mirror of
https://github.com/opencv/opencv.git
synced 2024-12-02 16:00:17 +08:00
119 lines
2.9 KiB
ReStructuredText
119 lines
2.9 KiB
ReStructuredText
.. _launching_viz:
|
|
|
|
Launching Viz
|
|
*************
|
|
|
|
Goal
|
|
====
|
|
|
|
In this tutorial you will learn how to
|
|
|
|
.. container:: enumeratevisibleitemswithsquare
|
|
|
|
* Open a visualization window.
|
|
* Access a window by its name.
|
|
* Start event loop.
|
|
* Start event loop for a given amount of time.
|
|
|
|
Code
|
|
====
|
|
|
|
You can download the code from :download:`here <../../../../samples/cpp/tutorial_code/viz/launching_viz.cpp>`.
|
|
|
|
.. code-block:: cpp
|
|
|
|
#include <opencv2/viz.hpp>
|
|
#include <iostream>
|
|
|
|
using namespace cv;
|
|
using namespace std;
|
|
|
|
/*
|
|
* @function main
|
|
*/
|
|
int main()
|
|
{
|
|
/// Create a window
|
|
viz::Viz3d myWindow("Viz Demo");
|
|
|
|
/// Start event loop
|
|
myWindow.spin();
|
|
|
|
/// Event loop is over when pressed q, Q, e, E
|
|
cout << "First event loop is over" << endl;
|
|
|
|
/// Access window via its name
|
|
viz::Viz3d sameWindow = viz::getWindowByName("Viz Demo");
|
|
|
|
/// Start event loop
|
|
sameWindow.spin();
|
|
|
|
/// Event loop is over when pressed q, Q, e, E
|
|
cout << "Second event loop is over" << endl;
|
|
|
|
/// Event loop is over when pressed q, Q, e, E
|
|
/// Start event loop once for 1 millisecond
|
|
sameWindow.spinOnce(1, true);
|
|
while(!sameWindow.wasStopped())
|
|
{
|
|
/// Interact with window
|
|
|
|
/// Event loop for 1 millisecond
|
|
sameWindow.spinOnce(1, true);
|
|
}
|
|
|
|
/// Once more event loop is stopped
|
|
cout << "Last event loop is over" << endl;
|
|
return 0;
|
|
}
|
|
|
|
Explanation
|
|
===========
|
|
|
|
Here is the general structure of the program:
|
|
|
|
* Create a window.
|
|
|
|
.. code-block:: cpp
|
|
|
|
/// Create a window
|
|
viz::Viz3d myWindow("Viz Demo");
|
|
|
|
* Start event loop. This event loop will run until user terminates it by pressing **e**, **E**, **q**, **Q**.
|
|
|
|
.. code-block:: cpp
|
|
|
|
/// Start event loop
|
|
myWindow.spin();
|
|
|
|
* Access same window via its name. Since windows are implicitly shared, **sameWindow** is exactly the same with **myWindow**. If the name does not exist, a new window is created.
|
|
|
|
.. code-block:: cpp
|
|
|
|
/// Access window via its name
|
|
viz::Viz3d sameWindow = viz::get("Viz Demo");
|
|
|
|
* Start a controlled event loop. Once it starts, **wasStopped** is set to false. Inside the while loop, in each iteration, **spinOnce** is called to prevent event loop from completely stopping. Inside the while loop, user can execute other statements including those which interact with the window.
|
|
|
|
.. code-block:: cpp
|
|
|
|
/// Event loop is over when pressed q, Q, e, E
|
|
/// Start event loop once for 1 millisecond
|
|
sameWindow.spinOnce(1, true);
|
|
while(!sameWindow.wasStopped())
|
|
{
|
|
/// Interact with window
|
|
|
|
/// Event loop for 1 millisecond
|
|
sameWindow.spinOnce(1, true);
|
|
}
|
|
|
|
Results
|
|
=======
|
|
|
|
Here is the result of the program.
|
|
|
|
.. image:: images/window_demo.png
|
|
:alt: Launching Viz
|
|
:align: center
|