package ocgtk

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OCaml bindings for GTK 4

Install 

dune-project
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github.com Edit opam file Versions (2)

Authors

  1. C
    Chris Armstrong

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  1. H
    hello@chrisarmstrong.dev

Sources

v0.1-preview2.tar.gz
sha256=4e50fdb5093136a10fc8ffbe388e44cbcb70d52f8afdd48863ec7e22580ff054

doc/ocgtk.pango/Ocgtk_pango/Pango/Wrappers/Matrix/index.html

Module Wrappers.Matrix

type t = [ `matrix ] Gobject.obj

A `PangoMatrix` specifies a transformation between user-space and device coordinates.

The transformation is given by

``` x_device = x_user * matrix->xx + y_user * matrix->xy + matrix->x0; y_device = x_user * matrix->yx + y_user * matrix->yy + matrix->y0; ```

val translate : t -> float -> float -> unit

Changes the transformation represented by @matrix to be the transformation given by first translating by (@tx, @ty) then applying the original transformation.

val transform_rectangle : t -> [ `rectangle ] Gobject.obj -> unit

First transforms @rect using @matrix, then calculates the bounding box of the transformed rectangle.

This function is useful for example when you want to draw a rotated @PangoLayout to an image buffer, and want to know how large the image should be and how much you should shift the layout when rendering.

If you have a rectangle in device units (pixels), use method@Pango.Matrix.transform_pixel_rectangle.

If you have the rectangle in Pango units and want to convert to transformed pixel bounding box, it is more accurate to transform it first (using this function) and pass the result to pango_extents_to_pixels(), first argument, for an inclusive rounded rectangle. However, there are valid reasons that you may want to convert to pixels first and then transform, for example when the transformed coordinates may overflow in Pango units (large matrix translation for example).

val transform_point : t -> float -> float -> unit

Transforms the point (@x, @y) by @matrix.

val transform_pixel_rectangle : t -> [ `rectangle ] Gobject.obj -> unit

First transforms the @rect using @matrix, then calculates the bounding box of the transformed rectangle.

This function is useful for example when you want to draw a rotated @PangoLayout to an image buffer, and want to know how large the image should be and how much you should shift the layout when rendering.

For better accuracy, you should use method@Pango.Matrix.transform_rectangle on original rectangle in Pango units and convert to pixels afterward using func@extents_to_pixels's first argument.

val transform_distance : t -> float -> float -> unit

Transforms the distance vector (@dx,@dy) by @matrix.

This is similar to method@Pango.Matrix.transform_point, except that the translation components of the transformation are ignored. The calculation of the returned vector is as follows:

``` dx2 = dx1 * xx + dy1 * xy; dy2 = dx1 * yx + dy1 * yy; ```

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.

val scale : t -> float -> float -> unit

Changes the transformation represented by @matrix to be the transformation given by first scaling by @sx in the X direction and @sy in the Y direction then applying the original transformation.

val rotate : t -> float -> unit

Changes the transformation represented by @matrix to be the transformation given by first rotating by @degrees degrees counter-clockwise then applying the original transformation.

val get_slant_ratio : t -> float

Gets the slant ratio of a matrix.

For a simple shear matrix in the form:

1 λ 0 1

this is simply λ.

val get_font_scale_factors : t -> float * float

Calculates the scale factor of a matrix on the width and height of the font.

That is, @xscale is the scale factor in the direction of the X coordinate, and @yscale is the scale factor in the direction perpendicular to the vector that the X coordinate is mapped to.

Note that output numbers will always be non-negative.

val get_font_scale_factor : t -> float

Returns the scale factor of a matrix on the height of the font.

That is, the scale factor in the direction perpendicular to the vector that the X coordinate is mapped to. If the scale in the X coordinate is needed as well, use method@Pango.Matrix.get_font_scale_factors.

val concat : t -> t -> unit

Changes the transformation represented by @matrix to be the transformation given by first applying transformation given by @new_matrix then applying the original transformation.

val get_type : unit -> Gobject.Type.t