[−][src]Module opencv::highgui

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

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 | CV_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

Structs

QtFont

QtFont available only for Qt. See cv::fontQt

Enums

WindowFlags	Flags for cv::namedWindow
WindowPropertyFlags	Flags for cv::setWindowProperty / cv::getWindowProperty

Constants

EVENT_FLAG_ALTKEY	indicates that ALT Key is pressed.
EVENT_FLAG_CTRLKEY	indicates that CTRL Key is pressed.
EVENT_FLAG_LBUTTON	indicates that the left mouse button is down.
EVENT_FLAG_MBUTTON	indicates that the middle mouse button is down.
EVENT_FLAG_RBUTTON	indicates that the right mouse button is down.
EVENT_FLAG_SHIFTKEY	indicates that SHIFT Key is pressed.
EVENT_LBUTTONDBLCLK	indicates that left mouse button is double clicked.
EVENT_LBUTTONDOWN	indicates that the left mouse button is pressed.
EVENT_LBUTTONUP	indicates that left mouse button is released.
EVENT_MBUTTONDBLCLK	indicates that middle mouse button is double clicked.
EVENT_MBUTTONDOWN	indicates that the middle mouse button is pressed.
EVENT_MBUTTONUP	indicates that middle mouse button is released.
EVENT_MOUSEHWHEEL	positive and negative values mean right and left scrolling, respectively.
EVENT_MOUSEMOVE	indicates that the mouse pointer has moved over the window.
EVENT_MOUSEWHEEL	positive and negative values mean forward and backward scrolling, respectively.
EVENT_RBUTTONDBLCLK	indicates that right mouse button is double clicked.
EVENT_RBUTTONDOWN	indicates that the right mouse button is pressed.
EVENT_RBUTTONUP	indicates that right mouse button is released.
QT_CHECKBOX	Checkbox button.
QT_FONT_BLACK	Weight of 87
QT_FONT_BOLD	Weight of 75
QT_FONT_DEMIBOLD	Weight of 63
QT_FONT_LIGHT	Weight of 25
QT_FONT_NORMAL	Weight of 50
QT_NEW_BUTTONBAR	Button should create a new buttonbar
QT_PUSH_BUTTON	Push button.
QT_RADIOBOX	Radiobox button.
QT_STYLE_ITALIC	Italic font.
QT_STYLE_NORMAL	Normal font.
QT_STYLE_OBLIQUE	Oblique font.
WINDOW_AUTOSIZE	the user cannot resize the window, the size is constrainted by the image displayed.
WINDOW_FREERATIO	the image expends as much as it can (no ratio constraint).
WINDOW_FULLSCREEN	change the window to fullscreen.
WINDOW_GUI_EXPANDED	status bar and tool bar
WINDOW_GUI_NORMAL	old fashious way
WINDOW_KEEPRATIO	the ratio of the image is respected.
WINDOW_NORMAL	the user can resize the window (no constraint) / also use to switch a fullscreen window to a normal size.
WINDOW_OPENGL	window with opengl support.
WND_PROP_ASPECT_RATIO	window's aspect ration (can be set to WINDOW_FREERATIO or WINDOW_KEEPRATIO).
WND_PROP_AUTOSIZE	autosize property (can be WINDOW_NORMAL or WINDOW_AUTOSIZE).
WND_PROP_FULLSCREEN	fullscreen property (can be WINDOW_NORMAL or WINDOW_FULLSCREEN).
WND_PROP_OPENGL	opengl support.
WND_PROP_VISIBLE	checks whether the window exists and is visible

Functions

add_text	Draws a text on the image.
add_text_with_font	Draws a text on the image.
create_button	Attaches a button to the control panel.
create_trackbar	Creates a trackbar and attaches it to the specified window.
destroy_all_windows	Destroys all of the HighGUI windows.
destroy_window	Destroys the specified window.
display_overlay	Displays a text on a window image as an overlay for a specified duration.
display_status_bar	Displays a text on the window statusbar during the specified period of time.
font_qt	Creates the font to draw a text on an image.
get_mouse_wheel_delta	Gets the mouse-wheel motion delta, when handling mouse-wheel events cv::EVENT_MOUSEWHEEL and cv::EVENT_MOUSEHWHEEL.
get_trackbar_pos	Returns the trackbar position.
get_window_image_rect	Provides rectangle of image in the window.
get_window_property	Provides parameters of a window.
imshow	Displays an image in the specified window.
load_window_parameters	Loads parameters of the specified window.
move_window	Moves window to the specified position
named_window	Creates a window.
resize_window	Resizes window to the specified size
resize_window_1	Resizes window to the specified size
save_window_parameters	Saves parameters of the specified window.
select_roi	Selects ROI on the given image. Function creates a window and allows user to select a ROI using mouse. Controls: use `space` or `enter` to finish selection, use key `c` to cancel selection (function will return the zero cv::Rect).
select_roi_for_window	Selects ROI on the given image. Function creates a window and allows user to select a ROI using mouse. Controls: use `space` or `enter` to finish selection, use key `c` to cancel selection (function will return the zero cv::Rect).
select_rois	Selects ROIs on the given image. Function creates a window and allows user to select a ROIs using mouse. Controls: use `space` or `enter` to finish current selection and start a new one, use `esc` to terminate multiple ROI selection process.
set_mouse_callback	Sets mouse handler for the specified window
set_opengl_context	Sets the specified window as current OpenGL context.
set_opengl_draw_callback	Sets a callback function to be called to draw on top of displayed image.
set_trackbar_max	Sets the trackbar maximum position.
set_trackbar_min	Sets the trackbar minimum position.
set_trackbar_pos	Sets the trackbar position.
set_window_property	Changes parameters of a window dynamically.
set_window_title	Updates window title
start_window_thread
stop_loop
update_window	Force window to redraw its context and call draw callback ( See cv::setOpenGlDrawCallback ).
wait_key	Waits for a pressed key.
wait_key_ex	Similar to #waitKey, but returns full key code.

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