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author | chai <chaifix@163.com> | 2021-10-30 13:28:39 +0800 |
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committer | chai <chaifix@163.com> | 2021-10-30 13:28:39 +0800 |
commit | c3e259f4d29e9bdcb73617ad8e4d71f117b4d289 (patch) | |
tree | 893ed7b892d0b3b49db2d3e219da28fc2eea4769 /ThirdParty/freetype/docs/DEBUG | |
parent | b2433cf2faf5c5c3d82d61c7b44928923c5fdcda (diff) |
+freetype
Diffstat (limited to 'ThirdParty/freetype/docs/DEBUG')
-rw-r--r-- | ThirdParty/freetype/docs/DEBUG | 203 |
1 files changed, 0 insertions, 203 deletions
diff --git a/ThirdParty/freetype/docs/DEBUG b/ThirdParty/freetype/docs/DEBUG deleted file mode 100644 index 828f294..0000000 --- a/ThirdParty/freetype/docs/DEBUG +++ /dev/null @@ -1,203 +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 `ftoption.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 io - - The value of the FT_COMPONENT macro is one of the component - names defined in the internal file `internal/fttrace.h'. If you - modify FreeType source and insert new FT_COMPONENT 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'. `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 (C) 2002-2019 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 --- |