[sdf] Added interface functions for `bsdf' converter.

* src/base/ftobjs.c (FT_Render_Glyph_Internal): Remove
  the bitmap check which prevent calling renderers
  if the glyph is already a bitmap. The `bsdf' renderer
  requires a bitmap for conversion.

* src/base/ftobjs.c (ft_add_renderer): Remove the glyph
  format check which ensures that the glyph format for
  a renderer is `FT_GLYPH_FORMAT_OUTLINE', again the `bsdf'
  renderer has `FT_GLYPH_FORMAT_BITMAP' as a glyph format,
  so we need to remove the condition to initialize the
  renderer properly.

* src/sdf/ftbsdf.c (*): Added a rasterizer for the
  `bsdf' renderer and created necessary functions.

* src/sdf/ftbsdf.h: Add forward declaration of the
  rasterizer.

* src/sdf/ftsdfrend.c (ft_bitmap_sdf_renderer_class):
  Define the new `bsdf' rendere and add the
  `FT_Renderer_RenderFunc' function, the rest is
  same as the `sdf' renderer.

* src/sdf/ftsdfrend.h: Add forward declaration of the
  renderer.

* src/sdf/rules.mk (SDF_DRV_SRC): Add the new `ftbsdf.c'
  file to the compile list.

* src/sdf/sdf.c: Inclue the `ftbsdf.c' file if making
  single object.

8 files changed, 218 insertions, 8 deletions

diff --git a/[GSoC]ChangeLog b/[GSoC]ChangeLog
index 8bdeb6048..3181991aa 100644
--- a/[GSoC]ChangeLog
+++ b/[GSoC]ChangeLog
@@ -1,5 +1,41 @@
 2020-07-19  Anuj Verma  <anujv@iitbhilai.ac.in>
 
+	[sdf] Added interface functions for `bsdf' converter.
+
+	* src/base/ftobjs.c (FT_Render_Glyph_Internal): Remove
+	  the bitmap check which prevent calling renderers
+	  if the glyph is already a bitmap. The `bsdf' renderer
+	  requires a bitmap for conversion.
+
+	* src/base/ftobjs.c (ft_add_renderer): Remove the glyph
+	  format check which ensures that the glyph format for
+	  a renderer is `FT_GLYPH_FORMAT_OUTLINE', again the `bsdf'
+	  renderer has `FT_GLYPH_FORMAT_BITMAP' as a glyph format,
+	  so we need to remove the condition to initialize the
+	  renderer properly.
+
+	* src/sdf/ftbsdf.c (*): Added a rasterizer for the
+	  `bsdf' renderer and created necessary functions.
+
+	* src/sdf/ftbsdf.h: Add forward declaration of the
+	  rasterizer.
+
+	* src/sdf/ftsdfrend.c (ft_bitmap_sdf_renderer_class):
+	  Define the new `bsdf' rendere and add the
+	  `FT_Renderer_RenderFunc' function, the rest is
+	  same as the `sdf' renderer.
+
+	* src/sdf/ftsdfrend.h: Add forward declaration of the
+	  renderer.
+
+	* src/sdf/rules.mk (SDF_DRV_SRC): Add the new `ftbsdf.c'
+	  file to the compile list.
+
+	* src/sdf/sdf.c: Inclue the `ftbsdf.c' file if making
+	  single object.
+
+2020-07-19  Anuj Verma  <anujv@iitbhilai.ac.in>
+
 	[sdf] Add alloc/free functions.
 
