Wt
3.2.3
|
A value class that defines a 2D affine transformation matrix. More...
#include <Wt/WTransform>
Classes | |
struct | TRSRDecomposition |
Result of a TRSR decomposition. More... | |
struct | TRSSDecomposition |
Result of a TRSS decomposition. More... | |
Public Member Functions | |
WTransform () | |
Default constructor. | |
WTransform (double m11, double m12, double m21, double m22, double dx, double dy) | |
Construct a custom matrix by specifying the parameters. | |
WTransform & | operator= (const WTransform &rhs) |
Assignment operator. | |
bool | operator== (const WTransform &rhs) const |
Comparison operator. | |
bool | operator!= (const WTransform &rhs) const |
Comparison operator. | |
bool | isIdentity () const |
Identity check. | |
double | m11 () const |
Returns the horizontal scaling factor. | |
double | m12 () const |
Returns the vertical shearing factor. | |
double | m13 () const |
Returns m13 = 0. | |
double | m21 () const |
Returns the horizontal shearing factor. | |
double | m22 () const |
Returns the vertical scaling factor. | |
double | m23 () const |
Returns m23 = 0. | |
double | m31 () const |
Returns the horizontal translation factor. | |
double | m32 () const |
Returns the vertical translation factor. | |
double | m33 () const |
Returns m33 = 1. | |
double | dx () const |
Returns the horizontal translation factor. | |
double | dy () const |
Returns the vertical translation factor. | |
WPointF | map (const WPointF &p) const |
Applys the transformation to a point. | |
void | map (double x, double y, double *tx, double *ty) const |
Applys the transformation to a point. | |
void | reset () |
Resets the transformation to the identity. | |
WTransform & | rotate (double angle) |
Rotates the transformation. | |
WTransform & | rotateRadians (double angle) |
Rotates the transformation. | |
WTransform & | scale (double sx, double sy) |
Scales the transformation. | |
WTransform & | shear (double sh, double sv) |
Shears the transformation. | |
WTransform & | translate (double dx, double dy) |
Translates the transformation. | |
WTransform & | operator*= (const WTransform &rhs) |
Adds a transform that is conceptually applied after this transform. | |
WTransform | operator* (const WTransform &rhs) const |
Multiply 2 transform objects. | |
double | determinant () const |
Returns the determinant. | |
WTransform | adjoint () const |
Returns the adjoint. | |
WTransform | inverted () const |
Returns the inverted transformation. | |
void | decomposeTranslateRotateScaleSkew (TRSSDecomposition &result) const |
Decomposes the transformation. | |
void | decomposeTranslateRotateScaleRotate (TRSRDecomposition &result) const |
Decomposes the transformation. | |
Static Public Member Functions | |
static double | degreesToRadians (double angle) |
Utility method to convert degrees to radians. | |
Static Public Attributes | |
static const WTransform | Identity |
A constant that represents the identity transform. |
A value class that defines a 2D affine transformation matrix.
The matrix is encoded using 6 parameters:
In this representation, dx() (= m31()) and dy() (= m32()) represent the translation components, and mxy represent a 2D matrix that contains the scale, rotation (and skew) components.
The transformation is used to represent a tansformed coordinate system, and provides methods to rotate(), scale(), shear() or translate() this coordinate system.
There are also 2 methods to decompose an arbitrary matrix into elementary operations:
with T a translation, R a rotation, Sxx a scale, and Sxy a skew component.
Wt::WTransform::WTransform | ( | ) |
Default constructor.
Creates the identity transformation matrix.
Wt::WTransform::WTransform | ( | double | m11, |
double | m12, | ||
double | m21, | ||
double | m22, | ||
double | dx, | ||
double | dy | ||
) |
Construct a custom matrix by specifying the parameters.
Creates a matrix from the specified parameters.
void Wt::WTransform::decomposeTranslateRotateScaleRotate | ( | TRSRDecomposition & | result | ) | const |
Decomposes the transformation.
Decomposes the transformation into elementary operations: translation (dx, dy
), followed by rotation (alpha2), followed by scale (sx, sy
) and again a rotation (alpha2
). The angles are expressed in radians.
This performs a Singular Value Decomposition (SVD).
void Wt::WTransform::decomposeTranslateRotateScaleSkew | ( | TRSSDecomposition & | result | ) | const |
Decomposes the transformation.
Decomposes the transformation into elementary operations: translation (dx, dy
), followed by rotation (alpha), followed by scale (sx, sy
) and vertical shearing factor (sh
). The angle is expressed in radians.
This performs a Gram-Schmidt orthonormalization.
double Wt::WTransform::dx | ( | ) | const |
Returns the horizontal translation factor.
Is equivalent to m31()
double Wt::WTransform::dy | ( | ) | const |
Returns the vertical translation factor.
Is equivalent to m32()
WTransform Wt::WTransform::inverted | ( | ) | const |
Returns the inverted transformation.
Returns this
if the transformation could not be inverted (determinant() == 0), and logs an error instead.
bool Wt::WTransform::isIdentity | ( | ) | const |
Identity check.
Returns true if the transform represents an identity transformation.
double Wt::WTransform::m31 | ( | ) | const |
Returns the horizontal translation factor.
Is equivalent to dx()
double Wt::WTransform::m32 | ( | ) | const |
Returns the vertical translation factor.
Is equivalent to dy()
Applys the transformation to a point.
Returns the transformed point.
void Wt::WTransform::map | ( | double | x, |
double | y, | ||
double * | tx, | ||
double * | ty | ||
) | const |
Applys the transformation to a point.
Sets the point (tx, ty
) to the transformation of the point (x, y
).
bool Wt::WTransform::operator!= | ( | const WTransform & | rhs | ) | const |
Comparison operator.
Returns true
if the transforms are different.
WTransform & Wt::WTransform::operator= | ( | const WTransform & | rhs | ) |
Assignment operator.
Copies the transformation from the rhs
.
bool Wt::WTransform::operator== | ( | const WTransform & | rhs | ) | const |
Comparison operator.
Returns true
if the transforms are exactly the same.
void Wt::WTransform::reset | ( | ) |
Resets the transformation to the identity.
WTransform & Wt::WTransform::rotate | ( | double | angle | ) |
Rotates the transformation.
Applies a clock-wise rotation to the current transformation matrix, over angle
degrees.
WTransform & Wt::WTransform::rotateRadians | ( | double | angle | ) |
Rotates the transformation.
Applies a clock-wise rotation to the current transformation matrix, over angle
radians.
WTransform & Wt::WTransform::scale | ( | double | sx, |
double | sy | ||
) |
Scales the transformation.
Applies a clock-wise rotation to the current transformation matrix, over angle
radians.
WTransform & Wt::WTransform::shear | ( | double | sh, |
double | sv | ||
) |
WTransform & Wt::WTransform::translate | ( | double | dx, |
double | dy | ||
) |
Translates the transformation.
Translates the current transformation.
const WTransform Wt::WTransform::Identity [static] |
A constant that represents the identity transform.