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python 截取矩形缩放，旋转

news 2026/4/16 18:07:20

python

import cv2 import numpy as np import time img = cv2.imread(r"C:\Users\ChanJing-01\Pictures\3_35_l.jpg") if img is None: raise ValueError("图片路径错误") clone = img.copy() cx, cy = img.shape[1] // 2, img.shape[0] // 2 w, h = 300, 200 angle = 0 dragging = None start_angle = 0 start_mouse_angle = 0 # ====================== # 工具函数 # ====================== def get_box_points(cx, cy, w, h, angle): rect = ((cx, cy), (w, h), angle) return cv2.boxPoints(rect).astype(np.float32) def order_points(pts): """ 固定顺序：左上、右上、右下、左下 """ pts = np.array(pts, dtype=np.float32) rect = np.zeros((4, 2), dtype=np.float32) s = pts.sum(axis=1) rect[0] = pts[np.argmin(s)] # 左上 rect[2] = pts[np.argmax(s)] # 右下 diff = np.diff(pts, axis=1) rect[1] = pts[np.argmin(diff)] # 右上 rect[3] = pts[np.argmax(diff)] # 左下 return rect def get_rotate_handle(cx, cy, w, h, angle): theta = np.radians(angle) rx = cx + (-np.sin(theta)) * (h / 2 + 40) ry = cy + ( np.cos(theta)) * (h / 2 + 40) return int(rx), int(ry) def warp_crop(): global cx, cy, w, h, angle rect = ((cx, cy), (w, h), angle) box = get_box_points(cx, cy, w, h, angle) box = order_points(box) # 自动真实宽高（避免翻转） widthA = np.linalg.norm(box[2] - box[3]) widthB = np.linalg.norm(box[1] - box[0]) maxW = int(max(widthA, widthB)) heightA = np.linalg.norm(box[1] - box[2]) heightB = np.linalg.norm(box[0] - box[3]) maxH = int(max(heightA, heightB)) dst = np.array([ [0, 0], [maxW, 0], [maxW, maxH], [0, maxH] ], dtype=np.float32) M = cv2.getPerspectiveTransform(box, dst) warped = cv2.warpPerspective(img, M, (maxW, maxH)) return warped def draw(): display = clone.copy() pts = get_box_points(cx, cy, w, h, angle) # 矩形 cv2.polylines(display, [pts.astype(np.int32)], True, (0,255,0), 2) # 角点 for p in pts: cv2.circle(display, tuple(p.astype(int)), 6, (0,0,255), -1) # 中心 cv2.circle(display, (int(cx), int(cy)), 5, (255,0,0), -1) # 旋转手柄 rx, ry = get_rotate_handle(cx, cy, w, h, angle) cv2.circle(display, (rx, ry), 6, (0,255,255), -1) cv2.line(display, (int(cx), int(cy)), (rx, ry), (0,255,255), 1) return display # ====================== # 鼠标事件 # ====================== def mouse(event, x, y, flags, param): global cx, cy, w, h, angle, dragging global start_angle, start_mouse_angle pts = get_box_points(cx, cy, w, h, angle) rx, ry = get_rotate_handle(cx, cy, w, h, angle) if event == cv2.EVENT_LBUTTONDOWN: # 角点 for i, p in enumerate(pts): if np.linalg.norm(np.array([x,y]) - p) < 10: dragging = i return # 中心 if np.linalg.norm(np.array([x,y]) - np.array([cx,cy])) < 10: dragging = 'center' return # 旋转 if np.linalg.norm(np.array([x,y]) - np.array([rx,ry])) < 12: dragging = 'rotate' start_angle = angle start_mouse_angle = np.degrees(np.arctan2(y - cy, x - cx)) return elif event == cv2.EVENT_MOUSEMOVE: if dragging == 'center': cx, cy = x, y elif dragging == 'rotate': current = np.degrees(np.arctan2(y - cy, x - cx)) angle = start_angle + (current - start_mouse_angle) elif isinstance(dragging, int): theta = np.radians(angle) dx = x - cx dy = y - cy local_x = dx * np.cos(theta) + dy * np.sin(theta) local_y = -dx * np.sin(theta) + dy * np.cos(theta) w = max(20, abs(local_x) * 2) h = max(20, abs(local_y) * 2) elif event == cv2.EVENT_LBUTTONUP: dragging = None # ====================== # 初始化 # ====================== cv2.namedWindow("ROI") cv2.setMouseCallback("ROI", mouse) # ====================== # 主循环 # ====================== while True: cv2.imshow("ROI", draw()) key = cv2.waitKey(1) & 0xFF # Enter预览 if key == 13: cv2.imshow("crop_preview", warp_crop()) # S保存 elif key == ord('s'): warped = warp_crop() filename = f"crop_{int(time.time())}.png" cv2.imwrite(filename, warped) print("已保存:", filename) # 重置 elif key == ord('r'): cx, cy = img.shape[1] // 2, img.shape[0] // 2 w, h = 300, 200 angle = 0 # 退出 elif key == 27: break cv2.destroyAllWindows()

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