[freetype2] anuj-distance-field 2c77a8a 70/93: [sdf] Started the `bsdf' rasterier.

[Anuj Verma]

branch: anuj-distance-field
commit 2c77a8acb29690aea309bab1165ca0542c1923c6
Author: Anuj Verma <anujv@iitbhilai.ac.in>
Commit: anujverma <anujv@iitbhilai.ac.in>

    [sdf] Started the `bsdf' rasterier.
    
    * src/sdf/ftbsdf.c (*): Fix line endings.
    
    * src/sdf/ftbsdf.c (bsdf_copy_source_to_target): Added
      function to copy the source bitmap to the center of
      the target bitmap and also convert it to normalized
      16 bits per pixel bitmap.
---
 [GSoC]ChangeLog  |  11 ++
 src/sdf/ftbsdf.c | 318 ++++++++++++++++++++++++++++++++++++++++++-------------
 2 files changed, 253 insertions(+), 76 deletions(-)

diff --git a/[GSoC]ChangeLog b/[GSoC]ChangeLog
index 3181991..f0e00f7 100644
--- a/[GSoC]ChangeLog
+++ b/[GSoC]ChangeLog
@@ -1,3 +1,14 @@
+2020-07-24  Anuj Verma  <anujv@iitbhilai.ac.in>
+
+       [sdf] Started the `bsdf' rasterier.
+
+       * src/sdf/ftbsdf.c (*): Fix line endings.
+
+       * src/sdf/ftbsdf.c (bsdf_copy_source_to_target): Added
+         function to copy the source bitmap to the center of
+         the target bitmap and also convert it to normalized
+         16 bits per pixel bitmap.
+
 2020-07-19  Anuj Verma  <anujv@iitbhilai.ac.in>
 
