import cv2

class CV_KEY:
    BLANK = 32
    ENTER = 13
    LSHIFT = 225 # Mac上不行
    NONE = 255
    TAB = 9
    q = 113
    ESC = 27
    BACKSPACE = 8
    WINDOW_WIDTH = int(1920*0.9)
    WINDOW_HEIGHT = int(1080*0.9)
    LEFT = ord('a')
    RIGHT = ord('d')
    UP = ord('w')
    DOWN = ord('s')
    MINUS = 45
    PLUS = 61

def get_key():
    k = cv2.waitKey(10) & 0xFF
    if k == CV_KEY.LSHIFT:
        key1 = cv2.waitKey(500) & 0xFF
        if key1 == CV_KEY.NONE:
            return key1
        # 转换为大写
        k = key1 - ord('a') + ord('A')
    return k

def point_callback(event, x, y, flags, param):
    """
        OpenCV使用的简单的回调函数，主要实现两个基础功能：
        1. 对于按住拖动的情况，记录起始点与终止点（当前点）
        2. 对于点击的情况，记录选择的点
    """
    if event not in [cv2.EVENT_LBUTTONDOWN, cv2.EVENT_MOUSEMOVE, cv2.EVENT_LBUTTONUP]:
        return 0
    # 判断出了选择了的点的位置，直接写入这个位置
    if event == cv2.EVENT_LBUTTONDOWN:
        param['click'] = None
        param['start'] = (x, y)
        param['end'] = (x, y)
        # 清除所有选择项
        for key in param['select'].keys():
            param['select'][key] = -1
    elif event == cv2.EVENT_MOUSEMOVE and flags == cv2.EVENT_FLAG_LBUTTON:
        param['end'] = (x, y)
    elif event == cv2.EVENT_LBUTTONUP:
        if x == param['start'][0] and y == param['start'][1]:
            param['click'] = param['start']
            param['start'] = None
            param['end'] = None
        else:
            param['click'] = None
    return 1