Class mapper

recipes/Python/578875_Analog_Clock/recipe-578875.py:45–83

#  to viewport coordinates.
#
class mapper:
    ## Constructor.
    #
    #  @param world window rectangle.
    #  @param viewport screen rectangle.
    #
    def __init__(self, world, viewport):
        self.world = world 
        self.viewport = viewport
        x_min, y_min, x_max, y_max = self.world
        X_min, Y_min, X_max, Y_max = self.viewport
        f_x = float(X_max-X_min) / float(x_max-x_min) 
        f_y = float(Y_max-Y_min) / float(y_max-y_min) 
        self.f = min(f_x,f_y)
        x_c = 0.5 * (x_min + x_max)
        y_c = 0.5 * (y_min + y_max)
        X_c = 0.5 * (X_min + X_max)
        Y_c = 0.5 * (Y_min + Y_max)
        self.c_1 = X_c - self.f * x_c
        self.c_2 = Y_c - self.f * y_c

    ## Maps a single point from world coordinates to viewport (screen) coordinates.
    #
    #  @param x, y given point.
    #  @return a new point in screen coordinates.
    #
    def __windowToViewport(self, x, y):
        X = self.f *  x + self.c_1
        Y = self.f * -y + self.c_2      # Y axis is upside down 
        return X , Y

    ## Maps two points from world coordinates to viewport (screen) coordinates.
    #
    #  @param x1, y1 first point.
    #  @param x2, y2 second point.
    #  @return two new points in screen coordinates.
    #
    def windowToViewport(self,x1,y1,x2,y2):
        return self.__windowToViewport(x1,y1),self.__windowToViewport(x2,y2)

## Class for creating a new thread.
#