关于waitKey()函数按键无反应情况
2016-02-06 12:19
936 查看
按下键的时候,焦点要落在窗口上,不能落在cmd窗口上。
另外,一般在imshow()后要使用waitKey(),给图像绘制留下时间,不然窗口会出现无响应情况,并且图像无法显示出来。
int waitKey(int delay=0)
- 延时delay毫秒,默认0则延时无限长,必须有键按下才继续执行。
- 函数返回值为按下的键的ASCII码值,没按键则返回-1。
OpenCV: waitKey
waitKey
Waits for a pressed key.
C++: int waitKey(int delay=0)
Python: cv2.waitKey([delay]) → retval¶
C: int cvWaitKey(int delay=0 )
Python: cv.WaitKey(delay=0) → int
Parameters: delay – Delay in milliseconds. 0 is the special value that means “forever”.
The function waitKey waits for a key event infinitely (when \texttt{delay}\leq 0 ) or for delay milliseconds, when it is positive. Since the OS has a minimum time between switching threads, the function will not wait exactly delay ms, it will wait at least delay ms, depending on what else is running on your computer at that time. It returns the code of the pressed key or -1 if no key was pressed before the specified time had elapsed.
Note
This function is the only method in HighGUI that can fetch and handle events, so it needs to be called periodically for normal event processing unless HighGUI is used within an environment that takes care of event processing.
Note
The function only works if there is at least one HighGUI window created and the window is active. If there are several HighGUI windows, any of them can be active.
另外,一般在imshow()后要使用waitKey(),给图像绘制留下时间,不然窗口会出现无响应情况,并且图像无法显示出来。
int waitKey(int delay=0)
- 延时delay毫秒,默认0则延时无限长,必须有键按下才继续执行。
- 函数返回值为按下的键的ASCII码值,没按键则返回-1。
OpenCV: waitKey
waitKey
Waits for a pressed key.
C++: int waitKey(int delay=0)
Python: cv2.waitKey([delay]) → retval¶
C: int cvWaitKey(int delay=0 )
Python: cv.WaitKey(delay=0) → int
Parameters: delay – Delay in milliseconds. 0 is the special value that means “forever”.
The function waitKey waits for a key event infinitely (when \texttt{delay}\leq 0 ) or for delay milliseconds, when it is positive. Since the OS has a minimum time between switching threads, the function will not wait exactly delay ms, it will wait at least delay ms, depending on what else is running on your computer at that time. It returns the code of the pressed key or -1 if no key was pressed before the specified time had elapsed.
Note
This function is the only method in HighGUI that can fetch and handle events, so it needs to be called periodically for normal event processing unless HighGUI is used within an environment that takes care of event processing.
Note
The function only works if there is at least one HighGUI window created and the window is active. If there are several HighGUI windows, any of them can be active.
相关文章推荐
- Indy 10 POP3 against MS Exchange 2010?
- How to send gmail by Indy (TIdSMTP)?
- pentaho saiku 安装全过程
- pentaho saiku 安装全过程
- hdu 1848 Fibonacci again and again
- aix平台安装10.2.0.5的CRS时遇到的bug
- 【题解】2016 BUPT Winter Training #2
- quailty's Contest #1 题解
- cf#AIM Tech Round -B. Making a String-贪心/set
- cf#AIM Tech Round -C. Graph and String-贪心/ 二分图染色
- cf#AIM Tech D. Array GCD (数学+枚举)
- AIM Tech Round (Div. 2) D. Array GCD(dp)
- codeforces AIM Tech Round
- WM_PAINT消息详解,使用InvalidateRect或InvalidateRgn函数刻意产生WM_PAINT消息(WIN7里有变化,“调整视觉效果”,将“启用桌面组合”去掉)
- WM_PAINT消息在窗口重绘的时候产生,那什么时候窗口会重绘(异步工作方式,效率更高,灵活性更强)
- 四川成都电信天邑TEWA-300AI EPON光猫各种折腾
- Cloud Foundry warden container 安全性探讨
- async await
- VIM配置:vim-airline插件安装
- AIM Tech Round (Div. 2) C. Graph and String