ftdebug.h

Go to the documentation of this file.

/****************************************************************************
 *
 * ftdebug.h
 *
 *   Debugging and logging component (specification).
 *
 * Copyright (C) 1996-2025 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.
 *
 *
 * IMPORTANT: A description of FreeType's debugging support can be
 *             found in 'docs/DEBUG.TXT'.  Read it if you need to use or
 *             understand this code.
 *
 */
 

#ifndef FTDEBUG_H_
#define FTDEBUG_H_
 
 
#include <ft2build.h>
#include FT_CONFIG_CONFIG_H
#include <freetype/freetype.h>
 
#include "compiler-macros.h"
 
#ifdef FT_DEBUG_LOGGING
#define DLG_STATIC
#include <dlg/output.h>
#include <dlg/dlg.h>
 
#include <freetype/ftlogging.h>
#endif /* FT_DEBUG_LOGGING */
 
 
FT_BEGIN_HEADER
 
  /* force the definition of FT_DEBUG_LEVEL_TRACE if FT_DEBUG_LOGGING is */
  /* already defined.                                                    */
  /*                                                                     */
#ifdef FT_DEBUG_LOGGING
#undef  FT_DEBUG_LEVEL_TRACE
#define FT_DEBUG_LEVEL_TRACE
#endif
 
  /* force the definition of FT_DEBUG_LEVEL_ERROR if FT_DEBUG_LEVEL_TRACE */
  /* is already defined; this simplifies the following #ifdefs            */
  /*                                                                      */
#ifdef FT_DEBUG_LEVEL_TRACE
#undef  FT_DEBUG_LEVEL_ERROR
#define FT_DEBUG_LEVEL_ERROR
#endif
 
 
  /**************************************************************************
   *
   * Define the trace enums as well as the trace levels array when they are
   * needed.
   *
   */
 
#ifdef FT_DEBUG_LEVEL_TRACE
 
#define FT_TRACE_DEF( x )  trace_ ## x ,
 
  /* defining the enumeration */
  typedef enum  FT_Trace_
  {
#include <freetype/internal/fttrace.h>
    trace_count
 
  } FT_Trace;
 
 
  /* a pointer to the array of trace levels, */
  /* provided by `src/base/ftdebug.c'        */
  extern int*  ft_trace_levels;
 
#undef FT_TRACE_DEF
 
#endif /* FT_DEBUG_LEVEL_TRACE */
 
 
  /**************************************************************************
   *
   * Define the FT_TRACE macro
   *
   * IMPORTANT!
   *
   * Each component must define the macro FT_COMPONENT to a valid FT_Trace
   * value before using any TRACE macro.
   *
   * To get consistent logging output, there should be no newline character
   * (i.e., '\n') or a single trailing one in the message string of
   * `FT_TRACEx` and `FT_ERROR`.
   */
 
 
  /*************************************************************************
   *
   * If FT_DEBUG_LOGGING is enabled, tracing messages are sent to dlg's API.
   * If FT_DEBUG_LOGGING is disabled, tracing messages are sent to
   * `FT_Message` (defined in ftdebug.c).
   */
#ifdef FT_DEBUG_LOGGING
 
  /* we need two macros to convert the names of `FT_COMPONENT` to a string */
#define FT_LOGGING_TAG( x )   FT_LOGGING_TAG_( x )
#define FT_LOGGING_TAG_( x )  #x
 
  /* we need two macros to convert the component and the trace level */
  /* to a string that combines them                                  */
#define FT_LOGGING_TAGX( x, y )   FT_LOGGING_TAGX_( x, y )
#define FT_LOGGING_TAGX_( x, y )  #x ":" #y
 
 
#define FT_LOG( level, varformat )                                         \
          do                                                               \
          {                                                                \
            const char*  dlg_tag = FT_LOGGING_TAGX( FT_COMPONENT, level ); \
                                                                           \
                                                                           \
            ft_add_tag( dlg_tag );                                         \
            if ( ft_trace_levels[FT_TRACE_COMP( FT_COMPONENT )] >= level ) \
            {                                                              \
              if ( custom_output_handler != NULL )                         \
                FT_Logging_Callback varformat;                             \
              else                                                         \
                dlg_trace varformat;                                       \
            }                                                              \
            ft_remove_tag( dlg_tag );                                      \
          } while( 0 )
 
