[freetype2] GSoC-2020-priyesh 9874e18: [base] Added necessary functions and variables to print logs to a files

[Priyesh Kumar]

branch: GSoC-2020-priyesh
commit 9874e18ea55f7a6174e4a52461c5e231b8b69972
Author: Priyeshkkumar <priyeshkkumar@gmail.com>
Commit: Priyeshkkumar <priyeshkkumar@gmail.com>

        [base] Added necessary functions and variables to print logs to a files
    
        * include/freetype/internal/ftdebug.h: Added dlg's header files.
        (FT_LOG): New macro to redirect trace logs to dlg's API's whenever
        `FT_LOGGING' macros is defined.
        (ft_logging_init, ft_logging_deinit): New functions to handle
        initialization and uninitialization of logging related variables.
        (ft_log_handler): A new function to handle logs of FreeType.
    
        * src/base/ftdebug.c: Added necessary logging related variables.
        (ft_logging_init, ft_logging_deinit, ft_log_handler): Added function
        definitions.
    
        * src/base/ftinit.c(FT_Init_FreeType): If `FT_LOGGING' macro is defined
        call `ft_logging_init' to initialize logging related variables.
        (FT_Done_FreeType): If `FT_LOGGING' macro is defined call
        `ft_logging_deinit' to uninitialize logging related variables.
---
 include/freetype/internal/ftdebug.h | 123 ++++++++++++++++++++++++++++++++++--
 src/base/ftdebug.c                  |  73 +++++++++++++++++++++
 src/base/ftinit.c                   |   9 +++
 3 files changed, 200 insertions(+), 5 deletions(-)

diff --git a/include/freetype/internal/ftdebug.h 
b/include/freetype/internal/ftdebug.h
index df5357a..35026a9 100644
--- a/include/freetype/internal/ftdebug.h
+++ b/include/freetype/internal/ftdebug.h
@@ -31,9 +31,28 @@
 
 #include "compiler-macros.h"
 
+  /**************************************************************************
+   *
+   * Additional include files for supporting logging in FreeType using
+   * external logging library ~ src/dlg and freetype/ftlogging.h
+   *
+   */
+
+#ifdef FT_LOGGING
+#include <../src/dlg/dlg/dlg.h>
+#include <../src/dlg/dlg/output.h>
+#endif /* FT_LOGGING */
+
 
 FT_BEGIN_HEADER
 
+  /* force the definition of FT_DEBUG_LEVEL_TRACE if FT_LOGGING is already*/
+  /* defined; therefore the following #ifdefs                             */
+  /*                                                                      */
+#ifdef FT_LOGGING
+#undef FT_DEBUG_LEVEL_TRACE
+#define FT_DEBUG_LEVEL_TRACE
+#endif /* FT_LOGGING */
 
   /* force the definition of FT_DEBUG_LEVEL_ERROR if FT_DEBUG_LEVEL_TRACE */
   /* is already defined; this simplifies the following #ifdefs            */
@@ -84,19 +103,48 @@ FT_BEGIN_HEADER
    *
    */
 
-#ifdef FT_DEBUG_LEVEL_TRACE
+#ifdef FT_LOGGING
 
-  /* 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
+  /*************************************************************************
+   *
+   * If FT_LOGGING is enabled, trace messages will be sent to dlg's API and
+   * if is FT_LOGGING is disabled trace messages will be sent to
+   * FT_Message(defined in ftdebug.c)
+   * Therefore the following macros:
+   *
+   */
 
-#define FT_TRACE( level, varformat )                                       \
+#define FT_LOG( level, varformat )                                         \
+          do                                                               \
+          {                                                                \
+            if( ft_trace_levels[FT_TRACE_COMP( FT_COMPONENT )] >= level )  \
+                dlg_trace varformat;                                       \
+          }while( 0 )
+
+#else
+
+#define FT_LOG( level, varformat )                                         \
           do                                                               \
           {                                                                \
             if ( ft_trace_levels[FT_TRACE_COMP( FT_COMPONENT )] >= level ) \
+            {                                                              \
               FT_Message varformat;                                        \
+            }                                                              \
           } while ( 0 )
 
+#endif /* FT_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 */
@@ -204,8 +252,29 @@ FT_BEGIN_HEADER
 
 #ifdef FT_DEBUG_LEVEL_ERROR
 
+#ifdef FT_LOGGING
+
+  /*************************************************************************
+   *
+   * If FT_LOGGING is enabled, error messages will be sent to dlg's API and
+   * if is FT_LOGGING is disabled error messages will be sent to
+   * FT_Message(defined in ftdebug.c)
+   * Therefore the following macros:
+   *
+   */
+
+#define FT_ERROR( varformat )                                               \
+          do                                                                \
+          {                                                                 \
+          dlg_trace varformat;                                              \
+          } while ( 0 )
+
+#else
+
 #define FT_ERROR( varformat )  FT_Message  varformat
 
