cairo_matrix_init ()

void
cairo_matrix_init (cairo_matrix_t *matrix,
                   double xx,
                   double yx,
                   double xy,
                   double yy,
                   double x0,
                   double y0);

Sets matrix to be the affine transformation given by xx , yx , xy , yy , x0 , y0 . The transformation is given by:

 x_new = xx * x + xy * y + x0;
 y_new = yx * x + yy * y + y0;

Since: 1.0

cairo_matrix_init_identity ()

void
cairo_matrix_init_identity (cairo_matrix_t *matrix);

Modifies matrix to be an identity transformation.

Since: 1.0

cairo_matrix_init_translate ()

void
cairo_matrix_init_translate (cairo_matrix_t *matrix,
                             double tx,
                             double ty);

Initializes matrix to a transformation that translates by tx and ty in the X and Y dimensions, respectively.

Since: 1.0

cairo_matrix_init_scale ()

void
cairo_matrix_init_scale (cairo_matrix_t *matrix,
                         double sx,
                         double sy);

Initializes matrix to a transformation that scales by sx and sy in the X and Y dimensions, respectively.

Since: 1.0

cairo_matrix_init_rotate ()

void
cairo_matrix_init_rotate (cairo_matrix_t *matrix,
                          double radians);

Initialized matrix to a transformation that rotates by radians .

Since: 1.0

cairo_matrix_translate ()

void
cairo_matrix_translate (cairo_matrix_t *matrix,
                        double tx,
                        double ty);

Applies a translation by tx , ty to the transformation in matrix . The effect of the new transformation is to first translate the coordinates by tx and ty , then apply the original transformation to the coordinates.

Since: 1.0

cairo_matrix_scale ()

void
cairo_matrix_scale (cairo_matrix_t *matrix,
                    double sx,
                    double sy);

Applies scaling by sx , sy to the transformation in matrix . The effect of the new transformation is to first scale the coordinates by sx and sy , then apply the original transformation to the coordinates.

Since: 1.0

cairo_matrix_rotate ()

void
cairo_matrix_rotate (cairo_matrix_t *matrix,
                     double radians);

Applies rotation by radians to the transformation in matrix . The effect of the new transformation is to first rotate the coordinates by radians , then apply the original transformation to the coordinates.

Since: 1.0

cairo_matrix_invert ()

cairo_status_t
cairo_matrix_invert (cairo_matrix_t *matrix);

Changes matrix to be the inverse of its original value. Not all transformation matrices have inverses; if the matrix collapses points together (it is degenerate), then it has no inverse and this function will fail.

Since: 1.0

cairo_matrix_multiply ()

void
cairo_matrix_multiply (cairo_matrix_t *result,
                       const cairo_matrix_t *a,
                       const cairo_matrix_t *b);

Multiplies the affine transformations in a and b together and stores the result in result . The effect of the resulting transformation is to first apply the transformation in a to the coordinates and then apply the transformation in b to the coordinates.

It is allowable for result to be identical to either a or b .

Since: 1.0

cairo_matrix_transform_distance ()

void
cairo_matrix_transform_distance (const cairo_matrix_t *matrix,
                                 double *dx,
                                 double *dy);

Transforms the distance vector (dx ,dy ) by matrix . This is similar to cairo_matrix_transform_point() except that the translation components of the transformation are ignored. The calculation of the returned vector is as follows:

dx2 = dx1 * a + dy1 * c;
dy2 = dx1 * b + dy1 * d;

Affine transformations are position invariant, so the same vector always transforms to the same vector. If (x1 ,y1 ) transforms to (x2 ,y2 ) then (x1 +dx1 ,y1 +dy1 ) will transform to (x1 +dx2 ,y1 +dy2 ) for all values of x1 and x2 .

Since: 1.0

cairo_matrix_transform_point ()

void
cairo_matrix_transform_point (const cairo_matrix_t *matrix,
                              double *x,
                              double *y);

Transforms the point (x , y ) by matrix .

Since: 1.0

cairo_matrix_t

typedef struct {
    double xx; double yx;
    double xy; double yy;
    double x0; double y0;
} cairo_matrix_t;

A cairo_matrix_t holds an affine transformation, such as a scale, rotation, shear, or a combination of those. The transformation of a point (x, y) is given by:

    x_new = xx * x + xy * y + x0;
    y_new = yx * x + yy * y + y0;

Since: 1.0