IlvTransformer Class Reference

Geometric transformation class. More...

#include <ilviews/ilv.h>

Public Member Functions
	IlvTransformer ()
	Constructor. More...
	IlvTransformer (IlvTransfoParam m11, IlvTransfoParam m12, IlvTransfoParam m21, IlvTransfoParam m22, IlvTransfoParam x0, IlvTransfoParam y0)
	Constructor. More...
	IlvTransformer (const IlvPoint &center, IlvTransfoParam angle)
	Constructor. More...
	IlvTransformer (IlvTransfoParam sx, IlvTransfoParam sy, IlvPoint *point=0)
	Constructor. More...
	IlvTransformer (const IlvRect &src, const IlvRect &dst)
	Constructor. More...
	IlvTransformer (const IlvPoint &delta)
	Constructor. More...
void	apply (IlvPoint &p) const
	Applies the transformer. More...
void	apply (IlvFloatPoint &p) const
	Applies the transformer to a point. More...
void	apply (IlvRect &rect) const
	Applies the transformer to a rectangle. More...
void	apply (IlUInt count, IlvPoint *points) const
	Applies the transformer to a point set. More...
void	applyAndFill (IlvRect &rect) const
	Applies the transformer. More...
void	compose (const IlvTransformer &t)
	Computes the composition of two transformers. More...
IlBoolean	compute (const IlvRect &src, const IlvRect &dst)
	Stores the scaling and translation factors. More...
IlBoolean	computeInverse (IlvTransformer &t) const
	Stores the inverse transformation values. More...
void	deltaApply (IlvPoint &p) const
	Applies the transformer without the translation. More...
IlDouble	getDeterminant () const
	Gets the determinant of the matrix. More...
void	getValues (IlvTransfoParam &x0, IlvTransfoParam &y0) const
void	getValues (IlvTransfoParam &m11, IlvTransfoParam &m12, IlvTransfoParam &m21, IlvTransfoParam &m22, IlvTransfoParam &x0, IlvTransfoParam &y0) const
IlBoolean	inverse (IlvPoint &p) const
	Applies the inverse transformation. More...
IlBoolean	inverse (IlvFloatPoint &p) const
	Applies the inverse transformation. More...
IlBoolean	inverse (IlvRect &rect) const
	Applies the inverse transformation. More...
IlBoolean	isBad () const
	Indicates whether the transformer is reversible. More...
IlBoolean	isIdentity () const
	Indicates whether the current object represents the identity transformation. More...
IlBoolean	isScale () const
	Indicates whether the current object is a scaling transformation. More...
IlBoolean	isTranslation () const
	Indicates whether the current object is a translation transformation. More...
void	rotate (IlvTransfoParam centerx, IlvTransfoParam centery, IlvTransfoParam angle)
	Composes the transformer with a rotation. More...
void	scale (IlvTransfoParam fixedx, IlvTransfoParam fixedy, IlvTransfoParam sx, IlvTransfoParam sy)
	Composes the transformer with a scaling operation. More...
void	setValues (IlvTransfoParam x0, IlvTransfoParam y0)
	Sets the values that define the current IlvTransformer object. More...
void	setValues (IlvTransfoParam m11, IlvTransfoParam m12, IlvTransfoParam m21, IlvTransfoParam m22, IlvTransfoParam x0, IlvTransfoParam y0)
	Sets the values that define the current IlvTransformer object. More...
void	translate (IlvTransfoParam dx, IlvTransfoParam dy)
	Composes the transformer with a translation. More...

Detailed Description

Geometric transformation class.

Library: display

The IlvTransformer class internally computes two-dimensional affine transformations, thus allowing geometrical transformations of graphic objects. The IlvTransformer API is based on the IlvTransfoParam type.

Constructor & Destructor Documentation

IlvTransformer::IlvTransformer

(

)

Constructor.

This constructor sets the values of the object so that the geometric transformation is the identity transformation; that is, a transformation that does not change its operands.

IlvTransformer::IlvTransformer	(	IlvTransfoParam	m11,
		IlvTransfoParam	m12,
		IlvTransfoParam	m21,
		IlvTransfoParam	m22,
		IlvTransfoParam	x0,
		IlvTransfoParam	y0
	)

Constructor.

This constructor sets the values of the object so that the represented transformation will be applied by transforming the coordinates of a point p at (x, y) to a transformed point tp at (t_x, t_y) according to the following formula:

which leads to:

These objects are used each time a geometrical transformation is computed.