+#endif /* FT_LOGGING */
+
 #else  /* !FT_DEBUG_LEVEL_ERROR */
 
 #define FT_ERROR( varformat )  do { } while ( 0 )      /* nothing */
@@ -277,6 +346,50 @@ FT_BEGIN_HEADER
   FT_BASE( void )
   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_log_handler( const struct dlg_origin* origin,
+                 const char* string,
+                 void* data );
+
+
+  /**************************************************************************
+   *
+   * Variables used when FT_LOGGING is enabled to control logging:
+   *
+   * 1. ft_default_log_handler: stores the function pointer which is used
+   *    internally by FreeType to print logs to file.
+   *
+   * These are defined in ftdebug.c
+   */
+  extern dlg_handler ft_default_log_handler;
+
+  /**************************************************************************
+   *
+   * If FT_LOGGING macro is enabled, Freetype needs to initialize and
+   * un-initialize FILE* using following functions
+   * These functions are defined in ftdebug.c
+   *
+   */
+
+  FT_BASE( void )
+  ft_logging_init( void );
+
+  FT_BASE( void )
+  ft_logging_deinit( void );
+
+#endif /* FT_LOGGING */
+
 FT_END_HEADER
 
 #endif /* FTDEBUG_H_ */
diff --git a/src/base/ftdebug.c b/src/base/ftdebug.c
index 62cf680..322dbb5 100644
--- a/src/base/ftdebug.c
+++ b/src/base/ftdebug.c
@@ -44,6 +44,27 @@
 #include <freetype/freetype.h>
 #include <freetype/internal/ftdebug.h>
 
+#ifdef FT_LOGGING
+
+  /**************************************************************************
+   *
+   * 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_fileptr: store the FILE*
+   *
+   * Static Variables are defined here to remove [ -Wunused-variable ]
+   * warning
+   *
+   */
+  static const char* ft_default_trace_level = NULL;
+  static FILE* ft_fileptr = NULL;
+
+  dlg_handler ft_default_log_handler = NULL;
+
+#endif
 
 #ifdef FT_DEBUG_LEVEL_ERROR
 
@@ -314,5 +335,57 @@
 
 #endif /* !FT_DEBUG_LEVEL_TRACE */
 
+#ifdef FT_LOGGING
+
+  /**************************************************************************
+   *
+   * If FT_LOGGING is enabled, FreeType needs to initialize all logging
+   * variables to write logs.
+   * 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_log_handler = ft_log_handler;
+    ft_default_trace_level = ft_getenv( "FT2_DEBUG" );
+    if( ft_getenv( "FT_LOGGING_FILE" ) )
+      ft_fileptr = fopen( ft_getenv( "FT_LOGGING_FILE" ) , "w" );
+    else
+      ft_fileptr = stderr;
+
+    ft_debug_init();
+    /* We need to set the default FreeType specific dlg's output handler */
+    dlg_set_handler( ft_default_log_handler, NULL );
+
+  }
+
+  FT_BASE_DEF( void )
+  ft_logging_deinit( void )
+  {
+    fclose( ft_fileptr );
+  }
+
+  /*************************************************************************
+   *
+   * An Output log handler specific to FreeType used by dlg library.
+   *
+   */
+  FT_BASE_DEF( void )
+  ft_log_handler( const struct dlg_origin* origin,
+                              const char* string, void* data )
+  {
+    ( void ) data;
+     const char*  features = "%c";
+
+          dlg_generic_outputf_stream( ft_fileptr, features, origin, string,
+                                dlg_default_output_styles, true );
+
+  }
+
+#endif /* FT_LOGGING */
 
 /* END */
diff --git a/src/base/ftinit.c b/src/base/ftinit.c
index 0acc75e..c4de2f3 100644
--- a/src/base/ftinit.c
+++ b/src/base/ftinit.c
@@ -201,6 +201,10 @@
     FT_Error   error;
     FT_Memory  memory;
 
+    /* If logging is enabled initialize the FILE* */
+#ifdef FT_LOGGING
+    ft_logging_init();
+#endif /* FT_LOGGING */
 
     /* check of `alibrary' delayed to `FT_New_Library' */
 
@@ -248,6 +252,11 @@
     /* discard memory manager */
     FT_Done_Memory( memory );
 
+    /* If logging is enabled we need to close the FILE* */
+#ifdef FT_LOGGING
+    ft_logging_deinit();
+#endif /* FT_LOGGING */
+
     return FT_Err_Ok;
   }