GimpMatrix: GIMP Math Library Reference Manual

GimpMatrix

GimpMatrix — Utilities to set up and manipulate 3x3 transformation matrices.

Functions

void	gimp_matrix2_identity ()
void	gimp_matrix2_mult ()
gdouble	gimp_matrix2_determinant ()
void	gimp_matrix2_invert ()
void	gimp_matrix2_transform_point ()
void	gimp_matrix3_identity ()
void	gimp_matrix3_mult ()
void	gimp_matrix3_translate ()
void	gimp_matrix3_scale ()
void	gimp_matrix3_rotate ()
void	gimp_matrix3_xshear ()
void	gimp_matrix3_yshear ()
void	gimp_matrix3_affine ()
void	gimp_matrix3_transform_point ()
gdouble	gimp_matrix3_determinant ()
void	gimp_matrix3_invert ()
gboolean	gimp_matrix3_is_identity ()
gboolean	gimp_matrix3_is_diagonal ()
gboolean	gimp_matrix3_is_affine ()
gboolean	gimp_matrix3_is_simple ()
gboolean	gimp_matrix3_equal ()
void	gimp_matrix4_identity ()
void	gimp_matrix4_mult ()
void	gimp_matrix4_to_deg ()
gdouble	gimp_matrix4_transform_point ()
#define	GIMP_IS_PARAM_SPEC_MATRIX2()
GParamSpec *	gimp_param_spec_matrix2 ()
#define	GIMP_VALUE_HOLDS_MATRIX2()
#define	GIMP_IS_PARAM_SPEC_MATRIX3()
GParamSpec *	gimp_param_spec_matrix3 ()
#define	GIMP_VALUE_HOLDS_MATRIX3()

Types and Values

struct	GimpMatrix2
struct	GimpMatrix3
struct	GimpMatrix4
#define	GIMP_TYPE_MATRIX2
#define	GIMP_TYPE_PARAM_MATRIX2
#define	GIMP_TYPE_MATRIX3
#define	GIMP_TYPE_PARAM_MATRIX3

Description

When doing image manipulation you will often need 3x3 transformation matrices that define translation, rotation, scaling, shearing and arbitrary perspective transformations using a 3x3 matrix. Here you'll find a set of utility functions to set up those matrices and to perform basic matrix manipulations and tests.

Each matrix class has a 2 dimensional gdouble coeff member. The element for row r and column c of the matrix is coeffr.

Functions

gimp_matrix2_identity ()

void
gimp_matrix2_identity (GimpMatrix2 *matrix);

Sets the matrix to the identity matrix.

Parameters

matrix

A matrix.

gimp_matrix2_mult ()

void
gimp_matrix2_mult (const GimpMatrix2 *matrix1,
                   GimpMatrix2 *matrix2);

Multiplies two matrices and puts the result into the second one.

Parameters

matrix1	The first input matrix.
matrix2	The second input matrix which will be overwritten by the result.

gimp_matrix2_determinant ()

gdouble
gimp_matrix2_determinant (const GimpMatrix2 *matrix);

Calculates the determinant of the given matrix.

Parameters

matrix

The input matrix.

Returns

The determinant.

Since: 2.10.16

gimp_matrix2_invert ()

void
gimp_matrix2_invert (GimpMatrix2 *matrix);

Inverts the given matrix.

Parameters

matrix

The matrix that is to be inverted.

Since: 2.10.16

gimp_matrix2_transform_point ()

void
gimp_matrix2_transform_point (const GimpMatrix2 *matrix,
                              gdouble x,
                              gdouble y,
                              gdouble *newx,
                              gdouble *newy);

Transforms a point in 2D as specified by the transformation matrix.

Parameters

matrix	The transformation matrix.
x	The source X coordinate.
y	The source Y coordinate.
newx	The transformed X coordinate.
newy	The transformed Y coordinate.

Since: 2.10.16

gimp_matrix3_identity ()

void
gimp_matrix3_identity (GimpMatrix3 *matrix);

Sets the matrix to the identity matrix.

Parameters

matrix

A matrix.

gimp_matrix3_mult ()

void
gimp_matrix3_mult (const GimpMatrix3 *matrix1,
                   GimpMatrix3 *matrix2);

Multiplies two matrices and puts the result into the second one.

Parameters

matrix1	The first input matrix.
matrix2	The second input matrix which will be overwritten by the result.

gimp_matrix3_translate ()

void
gimp_matrix3_translate (GimpMatrix3 *matrix,
                        gdouble x,
                        gdouble y);

Translates the matrix by x and y.