IlvTransformer::IlvTransformer	(	const IlvPoint &	center,
		IlvTransfoParam	angle
	)

Constructor.

This constructor initializes a new IlvTransformer instance that corresponds to a rotation of angle degrees around the center point center.

Parameters

center	The center point of the rotation.
angle	The angle of rotation in degrees.

IlvTransformer::IlvTransformer	(	IlvTransfoParam	sx,
		IlvTransfoParam	sy,
		IlvPoint *	point = 0
	)

Constructor.

This constructor initializes a new IlvTransformer instance that corresponds to a scaling operation specified by the sx and sy parameters. This transformation will leave the point coordinates unchanged. If you do not specify this point, (0, 0) will remain fixed.

Parameters

sx	Scaling in the x direction.
sy	Scaling in the y direction.

IlvTransformer::IlvTransformer	(	const IlvRect &	src,
		const IlvRect &	dst
	)

Constructor.

This constructor initializes a new IlvTransformer instance that stores the scaling and translation factors that transforms the rectangle src to dst, with no rotation.

Parameters

src	The initial rectangle.
dst	The final rectangle, after transformation.

IlvTransformer::IlvTransformer

(

const IlvPoint &

delta

)

Constructor.

This constructor initializes a new IlvTransformer instance that corresponds to the translation specified in the delta parameter.

Parameters

delta

The translation required.

Member Function Documentation

void IlvTransformer::apply

(

IlvPoint &

p

)

const

Applies the transformer.

Applies the transformer to the p parameter, which is modified by the function call.

Parameters

p	The point to transform.

void IlvTransformer::apply

(

IlvFloatPoint &

p

)

const

Applies the transformer to a point.

Applies the transformer to the p parameter, which is modified by the function call.

Parameters

p	The point to transform.

void IlvTransformer::apply

(

IlvRect &

rect

)

const

Applies the transformer to a rectangle.

Applies the transformer to the rect parameter, which is modified by the function call.

Parameters

rect	The rectangle to transform.

void IlvTransformer::apply	(	IlUInt	count,
		IlvPoint *	points
	)		const

Applies the transformer to a point set.

Applies the transformer to the all points of the array points, replacing them by their transformed version.

Parameters

count	The number of points to transform.
points	The array of at least count points to transform.

void IlvTransformer::applyAndFill

(

IlvRect &

rect

)

const

Applies the transformer.

Calls apply(IlvRect&) with the rect parameter. It ensures that the rectangle will not be returned empty once the transformer has been applied. It does so by setting to 1 any dimension previously set to 0.

Parameters

rect	The rectangle to transform.

void IlvTransformer::compose

(

const IlvTransformer &

t

)

Computes the composition of two transformers.

Computes the composition of two transformers. It modifies the current IlvTransformer by composing it with the one given in the t parameter. Using a mixture of mathematical and C++ notation, one could define the composed transformer as T1.compose(T2) (x) = T2(T1(x)) = T2 o T1 (x) .

Parameters

t	The transformer to compose with.

IlBoolean IlvTransformer::compute	(	const IlvRect &	src,
		const IlvRect &	dst
	)

Stores the scaling and translation factors.

Stores, in the current object, the scaling and translation factors that transform the rectangle src to dst with no rotation. If this operation cannot be performed it leaves the current object unmodified.

Parameters

src	The initial rectangle.
dst	The final rectangle, after transformation.

Returns

IlTrue if successful, and IlFalse otherwise.

IlBoolean IlvTransformer::computeInverse

(

IlvTransformer &

t

)

const

Stores the inverse transformation values.

Stores, in the inverse parameter, the inverse transformation values of the current object. If this operation cannot be performed it leaves inverse unmodified.

Returns

IlTrue if successful, and IlFalse otherwise.

void IlvTransformer::deltaApply

(

IlvPoint &

p

)

const

Applies the transformer without the translation.

Applies the current transformer to the p parameter but without the translation parameters. This lets you compute transformed vectors.

Parameters

p	The point to transform.

IlDouble IlvTransformer::getDeterminant

(

)

const

Gets the determinant of the matrix.

Returns

The determinant of the matrix.

void IlvTransformer::getValues	(	IlvTransfoParam &	x0,
		IlvTransfoParam &	y0
	)		const

Accesses the values stored in the object.

void IlvTransformer::getValues	(	IlvTransfoParam &	m11,
		IlvTransfoParam &	m12,
		IlvTransfoParam &	m21,
		IlvTransfoParam &	m22,
		IlvTransfoParam &	x0,
		IlvTransfoParam &	y0
	)		const

Accesses the values stored in the object.

