OpenCV 的 cvWaitKey() 函数有什么作用? [英] What does OpenCV's cvWaitKey( ) function do?

问题描述

cvWaitKey() 执行过程中会发生什么?有哪些典型的用例?我在 OpenCV 参考中看到了它，但文档并不清楚其确切用途.

What happens during the execution of cvWaitKey()? What are some typical use cases? I saw it in OpenCV reference but the documentation isn't clear on its exact purpose.

推荐答案

cvWaitKey(x)/cv::waitKey(x) 做了两件事:

1. 它等待 x 毫秒以等待 OpenCV 窗口(即从 cv::imshow() 创建)上的按键.请注意，它不会在 stdin 上侦听控制台输入.如果在此期间按下某个键，则返回该键的 ASCII 代码.否则，它返回 -1.(如果 x 为零，它会无限期地等待按键.)
2. 它处理任何窗口事件，例如使用 cv::namedWindow() 创建窗口，或使用 cv::imshow() 显示图像.

1. It waits for x milliseconds for a key press on a OpenCV window (i.e. created from cv::imshow()). Note that it does not listen on stdin for console input. If a key was pressed during that time, it returns the key's ASCII code. Otherwise, it returns -1. (If x is zero, it waits indefinitely for the key press.)
2. It handles any windowing events, such as creating windows with cv::namedWindow(), or showing images with cv::imshow().

opencv 新手的一个常见错误是通过视频帧循环调用 cv::imshow()，而不用 cv::waitKey(30) 跟踪每次绘制代码>.在这种情况下，屏幕上不会显示任何内容，因为 highgui 从来没有时间处理来自 cv::imshow() 的绘制请求.

A common mistake for opencv newcomers is to call cv::imshow() in a loop through video frames, without following up each draw with cv::waitKey(30). In this case, nothing appears on screen, because highgui is never given time to process the draw requests from cv::imshow().

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