        [sdf] Added interface functions for `bsdf' converter.
diff --git a/src/sdf/ftbsdf.c b/src/sdf/ftbsdf.c
index 132949c..b89eb4d 100644
--- a/src/sdf/ftbsdf.c
+++ b/src/sdf/ftbsdf.c
@@ -1,76 +1,242 @@
-
-#include <freetype/internal/ftobjs.h>
-#include <freetype/internal/ftdebug.h>
-
-#include "ftsdf.h"
-#include "ftsdferrs.h"
-
-  /**************************************************************************
-   *
-   * interface functions
-   *
-   */
-
-  static FT_Error
-  bsdf_raster_new( FT_Memory   memory,
-                   FT_Raster*  araster)
-  {
-    FT_UNUSED( memory );
-    FT_UNUSED( araster );
-
-    return FT_Err_Ok;
-  }
-
-  static void
-  bsdf_raster_reset( FT_Raster       raster,
-                     unsigned char*  pool_base,
-                     unsigned long   pool_size )
-  {
-    /* no use of this function */
-    FT_UNUSED( raster );
-    FT_UNUSED( pool_base );
-    FT_UNUSED( pool_size );
-  }
-
-  static FT_Error
-  bsdf_raster_set_mode( FT_Raster      raster,
-                        unsigned long  mode,
-                        void*          args )
-  {
-    FT_UNUSED( raster );
-    FT_UNUSED( mode );
-    FT_UNUSED( args );
-
-
-    return FT_Err_Ok;
-  }
-
-  static FT_Error
-  bsdf_raster_render( FT_Raster                raster,
-                      const FT_Raster_Params*  params )
-  {
-    FT_UNUSED( raster );
-    FT_UNUSED( params );
-
-    return FT_THROW( Unimplemented_Feature ) ;
-  }
-
-  static void
-  bsdf_raster_done( FT_Raster  raster )
-  {
-    FT_UNUSED( raster );
-  }
-
-  FT_DEFINE_RASTER_FUNCS(
-    ft_bitmap_sdf_raster,
-
-    FT_GLYPH_FORMAT_BITMAP,
-
-    (FT_Raster_New_Func)      bsdf_raster_new,       /* raster_new      */
-    (FT_Raster_Reset_Func)    bsdf_raster_reset,     /* raster_reset    */
-    (FT_Raster_Set_Mode_Func) bsdf_raster_set_mode,  /* raster_set_mode */
-    (FT_Raster_Render_Func)   bsdf_raster_render,    /* raster_render   */
-    (FT_Raster_Done_Func)     bsdf_raster_done       /* raster_done     */
-  )
-
-/* END */
+
+#include <freetype/internal/ftobjs.h>
+#include <freetype/internal/ftdebug.h>
+
+#include "ftsdf.h"
+#include "ftsdferrs.h"
+
+  /**************************************************************************
+   *
+   * useful macros
+   *
+   */
+
+  /* Convenient macro which calls the function */
+  /* and returns if any error occurs.          */
+  #define FT_CALL( x ) do                          \
+                       {                           \
+                         error = ( x );            \
+                         if ( error != FT_Err_Ok ) \
+                           goto Exit;              \
+                       } while ( 0 )
+
+  /**************************************************************************
+   *
+   * rasterizer functions
+   *
+   */
+
+  static FT_Error
+  bsdf_copy_source_to_target( const FT_Bitmap*  source,
+                              FT_Bitmap*        target )
+  {
+    FT_Error  error         = FT_Err_Ok;
+    FT_Bool   is_monochrome = 0;
+
+    FT_Int    x_diff, y_diff;
+    FT_Int    num_channels;
+    FT_Byte*  t, s;
+
+    /* again check the parameters (probably unnecessary) */
+    if ( !source || !target )
+    {
+      error = FT_THROW( Invalid_Argument );
+      goto Exit;
+    }
+
+    /* Because of the way we convert bitmap to SDF     */
+    /* i.e. aligning the source to the center of the   */
+    /* target, the target's width/rows must be checked */
+    /* before copying.                                 */
+    if ( target->width < source->width ||
+         target->rows  < source->rows )
+    {
+      error = FT_THROW( Invalid_Argument );
+      goto Exit;
+    }
+
+    /* check pixel mode */
+    if ( source->pixel_mode == FT_PIXEL_MODE_NONE )
+    {
+      FT_ERROR(( "[bsdf] bsdf_copy_source_to_target: "
+                 "Invalid pixel mode of source bitmap" ));
+      error = FT_THROW( Invalid_Argument );
+      goto Exit;
+    }
+
+    /* make sure target bitmap is 16bpp */
+    if ( target->pixel_mode != FT_PIXEL_MODE_GRAY16 )
+    {
+      FT_ERROR(( "[bsdf] bsdf_copy_source_to_target: "
+                 "Invalid pixel mode of target bitmap" ));
+      error = FT_THROW( Invalid_Argument );
+      goto Exit;
+    }
+
+  #ifdef FT_DEBUG_LEVEL_TRACE
+    if ( source->pixel_mode == FT_PIXEL_MODE_MONO )
+    {
+      FT_TRACE0(( "[bsdf] bsdf_copy_source_to_target:\n"
+                  "The `bsdf' renderer can convert monochrome bitmap\n"
