Replace `FT_Get_GlyphLayers' with `FT_Get_Color_Glyph_Layer'.

This avoids any additional allocation of COLR related structures in
a glyph slot.

* include/freetype/freetype.h (FT_Glyph_Layer, FT_Glyph_LayerRec,
FT_Get_GlyphLayers): Removed.

* include/freetype/internal/ftobjs.h (FT_Colr_InternalRec): Removed.
(FT_Slot_InternalRec): Remove `color_layers'.

* include/freetype/internal/sfnt.h (TT_Load_Colr_Layer_Func):
Removed.
(SFNT_Interface, FT_DEFINE_SFNT_INTERFACE): Remove
`load_colr_layer'.

* src/base/ftobjs.c (ft_glyph_slot_done): Updated.
(FT_Render_Glyph_Internal): Use `FT_Get_Color_Glyph_Layer'.
(FT_Get_GlyphLayers): Removed.

* src/sfnt/sfdriver.c (sfnt_interface): Updated.

* src/sfnt/ttcolr.c (tt_face_load_colr_layers): Removed.
* src/sfnt/ttcolr.h: Updated.

* src/truetype/ttgload.c (TT_Load_Glyph): Updated.

9 files changed, 82 insertions, 327 deletions

diff --git a/ChangeLog b/ChangeLog
index 5df7fa590..d1559ac2e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,34 @@
 2018-06-14  Werner Lemberg  <wl@gnu.org>
 
+	Replace `FT_Get_GlyphLayers' with `FT_Get_Color_Glyph_Layer'.
+
+	This avoids any additional allocation of COLR related structures in
+	a glyph slot.
+
+	* include/freetype/freetype.h (FT_Glyph_Layer, FT_Glyph_LayerRec,
+	FT_Get_GlyphLayers): Removed.
+
+	* include/freetype/internal/ftobjs.h (FT_Colr_InternalRec): Removed.
+	(FT_Slot_InternalRec): Remove `color_layers'.
+
+	* include/freetype/internal/sfnt.h (TT_Load_Colr_Layer_Func):
+	Removed.
+	(SFNT_Interface, FT_DEFINE_SFNT_INTERFACE): Remove
+	`load_colr_layer'.
+
+	* src/base/ftobjs.c (ft_glyph_slot_done): Updated.
+	(FT_Render_Glyph_Internal): Use `FT_Get_Color_Glyph_Layer'.
+	(FT_Get_GlyphLayers): Removed.
+
+	* src/sfnt/sfdriver.c (sfnt_interface): Updated.
+
+	* src/sfnt/ttcolr.c (tt_face_load_colr_layers): Removed.
+	* src/sfnt/ttcolr.h: Updated.
+
+	* src/truetype/ttgload.c (TT_Load_Glyph): Updated.
+
+2018-06-14  Werner Lemberg  <wl@gnu.org>
+
 	Provide iterative API to access `COLR' data.
 
 	This solution doesn't store any data in an `FT_GlyphSlot' object.
diff --git a/include/freetype/freetype.h b/include/freetype/freetype.h
index 02abd8a59..546e5d87e 100644
--- a/include/freetype/freetype.h
+++ b/include/freetype/freetype.h
@@ -4171,101 +4171,6 @@ FT_BEGIN_HEADER
 
