Updates on dynamic change of trace level

[priyesh]ChangeLog

@@ -1,3 +1,21 @@
+2020-07-03  Priyesh Kumar   <priyeshkkumar@gmail.com>
+    
+    * Code Cleanup and Added more comments
+
+    * include/freetype/internal/ftdebug.h:
+      1. Code Cleanup
+      2. Reverted back to the original `ft_debug_init()` function
+         Added respective code inside `ft_debug_init()` to handle 
+         default and custom trace levels in `ftdebug.c`
+      3. Introduced variables to control logging.
+
+    * src/base/ftdebug.c:
+      1. Updated definitions of following functions:
+         1.1. ft_debug_init()
+         1.2. FT_Trace_Set_Default_Level()
+         1.3. FT_Trace_Set_Level
+      2. Added more comments and Code Cleanup      
+
 2020-07-02  Priyesh Kumar   <priyeshkkumar@gmail.com>
 
     * Fixed some code layout

include/freetype/ftlogging.h

@@ -9,22 +9,33 @@ FT_BEGIN_HEADER
   * level as an argument.
   * User can also set the default trace level which is supplied by 
   * environment variable `FT2_DEBUG`
+  * See ftdebug.c for definitions
   * 
   */ 
 
-  typedef void
-  (*ft_ouput_handler)( const char* string ); 
-
   FT_EXPORT( void )
   FT_Trace_Set_Level( const char* level );
 
   FT_EXPORT( void )
   FT_Trace_Set_Default_Level( void );
 
+
+  /* An external callback function to be used to define an output handler */
+  typedef void 
+  (*ft_custom_output_handler)( const char* string ); 
+
+
+  /**************************************************************************
+   * 
+   * comments on callback
+   *
+   */ 
+  /*  
   FT_EXPORT( void )
   FT_Trace_Set_Output( ft_ouput_handler handler ); 
 
   FT_EXPORT( void )
   FT_Trace_Set_Default_Output();
+  */
 
 FT_END_HEADER

include/freetype/internal/ftdebug.h

@@ -110,25 +110,10 @@ FT_BEGIN_HEADER
    */
 
 #ifdef FT_LOGGING
-
-  static ft_ouput_handler freetype_output_handler = NULL;
   
 #undef FT_Log
 #define FT_Log dlg_trace
 
-/****************************************************************************
- * 
- * dlg uses output handlers to control how and where the log messages are 
- * printed.
- * Therefore we need to define an output handler specific to FreeType, it 
- * will act as a default output handler of Freetype. 
- * 
- */
-
- FT_BASE( void ) 
- ft_default_output_handler( const struct dlg_origin* origin, 
- const char* string, void* data );
-
 #else
 
 #undef FT_Log
@@ -263,7 +248,7 @@ FT_BEGIN_HEADER
           {                                                                 \
           dlg_add_tag( "error_log", NULL );                                 \
           dlg_trace varformat;                                              \
-          dlg_remove_tag( "error_log", NULL );                              \  
+          dlg_remove_tag( "error_log", NULL );                              \
           } while ( 0 )                            
 
 #else
@@ -341,10 +326,49 @@ FT_BEGIN_HEADER
 
 
   FT_BASE( void )
-  ft_debug_init( const char* level );
+  ft_debug_init( void );
 
 #ifdef FT_LOGGING
 
+
+/****************************************************************************
+ * 
+ * dlg uses output handlers to control how and where the log messages are 
+ * printed.
+ * Therefore we need to define an output handler specific to FreeType, it 
+ * will act as a default output handler of Freetype. 
+ * 
+ */
+
+ FT_BASE( void ) 
+ ft_output_handler( const struct dlg_origin* origin, const char* string, 
+                    void* data );
+
+
+  /**************************************************************************
+   * 
+   * Variable used when FT_LOGGING is enabled to control logging:
+   * 1. ft_default_trace_level: stores the value of trace levels which are 
+   *    provided to FreeType using FT2_DEBUG environment variable.
+   * 
+   * 2. ft_custom_trace_level: stores the value of custom trace level which 
+   *    is provided by user at run-time.
+   * 
+   * 3. custom_output_handler: stores the function pointer to the callback 
+   *    function provided by user.
+   * 
+   * 4. ft_default_output_handler: stores the function pointer which is used 
+   *    internally by FreeType to print logs to file.
+   * 
+   * 5. fileptr: store the FILE*
+   *     
+   */ 
+  static const char* ft_default_trace_level = NULL;
+  static const char* ft_custom_trace_level = NULL;
+  static ft_custom_output_handler custom_output_handler = NULL;
+  static dlg_handler ft_default_output_handler = NULL;
+  static FILE* fileptr = NULL;
+
   /**************************************************************************
    * 
    * If FT_LOGGING macro is enabled, Freetype needs to initialize and 