 	* src/sdf/ftsdf.c (*): Add `sdf_alloc' and `sdf_free'
diff --git a/src/base/ftobjs.c b/src/base/ftobjs.c
index 8adfdffe1..94b697214 100644
--- a/src/base/ftobjs.c
+++ b/src/base/ftobjs.c
@@ -4393,8 +4393,7 @@
       render->glyph_format = clazz->glyph_format;
 
       /* allocate raster object if needed */
-      if ( clazz->glyph_format == FT_GLYPH_FORMAT_OUTLINE &&
-           clazz->raster_class->raster_new                )
+      if ( clazz->raster_class->raster_new )
       {
         error = clazz->raster_class->raster_new( memory, &render->raster );
         if ( error )
@@ -4537,9 +4536,6 @@
 
     switch ( slot->format )
     {
-    case FT_GLYPH_FORMAT_BITMAP:   /* already a bitmap, don't do anything */
-      break;
-
     default:
       if ( slot->internal->load_flags & FT_LOAD_COLOR )
       {
diff --git a/src/sdf/ftbsdf.c b/src/sdf/ftbsdf.c
new file mode 100644
index 000000000..132949c75
--- /dev/null
+++ b/src/sdf/ftbsdf.c
@@ -0,0 +1,76 @@
+

+#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 */

diff --git a/src/sdf/ftsdf.h b/src/sdf/ftsdf.h
index d06f59a8e..e44081ac8 100644
--- a/src/sdf/ftsdf.h
+++ b/src/sdf/ftsdf.h
@@ -53,8 +53,12 @@ FT_BEGIN_HEADER
 
   } SDF_Raster_Params;
 
+  /* rasterizer to convert outline to SDF */
   FT_EXPORT_VAR( const FT_Raster_Funcs ) ft_sdf_raster;
 
+  /* rasterizer to convert bitmap to SDF */
+  FT_EXPORT_VAR( const FT_Raster_Funcs ) ft_bitmap_sdf_raster;
+
 FT_END_HEADER
 
 #endif /* FTSDF_H_ */
diff --git a/src/sdf/ftsdfrend.c b/src/sdf/ftsdfrend.c
index ffe8f497b..bc7bcabf9 100644
--- a/src/sdf/ftsdfrend.c
+++ b/src/sdf/ftsdfrend.c
@@ -3,6 +3,7 @@
 #include <freetype/internal/ftobjs.h>
 #include <freetype/internal/services/svprop.h>
 #include <freetype/ftoutln.h>
+#include <freetype/ftbitmap.h>
 #include "ftsdfrend.h"
 #include "ftsdf.h"
 
@@ -401,13 +402,108 @@
   /*************************************************************************/
   /*************************************************************************/
 
+  /* generate signed distance field from glyph's bitmap */
   static FT_Error
   ft_bsdf_render( FT_Renderer      module,
                  FT_GlyphSlot      slot,
                  FT_Render_Mode    mode,
                  const FT_Vector*  origin )
   {
+    FT_Error     error   = FT_Err_Ok;
+    FT_Bitmap*   bitmap  = &slot->bitmap;
+    FT_Memory    memory  = NULL;
+    FT_Renderer  render  = NULL;
+    FT_Bitmap    target;
+
+    FT_Pos      x_pad    = 0;
+    FT_Pos      y_pad    = 0;
+
+    SDF_Raster_Params  params;
+    SDF_Renderer       sdf_module = SDF_RENDERER( module );
+
     