Parameters

matrix	The matrix that is to be translated.
x	Translation in X direction.
y	Translation in Y direction.

gimp_matrix3_scale ()

void
gimp_matrix3_scale (GimpMatrix3 *matrix,
                    gdouble x,
                    gdouble y);

Scales the matrix by x and y

Parameters

matrix	The matrix that is to be scaled.
x	X scale factor.
y	Y scale factor.

gimp_matrix3_rotate ()

void
gimp_matrix3_rotate (GimpMatrix3 *matrix,
                     gdouble theta);

Rotates the matrix by theta degrees.

Parameters

matrix	The matrix that is to be rotated.
theta	The angle of rotation (in radians).

gimp_matrix3_xshear ()

void
gimp_matrix3_xshear (GimpMatrix3 *matrix,
                     gdouble amount);

Shears the matrix in the X direction.

Parameters

matrix	The matrix that is to be sheared.
amount	X shear amount.

gimp_matrix3_yshear ()

void
gimp_matrix3_yshear (GimpMatrix3 *matrix,
                     gdouble amount);

Shears the matrix in the Y direction.

Parameters

matrix	The matrix that is to be sheared.
amount	Y shear amount.

gimp_matrix3_affine ()

void
gimp_matrix3_affine (GimpMatrix3 *matrix,
                     gdouble a,
                     gdouble b,
                     gdouble c,
                     gdouble d,
                     gdouble e,
                     gdouble f);

Applies the affine transformation given by six values to matrix . The six values form define an affine transformation matrix as illustrated below:

( a c e ) ( b d f ) ( 0 0 1 )

Parameters

matrix	The input matrix.
a	the 'a' coefficient
b	the 'b' coefficient
c	the 'c' coefficient
d	the 'd' coefficient
e	the 'e' coefficient
f	the 'f' coefficient

gimp_matrix3_transform_point ()

void
gimp_matrix3_transform_point (const GimpMatrix3 *matrix,
                              gdouble x,
                              gdouble y,
                              gdouble *newx,
                              gdouble *newy);

Transforms a point in 2D as specified by the transformation matrix.

Parameters

matrix	The transformation matrix.
x	The source X coordinate.
y	The source Y coordinate.
newx	The transformed X coordinate.
newy	The transformed Y coordinate.

gimp_matrix3_determinant ()

gdouble
gimp_matrix3_determinant (const GimpMatrix3 *matrix);

Calculates the determinant of the given matrix.

Parameters

matrix

The input matrix.

Returns

The determinant.

gimp_matrix3_invert ()

void
gimp_matrix3_invert (GimpMatrix3 *matrix);

Inverts the given matrix.

Parameters

matrix

The matrix that is to be inverted.

gimp_matrix3_is_identity ()

gboolean
gimp_matrix3_is_identity (const GimpMatrix3 *matrix);

Checks if the given matrix is the identity matrix.

Parameters

matrix

The matrix that is to be tested.

Returns

TRUE if the matrix is the identity matrix, FALSE otherwise

gimp_matrix3_is_diagonal ()

gboolean
gimp_matrix3_is_diagonal (const GimpMatrix3 *matrix);

Checks if the given matrix is diagonal.

Parameters

matrix

The matrix that is to be tested.

Returns

TRUE if the matrix is diagonal, FALSE otherwise

gimp_matrix3_is_affine ()

gboolean
gimp_matrix3_is_affine (const GimpMatrix3 *matrix);

Checks if the given matrix defines an affine transformation.

Parameters

matrix

The matrix that is to be tested.

Returns

TRUE if the matrix defines an affine transformation, FALSE otherwise

Since: 2.4

gimp_matrix3_is_simple ()

gboolean
gimp_matrix3_is_simple (const GimpMatrix3 *matrix);

Checks if we'll need to interpolate when applying this matrix as a transformation.

Parameters

matrix

The matrix that is to be tested.

Returns

TRUE if all entries of the upper left 2x2 matrix are either 0 or 1, FALSE otherwise

gimp_matrix3_equal ()

gboolean
gimp_matrix3_equal (const GimpMatrix3 *matrix1,
                    const GimpMatrix3 *matrix2);

Checks if two matrices are equal.

Parameters

matrix1	The first matrix
matrix2	The second matrix

Returns

TRUE the matrices are equal, FALSE otherwise

Since: 2.10.16

gimp_matrix4_identity ()

void
gimp_matrix4_identity (GimpMatrix4 *matrix);

Sets the matrix to the identity matrix.

