ScanSlicer/scanslicer/slices.py

import numpy as np
import cv2


# PhotoSlice: class definition for ScanSlicer behavior.
class PhotoSlice:
    # __init__: function definition for ScanSlicer behavior.
    def __init__(self, bbox=None):
        self._bbox = None
        self._rect_cache = None
        self._rect_cache_tol = None
        if bbox is None:
            self.bbox = np.array([[10, 10], [800, 10], [800, 800], [10, 800]], dtype=np.float64).reshape(4, 2)
        else:
            self.bbox = np.array(bbox, dtype=np.float64).reshape(4, 2)
        self.normalize_top_left()

        self.locked = False
        # Side-length handles are an explicit edit mode, enabled by squarize.
        self.side_handles_enabled = False

    @property
    # bbox: function definition for ScanSlicer behavior.
    def bbox(self):
        return self._bbox

    @bbox.setter
    # bbox: function definition for ScanSlicer behavior.
    def bbox(self, value):
        self._bbox = np.array(value, dtype=np.float64).reshape(4, 2)
        self._rect_cache = None
        self._rect_cache_tol = None

    # normalize_top_left: function definition for ScanSlicer behavior.
    def normalize_top_left(self):
        # Assume the top-left point of the quad is the image upper-left corner.
        top_left_index = np.lexsort((self.bbox[:, 0], self.bbox[:, 1]))[0]
        ordered = np.roll(self.bbox, -int(top_left_index), axis=0)

        # Resolve winding ambiguity by choosing the variant where edge 0->1 is
        # the most horizontal "top" edge.
        reversed_winding = np.array([ordered[0], ordered[3], ordered[2], ordered[1]])

        # horizontal_score: function definition for ScanSlicer behavior.
        def horizontal_score(points):
            edge = points[1] - points[0]
            return (abs(edge[0]) - abs(edge[1]), edge[0])

        if horizontal_score(reversed_winding) > horizontal_score(ordered):
            ordered = reversed_winding

        self.bbox = ordered

    # toggle_locked: function definition for ScanSlicer behavior.
    def toggle_locked(self, locked=None):
        if locked is not None:
            self.locked = locked
        else:
            self.locked = not self.locked

    # update_corner: function definition for ScanSlicer behavior.
    def update_corner(self, ci, x, y):
        self._bbox[ci][0] = x
        self._bbox[ci][1] = y
        self._rect_cache = None
        self._rect_cache_tol = None
        # Freeform corner edits exit side-handle mode.
        self.side_handles_enabled = False

    # is_perfect_rectangle: function definition for ScanSlicer behavior.
    def is_perfect_rectangle(self, tol=1e-3):
        if self._rect_cache is not None and self._rect_cache_tol == tol:
            return self._rect_cache

        points = np.array(self.bbox, dtype=np.float64).reshape(4, 2)
        edges = [points[(i + 1) % 4] - points[i] for i in range(4)]
        lengths = [np.linalg.norm(e) for e in edges]
        if min(lengths) < 1e-6:
            self._rect_cache = False
            self._rect_cache_tol = tol
            return False

        units = [e / l for e, l in zip(edges, lengths)]

        # Adjacent edges should be perpendicular.
        for i in range(4):
            if abs(np.dot(units[i], units[(i + 1) % 4])) > tol:
                self._rect_cache = False
                self._rect_cache_tol = tol
                return False

        # Opposite edges should be parallel (possibly opposite direction).
        if abs(abs(np.dot(units[0], units[2])) - 1.0) > tol:
            self._rect_cache = False
            self._rect_cache_tol = tol
            return False
        if abs(abs(np.dot(units[1], units[3])) - 1.0) > tol:
            self._rect_cache = False
            self._rect_cache_tol = tol
            return False

        self._rect_cache = True
        self._rect_cache_tol = tol
        return True

    # squarize: function definition for ScanSlicer behavior.
    def squarize(self):
        points = np.array(self.bbox, dtype=np.float64).reshape(4, 2)
        center = np.mean(points, axis=0)

        top_width = np.linalg.norm(points[1] - points[0])
        bottom_width = np.linalg.norm(points[2] - points[3])
        left_height = np.linalg.norm(points[3] - points[0])
        right_height = np.linalg.norm(points[2] - points[1])

        width = (top_width + bottom_width) / 2.0
        height = (left_height + right_height) / 2.0

        # Preserve current tilt by building the rectangle on the quad's
        # averaged horizontal/vertical directions instead of axis-aligning it.
        horiz = (points[1] - points[0]) + (points[2] - points[3])
        horiz_norm = np.linalg.norm(horiz)
        if horiz_norm < 1e-6:
            horiz = points[1] - points[0]
            horiz_norm = np.linalg.norm(horiz)
        if horiz_norm < 1e-6:
            rot_rect = cv2.minAreaRect(points.astype(np.float32))
            box = cv2.boxPoints(rot_rect).astype(np.float64)
            self.bbox = box
            self.normalize_top_left()
            self.side_handles_enabled = True
            return
        u = horiz / horiz_norm

        vert = (points[3] - points[0]) + (points[2] - points[1])
        # Gram-Schmidt to enforce perpendicular axes.
        vert = vert - np.dot(vert, u) * u
        vert_norm = np.linalg.norm(vert)
        if vert_norm < 1e-6:
            vert = np.array([-u[1], u[0]], dtype=np.float64)
            vert_norm = np.linalg.norm(vert)
        v = vert / max(vert_norm, 1e-6)

        half_w = width / 2.0
        half_h = height / 2.0
        self.bbox = np.array(
            [
                center - (u * half_w) - (v * half_h),
                center + (u * half_w) - (v * half_h),
                center + (u * half_w) + (v * half_h),
                center - (u * half_w) + (v * half_h),
            ],
            dtype=np.float64,
        )
        self.normalize_top_left()
        self.side_handles_enabled = True

    # reset_rotation: function definition for ScanSlicer behavior.
    def reset_rotation(self):
        points = np.array(self.bbox, dtype=np.float64).reshape(4, 2)
        center = np.mean(points, axis=0)

        top_width = np.linalg.norm(points[1] - points[0])
        bottom_width = np.linalg.norm(points[2] - points[3])
        left_height = np.linalg.norm(points[3] - points[0])
        right_height = np.linalg.norm(points[2] - points[1])

        width = (top_width + bottom_width) / 2.0
        height = (left_height + right_height) / 2.0

        half_w = width / 2.0
        half_h = height / 2.0
        self.bbox = np.array(
            [
                [center[0] - half_w, center[1] - half_h],
                [center[0] + half_w, center[1] - half_h],
                [center[0] + half_w, center[1] + half_h],
                [center[0] - half_w, center[1] + half_h],
            ],
            dtype=np.float64,
        )
        self.normalize_top_left()
        self.side_handles_enabled = True