+    render = &sdf_module->root;
+    memory = render->root.memory;
+
+    /* check if slot format is correct before rendering */
+    if ( slot->format != render->glyph_format )
+    {
+      FT_ERROR(( "[bsdf] ft_bsdf_render: "
+                 "bsdf renderer require the slot "
+                 "format to be a bitmap\n" ));
+      error = FT_THROW( Invalid_Glyph_Format );
+      goto Exit;
+    }
+
+    /* check if render mode is correct */
+    if ( mode != FT_RENDER_MODE_SDF )
+    {
+      FT_ERROR(( "[bsdf] ft_bsdf_render: "
+                 "sdf module only render when "
+                 "using `FT_RENDER_MODE_SDF'\n" ));
+      error = FT_THROW( Cannot_Render_Glyph );
+      goto Exit;
+    }
+
+    if ( origin )
+    {
+      FT_ERROR(( "[bsdf] ft_bsdf_render: "
+                 "bsdf renderer can't translate "
+                 "the bitmap\n" ));
+      error = FT_THROW( Unimplemented_Feature );
+      goto Exit;
+    }
+
+    if ( !bitmap->rows || !bitmap->pitch )
+      goto Exit;
+
+    FT_Bitmap_New( &target );
+
+    /* the padding will simply be equal to the `spread' */
+    x_pad = sdf_module->spread;
+    y_pad = sdf_module->spread;
+
+    /* apply the padding, will be in all the directions */
+    target.rows = bitmap->rows + y_pad * 2;
+    target.width = bitmap->width + x_pad * 2;
+
+    /* setup the target bitmap */
+    target.pixel_mode = FT_PIXEL_MODE_GRAY16;
+    target.pitch = target.width * 2;
+    target.num_grays = 65535;
+
+    if ( FT_ALLOC_MULT( target.buffer, target.rows, target.pitch ) )
+      goto Exit;
+
+    /* set up parameters */
+    params.root.target = &target;
+    params.root.source = bitmap;
+    params.root.flags  = FT_RASTER_FLAG_SDF;
+    params.spread      = sdf_module->spread;
+    params.flip_sign   = sdf_module->flip_sign;
+    params.flip_y      = sdf_module->flip_y;
+
+    error = render->raster_render( render->raster,
+                                   (const FT_Raster_Params*)&params );
+  Exit:
+    if ( !error )
+    {
+      /* the glyph is successfully converted to a SDF */
+      if ( slot->internal->flags & FT_GLYPH_OWN_BITMAP )
+      {
+        FT_FREE( bitmap->buffer );
+        slot->internal->flags &= ~FT_GLYPH_OWN_BITMAP;
+      }
+
+      slot->bitmap = target;
+      slot->internal->flags |= FT_GLYPH_OWN_BITMAP;
+    }
+    else if ( target.buffer )
+    {
+      FT_FREE( target.buffer );
+    }
+
+    return error;
   }
 
   FT_DEFINE_RENDERER(
@@ -433,7 +529,7 @@
     (FT_Renderer_GetCBoxFunc)   ft_sdf_get_cbox,   /* get_glyph_cbox  */
     (FT_Renderer_SetModeFunc)   ft_sdf_set_mode,   /* set_mode        */
 
-    (FT_Raster_Funcs*)NULL                         /* raster_class    */
+    (FT_Raster_Funcs*)&ft_bitmap_sdf_raster        /* raster_class    */
   )
 
 /* END */
diff --git a/src/sdf/ftsdfrend.h b/src/sdf/ftsdfrend.h
index 3ba7b9d7f..08525a3dd 100644
--- a/src/sdf/ftsdfrend.h
+++ b/src/sdf/ftsdfrend.h
@@ -57,7 +57,7 @@ FT_BEGIN_HEADER
    *   convert bitmaps to signed distance fields.
    *
    * @note:
-   *   This is not a seperate module, it is a part of the `sdf' module.
+   *   This is not a separate module, it is a part of the `sdf' module.
    *
    */
   FT_DECLARE_RENDERER( ft_bitmap_sdf_renderer_class )
diff --git a/src/sdf/rules.mk b/src/sdf/rules.mk
index 214725eae..eba66faa9 100644
--- a/src/sdf/rules.mk
+++ b/src/sdf/rules.mk
@@ -16,7 +16,8 @@ SDF_COMPILE := $(CC) $(ANSIFLAGS)                            \
 # sdf driver sources (i.e., C files)
 #
 SDF_DRV_SRC := $(SDF_DIR)/ftsdfrend.c  \
-               $(SDF_DIR)/ftsdf.c
+               $(SDF_DIR)/ftsdf.c      \
+               $(SDF_DIR)/ftbsdf.c
 
 
 # sdf driver headers
diff --git a/src/sdf/sdf.c b/src/sdf/sdf.c
index 5481c8f5d..7428758e9 100644
--- a/src/sdf/sdf.c
+++ b/src/sdf/sdf.c
@@ -4,6 +4,7 @@
 
 #include "ftsdfrend.c"
 #include "ftsdf.c"
+#include "ftbsdf.c"
 
 
 /* END */