by calling their EraseHandles operation. Finally,
Init initializes each view's handles without drawing them (in case the
handles' appearance may have changed) by calling InitHandles on each.
- void Clear(Viewer* = nil)
- Remove all views from the Selection object, hiding their handles in the
process.
- void Append(GraphicView*)
- void Prepend(GraphicView*)
- void InsertAfter(Iterator, GraphicView*)
- void InsertBefore(Iterator, GraphicView*)
- void Remove(GraphicView*)
- void Remove(Iterator&)
- Operations for modifying the selection's list of views. Append and Prepend
add a GraphicView to the end and the beginning of the list, respectively.
InsertAfter and InsertBefore insert a GraphicView after and before the
GraphicView pointed to by the iterator, respectively. The Remove
operations remove a view from the list (without deleting it). You can
remove a view instance by referring to it explicitly or by specifying an
iterator. If an iterator is supplied, the Remove operation will advance it
to point to the following view as a side effect.
- GraphicView* GetView(Iterator)
- void SetView(GraphicView*, Iterator&)
- GetView returns the view to which an iterator points. SetView initializes
an iterator to point to a particular view in the list; it initializes the
iterator to point to a nil instance if the given GraphicView is not in the
selection list.
- void First(Iterator&)
- void Last(Iterator&)
- void Next(Iterator&)
- void Prev(Iterator&)
- boolean Done(Iterator)
- Operations for iterating over the selection list. First and Last
initialize an iterator to point to the beginning and end of the list,
respectively. Next increments the iterator to point to the following view,
while Prev decrements the iterator to point to the preceding view. Done
returns whether or not the iterator points beyond the first or last view
in the list.
- boolean IsEmpty()
- boolean Includes(GraphicView*)
- int Number()
- Operations that return information about the selection object's contents.
IsEmpty returns whether the selection list is empty, Includes returns
whether the list contains the given view, and Number returns the number of
views in the list.
- void Sort(GraphicView*)
- Sort the views in the selection list to conform to their order in the
given GraphicView's list of children. The selection list's order usually
reflects the order in which the user selected the objects, not their order
in their parent. Sort is useful in operations that modify or depend on the
parent view's structure.
- void Merge(Selection*)
- void Exclusive(Selection*)
- Operations that change the selection object's contents based on another
selection's. Merge adds the views in the given selection to those already
in the selection object (the union of the two sets), while Exclusive adds
those views not already in this object and removes those common to both
(the union minus the intersection of the two sets). Neither of these
operations change the contents of their argument.
- void GetBox(Coord&, Coord&, Coord&, Coord&)
- Return the bounding box circumscribing the views in the selection
list.
PROTECTED OPERATIONS¶
- UList* Elem(Iterator)
- GraphicView* View(UList*)
- Selection stores its views on a UList, which is accessible via the
_ulist protected member. The Selection's iteration operations store
the UList containing the current view in their iterator. Elem is a
convenience function for returning the UList to which an iterator points,
and View extracts the GraphicView that a UList element contains.
SEE ALSO¶
GraphicView(3U), Iterator(3U), UList(3U), Viewer(3U)