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where

The where command retrieves the rectangle specifying the source or destination area. This rectangle was specified using the put command. Digital-video, and video-overlay devices recognize this command.

To send this command, call the mciSendString function with the lpszCommand parameter set as follows.

_stprintf_s(
  lpszCommand, 
  TEXT("where %s %s %s"), 
  lpszDeviceID, 
  lpszRequestRect, 
  lpszFlags
); 

Parameters

lpszDeviceID

Identifier of an MCI device. This identifier or alias is assigned when the device is opened.

lpszRequestRect

Flag that identifies the rectangle whose dimensions are retrieved. The following table lists device types that recognize the where command and the flags used by each type.

Value Meaning Meaning
digitalvideo destination
destination max
frame
frame max
source
source max
video
video max
window
window max
overlay destination
frame
source
video

The following table lists the flags that can be specified in the lpszRequestRect parameter and their meanings.

Value Meaning
destination Retrieves the destination offset and extent. For video-overlay devices, the destination rectangle defines the area of the display window client area that displays the image data from the frame buffer.
destination max Retrieves the current size of the client rectangle.
frame Retrieves the offset and extent of the frame buffer rectangle. The frame buffer rectangle defines the area of the frame buffer that receives incoming video data. Images from the "video" rectangle are scaled into this region.
frame max Returns the maximum size of the frame buffer.
source Retrieves the source offset and extent. For video-overlay devices, the source rectangle defines the region of the frame buffer that is displayed in the destination window. The device uses this rectangle to crop the image before it is stretched to fit the destination rectangle on the display.
source max Retrieves the maximum size of the frame buffer.
video Retrieves the offset and extent of the video rectangle. The video rectangle defines the region of the incoming video data that is transferred to the frame buffer.
video max Returns the maximum size of the input.
window Retrieves the current size and position of the display-window frame.
window max Retrieves the size of the entire display.

lpszFlags

Can be "wait", "notify", or both. For digital-video devices, "test" can also be specified. For more information about these flags, see The Wait, Notify, and Test Flags.

Return Values

Returns a rectangle in the lpszReturnString parameter of the mciSendString function. The rectangle describes the area specified in the lpszRequestRect parameter of this command. The rectangle is specified as X1 Y1 X2 Y2. The coordinates X1 Y1 specify the upper left corner of the rectangle, and the coordinates X2 Y2 specify the width and height.

Remarks

The following command returns the display rectangle of the "movie" device:

where movie destination

Requirements

  Windows NT/2000/XP: Included in Windows NT 3.1 and later.
  Windows 95/98/Me: Included in Windows 95 and later.

See Also

MCI, MCI Command Strings, mciSendString, put

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