OpenCV  4.5.0-pre
Open Source Computer Vision
Some Data Structures

Goal

Scalar is array type in Javascript. Point, Size, Circle, Rect and RotatedRect are object type in JavaScript.

Point

There are 2 ways to construct a Point and they are the same:

// The first way
let point = new cv.Point(x, y);
// The second way
let point = {x: x, y: y};
Parameters
xx coordinate of the point.(the origin is the top left corner of the image)
yy coordinate of the point.

Scalar

There are 2 ways to construct a Scalar and they are the same:

// The first way
let scalar = new cv.Scalar(R, G, B, Alpha);
// The second way
let scalar = [R, G, B, Alpha];
Parameters
Rpixel value of red channel.
Gpixel value of green channel.
Bpixel value of blue channel.
Alphapixel value of alpha channel.

Size

There are 2 ways to construct a Size and they are the same:

// The first way
let size = new cv.Size(width, height);
// The second way
let size = {width : width, height : height};
Parameters
widththe width of the size.
heightthe height of the size.

Circle

There are 2 ways to construct a Circle and they are the same:

// The first way
let circle = new cv.Circle(center, radius);
// The second way
let circle = {center : center, radius : radius};
Parameters
centerthe center of the circle.
radiusthe radius of the circle.

Rect

There are 2 ways to construct a Rect and they are the same:

// The first way
let rect = new cv.Rect(x, y, width, height);
// The second way
let rect = {x : x, y : y, width : width, height : height};
Parameters
xx coordinate of the vertex which is the top left corner of the rectangle.
yy coordinate of the vertex which is the top left corner of the rectangle.
widththe width of the rectangle.
heightthe height of the rectangle.

RotatedRect

There are 2 ways to construct a RotatedRect and they are the same:

// The first way
let rotatedRect = new cv.RotatedRect(center, size, angle);
// The second way
let rotatedRect = {center : center, size : size, angle : angle};
Parameters
centerthe rectangle mass center.
sizewidth and height of the rectangle.
anglethe rotation angle in a clockwise direction. When the angle is 0, 90, 180, 270 etc., the rectangle becomes an up-right rectangle.

Learn how to get the vertices from rotatedRect:

We use the function: cv.RotatedRect.points(rotatedRect)

Parameters
rotatedRectrotated rectangle
let vertices = cv.RotatedRect.points(rotatedRect);
let point1 = vertices[0];
let point2 = vertices[1];
let point3 = vertices[2];
let point4 = vertices[3];

Learn how to get the bounding rectangle from rotatedRect:

We use the function: cv.RotatedRect.boundingRect(rotatedRect)

Parameters
rotatedRectrotated rectangle
let boundingRect = cv.RotatedRect.boundingRect(rotatedRect);