#else /* !FT_DEBUG_LOGGING */
 
#define FT_LOG( level, varformat )                                         \
          do                                                               \
          {                                                                \
            if ( ft_trace_levels[FT_TRACE_COMP( FT_COMPONENT )] >= level ) \
              FT_Message varformat;                                        \
          } while ( 0 )
 
#endif /* !FT_DEBUG_LOGGING */
 
 
#ifdef FT_DEBUG_LEVEL_TRACE
 
  /* we need two macros here to make cpp expand `FT_COMPONENT' */
#define FT_TRACE_COMP( x )   FT_TRACE_COMP_( x )
#define FT_TRACE_COMP_( x )  trace_ ## x
 
#define FT_TRACE( level, varformat )  FT_LOG( level, varformat )
 
#else /* !FT_DEBUG_LEVEL_TRACE */
 
#define FT_TRACE( level, varformat )  do { } while ( 0 )      /* nothing */
 
#endif /* !FT_DEBUG_LEVEL_TRACE */
 
 
  /**************************************************************************
   *
   * @function:
   *   FT_Trace_Get_Count
   *
   * @description:
   *   Return the number of available trace components.
   *
   * @return:
   *   The number of trace components.  0 if FreeType 2 is not built with
   *   FT_DEBUG_LEVEL_TRACE definition.
   *
   * @note:
   *   This function may be useful if you want to access elements of the
   *   internal trace levels array by an index.
   */
  FT_BASE( FT_Int )
  FT_Trace_Get_Count( void );
 
 
  /**************************************************************************
   *
   * @function:
   *   FT_Trace_Get_Name
   *
   * @description:
   *   Return the name of a trace component.
   *
   * @input:
   *   The index of the trace component.
   *
   * @return:
   *   The name of the trace component.  This is a statically allocated
   *   C~string, so do not free it after use.  `NULL` if FreeType is not
   *   built with FT_DEBUG_LEVEL_TRACE definition.
   *
   * @note:
   *   Use @FT_Trace_Get_Count to get the number of available trace
   *   components.
   */
  FT_BASE( const char* )
  FT_Trace_Get_Name( FT_Int  idx );
 
 
  /**************************************************************************
   *
   * @function:
   *   FT_Trace_Disable
   *
   * @description:
   *   Switch off tracing temporarily.  It can be activated again with
   *   @FT_Trace_Enable.
   */
  FT_BASE( void )
  FT_Trace_Disable( void );
 
 
  /**************************************************************************
   *
   * @function:
   *   FT_Trace_Enable
   *
   * @description:
   *   Activate tracing.  Use it after tracing has been switched off with
   *   @FT_Trace_Disable.
   */
  FT_BASE( void )
  FT_Trace_Enable( void );
 
 
  /**************************************************************************
   *
   * You need two opening and closing parentheses!
   *
   * Example: FT_TRACE0(( "Value is %i", foo ))
   *
   * Output of the FT_TRACEX macros is sent to stderr.
   *
   */
 
#define FT_TRACE0( varformat )  FT_TRACE( 0, varformat )
#define FT_TRACE1( varformat )  FT_TRACE( 1, varformat )
#define FT_TRACE2( varformat )  FT_TRACE( 2, varformat )
#define FT_TRACE3( varformat )  FT_TRACE( 3, varformat )
#define FT_TRACE4( varformat )  FT_TRACE( 4, varformat )
#define FT_TRACE5( varformat )  FT_TRACE( 5, varformat )
#define FT_TRACE6( varformat )  FT_TRACE( 6, varformat )
#define FT_TRACE7( varformat )  FT_TRACE( 7, varformat )
 
 
  /**************************************************************************
   *
   * Define the FT_ERROR macro.
   *
   * Output of this macro is sent to stderr.
   *
   */
 
#ifdef FT_DEBUG_LEVEL_ERROR
 
  /**************************************************************************
   *
   * If FT_DEBUG_LOGGING is enabled, error messages are sent to dlg's API.
   * If FT_DEBUG_LOGGING is disabled, error messages are sent to `FT_Message`
   * (defined in ftdebug.c).
   *
   */
#ifdef FT_DEBUG_LOGGING
 
#define FT_ERROR( varformat )                                      \
          do                                                       \
          {                                                        \
            const char*  dlg_tag = FT_LOGGING_TAG( FT_COMPONENT ); \
                                                                   \
                                                                   \
            ft_add_tag( dlg_tag );                                 \
            dlg_trace varformat;                                   \
            ft_remove_tag( dlg_tag );                              \
          } while ( 0 )
 
