Module opencv::highgui

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Expand description

High-level GUI

While OpenCV was designed for use in full-scale applications and can be used within functionally rich UI frameworks (such as Qt*, WinForms*, or Cocoa*) or without any UI at all, sometimes there it is required to try functionality quickly and visualize the results. This is what the HighGUI module has been designed for.

It provides easy interface to:

  • Create and manipulate windows that can display images and “remember” their content (no need to handle repaint events from OS).
  • Add trackbars to the windows, handle simple mouse events as well as keyboard commands.

OpenGL support

Qt New Functions

image

This figure explains new functionality implemented with Qt* GUI. The new GUI provides a statusbar, a toolbar, and a control panel. The control panel can have trackbars and buttonbars attached to it. If you cannot see the control panel, press Ctrl+P or right-click any Qt window and select Display properties window.

  • To attach a trackbar, the window name parameter must be NULL.

  • To attach a buttonbar, a button must be created. If the last bar attached to the control panel is a buttonbar, the new button is added to the right of the last button. If the last bar attached to the control panel is a trackbar, or the control panel is empty, a new buttonbar is created. Then, a new button is attached to it.

See below the example used to generate the figure:

    int main(int argc, char *argv[])
    {

        int value = 50;
        int value2 = 0;


        namedWindow("main1",WINDOW_NORMAL);
        namedWindow("main2",WINDOW_AUTOSIZE | WINDOW_GUI_NORMAL);
        createTrackbar( "track1", "main1", &value, 255,  NULL);

        String nameb1 = "button1";
        String nameb2 = "button2";

        createButton(nameb1,callbackButton,&nameb1,QT_CHECKBOX,1);
        createButton(nameb2,callbackButton,NULL,QT_CHECKBOX,0);
        createTrackbar( "track2", NULL, &value2, 255, NULL);
        createButton("button5",callbackButton1,NULL,QT_RADIOBOX,0);
        createButton("button6",callbackButton2,NULL,QT_RADIOBOX,1);

        setMouseCallback( "main2",on_mouse,NULL );

        Mat img1 = imread("files/flower.jpg");
        VideoCapture video;
        video.open("files/hockey.avi");

        Mat img2,img3;

        while( waitKey(33) != 27 )
        {
            img1.convertTo(img2,-1,1,value);
            video >> img3;

            imshow("main1",img2);
            imshow("main2",img3);
        }

        destroyAllWindows();

        return 0;
    }

WinRT support

This figure explains new functionality implemented with WinRT GUI. The new GUI provides an Image control, and a slider panel. Slider panel holds trackbars attached to it.

Sliders are attached below the image control. Every new slider is added below the previous one.

See below the example used to generate the figure:

    void sample_app::MainPage::ShowWindow()
    {
        static cv::String windowName("sample");
        cv::winrt_initContainer(this->cvContainer);
        cv::namedWindow(windowName); // not required

        cv::Mat image = cv::imread("Assets/sample.jpg");
        cv::Mat converted = cv::Mat(image.rows, image.cols, CV_8UC4);
        cv::cvtColor(image, converted, COLOR_BGR2BGRA);
        cv::imshow(windowName, converted); // this will create window if it hasn't been created before

        int state = 42;
        cv::TrackbarCallback callback = [](int pos, void* userdata)
        {
            if (pos == 0) {
                cv::destroyWindow(windowName);
            }
        };
        cv::TrackbarCallback callbackTwin = [](int pos, void* userdata)
        {
            if (pos >= 70) {
                cv::destroyAllWindows();
            }
        };
        cv::createTrackbar("Sample trackbar", windowName, &state, 100, callback);
        cv::createTrackbar("Twin brother", windowName, &state, 100, callbackTwin);
    }

C API

Modules

Structs

  • QtFont
    QtFont available only for Qt. See cv::fontQt

Enums

Constants

Traits

Functions

Type Definitions

  • ButtonCallback
    Callback function for a button created by cv::createButton
  • MouseCallback
    Callback function for mouse events. see cv::setMouseCallback
  • OpenGlDrawCallback
    Callback function defined to be called every frame. See cv::setOpenGlDrawCallback
  • TrackbarCallback
    Callback function for Trackbar see cv::createTrackbar