Add Java and Python code for trackbar tutorial.

doc/tutorials/highgui/table_of_content_highgui.markdown

@@ -5,6 +5,8 @@ This section contains tutorials about how to use the built-in graphical user int
 
 -   @subpage tutorial_trackbar
 
+    *Languages:* C++, Java, Python
+
     *Compatibility:* \> OpenCV 2.0
 
     *Author:* Ana Huamán

doc/tutorials/highgui/trackbar/trackbar.markdown

@@ -1,11 +1,11 @@
 Adding a Trackbar to our applications! {#tutorial_trackbar}
 ======================================
 
--   In the previous tutorials (about *linear blending* and the *brightness and contrast
-    adjustments*) you might have noted that we needed to give some **input** to our programs, such
-    as \f$\alpha\f$ and \f$beta\f$. We accomplished that by entering this data using the Terminal
--   Well, it is time to use some fancy GUI tools. OpenCV provides some GUI utilities (*highgui.hpp*)
-    for you. An example of this is a **Trackbar**
+-   In the previous tutorials (about @ref tutorial_adding_images and the @ref tutorial_basic_linear_transform)
+    you might have noted that we needed to give some **input** to our programs, such
+    as \f$\alpha\f$ and \f$beta\f$. We accomplished that by entering this data using the Terminal.
+-   Well, it is time to use some fancy GUI tools. OpenCV provides some GUI utilities (**highgui** module)
+    for you. An example of this is a **Trackbar**.
 
     ![](images/Adding_Trackbars_Tutorial_Trackbar.png)
 
@@ -24,26 +24,73 @@ Code
 
 Let's modify the program made in the tutorial @ref tutorial_adding_images. We will let the user enter the
 \f$\alpha\f$ value by using the Trackbar.
+
+@add_toggle_cpp
 This tutorial code's is shown lines below. You can also download it from
 [here](https://github.com/opencv/opencv/tree/master/samples/cpp/tutorial_code/HighGUI/AddingImagesTrackbar.cpp)
 @include cpp/tutorial_code/HighGUI/AddingImagesTrackbar.cpp
+@end_toggle
+
+@add_toggle_java
+This tutorial code's is shown lines below. You can also download it from
+[here](https://github.com/opencv/opencv/tree/master/samples/java/tutorial_code/highgui/trackbar/AddingImagesTrackbar.java)
+@include java/tutorial_code/highgui/trackbar/AddingImagesTrackbar.java
+@end_toggle
+
+@add_toggle_python
+This tutorial code's is shown lines below. You can also download it from
+[here](https://github.com/opencv/opencv/tree/master/samples/python/tutorial_code/highgui/trackbar/AddingImagesTrackbar.py)
+@include python/tutorial_code/highgui/trackbar/AddingImagesTrackbar.py
+@end_toggle
 
 Explanation
 -----------
 
 We only analyze the code that is related to Trackbar:
 
--#  First, we load two images, which are going to be blended.
-    @snippet cpp/tutorial_code/HighGUI/AddingImagesTrackbar.cpp load
+-  First, we load two images, which are going to be blended.
 
--#  To create a trackbar, first we have to create the window in which it is going to be located. So:
-    @snippet cpp/tutorial_code/HighGUI/AddingImagesTrackbar.cpp window
+@add_toggle_cpp
+@snippet cpp/tutorial_code/HighGUI/AddingImagesTrackbar.cpp load
+@end_toggle
 
--#  Now we can create the Trackbar:
-    @snippet cpp/tutorial_code/HighGUI/AddingImagesTrackbar.cpp create_trackbar
+@add_toggle_java
+@snippet java/tutorial_code/highgui/trackbar/AddingImagesTrackbar.java load
+@end_toggle
 
-    Note the following:
+@add_toggle_python
+@snippet python/tutorial_code/highgui/trackbar/AddingImagesTrackbar.py load
+@end_toggle
 
+-  To create a trackbar, first we have to create the window in which it is going to be located. So:
+
+@add_toggle_cpp
+@snippet cpp/tutorial_code/HighGUI/AddingImagesTrackbar.cpp window
+@end_toggle
+
+@add_toggle_java
+@snippet java/tutorial_code/highgui/trackbar/AddingImagesTrackbar.java window
+@end_toggle
+
+@add_toggle_python
+@snippet python/tutorial_code/highgui/trackbar/AddingImagesTrackbar.py window
+@end_toggle
+
+-  Now we can create the Trackbar:
+
+@add_toggle_cpp
+@snippet cpp/tutorial_code/HighGUI/AddingImagesTrackbar.cpp create_trackbar
+@end_toggle
+
+@add_toggle_java
+@snippet java/tutorial_code/highgui/trackbar/AddingImagesTrackbar.java create_trackbar
+@end_toggle
+
+@add_toggle_python
+@snippet python/tutorial_code/highgui/trackbar/AddingImagesTrackbar.py create_trackbar
+@end_toggle
+
+Note the following (C++ code):
     -   Our Trackbar has a label **TrackbarName**
     -   The Trackbar is located in the window named **Linear Blend**
     -   The Trackbar values will be in the range from \f$0\f$ to **alpha_slider_max** (the minimum
@@ -51,10 +98,21 @@ We only analyze the code that is related to Trackbar:
     -   The numerical value of Trackbar is stored in **alpha_slider**
     -   Whenever the user moves the Trackbar, the callback function **on_trackbar** is called
 
--#  Finally, we have to define the callback function **on_trackbar**
-    @snippet cpp/tutorial_code/HighGUI/AddingImagesTrackbar.cpp on_trackbar
+Finally, we have to define the callback function **on_trackbar** for C++ and Python code, using an anonymous inner class listener in Java
 
-    Note that:
+@add_toggle_cpp
+@snippet cpp/tutorial_code/HighGUI/AddingImagesTrackbar.cpp on_trackbar
+@end_toggle
+
+@add_toggle_java
+@snippet java/tutorial_code/highgui/trackbar/AddingImagesTrackbar.java on_trackbar
+@end_toggle
+
+@add_toggle_python
+@snippet python/tutorial_code/highgui/trackbar/AddingImagesTrackbar.py on_trackbar
+@end_toggle
+
+Note that (C++ code):
     -   We use the value of **alpha_slider** (integer) to get a double value for **alpha**.
     -   **alpha_slider** is updated each time the trackbar is displaced by the user.
     -   We define *src1*, *src2*, *dist*, *alpha*, *alpha_slider* and *beta* as global variables,