WinRT glue for video I/O

Collaboration diagram for WinRT glue for video I/O:

Enumerations
enum	{   cv::OPEN_CAMERA = 300,   cv::CLOSE_CAMERA,   cv::UPDATE_IMAGE_ELEMENT,   cv::SHOW_TRACKBAR }

Functions
void	cv::winrt_imshow ()
void	cv::winrt_onVisibilityChanged (bool visible)
void	cv::winrt_setFrameContainer (::Windows::UI::Xaml::Controls::Image^ image)
template<typename ... Args>
void	cv::winrt_startMessageLoop (std::function< void(Args...)> &&callback, Args... args)
template<typename ... Args>
void	cv::winrt_startMessageLoop (void callback(Args...), Args... args)
template void	cv::winrt_startMessageLoop (void callback(void))

Detailed Description

Enumeration Type Documentation

anonymous enum

anonymous enum

#include <opencv2/videoio/cap_winrt.hpp>

Enumerator
OPEN_CAMERA
CLOSE_CAMERA
UPDATE_IMAGE_ELEMENT
SHOW_TRACKBAR

Function Documentation

winrt_imshow()

void cv::winrt_imshow

(

)

#include <opencv2/videoio/cap_winrt.hpp>

Note

Must be called to update attached image source. Code sample is available for winrt_startMessageLoop().

winrt_onVisibilityChanged()

void cv::winrt_onVisibilityChanged

(

bool

visible

)

#include <opencv2/videoio/cap_winrt.hpp>

Note

Must be called from WinRT specific callback to handle image grabber state. Here is how the class can be used:

MainPage::MainPage()
{
    // ...
    Window::Current->VisibilityChanged += ref new Windows::UI::Xaml::WindowVisibilityChangedEventHandler(this, &Application::MainPage::OnVisibilityChanged);
    // ...
}

void Application::MainPage::OnVisibilityChanged(Platform::Object ^sender,
    Windows::UI::Core::VisibilityChangedEventArgs ^e)
{
    cv::winrt_onVisibilityChanged(e->Visible);
}

winrt_setFrameContainer()

void cv::winrt_setFrameContainer

(

::Windows::UI::Xaml::Controls::Image^

image

)

#include <opencv2/videoio/cap_winrt.hpp>

Note

Must be called to assign WinRT control holding image you're working with. Code sample is available for winrt_startMessageLoop().

winrt_startMessageLoop() [1/3]

template<typename ... Args>

void cv::winrt_startMessageLoop	(	std::function< void(Args...)> &&	callback,
		Args...	args
	)

#include <opencv2/videoio/cap_winrt.hpp>

winrt_startMessageLoop() [2/3]

template<typename ... Args>

void cv::winrt_startMessageLoop	(	void	callbackArgs...,
		Args...	args
	)

#include <opencv2/videoio/cap_winrt.hpp>

winrt_startMessageLoop() [3/3]

template void cv::winrt_startMessageLoop

(

void

callbackvoid

)

#include <opencv2/videoio/cap_winrt.hpp>

Note

Starts (1) frame-grabbing loop and (2) message loop

1. Function passed as an argument must implement common OCV reading frames pattern (see cv::VideoCapture documentation) AND call cv::winrt_imgshow().
2. Message processing loop required to overcome WinRT container and type conversion restrictions. OCV provides default implementation Here is how the class can be used:

   void cvMain()
   {
       Mat frame;
       VideoCapture cam;
       cam.open(0);
   
       while (1)
       {
           cam >> frame;
   
           // don't reprocess the same frame again
           if (!cam.grab()) continue;
   
           // your processing logic goes here
   
           // obligatory step to get XAML image component updated
           winrt_imshow();
       }
   }
   
   MainPage::MainPage()
   {
       InitializeComponent();
   
       cv::winrt_setFrameContainer(cvImage);
       cv::winrt_startMessageLoop(cvMain);
   }