Imager::Preprocess(3pm) User Contributed Perl Documentation Imager::Preprocess(3pm)
NAME
Imager::Preprocess - simple preprocessor for handling multiple sample sizes
SYNOPSIS
/* in the source: */
#code condition true to work with 8-bit samples
... code using preprocessor types/values ...
#/code
# process and make #line directives
perl -MImager::Preprocess -epreprocess foo.im foo.c
# process and no #line directives
perl -MImager::Preprocess -epreprocess -l foo.im foo.c
DESCRIPTION
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 8-bits/sample.
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
#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 object.
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 identifier.
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.
AUTHOR
Tony Cook <tonyc@cpan.org>
perl v5.14.2 2011-06-06 Imager::Preprocess(3pm)