2014-11-27 20:39:05 +08:00
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Launching Viz {#tutorial_launching_viz}
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=============
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Goal
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----
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In this tutorial you will learn how to
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- Open a visualization window.
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- Access a window by its name.
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- Start event loop.
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- Start event loop for a given amount of time.
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Code
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----
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2014-12-26 19:35:46 +08:00
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You can download the code from [here ](https://github.com/Itseez/opencv/tree/master/samples/cpp/tutorial_code/viz/launching_viz.cpp).
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2015-04-29 15:31:53 +08:00
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@include samples/cpp/tutorial_code/viz/launching_viz.cpp
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2014-11-27 20:39:05 +08:00
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2014-11-28 21:21:28 +08:00
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Explanation
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-----------
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2014-11-27 20:39:05 +08:00
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2014-11-28 21:21:28 +08:00
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Here is the general structure of the program:
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- Create a window.
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@code{.cpp}
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2014-11-27 20:39:05 +08:00
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/// Create a window
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viz::Viz3d myWindow("Viz Demo");
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2014-11-28 21:21:28 +08:00
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@endcode
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- Start event loop. This event loop will run until user terminates it by pressing **e**, **E**,
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**q**, **Q**.
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@code{.cpp}
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2014-11-27 20:39:05 +08:00
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/// Start event loop
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myWindow.spin();
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2014-11-28 21:21:28 +08:00
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@endcode
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- Access same window via its name. Since windows are implicitly shared, **sameWindow** is exactly
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the same with **myWindow**. If the name does not exist, a new window is created.
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@code{.cpp}
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2014-11-27 20:39:05 +08:00
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/// Access window via its name
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2014-11-28 21:21:28 +08:00
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viz::Viz3d sameWindow = viz::get("Viz Demo");
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@endcode
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- Start a controlled event loop. Once it starts, **wasStopped** is set to false. Inside the while
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loop, in each iteration, **spinOnce** is called to prevent event loop from completely stopping.
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Inside the while loop, user can execute other statements including those which interact with the
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window.
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@code{.cpp}
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2014-11-27 20:39:05 +08:00
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/// Event loop is over when pressed q, Q, e, E
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/// Start event loop once for 1 millisecond
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sameWindow.spinOnce(1, true);
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while(!sameWindow.wasStopped())
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{
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/// Interact with window
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/// Event loop for 1 millisecond
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sameWindow.spinOnce(1, true);
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}
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2014-11-28 21:21:28 +08:00
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@endcode
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2014-11-27 20:39:05 +08:00
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Results
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-------
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Here is the result of the program.
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2014-11-28 21:21:28 +08:00
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![](images/window_demo.png)
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