BShape

Derived from: (none)
Mix-in classes: BArchivable
Declared in:  be/interface/Shape.h
Library: libbe.so
Allocation: Constructor only
Summary:  more...

The BShape class provides a powerful means of representing the outline of any shape that can be comprised of lines or Beziér curves.

The BShapeIterator class provides a means for utilizing BShape objects in your own code. You can also use BShape objects to obtain outlines of characters in a BFont by calling BFont::GetGlyphShapes().

Creating a BShape

A BShape is essentially a list of graphics commands, of which there are four types:

• MoveTo. This sets the BShape's coordinates to a specified point in the shape's space.

• LineTo. This represents a line from the current point to the next point in the shape.

• BeziérTo. This represents a Bezier curve, connecting the current point to a new point, with other points serving to control the shape of the curve.

• Close. This indicates the end of the shape's command list.

Functions by the same names are used to add the corresponding commands to the BShape object. For example, to create a BShape that represents two vertical lines, the following code might be used:

BShape shape; shape.MoveTo(0,0); shape.LineTo(0,100); shape.MoveTo(5,0); shape.LineTo(5,100);

Constructor and Destructor

BShape() BShape(const BShape &copyFrom) BShape(BMessage *archive)

Creates a new BShape object. The first form of the BShape constructor creates an empty shape. The second form, which accepts another BShape as an argument, copies that shape into the new one. The third form reconstructs a BShape from an archive.

virtual ~BShape()

Releases memory occupied by the BShape object.

Static Functions

static BArchivable *Instantiate(BMessage *archive)

Returns a new BShape object, allocated by new and created with the version of the constructor that takes a BMessage archive. However, if the archive message doesn't contain data for a BShape object, the return value will be NULL.

See also: BArchivable::Instantiate(), instantiate_object(), Archive()

Member Functions

status_t AddShape(const BShape *otherShape)

AddShape() adds the lines and curves that comprise the otherShape to the shape.

RETURN CODES

• B_OK. No error.

• Other errors. None are defined at this time, but you should always check for errors returned by this function.

status_t BezierTo(BPoint controlPoints[3])

Adds a command to the BShape that represents a Beziér curve that begins at the current coordinates and is constructed using the specified control points.

RETURN CODES

• B_OK. No error.

• Other errors. None are defined at this time, but you should always check for errors returned by this function.

BRect Bounds(void) const

Bounds() returns the bounds rectangle of the entire shape; this rectangle encloses all the lines and Beziér curves that comprise the shape.

void Clear(void)

Clear() deletes all the lines and Beziér curves that comprise the shape, leaving it empty.

void Close(void)

Close() should be called when the shape has been fully-constructed by calls to the BezierTo(), LineTo(), and MoveTo() functions.

RETURN CODES

• B_OK. No error.

• Other errors. None are defined at this time, but you should always check for errors returned by this function.

status_t LineTo(BPoint point)

Adds a "draw line" command to the BShape. A line will be drawn from the previous coordinates to the specified coordinates.

RETURN CODES

• B_OK. No error.

• Other errors. None are defined at this time, but you should always check for errors returned by this function.

status_t MoveTo(BPoint point)

Adds a "move to" command to the BShape. The next LineTo() or BezierTo() will begin at this point. This lets you create noncontiguous shapes.

RETURN CODES

• B_OK. No error.

• Other errors. None are defined at this time, but you should always check for errors returned by this function.

Archived Fields

The Archive() function adds the following fields to its BMessage argument:

Field	Type code	Meaning
"pts"	B_POINT_TYPE	The list of points used by the shape's commands.
"ops"	B_INT32_TYPE	The list of command opcodes indicating the shape's commands.

In the Play() function, the table lists items 15 and 16 as "RESERVED", this is not true, these are used for BShape drawing.

The functions look like:

StrokeShape(void* user, BShape* shape);

and

FillShape(void* user, BShape* shape);
--Alan Ellis on December 4, 2001