1Imager::Preprocess(3) User Contributed Perl DocumentationImager::Preprocess(3)
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NAME

6       Imager::Preprocess - simple preprocessor for handling multiple sample
7       sizes
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SYNOPSIS

10         /* in the source: */
11         #code condition true to work with 8-bit samples
12         ... code using preprocessor types/values ...
13         #/code
14
15         # process and make #line directives
16         perl -MImager::Preprocess -epreprocess foo.im foo.c
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18         # process and no #line directives
19         perl -MImager::Preprocess -epreprocess -l foo.im foo.c
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DESCRIPTION

22       This is a simple preprocessor that aims to reduce duplication of source
23       code when implementing an algorithm both for 8-bit samples and double
24       samples in Imager.
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26       Imager's "Makefile.PL" currently scans the MANIFEST for .im files and
27       adds Makefile files to convert these to .c files.
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29       The beginning of a sample-independent section of code is preceded by:
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31         #code expression
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33       where expression should return true if processing should be done at
34       8-bits/sample.
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36       You can also use a #code block around a function definition to produce
37       8-bit and double sample versions of a function.  In this case #code has
38       no expression and you will need to use IM_SUFFIX() to produce different
39       function names.
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41       The end of a sample-independent section of code is terminated by:
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43         #/code
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45       #code sections cannot be nested.
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47       #/code without a starting #code is an error.
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49       You can also define extra sample-size dependent macros with "#!define":
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51           "#define" common-name eight-bit-name floating-point-name
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53       The following types and values are defined in a #code section:
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55       •   IM_GPIX("im", "x", "y", &col)
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57       •   IM_GLIN("im", "l", "r", "y", "colors")
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59       •   IM_PPIX("im", "x", "y", &col)
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61       •   IM_PLIN("im", "x", "y", "colors")
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63       •   IM_GSAMP("im", "l", "r", "y", "samples", "chans", "chan_count")
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65           These correspond to the appropriate image function, eg. IM_GPIX()
66           becomes i_gpix() or i_gpixf() as appropriate.
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68       •   IM_ADAPT_COLORS("dest_channels", "src_channels", "colors", "count")
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70           Call i_adapt_colors() or i_adapt_fcolors().
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72       •   IM_FILL_COMBINE("fill") - retrieve the combine function from a fill
73           object.
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75       •   IM_FILL_FILLER("fill") - retrieve the fill_with_* function from a
76           fill object.
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78       •   IM_ABS(sample) - calculate the absolute value of an IM_WORK_T
79           value.
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81       •   IM_SAMPLE_MAX - maximum value for a sample
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83       •   IM_SAMPLE_MAX2 - maximum value for a sample, squared
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85       •   IM_SAMPLE_T - type of a sample (i_sample_t or i_fsample_t)
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87       •   IM_COLOR - color type, either i_color or i_fcolor.
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89       •   IM_WORK_T - working sample type, either int or double.
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91       •   IM_Sf - format string for the sample type, "%d" or "%f".
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93       •   IM_Wf - format string for the work type, "%d" or "%f".
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95       •   IM_SUFFIX(identifier) - adds _8 or _double onto the end of
96           identifier.
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98       •   IM_EIGHT_BIT - this is a macro defined only in 8-bit/sample code.
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100       Other types, functions and values may be added in the future.
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AUTHOR

103       Tony Cook <tonyc@cpan.org>
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107perl v5.38.0                      2023-07-20             Imager::Preprocess(3)