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Implementing Render Sample

  • Статья

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 It has been superseded by MediaPlayer.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

The following code is used to implement the Render function:

STDMETHODIMP CGlow::Render(TimedLevel *pLevels, HDC hdc, RECT *prc)
{
    COLORREF mycolor;
    int mylevel = pLevels->waveform[0][0];
    
    switch (m_nPreset)
    {
    case PRESET_RED:
        {
        mycolor = RGB( mylevel, 0, 0);    
        }
        break;
    case PRESET_GREEN:
        {
        mycolor = RGB( 0, mylevel, 0);        
        }
        break;
    case PRESET_BLUE:
        {
        mycolor = RGB( 0, 0, mylevel);        
        }
        break;
    }

     HBRUSH hNewBrush = ::CreateSolidBrush( mycolor );
    ::FillRect( hdc, prc, hNewBrush );

    if (hNewBrush)
    {
        ::DeleteObject( hNewBrush );
    }

    return S_OK;
}

Here is an explanation of the code:

A variable named mycolor is used for the color of the glow and is declared with COLORREF. All colors should use the COLORREF data type.

A variable named mylevel is used for the audio waveform level snapshot. This value will depend on the actual power level at the moment of the snapshot.

The switch statement is set by the preset that the user has chosen on Windows Media Player. The choice will set mycolor to the desired color (red, green, or blue). However, the exact color will be determined by the audio power level. For example, if the red preset is chosen, the color will be a solid red, but it will be lighter or darker depending on the audio waveform at the moment of the snapshot. Be sure to use the RBG macro to create your color.

A brush is created called hNewBrush, and it is used to fill the prc rectangle provided by Windows Media Player. The drawing surface is the hdc device context provided by Windows Media Player.

The brush is deleted by DeleteObject. Always be sure to delete any pens or brushes you create.

Once the Render code is finished, Windows Media Player will display the hdc graphics in a window determined by the skin being used.

The Glow Sample