OpenCV with Python - Trackbar

aemon

于 2010-08-25 15:08:00 发布

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分类专栏： openCV with python 文章标签： Python F#

本文链接：https://blog.youkuaiyun.com/aemon/article/details/83699383

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本文介绍了一个关于OpenCV中Trackbar回调函数的问题及其解决方案。当Trackbar的回调函数被调用时，传入的'value'参数不会更新。解决方法是在回调函数内部使用cvGetTrackbarPos函数获取最新的滑块位置。

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Issue about CreateTrackbar

Creates a trackbar and attaches it to the specified window

[b]Usage:[/b]
int cvCreateTrackbar(trackbar name, window name, int* value, int count, callback on change );

value: Pointer to an integer variable, whose value will reflect the position of the slider. Upon creation, the slider position is defined by this variable.

[b]The problem[/b] is when the callback function is invoked, the 'value' will not change.

The solution is call GetTrackbarPos in the callback Func..

Example:


fPos = 0
sPos = 0
def bar(pos):
    global fPos
    global sPos

    print pos
    fPos = cvGetTrackbarPos('f', 'Test')
    sPos = cvGetTrackbarPos('s', 'Test')
    print fPos
    print sPos
def show():
    global fPos
    global sPos

    cvNamedWindow('Test', 1)
    cvCreateTrackbar('f', 'Test', fPos, 10, bar)
    cvCreateTrackbar('s', 'Test', sPos, 10, bar)

    cvShowImage('Test', cvCreateImage(cvSize(240, 240), IPL_DEPTH_8U, 3))
    cvResizeWindow('Test', 240, 240)
    cvWaitKey(0)
    cvDestroyWindow('Test')