Add an experimental .clang-format file.

This file can be used with clang-format to format c and c++ source
files according to the FLTK CMP -- at least "almost" in its current
version. It should not (yet) be used without further checking of the
result.

Note: there are some deliberate non-conformant formattings in current
source files, such as formatting like (better readable?) tables with
columns etc.. Such special formatting can be preserved with clang-format
"pragma's" (see documentation in .clang-format), but this needs source
file changes before formatting.


git-svn-id: file:///fltk/svn/fltk/branches/branch-1.4@12598 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

.clang-format

@@ -0,0 +1,144 @@
+#
+# "$Id$"
+#
+# clang-format control file for the FLTK project.
+#
+# Copyright 2017 by Bill Spitzak and others.
+#
+# This library is free software. Distribution and use rights are outlined in
+# the file "COPYING" which should have been included with this file.  If this
+# file is missing or damaged, see the license at:
+#
+#     http://www.fltk.org/COPYING.php
+#
+# Please report all bugs and problems on the following page:
+#
+#     http://www.fltk.org/str.php
+#
+#
+#  Important notes:
+#
+#  This is a preliminary, experimental version of a clang-format control file.
+#  To use all options including embedded comments to switch formatting on
+#  and off in source files (see below) clang-format 3.6 or later is required.
+#
+#  DO NOT USE WITHOUT CHECKING THE RESULT OF FORMATTING FOR CORRECTNESS
+#  AND COMPATIBILITY WITH THE FLTK CMP!
+#
+#  For more information about clang-format please refer to the online docs at:
+#  http://clang.llvm.org/docs/ClangFormat.html
+#  http://clang.llvm.org/docs/ClangFormatStyleOptions.html
+#
+#  Embedded comments ("pragma"s) in the source code:
+#    // clang-format on
+#    // clang-format off
+#  The above comments or their C equivalents /* clang-format on|off */
+#  can be used to switch clang-format(ting) temporary off in a source file.
+#  This is particularly useful for embedded pixmaps and other tables
+#  like menu arrays that are pre-formatted for better readability.
+
+
+#  The options used for FLTK are based on pre-defined style options of LLVM
+
+BasedOnStyle:		LLVM
+
+#  The Language tag marks C++ options
+
+Language:					Cpp
+
+# The following block of commented options is an excerpt of all
+# LLVM style options with their respective values.
+# For a full list of LLVM options please use:
+#   clang-format -style=llvm -dump-config
+
+# Please do not change the following block of comments unless the LLVM
+# default values have changed or to add or remove (ir)relevant options.
+
+# IndentWidth:					2
+# TabWidth:					8
+# ColumnLimit:					80
+# UseTab:					Never
+# AccessModifierOffset:				-2
+# AllowShortBlocksOnASingleLine:		false
+# AllowShortFunctionsOnASingleLine:		All
+# AllowShortIfStatementsOnASingleLine:		false
+# AllowShortLoopsOnASingleLine:			false
+# MaxEmptyLinesToKeep:				1
+# KeepEmptyLinesAtTheStartOfBlocks:		true
+# PenaltyBreakBeforeFirstCallParameter:		19
+# PenaltyBreakComment:				300
+# PenaltyBreakString:				1000
+# PenaltyBreakFirstLessLess:			120
+# PenaltyExcessCharacter:			1000000
+# PenaltyReturnTypeOnItsOwnLine:		60
+# PointerAlignment:				Right
+# BreakBeforeBraces:				Attach
+# ContinuationIndentWidth:			4
+# SpaceBeforeParens:				ControlStatements
+
+# FLTK specific settings (currently experimental).
+# The following options override the LLVM style definitions, if set.
+# Refer to the default values above.
+
+# Uncomment the next option if indenting with tabs should be used.
+# Note: tab spacing is still 8 columns, tabs are only used for
+# indents of 8 columns or more.
+# Might have bugs counting columns, comments may not be adjusted
+# as expected (as of clang-format 3.6 and 3.8).
+# UseTab can be set to 'Never' or 'ForIndentation' to avoid this
+# annoying bug of clang-format.
+# UseTab:					Always
+# UseTab:					Never
+UseTab:						ForIndentation
+
+# Should we extend beyond 80 columns ?
+# ColumnLimit:					100
+ColumnLimit:					120
+
+# LLVM: IndentCaseLabels:			false
+IndentCaseLabels:				true
+
+# There are sometimes more than 1 empty lines; should we keep 2 or more ?
+
+# Default (LLVM):				1
+MaxEmptyLinesToKeep:				2
+
+# The existent FLTK source code has some short blocks and if statements
+# in one line, but we should better make it consistent and NOT use the
+# following two "Allow..." statements (leave them commented out):
+
+# AllowShortBlocksOnASingleLine:		true
+# AllowShortIfStatementsOnASingleLine:		true
+
+# Short inline functions in header files are an exception to the above "rule":
+
+# LLVM: AllowShortFunctionsOnASingleLine:	All
+AllowShortFunctionsOnASingleLine:		Inline
+
+# This is particularly useful for macros with continuation lines:
+
+AlignEscapedNewlinesLeft:			true
+
+# Include files should be left as-is until we know we can sort them
+# without any bad side effects:
+
+SortIncludes:					false
+
+# Multiple constructor initializers must be on consecutive lines:
+
+BreakConstructorInitializersBeforeComma:	true
+
+# Constructor initializers will be indented by 2 spaces:
+
+# LLVM: ConstructorInitializerIndentWidth:	4
+ConstructorInitializerIndentWidth:		2
+
+# *FIXME* Default (LLVM):			4
+# ContinuationIndentWidth:			2
+
+PointerAlignment:				Right
+DerivePointerAlignment:				false
+
+#
+# End of "$Id$".
+#