Test for Zoom calculations

test_zoom.py

MIN_DPI = 200
MM_PER_INCH = 25.4


class ZoomCalculator:
    def __init__(
        self,
        view_width_in_mm: float,
        view_width_in_pixel: int,
        view_height_in_pixel: int,
        image_width_in_pixel: int,
        image_height_in_pixel: int,
    ):
        view_width_in_inch = view_width_in_mm / MM_PER_INCH
        view_ratio = view_width_in_pixel / view_height_in_pixel
        image_ratio = image_width_in_pixel / image_height_in_pixel
        is_scale_on_width = view_ratio > image_ratio
        if is_scale_on_width:
            self.min_zoom = view_width_in_pixel / image_width_in_pixel
            min_image_width_in_inch = image_width_in_pixel / MIN_DPI
            self.max_zoom = min_image_width_in_inch / view_width_in_inch
        else:
            self.min_zoom = view_height_in_pixel / image_height_in_pixel
            view_height_in_inch = view_width_in_inch * view_ratio
            min_image_height_in_inch = image_height_in_pixel / MIN_DPI
            self.max_zoom = min_image_height_in_inch / view_height_in_inch
        self.ugliness = max(0.0, (self.min_zoom / self.max_zoom) - 1.0)

    def __str__(self):
        return f"ZoomCalculator(min_zoom={self.min_zoom}, max_zoom={self.max_zoom}, ugliness={self.ugliness})"


def test_can_compute_zoom():
    print()
    print("*****************************")
    print(ZoomCalculator(150.0, 600, 200, 800, 600))
    print(ZoomCalculator(150.0, 600, 200, 8000, 6000))

    print(ZoomCalculator(30.0, 300, 500, 800, 600))
    print(ZoomCalculator(30.0, 300, 500, 200, 200))

    print("*****************************")