The Be Book - Classes And Methods

BRegion

Derived From:	–
Mix-in Classes:	–
Declared In:	`interface/Region.h`
Library:	`libbe.so`
Allocation:	–

Class Overview

Constructor and Destructor

BRegion()

BRegion (const BRegion& region); BRegion (const BRect& rect); BRegion ();

Initializes the BRegion object to be a copy of region, or to be a rectangular region containing the space indicated by rect. If no argument is supplied, the BRegion is empty and Frame() returns and invalid BRect.

~BRegion()

virtual ~BRegion();

Frees the memory that was allocated to hold data describing the region.

Member Functions

Contains()

bool Contains(BPoint point) const;

Returns true if point lies within the region, and false if not.

Frame()

BRect Frame() const;

Returns the smallest rectangle that encloses all the rectangles in the region.

If the region is empty, the returned object will be invalid. Check the return thus:

rect = region.Frame();
if (rect.IsValid())
   /* okay */
else
   /* nope */

Intersects()

bool Intersects(BRect rect) const;

Returns true if the BRegion has any area in common with rect, and false if not.

MakeEmpty()

void MakeEmpty();

Empties the BRegion and invalidates the object's Frame() rectangle.

OffsetBy()

void OffsetBy(int32 horizontal,
              int32 vertical);

Offsets all rectangles in the region by horizontal and vertical deltas.

PrintToStream()

void PrintToStream() const;

Prints (to standard out) each rectangle in the BRegion in the form:

"BRect(left, top, right, bottom)"

The first string that's printed is the object's frame rectangle. Each subsequent string describes a single rectangle in the BRegion.

RectAt(), CountRects()

BRect RectAt(int32 index);int32 CountRects();

CountRects() returns the total number of rectangles in the BRegion; RectAt() returns the rectangle at a particular index. The order of the rectangles is unimportant.

Set(), Include(), Exclude(), IntersectWith()

void Set(BRect rect);

void Include(BRect rect); void Include(const BRegion* region);

void Exclude(BRect rect); void Exclude(const BRegion* region);

void IntersectWith(const BRegion* region);

Set() modifies the BRegion so that it only contains rect.

Include() modifies the region to include (copies of) the rectangles contained in rect or region.

Exclude() modifies the region to exclude all rectangles contained in rect or region..

IntersectWith() modifies the region so that it includes only those areas that it has in common with another region.

Operators

= (assignment)

BRegion& operator =(const BRegion& );

Sets the left region to be an independent copy of the right region:

BRegion left_region = right_region;