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Pixman coding style.
====================
The pixman coding style is close to cairo's with one exception: braces
go on their own line, rather than on the line of the if/while/for:
if (condition)
{
do_something();
do_something_else();
}
not
if (condition) {
do_something();
do_something_else();
}
Specific guidelines:
Indentation
===========
Each new level is indented four spaces:
if (condition)
do_something();
This may be achieved with space characters or with a combination of
tab characters and space characters. Tab characters are interpreted as
Advance to the next column which is a multiple of 8.
Names
=====
In all names, words are separated with underscores. Do not use
CamelCase for any names.
Macros have ALL_CAPITAL_NAMES
Type names are in lower case and end with "_t". For example
pixman_image_t.
Labels, functions and variables have lower case names.
Braces
======
Braces always go on their own line:
if (condition)
{
do_this ();
do_that ();
}
else
{
do_the_other ();
}
Rules for braces and substatements of if/while/for/do:
* If a substatement spans multiple lines, then there must be braces
around it.
* If the condition of an if/while/for spans multiple lines, then
braces must be used for the substatements.
* If one substatement of an if statement has braces, then the other
must too.
* Otherwise, don't add braces.
Comments
========
For comments either like this:
/* One line comment */
or like this:
/* This is a multi-line comment
*
* It extends over multiple lines
*/
Generally comments should say things that is clear from the code
itself. If too many comments say obvious things, then people will just
stop reading all comments, including the good ones.
Whitespace
==========
* Put a single space after commas
* Put spaces around arithmetic operators such a +, -, *, /:
y * stride + x
x / unit_x
* Do not put spaces after the address-of operator, the * when used as
a pointer derefernce or the ! and ~ operators:
&foo;
~0x00000000
!condition
*result = 100
* Break up long lines (> ~80 characters) and use whitespace to align
things nicely. This is one way:
some_very_long_function name (
implementation, op, src, mask, dest,
src_x, src_y, mask_x, mask_y, dest_x, dest_y,
width, height);
This is another:
some_very_long_function_name (implementation, op,
src, mask, dest,
src_x, src_y,
mask_x, mask_y,
dest_x, dest_y,
width, height);
* Separate logically distinct chunks with a single newline. This
obviously applies between functions, but also applies within a
function or block or structure definition.
* Use a newline after a block of variable declarations.
* Use a single space before a left parenthesis, except where the
standard will not allow it, (eg. when defining a parameterized macro).
* Don't eliminate newlines just because things would still fit on one
line. This breaks the expected visual structure of the code making
it much harder to read and understand:
if (condition) foo (); else bar (); /* Yuck! */
* Do eliminate trailing whitespace (space or tab characters) on any
line. Also, avoid putting initial or final blank lines into any
file, and never use multiple blank lines instead of a single blank
line.
* Do enable the default git pre-commit hook that detect trailing
whitespace for you and help you to avoid corrupting cairo's tree
with it. Do that as follows:
chmod a+x .git/hooks/pre-commit
* You might also find the git-stripspace utility helpful which acts as
a filter to remove trailing whitespace as well as initial, final,
and duplicate blank lines.
Function Definitions
====================
Function definitions should take the following form:
void
my_function (argument)
{
do_my_things ();
}
If all the parameters to a function fit naturally on one line, format
them that way. Otherwise, put one argument on each line, adding
whitespace so that the parameter names are aligned with each other.
I.e., do either this:
void
short_arguments (const char *str, int x, int y, int z)
{
}
or this:
void
long_arguments (const char *char_star_arg,
int int_arg,
double *double_star_arg,
double double_arg)
{
}
Mode lines
==========
Given the rules above, what is the best way to simplify one's life as
a code monkey? Get your editor to do most of the tedious work of
beautifying your code!
As a reward for reading this far, here are some mode lines for the more
popular editors:
/*
* vim:sw=4:sts=4:ts=8:tw=78:fo=tcroq:cindent:cino=\:0,(0
* vim:isk=a-z,A-Z,48-57,_,.,-,>
*/
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