src/base/ftdebug.c

@@ -193,9 +193,20 @@
    * runtime errors), and 7 means _very_ verbose.
    */
   FT_BASE_DEF( void )
-  ft_debug_init( const char* level )
+  ft_debug_init( void )
   {
-    const char*  ft2_debug = level;
+    const char*  ft2_debug = NULL;
+
+#ifdef FT_LOGGING
+
+if( ft_custom_trace_level != NULL )
+    ft2_debug = ft_custom_trace_level;
+else  
+    ft2_debug = ft_default_trace_level;
+
+#else
+    ft2_debug = ft_getenv( "FT2_DEBUG" );
+#endif /* FT_LOGGIGN */
 
 
     if ( ft2_debug )
@@ -274,7 +285,7 @@
 
 
   FT_BASE_DEF( void )
-  ft_debug_init( const char* level )
+  ft_debug_init( void )
   {
     /* nothing */
   }
@@ -316,31 +327,27 @@
 
 #ifdef FT_LOGGING
 
-
-  /**************************************************************************
-   * If FT_LOGGING is enabled FreeType needs a FILE* to write logs 
-   * to file.
-   */
-  static FILE* fileptr = NULL; 
-
-
-
   /**************************************************************************
    * 
-   * If FT_LOGGING is enabled, FreeType needs a FILE* to write logs 
+   * If FT_LOGGING is enabled, FreeType needs to initialize all logging 
-   * therefore it uses `ft_logging_init()` function to initialize a 
+   * variables to write logs. 
-   * FILE* and `ft_logging_deinit()` to un-initialize the FILE*
+   * Therefore it uses `ft_logging_init()` function to initialize a 
+   * loggging variables and `ft_logging_deinit()` to un-initialize the 
+   * logging variables.
    * 
    */
   
   FT_BASE_DEF( void )
   ft_logging_init( void )
   {
+    ft_default_output_handler = &ft_output_handler;
+    ft_default_trace_level = ft_getenv( "FT2_DEBUG" );
     fileptr = fopen( "freetype2.log", "w" );
-    FT_Trace_Set_Default_Level();
     
+    ft_debug_init();
     /* We need to set the default FreeType specific dlg's output handler */
-    dlg_set_handler( &ft_default_output_handler, NULL );
+    dlg_set_handler( ft_default_output_handler, NULL );
+
   }
 
   FT_BASE_DEF( void )
@@ -356,7 +363,7 @@
    *    
    */
   FT_BASE_DEF( void ) 
-  ft_default_output_handler( const struct dlg_origin* origin, 
+  ft_output_handler( const struct dlg_origin* origin, 
                               const char* string, void* data )
  {
      unsigned int features; 
@@ -375,39 +382,48 @@
 
  /**************************************************************************
   * 
+  * Functions to set trace levels at run-time
+  * 1. FT_Trace_Set_Level() - Use this function to change the trace level 
+  *    at run-time. e.g. FT_Trace_Set_Level( "any:6 io:2" );
   * 
+  * 2. FT_Trace_Set_Default_Level() - Use this function to set the default 
+  *    value of trace levels which is provided by environment variable 
+  *    FT2_DEBUG
   * 
   */
+ 
   FT_EXPORT_DEF( void )
   FT_Trace_Set_Level( const char* level )
   {  
-    ft_debug_init( level );
+    ft_custom_trace_level = level;
+    ft_debug_init();
   }
 
   FT_EXPORT_DEF( void )
   FT_Trace_Set_Default_Level( void )
   {
-    ft_debug_init( ft_getenv( "FT2_DEBUG" ) );
+    ft_custom_trace_level = NULL ;
+    ft_debug_init();
   }
 
 /****************************************************************************
  * 
- * 
+ * comments on callback
  * 
  */
-
+  /*
   FT_EXPORT_DEF( void )
   FT_Trace_Set_Output( ft_ouput_handler handler )
   {
-    freetype_output_handler = handler;
+    ft_custom_output_handler = handler;
   }
 
   FT_EXPORT_DEF( void )
   FT_Trace_Set_Default_Output()
   {
-    freetype_output_handler = NULL;
+    ft_custom_output_handler = NULL;
   }
-
+  */
 #endif /* FT_LOGGING */
 
 /* END */

src/base/ftobjs.c

@@ -5276,7 +5276,7 @@
 #ifndef FT_LOGGING 
 #ifdef FT_DEBUG_LEVEL_ERROR
     /* init debugging support */
-    ft_debug_init( ft_getenv( "FT2_DEBUG" ) );
+    ft_debug_init();
 #endif /* FT_DEBUG_LEVEL_ERROR */
 #endif /* FT_LOGGING */