The Interface Kit: BShape

BShape

Derived from: BArchivable

Declared in: be/interface/Shape.h

Library: libbe.so

[method summary]

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

Bezié\rTo. 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() 
      BShape(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.

~BShape()

      virtual ~BShape()

Releases memory occupied by the BShape object.

Static Functions

Instantiate()

      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 BWindow object, the return value will be NULL.

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

Member Functions

AddShape()

      status_t AddShape(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.

BezierTo()

      status_t BezierTo(BPoint controlPoints[3])

Adds a command to the BShape that represents a Bezié\r 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.

Bounds()

      BRect Bounds(void)

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

Clear()

      void Clear(void)

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

Close()

      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.

LineTo()

      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.

MoveTo()

      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.

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.

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Last modified December 14, 1998.