package cairo2

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Module Cairo.MatrixSource

This is used throughout cairo to convert between different coordinate spaces.

Sourcetype t = matrix
Sourceval init_identity : unit -> t

init_identity() returns the identity transformation.

Sourceval init_translate : float -> float -> t

init_translate tx ty return a transformation that translates by tx and ty in the X and Y dimensions, respectively.

Sourceval init_scale : float -> float -> t

init_scale sx sy return a transformation that scales by sx and sy in the X and Y dimensions, respectively.

Sourceval init_rotate : float -> t

init_rotate radians returns a a transformation that rotates by radians.

Sourceval translate : t -> float -> float -> unit

translate matrix tx 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.

Sourceval scale : t -> float -> float -> unit

scale matrix sx 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.

Sourceval rotate : t -> float -> unit

rotate matrix 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.

Sourceval invert : t -> unit

invert matrix changes matrix to be the inverse of it's 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 raise Error INVALID_MATRIX.

Sourceval multiply : t -> t -> t

multiply a b multiplies the affine transformations in a and b together and return the 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.

Sourceval transform_distance : t -> dx:float -> dy:float -> float * float

transform_distance matrix dx 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.

Sourceval transform_point : t -> float -> float -> float * float

transform_point matrix x y transforms the point (x, y) by matrix.