David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 1 | Debugging within the FreeType sources: |
| 2 | ====================================== |
| 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 |
| 15 | used to print error messages during program execution. This will |
| 16 | not stop the program, but is very useful to spot invalid fonts |
| 17 | during development and code wordarounds 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 | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame^] | 21 | #define this macro if you want to compile both the FT_ERROR macro |
| 22 | and the FT_TRACE one. This also includes the variants FT_TRACE0, |
| 23 | FT_TRACE1, 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 | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame^] | 31 | If this macro is #defined, the FreeType engines is linked with a |
| 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 |
| 38 | where these were allocated. It's always a very good idea to define |
| 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 |
| 45 | manager is ignored, and performance is un-affected. |
| 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 | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame^] | 62 | Note that you must use with a printf-like signature, but with double |
| 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 | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame^] | 96 | Each such component is assigned a "debug level", ranging from 0 to 6 |
| 97 | when a program linked with FreeType starts, through the use of the |
| 98 | FT2_DEBUG environment variable, described later. |
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 |
| 109 | correspond to a print-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 | |
| 126 | |
| 127 | FT2_DEBUG |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 128 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame^] | 129 | This variable is only used when FreeType is built with |
| 130 | FT_DEBUG_LEVEL_TRACE defined. It contains a list of component level |
| 131 | definitions, following this format: |
| 132 | |
| 133 | component1:level1 component2:level2 component3:level3 ... |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 134 | |
| 135 | where "componentX" is the name of a tracing component, as defined in |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame^] | 136 | "fttrace.h", but without the "trace_" prefix, and "levelX" is the |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 137 | corresponding level to use at runtime. |
| 138 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame^] | 139 | "any" is a special component name that will be interpreted as |
| 140 | "any/all components". For example, the following definitions |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 141 | |
| 142 | set FT2_DEBUG=any:2 memory:5 io:4 (on Windows) |
| 143 | export FT2_DEBUG="any:2 memory:5 io:4" (on Linux) |
| 144 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame^] | 145 | both stipulate that all components should have level 2, except for |
| 146 | the memory and io components which will be set to trace levels 5 and |
| 147 | 4 respectively. |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 148 | |
| 149 | FT2_DEBUG_MEMORY |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 150 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame^] | 151 | This environment variable, when defined, tells FreeType to use a |
| 152 | debugging memory manager that will track leaked memory blocks as |
| 153 | well as other common errors like double frees. It is also capable |
| 154 | of reporting _where_ the leaked blocks were allocated, which |
| 155 | considerably saves time when debugging new additions to the library. |
| 156 | |
| 157 | This code is only compiled when FreeType is built with the |
| 158 | FT_DEBUG_MEMORY macro #defined in "ftoption.h" though, it will be |
| 159 | ignored in other builds. |
David Turner | 02c3aed | 2002-07-08 23:02:32 +0000 | [diff] [blame] | 160 | |
| 161 | |
Werner Lemberg | 7f74a52 | 2002-07-26 09:09:10 +0000 | [diff] [blame^] | 162 | End of file |