Class (GI Struct)

Pango-1.0 ▶ Pango ▶ MatrixSince 1.6

A Pango.Matrix 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;

1.6

Index

Constructors

constructor

Properties

x0 xx xy y0 yx yy $gtype

Methods

concat copy free get_font_scale_factor get_font_scale_factors get_slant_ratio rotate scale transform_distance transform_pixel_rectangle transform_point transform_rectangle translate

Constructors

  • Parameters

    • Optionalproperties: Partial<
          {
              x0: number;
              xx: number;
              xy: number;
              y0: number;
              yx: number;
              yy: number;
          },
      >

    Returns Pango.Matrix

Properties

x0: number
xx: number
xy: number
y0: number
yx: number
yy: number
$gtype: GType<Pango.Matrix>

Methods

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

    Parameters

    Returns void

  • 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 Pango.Matrix.get_font_scale_factors.

    Returns number

    the scale factor of matrix on the height of the font, or 1.0 if matrix is null.

  • 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.

    Returns [number, number]

  • Gets the slant ratio of a matrix.

    For a simple shear matrix in the form:

    1 λ
0 1

    this is simply λ.

    Returns number

    the slant ratio of matrix

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

    Parameters

    • degrees: number

      degrees to rotate counter-clockwise

    Returns void

  • 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.

    Parameters

    • scale_x: number

      amount to scale by in X direction

    • scale_y: number

      amount to scale by in Y direction

    Returns void

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

    This is similar to 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.

    Parameters

    • dx: number

      in/out X component of a distance vector

    • dy: number

      in/out Y component of a distance vector

    Returns [number, number]

  • 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 Pango.Matrix.transform_rectangle on original rectangle in Pango units and convert to pixels afterward using extents_to_pixels's first argument.

    Parameters

    Returns Pango.Rectangle

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

    Parameters

    • x: number

      in/out X position

    • y: number

      in/out Y position

    Returns [number, number]

  • 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 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).

    Parameters

    Returns Pango.Rectangle

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

    Parameters

    • tx: number

      amount to translate in the X direction

    • ty: number

      amount to translate in the Y direction

    Returns void