IG_ISIS_tag_get

Get current value of a tag of type rational.

Declaration:

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AT_ERRCOUNT ACCUAPI IG_ISIS_tag_get_rational( HISISDRV hDriver, AT_MODE nTag, WORD wIndex, LPAT_ISIS_RAT lpValue );

Arguments:

hDriver	The handle to the driver.
nTag	Specifies the type rational tag for which to return the current value.
wIndex	Specifies the index of the element to get. Most tags have only one element, in which case wIndex must be zero. Use IG_ISIS_tag_get_length to determine how many elements a tag contains.
lpValue	Points to the current value of the tag after this function completes.

Return Value:

Returns the number of ImageGear errors that occurred during this function call. If there are no errors, the return value is IGE_SUCCESS.

Supported Raster Image Formats:

This function does not process image pixels.

Remarks:

The IG_ISIS_tag_get_rational function retrieves the rational value that is the current value of the specified tag.

Use IG_ISIS_tag_get_rational to retrieve the current value of the type rational tag specified in nTag. Use IG_ISIS_tag_get_length to get the number of elements in the tag. If the tag has only one element, wIndex must be zero. If the tag has multiple elements, loop on IG_ISIS_tag_get_rational to obtain all elements of the current value of the tag.

Use of IG_ISIS_tag_get_rational on a tag other than one of type rational is undefined. At best, this will cause an invalid return value or a operating system error message, and at worst will cause the system to crash.

The tags most commonly defined as rational are the X and Y position and X and Y resolution tags.

Example:

The following example gets the current scanning resolution and prints it to the standard output:

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AT_ISIS_RAT ratValue;IG_ISIS_tag_get_rational(hDriver, IG_ISIS_TAG_XRESOLUTION, 0, &ratValue); sprintf(caBuffer, "Scanning resolution is %ld DPI\n", (long)(ratValue.Num / ratValue.Denom));