P83 为啥我的裁剪框不能拖拽
import pygameimport sys
from pygame.locals import *
pygame.init()
size=width,height = 1600,1000
bg=(255,255,255)
clock = pygame.time.Clock()
screen = pygame.display.set_mode(size)
pygame.display.set_caption("FishC Demo")
turtle = pygame.image.load('wugui.png')
# 0 -> 未选择 , 1 -> 选择中 , 2 -> 完成选择
select = 0
select_rect = pygame.Rect(0,0,0,0)
# 0 -> 未拖拽 , 1 -> 拖拽中 , 2 -> 完成拖拽
drag = 0
position = turtle.get_rect()
position.center = width //2 , height //2
while True:
for event in pygame.event.get():
if event.type == QUIT:
sys.exit()
elif event.type == MOUSEBUTTONDOWN:
if event.button == 1:
# 第一次点击，选择范围
if select == 0 and drag == 0:
pos_start = event.pos
select = 1
# 第二次点击，拖拽图像
elif select == 2 and drag == 0:
capture = screen.subsurface(select_rect).copy()
cap_rect = capture.get_rect()
drag = 1
# 第三次点击,初始化
elif select == 2 and drag == 2:
select = 0
drag = 0
elif event.type == MOUSEBUTTONUP:
if event.button == 1:
#第一次释放,结束进程
if select == 1 and drag == 0:
pos_start = event.pos
select =2
#第二次释放，结束拖拽
if select == 2 and drag == 1:
drag = 2
screen.fill(bg)
screen.blit(turtle,position)
#实时绘制选择框
if select:
mouse_pos = pygame.mouse.get_pos()
if select == 1:
pos_stop = mouse_pos
select_rect.left,select_rect.top=pos_start
select_rect.width,select_rect.height=pos_stop - pos_start,pos_stop - pos_start
pygame.draw.rect(screen,(0,0,0),select_rect,1)
#拖拽裁剪的图像
if drag:
if drag == 1:
cap_rect.center = mouse_pos
screen.blit(capture,cap_rect)
pygame.display.flip()
clock.tick(30)
elif event.type == MOUSEBUTTONUP:
if event.button == 1:
#第一次释放,结束进程
if select == 1 and drag == 0:
pos_start = event.pos
select =2
#第二次释放，结束拖拽
if select == 2 and drag == 1:
drag = 2
这一段错了，第一次释放的event.pos应该赋值给pos_stop，否则你的选框一直是一个点，根本就没有选定范围，所以也当然拖曳不了了，所以只要把pos_start = event.pos改成if select == 1 and drag == 0:
pos_stop = event.pos
select =2
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