Quad

Represents a four-sided mathematical shape (also called “quadrilateral” or “tetragon”) in the plane, defined as a sequence of four Point objects ul, ur, ll, lr (conveniently called upper left, upper right, lower left, lower right).

In (Py) MuPDF, only quads with four 90-degree angles and non-empty areas are of actual interest.

Such “interesting” quads can be obtained as results of text search methods (Page.searchFor()), and they are used to define text marker annotations (see e.g. Page.addSquigglyAnnot() and friends).

Note

If m is a rotation, scale or a translation Matrix, and rect is a rectangle, then the four points rect.tl * m, rect.tr * m, rect.bl * m, and rect.br * m are the corners of a rectangular quad. This is not in general true – examples are shear matrices which produce parallelograms.

Note

This class provides an attribute to calculate the envelopping rectangle. Vice versa, rectangles now have the attribute Rect.quad, resp. IRect.quad to obtain their respective tetragon versions.

Methods / Attributes

Short Description

Quad.transform()

transform with a matrix

Quad.ul

upper left point

Quad.ur

upper right point

Quad.ll

lower left point

Quad.lr

lower right point

Quad.isEmpty

true if corners define an empty area

Quad.isRectangular

true if all angles are 90 degrees

Quad.rect

smallest containing Rect

Quad.width

the longest width value

Quad.height

the longest height value

Class API

class Quad
__init__(self)
__init__(self, ul, ur, ll, lr)
__init__(self, quad)
__init__(self, sequence)

Overloaded constructors: ul, ur, ll, lr stand for Point objects (the 4 corners), “sequence” is a Python sequence type with 4 Point objects.

If “quad” is specified, the constructor creates a new copy of it.

Without parameters, a quad consisting of 4 copies of Point(0, 0) is created.

transform(matrix)

Modify the quadrilateral by transforming each of its corners with a matrix.

rect

The smallest rectangle containing the quad, represented by the blue area in the following picture.

_images/img-quads.jpg
Type

Rect

ul

Upper left point.

Type

Point

ur

Upper right point.

Type

Point

ll

Lower left point.

Type

Point

lr

Lower right point.

Type

Point

isEmpty

True if enclosed area is zero, i.e. all points are on the same line. If this is false, the quad may still not look like a rectangle (but more like a triangle, trapezoid, etc.).

Type

bool

isRectangular

True if all angles are 90 degrees. This also implies that the area is not empty.

Type

bool

width

The maximum length of the top and the bottom side.

Type

float

height

The maximum length of the left and the right side.

Type

float

Remark

This class adheres to the sequence protocol, so components can be dealt with via their indices, too. Also refer to Using Python Sequences as Arguments in PyMuPDF.

We are still in process to extend algebraic operations to quads. Multiplication and division with / by numbers and matrices are already defined. Addition, subtraction and any unary operations may follow when we see an actual need.