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IMcImageGetArea Method

Get a block of pixel values from the image

Namespace:  MediaCy.IQL.Engine
Assembly:  MediaCy.IQL.Engine (in MediaCy.IQL.Engine.dll) Version: 10.0.6912.0
Syntax
VB
Copy
Function GetArea ( 
	<OutAttribute> ByRef pvArea As Object,
	Optional lLeft As Integer = -1,
	Optional lTop As Integer = -1,
	Optional lRight As Integer = -1,
	Optional lBottom As Integer = -1,
	Optional Frame As Integer = -2
) As Integer

Parameters

pvArea
Type: SystemObject
A pointer to a VARIANT receiving the pixel values. If the VARIANT is empty, the function will return one containing a two-dimensional SAFEARRAY (for one channel per pixel) or a three-dimensional SAFEARRAY (for multiple channels per pixel). If a 2-D array is created, it will be shaped as vLine(0 to lWidth-1, 0 to lHeight-1) for VB arrays and as vLine[lHeight][lWidth] for C/C++/Java arrays. If a 2-D array is created, it will be shaped as vLine(0 to nChannels-1, 0 to lWidth-1, 0 to lHeight-1) for VB arrays and as vLine[lHeight][lWidth][nChannels] for C/C++/Java arrays. The number of values contained in the SAFEARRAY is equal to the height times the width times the number of channels (3 for color images). For color images, red, green, and blue values are interlaced.
lLeft (Optional)
Type: SystemInt32
lTop (Optional)
Type: SystemInt32
lRight (Optional)
Type: SystemInt32
lBottom (Optional)
Type: SystemInt32
Frame (Optional)
Type: SystemInt32

Return Value

Type: Int32
The number of values returned in the array. Should be (right - left + 1)*(bottom - top + 1)*image.NumberOfChannels.
Remarks
See CreateRegionAccess for a more controlled way to get pixel values. When the routine itself creates the array it is typed after the image type, which guarantees that the pixel values will fit into the array. If pvArea already contains an array it must be of the right data type and size. For languages that do not support the unsigned integer type (like Visual Basic or VBA), 16 bits values bigger than 32767 will be reported as negative because their sign bit is set. The best way to work around this limitation is to create a "long" McRegionAccess using CreateRegionAccess and call its own version of GetArea, which will then return long positive values (4 bytes) instead of unsigned integers (2 bytes).
Note Note
Avoid using GetArea followed by PutArea to copy large image frames. This causes the entire image frame being copied to need to reside in memory. Instead use the IMcRegionAccess.CopyInEntireArea method. Or set up your own per line loop and use GetLine followed by PutLine (you will need to call BeginEndUpdateBlock(TRUE/FALSE) around such a loop to avoid excessive image updating).
See Also