IlBoolean IlvTransformer::inverse

(

IlvPoint &

p

)

const

Applies the inverse transformation.

Applies the inverse transformation stored in this object to p, which is modified by the function call. The argument is not modified if the transformation cannot be inverted.

Parameters

p	The point to transform.

Returns

IlFalse if the transformation cannot be inverted. Otherwise, it returns IlTrue.

IlBoolean IlvTransformer::inverse

(

IlvFloatPoint &

p

)

const

Applies the inverse transformation.

Applies the inverse transformation stored in this object to the p parameter, which is modified by the function call. The argument is not modified if the transformation cannot be inverted.

Parameters

p	The point to transform.

Returns

IlFalse if the transformation cannot be inverted. Otherwise, it returns IlTrue.

IlBoolean IlvTransformer::inverse

(

IlvRect &

rect

)

const

Applies the inverse transformation.

Applies the inverse transformation stored in this object to the rect parameter, which is modified by the function call. The argument is not modified if the transformation cannot be inverted.

Parameters

rect	The rectangle to transform.

Returns

IlFalse if the transformation cannot be inverted. Otherwise, it returns IlTrue.

IlBoolean IlvTransformer::isBad

(

)

const

Indicates whether the transformer is reversible.

Returns an IlBoolean value that indicates whether the transformer is reversible. If it is not reversible, you cannot call inverse.

Returns

An IlBoolean value that, if IlTrue, indicates that the transformer is not reversible.

IlBoolean IlvTransformer::isIdentity

(

)

const

Indicates whether the current object represents the identity transformation.

Indicates whether the current object represents the identity transformation; that is, a transformation that does not change its operands.

Returns

IlTrue if the current object represents the identity transformation. Otherwise, it returns IlFalse.

IlBoolean IlvTransformer::isScale

(

)

const

Indicates whether the current object is a scaling transformation.

Indicates whether the current object is a scaling transformation; that is, a transformation that applies itself without changing the definition axis of the operands. If it returns IlFalse the transformer is more complex (for example, a rotation, or a shearing effect).

Returns

IlTrue if the current object is a scaling transformation. Otherwise, it returns IlFalse.

IlBoolean IlvTransformer::isTranslation

(

)

const

Indicates whether the current object is a translation transformation.

Indicates whether the current object is a translation transformation; that is, a transformation that applies itself without changing the direction and dimensions of its operands.

Returns

IlTrue if the current object is a translation transformation. Otherwise, it returns IlFalse.

void IlvTransformer::rotate	(	IlvTransfoParam	centerx,
		IlvTransfoParam	centery,
		IlvTransfoParam	angle
	)

Composes the transformer with a rotation.

Composes the current transformer with a rotation of angle degrees around the (centerx, centery) point.x

Parameters

centerx	Center of rotation in the x direction.
centery	Center of rotation in the y direction.
angle	Angle of rotation in degrees.

void IlvTransformer::scale	(	IlvTransfoParam	fixedx,
		IlvTransfoParam	fixedy,
		IlvTransfoParam	sx,
		IlvTransfoParam	sy
	)

Composes the transformer with a scaling operation.

Composes the current transformer with a scaling operation of sx by sy, leaving the point (fixedx, fixedy) unchanged.

Parameters

fixedx	x point to leave unchanged.
fixedy	y point to leave unchanged.
sx	Scaling in the x direction.
sy	Scaling in the y direction.

void IlvTransformer::setValues	(	IlvTransfoParam	x0,
		IlvTransfoParam	y0
	)

Sets the values that define the current IlvTransformer object.

Changes the values that define the current IlvTransformer object.

void IlvTransformer::setValues	(	IlvTransfoParam	m11,
		IlvTransfoParam	m12,
		IlvTransfoParam	m21,
		IlvTransfoParam	m22,
		IlvTransfoParam	x0,
		IlvTransfoParam	y0
	)

Sets the values that define the current IlvTransformer object.

Changes the values that define the current IlvTransformer object.

void IlvTransformer::translate	(	IlvTransfoParam	dx,
		IlvTransfoParam	dy
	)

Composes the transformer with a translation.

Composes the current transformer with a (dx, dy) translation.

Parameters

dx	Distance to translate in the x direction.
dy	Distance to translate in the y direction.