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.
Imager's Makefile.PL currently scans the MANIFEST for .im files and adds Makefile files to convert these to .c files.
Makefile.PL
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.
You can also define extra sample-size dependent macros with #!define:
#!define
#define common-name eight-bit-name floating-point-name
#define
The following types and values are defined in a #code section:
IM_GPIX(im, x, y, &col)
im
x
y
&col
IM_GLIN(im, l, r, y, colors)
l
r
colors
IM_PPIX(im, x, y, &col)
IM_PLIN(im, x, y, colors)
IM_GSAMP(im, l, r, y, samples, chans, chan_count)
samples
chans
chan_count
These correspond to the appropriate image function, eg. IM_GPIX() becomes i_gpix() or i_gpixf() as appropriate.
IM_ADAPT_COLORS(dest_channels, src_channels, colors, count)
dest_channels
src_channels
count
Call i_adapt_colors() or i_adapt_fcolors().
IM_FILL_COMBINE(fill) - retrieve the combine function from a fill object.
fill
IM_FILL_FILLER(fill) - retrieve the fill_with_* function from a fill object.
IM_ABS(sample) - calculate the absolute value of an IM_WORK_T value.
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, "%d" or "%f".
"%d"
"%f"
IM_Wf - format string for the work type, "%d" or "%f".
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 <tonyc@cpan.org>
To install Imager, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Imager
CPAN shell
perl -MCPAN -e shell install Imager
For more information on module installation, please visit the detailed CPAN module installation guide.