Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 1 | Debugging within the FreeType sources |
| 2 | ===================================== |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 3 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 4 | I. Configuration macros |
| 5 | ----------------------- |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 6 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 7 | There are several ways to enable debugging features in a FreeType 2 |
| 8 | builds. This is controlled through the definition of special macros |
| 9 | located in the file "ftoptions.h". The macros are: |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 10 | |
| 11 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 12 | FT_DEBUG_LEVEL_ERROR |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 13 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 14 | #define this macro if you want to compile the FT_ERROR macro calls |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 15 | to print error messages during program execution. This will not |
| 16 | stop the program. Very useful to spot invalid fonts during |
| 17 | development and to code workarounds for them. |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 18 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 19 | FT_DEBUG_LEVEL_TRACE |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 20 | |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 21 | #define this macro if you want to compile both macros FT_ERROR and |
| 22 | FT_TRACE. This also includes the variants FT_TRACE0, FT_TRACE1, |
| 23 | FT_TRACE2, ..., FT_TRACE6. |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 24 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 25 | The trace macros are used to send debugging messages when an |
| 26 | appropriate "debug level" is configured at runtime through the |
| 27 | FT2_DEBUG environment variable (more on this later). |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 28 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 29 | FT_DEBUG_MEMORY |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 30 | |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 31 | If this macro is #defined, the FreeType engine is linked with a |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 32 | small but effective debugging memory manager that tracks all |
| 33 | allocations and frees that are performed within the font engine. |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 34 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 35 | When the FT2_DEBUG_MEMORY environment variable is defined at |
| 36 | runtime, a call to FT_Done_FreeType will dump memory statistics, |
| 37 | including the list of leaked memory blocks with the source locations |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 38 | where these were allocated. It is always a very good idea to define |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 39 | this in development builds. This works with _any_ program linked to |
| 40 | FreeType, but requires a big deal of memory (the debugging memory |
| 41 | manager never frees the blocks to the heap in order to detect double |
| 42 | frees). |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 43 | |
| 44 | When FT2_DEBUG_MEMORY isn't defined at runtime, the debugging memory |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 45 | manager is ignored, and performance is unaffected. |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 46 | |
| 47 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 48 | II. Debugging macros |
| 49 | -------------------- |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 50 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 51 | Several macros can be used within the FreeType sources to help debugging |
| 52 | its code: |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 53 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 54 | 1. FT_ERROR(( ... )) |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 55 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 56 | This macro is used to send debug messages that indicate relatively |
| 57 | serious errors (like broken font files), but will not stop the |
| 58 | execution of the running program. Its code is compiled only when |
| 59 | either FT_DEBUG_LEVEL_ERROR or FT_DEBUG_LEVEL_TRACE are defined in |
| 60 | "ftoption.h". |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 61 | |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 62 | Note that you have to use a printf-like signature, but with double |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 63 | parentheses, like in: |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 64 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 65 | FT_ERROR(( "your %s is not %s\n", "foo", "bar" )); |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 66 | |
| 67 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 68 | 2. FT_ASSERT( condition ) |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 69 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 70 | This macro is used to check strong assertions at runtime. If its |
| 71 | condition isn't TRUE, the program will abort with a panic message. |
| 72 | Its code is compiled when either FT_DEBUG_LEVEL_ERROR or |
| 73 | FT_DEBUG_LEVEL_TRACE are defined. You don't need double-parentheses |
| 74 | here. For example: |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 75 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 76 | FT_ASSERT( ptr != NULL ); |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 77 | |
| 78 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 79 | 3. FT_TRACE( level, (message...) ) |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 80 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 81 | The FT_TRACE macro is used to send general-purpose debugging |
| 82 | messages during program execution. This macro uses an *implicit* |
| 83 | macro named FT_COMPONENT used to name the current FreeType component |
| 84 | being run. |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 85 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 86 | The developer should always define FT_COMPONENT as appropriate, for |
| 87 | example as in: |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 88 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 89 | #undef FT_COMPONENT |
| 90 | #define FT_COMPONENT trace_io |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 91 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 92 | The value of the FT_COMPONENT macro is an enumeration named |