Parameters

matrix

A matrix.

Since: 2.10.16

gimp_matrix4_mult ()

void
gimp_matrix4_mult (const GimpMatrix4 *matrix1,
                   GimpMatrix4 *matrix2);

Multiplies two matrices and puts the result into the second one.

Parameters

matrix1	The first input matrix.
matrix2	The second input matrix which will be overwritten by the result.

Since: 2.10.16

gimp_matrix4_to_deg ()

void
gimp_matrix4_to_deg (const GimpMatrix4 *matrix,
                     gdouble *a,
                     gdouble *b,
                     gdouble *c);

gimp_matrix4_transform_point ()

gdouble
gimp_matrix4_transform_point (const GimpMatrix4 *matrix,
                              gdouble x,
                              gdouble y,
                              gdouble z,
                              gdouble *newx,
                              gdouble *newy,
                              gdouble *newz);

Transforms a point in 3D as specified by the transformation matrix.

Parameters

matrix	The transformation matrix.
x	The source X coordinate.
y	The source Y coordinate.
z	The source Z coordinate.
newx	The transformed X coordinate.
newy	The transformed Y coordinate.
newz	The transformed Z coordinate.

Returns

The transformed W coordinate.

Since: 2.10.16

GIMP_IS_PARAM_SPEC_MATRIX2()

#define GIMP_IS_PARAM_SPEC_MATRIX2(pspec)  (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_MATRIX2))

gimp_param_spec_matrix2 ()

GParamSpec *
gimp_param_spec_matrix2 (const gchar *name,
                         const gchar *nick,
                         const gchar *blurb,
                         const GimpMatrix2 *default_value,
                         GParamFlags flags);

Creates a param spec to hold a GimpMatrix2 value. See g_param_spec_internal() for more information.

Parameters

name	Canonical name of the param
nick	Nickname of the param
blurb	Brief description of param.
default_value	Value to use if none is assigned.
flags	a combination of GParamFlags

Returns

a newly allocated GParamSpec instance

Since: 2.4

GIMP_VALUE_HOLDS_MATRIX2()

#define GIMP_VALUE_HOLDS_MATRIX2(value) (G_TYPE_CHECK_VALUE_TYPE ((value), GIMP_TYPE_MATRIX2))

GIMP_IS_PARAM_SPEC_MATRIX3()

#define GIMP_IS_PARAM_SPEC_MATRIX3(pspec)  (G_TYPE_CHECK_INSTANCE_TYPE ((pspec), GIMP_TYPE_PARAM_MATRIX3))

gimp_param_spec_matrix3 ()

GParamSpec *
gimp_param_spec_matrix3 (const gchar *name,
                         const gchar *nick,
                         const gchar *blurb,
                         const GimpMatrix3 *default_value,
                         GParamFlags flags);

Creates a param spec to hold a GimpMatrix3 value. See g_param_spec_internal() for more information.

Parameters

name	Canonical name of the param
nick	Nickname of the param
blurb	Brief description of param.
default_value	Value to use if none is assigned.
flags	a combination of GParamFlags

Returns

a newly allocated GParamSpec instance

Since: 2.8

GIMP_VALUE_HOLDS_MATRIX3()

#define GIMP_VALUE_HOLDS_MATRIX3(value) (G_TYPE_CHECK_VALUE_TYPE ((value), GIMP_TYPE_MATRIX3))

Types and Values

struct GimpMatrix2

struct GimpMatrix2 {
  gdouble coeff[2][2];
};

A two by two matrix.

Members

gdouble coeff[2][2];

the coefficients

struct GimpMatrix3

struct GimpMatrix3 {
  gdouble coeff[3][3];
};

A three by three matrix.

Members

gdouble coeff[3][3];

the coefficients

struct GimpMatrix4

struct GimpMatrix4 {
  gdouble coeff[4][4];
};

A four by four matrix.

Members

gdouble coeff[4][4];

the coefficients

GIMP_TYPE_MATRIX2

#define GIMP_TYPE_MATRIX2               (gimp_matrix2_get_type ())

GIMP_TYPE_PARAM_MATRIX2

#define GIMP_TYPE_PARAM_MATRIX2            (gimp_param_matrix2_get_type ())

GIMP_TYPE_MATRIX3

#define GIMP_TYPE_MATRIX3               (gimp_matrix3_get_type ())

GIMP_TYPE_PARAM_MATRIX3

#define GIMP_TYPE_PARAM_MATRIX3            (gimp_param_matrix3_get_type ())