IMFPMediaPlayer::UpdateVideo method (mfplay.h)

项目
12/05/2018

[The feature associated with this page, MFPlay, is a legacy feature. It has been superseded by MediaPlayer and IMFMediaEngine. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer and IMFMediaEngine instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

Updates the video frame.

Syntax

HRESULT UpdateVideo();

Return value

The method returns an HRESULT. Possible values include, but are not limited to, those in the following table.

Return code	Description
S_OK	The method succeeded.
MF_E_INVALIDREQUEST	The current media item does not contain video.
MF_E_SHUTDOWN	The object's Shutdown method was called.

Remarks

Call this method when your application's video playback window receives either a WM_PAINT or WM_SIZE message. This method performs two functions:

Ensures that the video frame is repainted while playback is paused or stopped.
Adjusts the displayed video to match the current size of the video window.

Important Call the GDI BeginPaint function before calling UpdateVideo.

Examples

IMFPMediaPlayer *g_pPlayer;

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    HDC hdc;
    PAINTSTRUCT ps;

    switch (uMsg)
    {
    case WM_PAINT:
        hdc = BeginPaint(hwnd, &ps);
        if (g_pPlayer)
        {
            g_pPlayer->UpdateVideo();
        }
       	EndPaint(hwnd, &ps);
        break;

    case WM_SIZE:        
        hdc = BeginPaint(hwnd, &ps);
        if (g_pPlayer)
        {
            g_pPlayer->UpdateVideo();
        }
       	EndPaint(hwnd, &ps);
        break;

    // other messages

    default:
        return DefWindowProc(hwnd, uMsg, wParam, lParam); 
    }
    return 0;
}

Requirements

Requirement	Value
Minimum supported client	Windows 7 [desktop apps only]
Minimum supported server	Windows Server 2008 R2 [desktop apps only]
Target Platform	Windows
Header	mfplay.h

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