GetLine Method (McImage)
      
 

Description

Get a line of pixels values.

Return Type

A Long value.  

The number of values contained in the line. Should be image.width*image.NumberOfChannels.

Syntax

object.GetLine (pvLine, y, [Frame])

The GetLine Method syntax has these parts:

PartDescription
objectAn expression evaluating to an object of type McImage.
pvLineRequired. A Variant value.

A pointer to a VARIANT receiving the pixel values. If the VARIANT is empty, the function will return one containing a one-dimensional SAFEARRAY (for one channel per pixel) or a two-dimensional SAFEARRAY (for multiple channels per pixel). If a 1-D array is created, it will be shaped as vLine(0 to lWidth-1) for VB arrays and as vLine[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) for VB arrays and as vLine[lWidth][nChannels] for C/C++/Java arrays.

The number of values contained in the SAFEARRAY is equal to the with of the image times the number of channels (width for gray scale, 3*width for color images). For color images, red, green, and blue values are interlaced.

yRequired. A Long value.

The 0-based line number.

FrameOptional. A Long value.

Optional. 0-based frame number, McActiveFrame, McLastFrame. Default = McActiveFrame.

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 pvLine 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 GetLine, which will then return long positive values (4 bytes) instead of unsigned integers (2 bytes).