#else /* !FT_DEBUG_LOGGING */
 
#define FT_ERROR( varformat )  FT_Message varformat
 
#endif /* !FT_DEBUG_LOGGING */
 
 
#else  /* !FT_DEBUG_LEVEL_ERROR */
 
#define FT_ERROR( varformat )  do { } while ( 0 )      /* nothing */
 
#endif /* !FT_DEBUG_LEVEL_ERROR */
 
 
  /**************************************************************************
   *
   * Define the FT_ASSERT and FT_THROW macros.  The call to `FT_Throw` makes
   * it possible to easily set a breakpoint at this function.
   *
   */
 
#ifdef FT_DEBUG_LEVEL_ERROR
 
#define FT_ASSERT( condition )                                      \
          do                                                        \
          {                                                         \
            if ( !( condition ) )                                   \
              FT_Panic( "assertion failed on line %d of file %s\n", \
                        __LINE__, __FILE__ );                       \
          } while ( 0 )
 
#define FT_THROW( e )                                   \
          ( FT_Throw( FT_ERR_CAT( FT_ERR_PREFIX, e ),   \
                      __LINE__,                         \
                      __FILE__ )                      | \
            FT_ERR_CAT( FT_ERR_PREFIX, e )            )
 
#else /* !FT_DEBUG_LEVEL_ERROR */
 
#define FT_ASSERT( condition )  do { } while ( 0 )
 
#define FT_THROW( e )  FT_ERR_CAT( FT_ERR_PREFIX, e )
 
#endif /* !FT_DEBUG_LEVEL_ERROR */
 
 
  /**************************************************************************
   *
   * Define `FT_Message` and `FT_Panic` when needed.
   *
   */
 
#ifdef FT_DEBUG_LEVEL_ERROR
 
#include "stdio.h"  /* for vfprintf() */
 
  /* print a message */
  FT_BASE( void )
  FT_Message( const char*  fmt,
              ... );
 
  /* print a message and exit */
  FT_BASE( void )
  FT_Panic( const char*  fmt,
            ... );
 
  /* report file name and line number of an error */
  FT_BASE( int )
  FT_Throw( FT_Error     error,
            int          line,
            const char*  file );
 
#endif /* FT_DEBUG_LEVEL_ERROR */
 
 
  FT_BASE( void )
  ft_debug_init( void );
 
 
#ifdef FT_DEBUG_LOGGING
 
  /**************************************************************************
   *
   * 'dlg' uses output handlers to control how and where log messages are
   * printed.  Therefore we need to define a default output handler for
   * FreeType.
   */
  FT_BASE( void )
  ft_log_handler( const struct dlg_origin*  origin,
                  const char*               string,
                  void*                     data );
 
 
  /**************************************************************************
   *
   * 1. `ft_default_log_handler` stores the function pointer that is used
   *    internally by FreeType to print logs to a file.
   *
   * 2. `custom_output_handler` stores the function pointer to the callback
   *    function provided by the user.
   *
   * It is defined in `ftdebug.c`.
   */
  extern dlg_handler            ft_default_log_handler;
  extern FT_Custom_Log_Handler  custom_output_handler;
 
 
  /**************************************************************************
   *
   * If FT_DEBUG_LOGGING macro is enabled, FreeType needs to initialize and
   * un-initialize `FILE*`.
   *
   * These functions are defined in `ftdebug.c`.
   */
  FT_BASE( void )
  ft_logging_init( void );
 
  FT_BASE( void )
  ft_logging_deinit( void );
 
 
  /**************************************************************************
   *
   * For printing the name of `FT_COMPONENT` along with the actual log we
   * need to add a tag with the name of `FT_COMPONENT`.
   *
   * These functions are defined in `ftdebug.c`.
   */
  FT_BASE( void )
  ft_add_tag( const char*  tag );
 
  FT_BASE( void )
  ft_remove_tag( const char*  tag );
 
 
  /**************************************************************************
   *
   * A function to print log data using a custom callback logging function
   * (which is set using `FT_Set_Log_Handler`).
   *
   * This function is defined in `ftdebug.c`.
   */
  FT_BASE( void )
  FT_Logging_Callback( const char*  fmt,
                       ... );
 
#endif /* FT_DEBUG_LOGGING */
 
 
FT_END_HEADER
 
#endif /* FTDEBUG_H_ */
 
 
/* END */