   /**********************************************************************
    *
-   * @type:
-   *    FT_Glyph_Layer
-   *
-   * @description:
-   *    A handle to an @FT_Glyph_LayerRec structure to model a given
-   *    colored glyph layer.
-   */
-  typedef struct FT_Glyph_LayerRec_*  FT_Glyph_Layer;
-
-
-  /**********************************************************************
-   *
-   * @struct:
-   *   FT_Glyph_LayerRec
-   *
-   * @description:
-   *   This structure models a given colored glyph layer as defined in the
-   *   OpenType `COLR' table.  It is used by @FT_Get_GlyphLayers.
-   *
-   * @fields:
-   *   glyph_index ::
-   *     The glyph index of the current glyph layer.
-   *
-   *   color_index ::
-   *     The color index into the font face's color palette, which can be
-   *     retrieved with @FT_Palette_Select.  The value 0xFFFF is special; it
-   *     doesn't reference a palette entry but indicates that the text
-   *     foreground color should be used instead (to be set up by the
-   *     application outside of FreeType).
-   */
-  typedef struct  FT_Glyph_LayerRec_
-  {
-    FT_UShort  glyph_index;
-    FT_UShort  color_index;
-
-  } FT_Glyph_LayerRec;
-
-
-  /*************************************************************************
-   *
-   * @func:
-   *   FT_Get_GlyphLayers
-   *
-   * @description:
-   *   This is an interface to the `COLR' table in OpenType fonts to
-   *   retrieve the colored glyph layers array associated with the current
-   *   glyph slot.
-   *
-   *     https://docs.microsoft.com/en-us/typography/opentype/spec/colr
-   *
-   *   The glyph layer data for a given glyph slot, if present, provides an
-   *   alternative, multi-colour glyph representation: Instead of rendering
-   *   the outline or bitmap in the glyph slot, glyphs with the indices and
-   *   colors returned in the @FT_Glyph_Layer array are rendered layer by
-   *   layer.
-   *
-   * @input:
-   *   glyph ::
-   *     The source glyph slot.
-   *
-   * @output:
-   *   anum_layers ::
-   *     The number of colored glyph layers for `glyph'.
-   *
-   *   alayers ::
-   *     An @FT_Glyph_Layer array with `anum_layers' elements.  NULL if there
-   *     aren't glyph layers.
-   *
-   *     The elements are ordered in the z~direction from bottom to top; an
-   *     element `n' should be rendered with the associated palette color
-   *     and blended on top of the already rendered layers (elements 0, 1,
-   *     ..., n-1).
-   *
-   * @return:
-   *   FreeType error code.  0~means success.
-   *
-   * @note:
-   *   The data in `alayers' is owned and managed by the glyph slot.
-   *
-   *   This function is necessary if you want to handle glyph layers by
-   *   yourself.  In particular, functions that operate with @FT_GlyphRec
-   *   objects (like @FT_Get_Glyph or @FT_Glyph_To_Bitmap) don't have access
-   *   to this information.
-   *
-   *   @FT_Render_Glyph, however, handles colored glyph layers
-   *   automatically if the @FT_LOAD_COLOR flag is passed to it.
-   */
-  FT_EXPORT( FT_Error )
-  FT_Get_GlyphLayers( FT_GlyphSlot     glyph,
-                      FT_UShort       *anum_layers,
-                      FT_Glyph_Layer  *alayers );
-
-
-  /**********************************************************************
-   *
    * @struct:
    *   FT_LayerIterator
    *
diff --git a/include/freetype/internal/ftobjs.h b/include/freetype/internal/ftobjs.h
index 9e92a31da..54f973a60 100644
--- a/include/freetype/internal/ftobjs.h
+++ b/include/freetype/internal/ftobjs.h
@@ -384,15 +384,6 @@ FT_BEGIN_HEADER
   } FT_Face_InternalRec;
 
 
-  typedef struct  FT_Colr_InternalRec_
-  {
-    FT_Glyph_Layer  layers;
-    FT_UShort       num_layers;
-    FT_Int32        load_flags;
-
-  } FT_Colr_InternalRec, *FT_Colr_Internal;
-
-
   /**************************************************************************
    *
    * @Struct:
@@ -432,9 +423,6 @@ FT_BEGIN_HEADER
    *   glyph_hints ::
    *     Format-specific glyph hints management.
    *
-   *   color_layers ::
-   *     Data from (SFNT) COLR/CPAL tables.
-   *
    *   load_flags ::
    *     The load flags passed as an argument to @FT_Load_Glyph while
    *     initializing the glyph slot.
@@ -451,8 +439,6 @@ FT_BEGIN_HEADER
     FT_Vector       glyph_delta;
     void*           glyph_hints;
 
-    FT_Colr_Internal  color_layers;
-
     FT_Int32        load_flags;
 
