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Wt
3.3.0
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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.
1.7.5.1