--- a/misc/libfreetype/docs/DEBUG Thu Jul 25 23:16:06 2013 +0200
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,202 +0,0 @@
-Debugging within the FreeType sources
-=====================================
-
-I. Configuration macros
------------------------
-
-There are several ways to enable debugging features in a FreeType 2
-builds. This is controlled through the definition of special macros
-located in the file `ftoptions.h'. The macros are:
-
-
- FT_DEBUG_LEVEL_ERROR
-
- #define this macro if you want to compile the FT_ERROR macro calls
- to print error messages during program execution. This will not
- stop the program. Very useful to spot invalid fonts during
- development and to code workarounds for them.
-
- FT_DEBUG_LEVEL_TRACE
-
- #define this macro if you want to compile both macros FT_ERROR and
- FT_TRACE. This also includes the variants FT_TRACE0, FT_TRACE1,
- FT_TRACE2, ..., FT_TRACE7.
-
- The trace macros are used to send debugging messages when an
- appropriate `debug level' is configured at runtime through the
- FT2_DEBUG environment variable (more on this later).
-
- FT_DEBUG_MEMORY
-
- If this macro is #defined, the FreeType engine is linked with a
- small but effective debugging memory manager that tracks all
- allocations and frees that are performed within the font engine.
-
- When the FT2_DEBUG_MEMORY environment variable is defined at
- runtime, a call to FT_Done_FreeType will dump memory statistics,
- including the list of leaked memory blocks with the source locations
- where these were allocated. It is always a very good idea to define
- this in development builds. This works with _any_ program linked to
- FreeType, but requires a big deal of memory (the debugging memory
- manager never frees the blocks to the heap in order to detect double
- frees).
-
- When FT2_DEBUG_MEMORY isn't defined at runtime, the debugging memory
- manager is ignored, and performance is unaffected.
-
-
-II. Debugging macros
---------------------
-
-Several macros can be used within the FreeType sources to help debugging
-its code:
-
-
- 1. FT_ERROR(( ... ))
-
- This macro is used to send debug messages that indicate relatively
- serious errors (like broken font files), but will not stop the
- execution of the running program. Its code is compiled only when
- either FT_DEBUG_LEVEL_ERROR or FT_DEBUG_LEVEL_TRACE are defined in
- `ftoption.h'.
-
- Note that you have to use a printf-like signature, but with double
- parentheses, like in
-
- FT_ERROR(( "your %s is not %s\n", "foo", "bar" ));
-
-
- 2. FT_ASSERT( condition )
-
- This macro is used to check strong assertions at runtime. If its
- condition isn't TRUE, the program will abort with a panic message.
- Its code is compiled when either FT_DEBUG_LEVEL_ERROR or
- FT_DEBUG_LEVEL_TRACE are defined. You don't need double parentheses
- here. For example
-
- FT_ASSERT( ptr != NULL );
-
-
- 3. FT_TRACE( level, (message...) )
-
- The FT_TRACE macro is used to send general-purpose debugging
- messages during program execution. This macro uses an *implicit*
- macro named FT_COMPONENT used to name the current FreeType component
- being run.
-
- The developer should always define FT_COMPONENT as appropriate, for
- example as in
-
- #undef FT_COMPONENT
- #define FT_COMPONENT trace_io
-
- The value of the FT_COMPONENT macro is an enumeration named
- trace_XXXX where XXXX is one of the component names defined in the
- internal file `freetype/internal/fttrace.h'. If you modify FreeType
- source and insert new trace_XXXX macro, you must register it in
- fttrace.h. If you insert or remove many trace macros, you can check
- the undefined or the unused trace macro by src/tools/chktrcmp.py.
-
- Each such component is assigned a `debug level', ranging from 0
- to 7, through the use of the FT2_DEBUG environment variable
- (described below) when a program linked with FreeType starts.
-
- When FT_TRACE is called, its level is compared to the one of the
- corresponding component. Messages with trace levels *higher* than
- the corresponding component level are filtered and never printed.
-
- This means that trace messages with level 0 are always printed,
- those with level 2 are only printed when the component level is *at
- least* 2.
-
- The second parameter to FT_TRACE must contain parentheses and
- correspond to a printf-like call, as in
-
- FT_TRACE( 2, ( "your %s is not %s\n", "foo", "bar" ) )
-
- The shortcut macros FT_TRACE0, FT_TRACE1, FT_TRACE2, ..., FT_TRACE7
- can be used with constant level indices, and are much cleaner to
- use, as in
-
- FT_TRACE2(( "your %s is not %s\n", "foo", "bar" ));
-
-
-III. Environment variables
---------------------------
-
-The following environment variables control debugging output and
-behaviour of FreeType at runtime.
-
-
- FT2_DEBUG
-
- This variable is only used when FreeType is built with
- FT_DEBUG_LEVEL_TRACE defined. It contains a list of component level
- definitions, following this format:
-
- component1:level1 component2:level2 component3:level3 ...
-
- where `componentX' is the name of a tracing component, as defined in
- `fttrace.h', but without the `trace_' prefix. `levelX' is the
- corresponding level to use at runtime.
-
- `any' is a special component name that will be interpreted as
- `any/all components'. For example, the following definitions
-
- set FT2_DEBUG=any:2 memory:5 io:4 (on Windows)
- export FT2_DEBUG="any:2 memory:5 io:4" (on Linux with bash)
-
- both stipulate that all components should have level 2, except for
- the memory and io components which will be set to trace levels 5 and
- 4, respectively.
-
-
- FT2_DEBUG_MEMORY
-
- This environment variable, when defined, tells FreeType to use a
- debugging memory manager that will track leaking memory blocks as
- well as other common errors like double frees. It is also capable
- of reporting _where_ the leaking blocks were allocated, which
- considerably saves time when debugging new additions to the library.
-
- This code is only compiled when FreeType is built with the
- FT_DEBUG_MEMORY macro #defined in `ftoption.h' though, it will be
- ignored in other builds.
-
-
- FT2_ALLOC_TOTAL_MAX
-
- This variable is ignored if FT2_DEBUG_MEMORY is not defined. It
- allows you to specify a maximum heap size for all memory allocations
- performed by FreeType. This is very useful to test the robustness
- of the font engine and programs that use it in tight memory
- conditions.
-
- If it is undefined, or if its value is not strictly positive, then
- no allocation bounds are checked at runtime.
-
-
- FT2_ALLOC_COUNT_MAX
-
- This variable is ignored if FT2_DEBUG_MEMORY is not defined. It
- allows you to specify a maximum number of memory allocations
- performed by FreeType before returning the error
- FT_Err_Out_Of_Memory. This is useful for debugging and testing the
- engine's robustness.
-
- If it is undefined, or if its value is not strictly positive, then
- no allocation bounds are checked at runtime.
-
-------------------------------------------------------------------------
-
-Copyright 2002, 2003, 2004, 2005, 2009 by
-David Turner, Robert Wilhelm, and Werner Lemberg.
-
-This file is part of the FreeType project, and may only be used,
-modified, and distributed under the terms of the FreeType project
-license, LICENSE.TXT. By continuing to use, modify, or distribute this
-file you indicate that you have read the license and understand and
-accept it fully.
-
-
---- end of DEBUG ---