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Cairo: A Vector Graphics Library | |
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void cairo_translate (cairo_t *cr, double tx, double ty); void cairo_scale (cairo_t *cr, double sx, double sy); void cairo_rotate (cairo_t *cr, double angle); void cairo_transform (cairo_t *cr, const cairo_matrix_t *matrix); void cairo_set_matrix (cairo_t *cr, const cairo_matrix_t *matrix); void cairo_get_matrix (cairo_t *cr, cairo_matrix_t *matrix); void cairo_identity_matrix (cairo_t *cr); void cairo_user_to_device (cairo_t *cr, double *x, double *y); void cairo_user_to_device_distance (cairo_t *cr, double *dx, double *dy); void cairo_device_to_user (cairo_t *cr, double *x, double *y); void cairo_device_to_user_distance (cairo_t *cr, double *dx, double *dy);
void cairo_translate (cairo_t *cr, double tx, double ty);
Modifies the current transformation matrix (CTM) by translating the
user-space origin by (tx, ty). This offset is interpreted as a
user-space coordinate according to the CTM in place before the new
call to cairo_translate. In other words, the translation of the
user-space origin takes place after any existing transformation.
cr : |
a cairo context |
tx : |
amount to translate in the X direction |
ty : |
amount to translate in the Y direction |
void cairo_scale (cairo_t *cr, double sx, double sy);
Modifies the current transformation matrix (CTM) by scaling the X
and Y user-space axes by sx and sy respectively. The scaling of
the axes takes place after any existing transformation of user
space.
cr : |
a cairo context |
sx : |
scale factor for the X dimension |
sy : |
scale factor for the Y dimension |
void cairo_rotate (cairo_t *cr, double angle);
Modifies the current transformation matrix (CTM) by rotating the
user-space axes by angle radians. The rotation of the axes takes
places after any existing transformation of user space. The
rotation direction for positive angles is from the positive X axis
toward the positive Y axis.
cr : |
a cairo context |
angle : |
angle (in radians) by which the user-space axes will be rotated |
void cairo_transform (cairo_t *cr, const cairo_matrix_t *matrix);
Modifies the current transformation matrix (CTM) by applying
matrix as an additional transformation. The new transformation of
user space takes place after any existing transformation.
cr : |
a cairo context |
matrix : |
a transformation to be applied to the user-space axes |
void cairo_set_matrix (cairo_t *cr, const cairo_matrix_t *matrix);
Modifies the current transformation matrix (CTM) by setting it
equal to matrix.
cr : |
a cairo context |
matrix : |
a transformation matrix from user space to device space |
void cairo_get_matrix (cairo_t *cr, cairo_matrix_t *matrix);
Stores the current transformation matrix (CTM) into matrix.
cr : |
a cairo context |
matrix : |
return value for the matrix |
void cairo_identity_matrix (cairo_t *cr);
Resets the current transformation matrix (CTM) by setting it equal to the identity matrix. That is, the user-space and device-space axes will be aligned and one user-space unit will transform to one device-space unit.
cr : |
a cairo context |
void cairo_user_to_device (cairo_t *cr, double *x, double *y);
Transform a coordinate from user space to device space by multiplying the given point by the current transformation matrix (CTM).
cr : |
a cairo context |
x : |
X value of coordinate (in/out parameter) |
y : |
Y value of coordinate (in/out parameter) |
void cairo_user_to_device_distance (cairo_t *cr, double *dx, double *dy);
Transform a distance vector from user space to device space. This
function is similar to cairo_user_to_device() except that the
translation components of the CTM will be ignored when transforming
(dx,dy).
cr : |
a cairo context |
dx : |
X component of a distance vector (in/out parameter) |
dy : |
Y component of a distance vector (in/out parameter) |
void cairo_device_to_user (cairo_t *cr, double *x, double *y);
Transform a coordinate from device space to user space by multiplying the given point by the inverse of the current transformation matrix (CTM).
cr : |
a cairo |
x : |
X value of coordinate (in/out parameter) |
y : |
Y value of coordinate (in/out parameter) |
void cairo_device_to_user_distance (cairo_t *cr, double *dx, double *dy);
Transform a distance vector from device space to user space. This
function is similar to cairo_device_to_user() except that the
translation components of the inverse CTM will be ignored when
transforming (dx,dy).
cr : |
a cairo context |
dx : |
X component of a distance vector (in/out parameter) |
dy : |
Y component of a distance vector (in/out parameter) |