| 93 | trace_XXXX where XXXX is one of the component names defined in the |
| 94 | internal file <freetype/internal/fttrace.h>. |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 95 | |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 96 | Each such component is assigned a "debug level", ranging from 0 |
| 97 | to 6, through the use of the FT2_DEBUG environment variable |
| 98 | (described below) when a program linked with FreeType starts. |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 99 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 100 | When FT_TRACE is called, its level is compared to the one of the |
| 101 | corresponding component. Messages with trace levels *higher* than |
| 102 | the corresponding component level are filtered and never printed. |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 103 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 104 | This means that trace messages with level 0 are always printed, |
| 105 | those with level 2 are only printed when the component level is *at |
| 106 | least* 2. |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 107 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 108 | The second parameter to FT_TRACE must contain parentheses and |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 109 | correspond to a printf-like call, as in: |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 110 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 111 | FT_TRACE( 2, ( "your %s is not %s\n", "foo", "bar" ) ) |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 112 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 113 | The shortcut macros FT_TRACE0, FT_TRACE1, FT_TRACE2_, ... FT_TRACE6 |
| 114 | can be used with constant level indices, and are much cleaner to |
| 115 | use, as in |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 116 | |
| 117 | FT_TRACE2(( "your %s is not %s\n", "foo", "bar" )); |
| 118 | |
| 119 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 120 | III. Environment variables |
| 121 | -------------------------- |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 122 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 123 | The following environment variables control debugging output and |
| 124 | behaviour of FreeType at runtime: |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 125 | |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 126 | FT2_DEBUG |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 127 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 128 | This variable is only used when FreeType is built with |
| 129 | FT_DEBUG_LEVEL_TRACE defined. It contains a list of component level |
| 130 | definitions, following this format: |
| 131 | |
| 132 | component1:level1 component2:level2 component3:level3 ... |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 133 | |
| 134 | where "componentX" is the name of a tracing component, as defined in |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 135 | "fttrace.h", but without the "trace_" prefix. "levelX" is the |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 136 | corresponding level to use at runtime. |
| 137 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 138 | "any" is a special component name that will be interpreted as |
| 139 | "any/all components". For example, the following definitions |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 140 | |
| 141 | set FT2_DEBUG=any:2 memory:5 io:4 (on Windows) |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 142 | export FT2_DEBUG="any:2 memory:5 io:4" (on Linux with bash) |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 143 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 144 | both stipulate that all components should have level 2, except for |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 145 | the memory and io components which will be set to trace levels 5 |
| 146 | and 4, respectively. |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 147 | |
| 148 | FT2_DEBUG_MEMORY |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 149 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 150 | This environment variable, when defined, tells FreeType to use a |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 151 | debugging memory manager that will track leaking memory blocks as |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 152 | well as other common errors like double frees. It is also capable |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 153 | of reporting _where_ the leaking blocks were allocated, which |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame] | 154 | considerably saves time when debugging new additions to the library. |
| 155 | |
| 156 | This code is only compiled when FreeType is built with the |
| 157 | FT_DEBUG_MEMORY macro #defined in "ftoption.h" though, it will be |
| 158 | ignored in other builds. |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 159 | |
David Turner | b280537 | 2003-03-13 21:07:51 +0000 | [diff] [blame] | 160 | FT2_ALLOC_TOTAL_MAX |
| 161 | |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 162 | This variable is ignored if FT2_DEBUG_MEMORY is not defined. It |
| 163 | allows you to specify a maximum heap size for all memory allocations |
| 164 | performed by FreeType. This is very useful to test the robustness |
| 165 | of the font engine and programs that use it in tight memory |
| 166 | conditions. |
David Turner | b280537 | 2003-03-13 21:07:51 +0000 | [diff] [blame] | 167 | |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 168 | If it is undefined, or if its value is not strictly positive, then |
| 169 | no allocation bounds are checked at runtime. |
David Turner | b280537 | 2003-03-13 21:07:51 +0000 | [diff] [blame] | 170 | |
| 171 | FT2_ALLOC_COUNT_MAX |
| 172 | |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 173 | This variable is ignored if FT2_DEBUG_MEMORY is not defined. It |
| 174 | allows you to specify a maximum number of memory allocations |
| 175 | performed by FreeType before returning the error |
| 176 | FT_Err_Out_Of_Memory. This is useful for debugging and testing the |
| 177 | engine's robustness. |
David Turner | b280537 | 2003-03-13 21:07:51 +0000 | [diff] [blame] | 178 | |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 179 | If it is undefined, or if its value is not strictly positive, then |
| 180 | no allocation bounsd are checked at runtime. |
David Turner | b280537 | 2003-03-13 21:07:51 +0000 | [diff] [blame] | 181 | |
Werner Lemberg | a16c4a7 | 2003-04-21 13:30:27 +0000 | [diff] [blame^] | 182 | |
| 183 | --- end of DEBUG --- |