OverlayBitmap::getDC Method

HDC getDC() const;

If the method succeeds, the return value identifies the currently used device context of the OverlayBitmap object.

If the function fails, the return value is NULL.

An application can use the returned device context to perform GDI operations that are not provided by a method of the OverlayBitmap class.

Before getDC can be called, an application must call OverlayBitmap::beginPaint. OverlayBitmap::beginPaint creates the device context and selects the bitmap of the OverlayBitmap object in this new device context.

If getDC is called without a preceding call to OverlayBitmap::beginPaint, getDC returns NULL and an exception is thrown.

After all GDI operations have been performed, the OverlayBitmap::endPaint method must be called to release the device context and make the result of the GDI operations visible on the live video.

This example demonstrates how to retrieve the device context of the OverlayBitmap object.

smart_ptr<DShowLib::OverlayBitmap> pOverlayBitmap;
HDC hDC;
pOverlayBitmap = m_Grabber.getOverlay( ePP_DEVICE );
pOverlayBitmap->beginPaint();
hDC = pOverlayBitmap->getDC();
if( hDC != NULL)
{
    // Now, perform some GDI functions, using the hDC.
}
pOverlayBitmap->endPaint();