Imager::Preprocess - simple preprocessor for handling multiple sample sizes
/* 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
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.
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:
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 sections cannot be nested.
#/code without a starting #code is an error.
The following types and values are defined in a #code section:
These correspond to the appropriate image function, eg. IM_GPIX() becomes i_gpix() or i_gpixf() as appropriate.
Call i_adapt_colors() or i_adapt_fcolors().
fill) - retrieve the combine function from a fill object.
fill) - retrieve the fill_with_* function from a fill object.
IM_SAMPLE_MAX - maximum value for a sample
IM_SAMPLE_MAX2 - maximum value for a sample, squared
IM_SAMPLE_T - type of a sample (i_sample_t or i_fsample_t)
IM_COLOR - color type, either i_color or i_fcolor.
IM_WORK_T - working sample type, either int or double.
IM_Sf - format string for the sample type,
IM_Wf - format string for the work type,
IM_SUFFIX(identifier) - adds _8 or _double onto the end of identifier.
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 <email@example.com>