Learning OpenCV, 2nd Edition

cv::createButton( "", NULL, NULL, cv::PUSH_BUTTON );

cv::createTrackbar( "Trackbar2", "", &mybar1, 255 );

cv::createButton( "Button3", NULL, NULL, cv::RADIOBOX, 1 );

cv::createButton( "Button4", NULL, NULL, cv::RADIOBOX, 0 );

cv::createButton( "Button5", NULL, NULL, cv::CHECKBOX, 0 );

You will notice that Trackbar0 and Trackbar1 are created in the window called “Image,” while Trackbar2

is created in an unnamed window (the Control Panel). The first three cv::createButton() calls are

not given a name for the button, and you can see in Figure 4-5 the automatically assigned names are placed

onto the buttons. You will also notice in Figure 4-5 that the first three buttons are in one row, while the

second group of three is on another. This is because of the trackbar.

Buttons are created one after another, each to the right of its predecessor, until (unless) a trackbar is

created. Because a trackbar consumes an entire row, it is given its own row below the buttons. If more

buttons are created, they will appear on a new row thereafter.

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Text and Fonts

Just as the Qt interface allowed for much prettier trackbars and other elements, Qt also allows for much

prettier and more versatile text. To write text using the Qt interface, you must first create a CvFont

object,

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which you then use whenever you want to put some text on the ...