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Imager::Preprocess(3) User Contributed Perl DocumentationImager::Preprocess(3)

       Imager::Preprocess - simple preprocessor	for handling multiple sample

	 /* in the source: */
	 #code condition true to work with 8-bit samples
	 ... code using	preprocessor types/values ...

	 # process and make #line directives
	 perl -MImager::Preprocess -epreprocess foo.c

	 # process and no #line	directives
	 perl -MImager::Preprocess -epreprocess	-l foo.c

       This is a simple	preprocessor that aims to reduce duplication of	source
       code when implementing an algorithm both	for 8-bit samples and double
       samples in Imager.

       Imager's	"Makefile.PL" currently	scans the MANIFEST for .im files and
       adds Makefile files to convert these to .c files.

       The beginning of	a sample-independent section of	code is	preceded by:

	 #code expression

       where expression	should return true if processing should	be done	at

       You can also use	a #code	block around a function	definition to produce
       8-bit and double	sample versions	of a function.	In this	case #code has
       no expression and you will need to use IM_SUFFIX() to produce different
       function	names.

       The end of a sample-independent section of code is terminated by:


       #code sections cannot be	nested.

       #/code without a	starting #code is an error.

       The following types and values are defined in a #code section:

       o   IM_GPIX("im", "x", "y", &col)

       o   IM_GLIN("im", "l", "r", "y",	"colors")

       o   IM_PPIX("im", "x", "y", &col)

       o   IM_PLIN("im", "x", "y", "colors")

       o   IM_GSAMP("im", "l", "r", "y", "samples", "chans", "chan_count")

	   These correspond to the appropriate image function, eg. IM_GPIX()
	   becomes i_gpix() or i_gpixf() as appropriate.

       o   IM_ADAPT_COLORS("dest_channels", "src_channels", "colors", "count")

	   Call	i_adapt_colors() or i_adapt_fcolors().

       o   IM_FILL_COMBINE("fill") - retrieve the combine function from	a fill

       o   IM_FILL_FILLER("fill") - retrieve the fill_with_* function from a
	   fill	object.

       o   IM_SAMPLE_MAX - maximum value for a sample

       o   IM_SAMPLE_MAX2 - maximum value for a	sample,	squared

       o   IM_SAMPLE_T - type of a sample (i_sample_t or i_fsample_t)

       o   IM_COLOR - color type, either i_color or i_fcolor.

       o   IM_WORK_T - working sample type, either int or double.

       o   IM_Sf - format string for the sample	type, "%d" or "%f".

       o   IM_Wf - format string for the work type, "%d" or "%f".

       o   IM_SUFFIX(identifier) - adds	_8 or _double onto the end of

       o   IM_EIGHT_BIT	- this is a macro defined only in 8-bit/sample code.

       Other types, functions and values may be	added in the future.

       Tony Cook <>

perl v5.32.0			  2020-06-13		 Imager::Preprocess(3)


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