multitouch/tests/utils.py

from numpy import array, diag, dot, cos, sin
from src import RectangularArea


class BoundingBoxArea(RectangularArea):
    def __init__(self, x, y, points):
        super(BoundingBoxArea, self).__init__(x, y, 0, 0)
        self.points = array(points).T
        self.update_bounds()

    def translate_points(self, tx, ty):
        self.points += [[tx], [ty]]

    def scale_points(self, scale, cx, cy):
        self.translate_points(-cx, -cy)
        self.points = dot(diag([scale, scale]), self.points)
        self.translate_points(cx, cy)

    def rotate_points(self, angle, cx, cy):
        cosa = cos(angle)
        sina = sin(angle)
        mat = array([[cosa, -sina], [sina, cosa]])

        self.translate_points(-cx, -cy)
        self.points = dot(mat, self.points)
        self.translate_points(cx, cy)

    def update_bounds(self):
        min_x, min_y = self.points.min(1)
        max_x, max_y = self.points.max(1)
        self.set_size(max_x - min_x, max_y - min_y)

        if min_x or min_y:
            self.translate(min_x, min_y)
            self.translate_points(-min_x, -min_y)