+                  "to SDF, but the results are not perfect because there\n"
+                  "is no way to approximate actual outline from monochrome\n"
+                  "bitmap. Consider using anti-aliased bitmap instead.\n" ));
+    }
+  #endif
+
+    /* Calculate the difference in width and rows */
+    /* of the target and source.                  */
+    x_diff = target->width - source->width;
+    y_diff = target->rows - source->rows;
+
+    x_diff /= 2;
+    y_diff /= 2;
+
+    t = target->buffer;
+    s = source->buffer;
+
+    /* For now we only support pixel mode `FT_PIXEL_MODE_MONO'  */
+    /* and `FT_PIXEL_MODE_GRAY'. More will be added later.      */
+    /* [NOTE]: We can also use `FT_Bitmap_Convert' to convert   */
+    /*         bitmap to 8bpp. To avoid extra allocation and    */
+    /*         since the target bitmap can be 16bpp we manually */
+    /*         convert the source bitmap to desired bpp.        */
+    switch ( source->pixel_mode ) {
+    case FT_PIXEL_MODE_MONO:
+      /* [TODO] */
+      error = FT_THROW( Unimplemented_Feature );
+      break;
+    case FT_PIXEL_MODE_GRAY:
+      /* [TODO] */
+      error = FT_THROW( Unimplemented_Feature );
+      break;
+    default:
+      FT_ERROR(( "[bsdf] bsdf_copy_source_to_target: "
+                 "unsopported pixel mode of source bitmap\n" ));
+      error = FT_THROW( Unimplemented_Feature );
+      break;
+    }
+
+  Exit:
+    return error;
+  }
+  
+
+  /**************************************************************************
+   *
+   * interface functions
+   *
+   */
+
+  static FT_Error
+  bsdf_raster_new( FT_Memory   memory,
+                   FT_Raster*  araster)
+  {
+    FT_UNUSED( memory );
+    FT_UNUSED( araster );
+
+    return FT_Err_Ok;
+  }
+
+  static void
+  bsdf_raster_reset( FT_Raster       raster,
+                     unsigned char*  pool_base,
+                     unsigned long   pool_size )
+  {
+    /* no use of this function */
+    FT_UNUSED( raster );
+    FT_UNUSED( pool_base );
+    FT_UNUSED( pool_size );
+  }
+
+  static FT_Error
+  bsdf_raster_set_mode( FT_Raster      raster,
+                        unsigned long  mode,
+                        void*          args )
+  {
+    FT_UNUSED( raster );
+    FT_UNUSED( mode );
+    FT_UNUSED( args );
+
+
+    return FT_Err_Ok;
+  }
+
+  static FT_Error
+  bsdf_raster_render( FT_Raster                raster,
+                      const FT_Raster_Params*  params )
+  {
+    FT_Error    error  = FT_Err_Ok;
+    FT_Bitmap*  source = NULL;
+    FT_Bitmap*  target = NULL;
+
+    const SDF_Raster_Params*  sdf_params = (const SDF_Raster_Params*)params;
+
+
+    FT_UNUSED( raster );
+
+    /* check for valid parameters */
+    if ( !params )
+    {
+      error = FT_THROW( Invalid_Argument );
+      goto Exit;
+    }
+
+    /* check if the flag is set */
+    if ( sdf_params->root.flags != FT_RASTER_FLAG_SDF )
+    {
+      error = FT_THROW( Raster_Corrupted );
+      goto Exit;
+    }
+
+    source = sdf_params->root.source;
+    target = sdf_params->root.target;
+
+    /* check the source and target bitmap */
+    if ( !source || !target )
+    {
+      error = FT_THROW( Invalid_Argument );
+      goto Exit; 
+    }
+
+    /* check if spread is set properly */
+    if ( sdf_params->spread > MAX_SPREAD ||
+         sdf_params->spread < MIN_SPREAD )
+    {
+      FT_TRACE0(( 
+        "[bsdf] bsdf_raster_render:\n"
+        "       The `spread' field of `SDF_Raster_Params' is invalid,\n"
+        "       the value of this field must be within [%d, %d].\n"
+        "       Also, you must pass `SDF_Raster_Params' instead of the\n"
+        "       default `FT_Raster_Params' while calling this function\n"
+        "       and set the fields properly.\n"
+        , MIN_SPREAD, MAX_SPREAD) );
+      error = FT_THROW( Invalid_Argument );
+      goto Exit;
+    }
+
+    FT_CALL( bsdf_copy_source_to_target( source, target ) );
+
+  Exit:
+    return error;
+  }
+
+  static void
+  bsdf_raster_done( FT_Raster  raster )
+  {
+    FT_UNUSED( raster );
+  }
+
+  FT_DEFINE_RASTER_FUNCS(
+    ft_bitmap_sdf_raster,
+
+    FT_GLYPH_FORMAT_BITMAP,
+
+    (FT_Raster_New_Func)      bsdf_raster_new,       /* raster_new      */
+    (FT_Raster_Reset_Func)    bsdf_raster_reset,     /* raster_reset    */
+    (FT_Raster_Set_Mode_Func) bsdf_raster_set_mode,  /* raster_set_mode */
+    (FT_Raster_Render_Func)   bsdf_raster_render,    /* raster_render   */
+    (FT_Raster_Done_Func)     bsdf_raster_done       /* raster_done     */
+  )
+
+/* END */