TEllipse Class Reference

#include <bitstd.h>

Link against: bitgdi.lib

class TEllipse

Protected Attributes
TInt	iA
TInt64	iASquBSqu
TInt64	iASquared
TInt	iB
TInt64	iBSquared
TInt64	iD1
TInt64	iD2
TPoint	iOffset
TEllipseStatus	iStatus
TInt	iX
TInt	iXAdj
TInt	iY
TInt	iYAdj

Public Member Enumerations
enum	TEllipseStatus { EInitialised, EFirstSector, ESecondSector, EComplete, ELine }

Public Member Functions
IMPORT_C void	Construct(const TRect &)
IMPORT_C TPoint	Intersection(const TRect &, const TPoint &)
IMPORT_C TBool	NextStep(TPoint &, TPoint &, TPoint &, TPoint &)
IMPORT_C TBool	SingleStep(TPoint &, TPoint &, TPoint &, TPoint &)

Protected Member Functions
IMPORT_C TBool	Output(TPoint &, TPoint &, TPoint &, TPoint &)

Member Attribute Documentation

iA

TInt

[protected]

iASquBSqu

TInt64

iASquBSqu

[protected]

iASquared

TInt64

iASquared

[protected]

iB

TInt

[protected]

iBSquared

TInt64

iBSquared

[protected]

iD1

TInt64

iD1

[protected]

iD2

TInt64

iD2

[protected]

iOffset

TPoint

iOffset

[protected]

iStatus

TEllipseStatus

iStatus

[protected]

iX

TInt

[protected]

iXAdj

TInt

iXAdj

[protected]

iY

TInt

[protected]

iYAdj

TInt

iYAdj

[protected]

Member Enumeration Documentation

Enum TEllipseStatus

Enumeration for the ellipse production life cycle

Enumerator	Value	Description
EInitialised		Ellipse has been initialised but has no area
EFirstSector		The ellipse is drawn as two parabolas. These are in two sectors, the top and bottom half of the rectangle. The first sector means the top parabola has been produced.
ESecondSector		The parabola that occupies the bottom half of the rectangle has been produced.
EComplete		The ellipse is complete
ELine		The ellipse has either a height or width of two units or less and so takes the appearance of a line

Member Function Documentation

Construct ( const TRect & )

IMPORT_C void

Construct

(

const TRect &

aRect

)

Initialises the values of the ellipse so that it conforms to a rectangle entered as a parameter.

Parameters
aRect	the rectangle within which the ellipse is drawn

Intersection ( const TRect &, const TPoint & )

IMPORT_C TPoint	Intersection	(	const TRect &	aRect,
			const TPoint &	aPoint
		)

Constructs an ellipse from the rectangle which it is given and assesses the points position with regard to the ellipse and where they intersect.

Parameters
aRect	The rectangle within which the ellipse is drawn.
aPoint	A point to compare with the ellipse to determine if intersection occurs.

Return Value: TPoint The point is set to the corner which the intersection is nearest to.

NextStep ( TPoint &, TPoint &, TPoint &, TPoint & )

IMPORT_C TBool	NextStep	(	TPoint &	aTopLeft,
			TPoint &	aTopRight,
			TPoint &	aBottomLeft,
			TPoint &	aBottomRight
		)

By analysing the current state of the ellipse the process is taken to the next appropriate step. If iStatus = EInitialised only one step will be taken, if the ellipse is already semi constructed then it will be taken to completion. Takes in four point parameters that defines the rectangle in order to pass to SingleStep(aTopLeft,aTopRight,aBottomLeft,aBottomRight).

Parameters
aTopLeft	Top left corner of rectangle
aTopRight	Top right corner of rectangle
aBottomLeft	Bottom left corner of rectangle
aBottomRight	Bottom right corner of rectangle

Return Value: TBool ETrue if a valid rectangle is produced, else EFalse.

Output ( TPoint &, TPoint &, TPoint &, TPoint & )

IMPORT_C TBool	Output	(	TPoint &	aTopLeft,
			TPoint &	aTopRight,
			TPoint &	aBottomLeft,
			TPoint &	aBottomRight
		)	[protected]

Sets the absolute points that define the ellipse as calculated using its iOffset from the origin and using the half width and half height of the rectangle iA and iB.

Parameters
aTopLeft	The absolute (x,y) position for the top left point.
aTopRight	The absolute (x,y) position for the top right point.
aBottomLeft	The absolute (x,y) position for the bottom left point.
aBottomRight	The absolute (x,y) position for the bottom right point.

Return Value: TBool ETrue if a valid rectangle is produced, else EFalse. Also sets iStatus to EComplete.

SingleStep ( TPoint &, TPoint &, TPoint &, TPoint & )

IMPORT_C TBool	SingleStep	(	TPoint &	aTopLeft,
			TPoint &	aTopRight,
			TPoint &	aBottomLeft,
			TPoint &	aBottomRight
		)

Does the next stage in producing an ellipse by taking four points (the corners of the rectangle the ellipse should fill) as parameters. Updates TEllipse status accordingly and calls Output(aTopLeft,aTopRight,aBottomLeft,aBottomRight).

Parameters
aTopLeft	Top left corner of rectangle
aTopRight	Top right corner of rectangle
aBottomLeft	Bottom left corner of rectangle
aBottomRight	Bottom right corner of rectangle

Return Value: TBool ETrue if step completed successfully.