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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);
The current transformation matrix, ctm, is a two-dimensional affine transformation that maps all coordinates and other drawing instruments from the user space into the surface's canonical coordinate system, also known as the device space.
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.
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a cairo context |
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amount to translate in the X direction |
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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.
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a cairo context |
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scale factor for the X dimension |
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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.
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a cairo context |
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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.
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a cairo context |
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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.
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a cairo context |
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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.
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a cairo context |
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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.
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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).
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a cairo context |
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X value of coordinate (in/out parameter) |
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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).
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a cairo context |
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X component of a distance vector (in/out parameter) |
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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).
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a cairo |
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X value of coordinate (in/out parameter) |
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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).
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a cairo context |
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X component of a distance vector (in/out parameter) |
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Y component of a distance vector (in/out parameter) |