NAME¶
Damage - repairs damaged graphics
SYNOPSIS¶
#include <Unidraw/Graphic/damage.h>
DESCRIPTION¶
Damage objects store damaged areas of a graphic for subsequent incremental
repair. Areas of a graphic are "damaged" if they need to be redrawn
for any reason, e.g., if their state has been modified or if under/overlapping
graphics change their appearance. Damage objects try to minimize the amount of
redrawing needed to repair a graphic. They are most useful when the graphic is
complicated enough that it would be undesirable to redraw the entire canvas
when the graphic is modified. Damage objects do
not eliminate the need
for an interactor's
Redraw member function, though they could be used
to implement it.
PUBLIC OPERATIONS¶
- Damage(Canvas* = nil, Painter* = nil, Graphic* = nil)
- Create a new Damage object for a graphic on the given canvas. The painter
is used to erase damaged areas using its ClearRect function prior to
redrawing them.
- virtual void Incur(Graphic*)
- virtual void Incur(BoxObj&)
- virtual void Incur(
- Coord left, Coord bottom, Coord right, Coord top
- )
-
Notify the damage object that a rectangular area has been damaged, either by
passing the graphic that contributed the area or the area itself.
- virtual void Added(Graphic*)
- Notify the damage object that the given graphic was appended ( not
inserted) to the graphic but never drawn. The damage object can thus be
responsible for drawing newly added graphics as well.
- virtual void Repair()
- Repair all damage incurred since the last Repair (or since the damage
object was created if this is the first Repair).
- virtual void Reset()
- Reset the damage object. Any damage incurred is lost.
- virtual boolean Incurred()
- Returns true if any damage has been incurred.
- void SetCanvas(Canvas*)
- void SetPainter(Painter*)
- void SetGraphic(Graphic*)
- Canvas* GetCanvas()
- Painter* GetPainter()
- Graphic* GetGraphic()
- Set and get attributes of the damage object.
PROTECTED OPERATIONS¶
- int Area(BoxObj&)
- A helper function that returns the area in square pixels occupied by the
given BoxObj.
- virtual void DrawAreas()
- virtual void DrawAdditions()
- Explicitly draw the areas of incurred and added damage, respectively.
- virtual void Merge(BoxObj&)
- Merge the given BoxObj into the list of incur-damaged areas, coalescing it
into an existing area if the number of non-overlapping areas exceeds
2.
- void FirstArea(Iterator&)
- void FirstAddition(Iterator&)
- void Next(Iterator&)
- boolean Done(Iterator)
- BoxObj* GetArea(Iterator)
- Graphic* GetAddition(Iterator)
- Operations for iterating over the lists of damaged areas (represented with
BoxObj objects) and added Graphics. FirstArea and FirstAddition initialize
the iterator to point to the first item on the corresponding list, Next
advances the iterator, and Done returns true if the iterator points beyond
the end of the list. GetArea and GetAddition return the BoxObj or Graphic
to which the iterator points.
- UList* Elem(Iterator)
- A helper function for returning the UList to which an iterator points. The
_areas protected member is a UList that stores the list of damaged
areas, and the _additions protected stores the list of added
graphics.
- void DeleteArea(BoxObj*)
- void DeleteAreas()
- DeleteArea is a helper function for deleting the storage associated with a
damaged area, including the area itself and the UList element. DeleteAreas
is a helper function that deletes the list of damaged areas.
SEE ALSO¶
Canvas(3I), Graphic(3U), Iterator(3U), Painter(3I), UList(3U),
geomobjs(3U)