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Module Pdftransform

module Pdftransform: sig .. end

Affine Transformations in Two Dimensions

Types

type transform_op =
| Scale of (float * float) * float * float
| Rotate of (float * float) * float
| Translate of float * float
| ShearX of (float * float) * float
| ShearY of (float * float) * float

A single transformation operation.

type transform = transform_op list

A list of transformations, the first at the end of the list (thus, to append another transformation, just cons to the beginning.)

type transform_matrix = {
   a : float;
   b : float;
   c : float;
   d : float;
   e : float;
   f : float;
}

A transformation matrix (first row a c e, second row b d f, third row 0 0 1)

val i : transform

The identity transform

val string_of_transform : transform -> string

Make a string of a transform for debug purposes.

Making transformation matrices

val i_matrix : transform_matrix

The identity matrix

val string_of_matrix : transform_matrix -> string

String of a transformation matrix.

val mktranslate : float -> float -> transform_matrix

Make a transformation matrix from x and y translation.

val mkscale : float * float -> float -> float -> transform_matrix

Make a transformation matrix from an x and y scale and a point to scale about.

val mkrotate : float * float -> float -> transform_matrix

Make a rotation matrix to rotate by a number of radians around a point.

val mkshearx : float * float -> float -> transform_matrix

Matrix to shear in x by a given factor about a point.

val mksheary : float * float -> float -> transform_matrix

Matrix to shear in y by a given factor about a point.

Composing and manipulating transforms

val compose : transform_op -> transform -> transform

compose t ts adds operation t to the transform ts.

val append : transform -> transform -> transform

append a b is a transform with the same effect as performing b then a

val matrix_compose : transform_matrix ->
       transform_matrix -> transform_matrix

compose a b produces a matrix equivalent to performing b then a.

val matrix_of_op : transform_op -> transform_matrix

Make a matrix from a single transformation operation

val matrix_of_transform : transform -> transform_matrix

Make a matrix from a transform

Inverting transforms

exception NonInvertable

Exception raised if a matrix is non-invertable

val matrix_invert : transform_matrix -> transform_matrix

Matrix inversion. May raise NonInvertable

val transform : transform -> float * float -> float * float

Transform a coordinate by a given transform.

val transform_matrix : transform_matrix -> float * float -> float * float

Transform a coordinate by a given transformation matrix.

Decomposing and recomposing matrices

val decompose : transform_matrix ->
       float * float * float * float * float * float

Decompose a transformation matrix to scale, aspect, rotation, shear, translation in x, translation in y. Always succeeds, but results are not guaranteed to mean anything.

val recompose : float ->
       float -> float -> float -> float -> float -> transform_matrix

Recompose from the above information. It is not guaranteed that recompose (decompose t) = t