vendor: OpenCV 5.0.0 snapshot at 755e50675d97db9b7d449d8bd6b09888646f6c6e

2026-08-22 00:11:13 +08:00
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+Launching Viz {#tutorial_launching_viz}
+=============
+
+@next_tutorial{tutorial_widget_pose}
+
+Goal
+----
+
+In this tutorial you will learn how to
+
+-   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 [here ](https://github.com/opencv/opencv_contrib/tree/master/modules/viz/samples/launching_viz.cpp).
+@include viz/samples/launching_viz.cpp
+
+Explanation
+-----------
+
+Here is the general structure of the program:
+
+-   Create a window.
+    @code{.cpp}
+    /// Create a window
+    viz::Viz3d myWindow("Viz Demo");
+    @endcode
+-   Start event loop. This event loop will run until user terminates it by pressing **e**, **E**,
+    **q**, **Q**.
+    @code{.cpp}
+    /// Start event loop
+    myWindow.spin();
+    @endcode
+-   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{.cpp}
+    /// Access window via its name
+    viz::Viz3d sameWindow = viz::getWindowByName("Viz Demo");
+    @endcode
+-   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{.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);
+    }
+    @endcode
+
+Results
+-------
+
+Here is the result of the program.
+
+![](images/window_demo.png)