   } FT_GlyphSlot_InternalRec;
diff --git a/include/freetype/internal/sfnt.h b/include/freetype/internal/sfnt.h
index 2093c28e7..bcc266563 100644
--- a/include/freetype/internal/sfnt.h
+++ b/include/freetype/internal/sfnt.h
@@ -495,40 +495,6 @@ FT_BEGIN_HEADER
   /**************************************************************************
    *
    * @FuncType:
-   *   TT_Load_Colr_Layer_Func
-   *
-   * @Description:
-   *   Load the color layer data given a glyph index.
-   *
-   * @Input:
-   *   face ::
-   *     The target face object.
-   *
-   *   idx ::
-   *     The glyph index.
-   *
-   * @Output:
-   *   layers ::
-   *     The layer info with color index and glyph index.
-   *     Deallocate with `FT_FREE'.
-   *
-   *   num_layers ::
-   *     Number of layers.
-   *
-   * @Return:
-   *   FreeType error code.  0 means success.  Returns an error if no
-   *   color layer information exists for `idx'.
-   */
-  typedef FT_Error
-  (*TT_Load_Colr_Layer_Func)( TT_Face          face,
-                              FT_UInt          idx,
-                              FT_Glyph_Layer  *layers,
-                              FT_UShort*       num_layers );
-
-
-  /**************************************************************************
-   *
-   * @FuncType:
    *   TT_Get_Colr_Layer_Func
    *
    * @Description:
@@ -808,7 +774,6 @@ FT_BEGIN_HEADER
     TT_Free_Table_Func           free_cpal;
     TT_Free_Table_Func           free_colr;
     TT_Set_Palette_Func          set_palette;
-    TT_Load_Colr_Layer_Func      load_colr_layer;
     TT_Get_Colr_Layer_Func       get_colr_layer;
     TT_Blend_Colr_Func           colr_blend;
 
@@ -859,7 +824,6 @@ FT_BEGIN_HEADER
           free_cpal_,                    \
           free_colr_,                    \
           set_palette_,                  \
-          load_colr_layer_,              \
           get_colr_layer_,               \
           colr_blend_,                   \
           get_metrics_,                  \
@@ -900,7 +864,6 @@ FT_BEGIN_HEADER
     free_cpal_,                          \
     free_colr_,                          \
     set_palette_,                        \
-    load_colr_layer_,                    \
     get_colr_layer_,                     \
     colr_blend_,                         \
     get_metrics_,                        \
diff --git a/src/base/ftobjs.c b/src/base/ftobjs.c
index 29a1c114c..e733f955e 100644
--- a/src/base/ftobjs.c
+++ b/src/base/ftobjs.c
@@ -532,16 +532,6 @@
     /* free bitmap buffer if needed */
     ft_glyphslot_free_bitmap( slot );
 
-    /* free glyph color layers if needed */
-    if ( slot->internal->color_layers )
-    {
-      FT_Colr_InternalRec*  color_layers = slot->internal->color_layers;
-
-
-      FT_FREE( color_layers->layers );
-      FT_FREE( slot->internal->color_layers );
-    }
-
     /* slot->internal might be NULL in out-of-memory situations */
     if ( slot->internal )
     {
@@ -4513,69 +4503,85 @@
                             FT_Render_Mode  render_mode )
   {
     FT_Error     error = FT_Err_Ok;
+    FT_Face      face  = slot->face;
     FT_Renderer  renderer;
 
 
-    /* if it is already a bitmap, no need to do anything */
     switch ( slot->format )
     {
     case FT_GLYPH_FORMAT_BITMAP:   /* already a bitmap, don't do anything */
       break;
 
     default:
-      if ( slot->internal->color_layers )
+      if ( slot->internal->load_flags & FT_LOAD_COLOR )
       {
-        FT_Face  face = slot->face;
+        FT_LayerIterator  iterator;
 
+        FT_UInt  base_glyph = slot->glyph_index;
 
-        error = FT_New_GlyphSlot( face, NULL );
-        if ( !error )
+        FT_UInt  glyph_index;
+        FT_UInt  color_index;
+
+
+        /* check whether we have colored glyph layers */
+        iterator.p  = NULL;
+        glyph_index = FT_Get_Color_Glyph_Layer( face,
+                                                base_glyph,
+                                                &color_index,
+                                                &iterator );
+        if ( glyph_index )
         {
-          TT_Face       ttface = (TT_Face)face;
-          SFNT_Service  sfnt   = (SFNT_Service)ttface->sfnt;
+          error = FT_New_GlyphSlot( face, NULL );
+          if ( !error )
+          {
+            TT_Face       ttface = (TT_Face)face;
+            SFNT_Service  sfnt   = (SFNT_Service)ttface->sfnt;
 
-          FT_Glyph_Layer  glyph_layers =
-                            slot->internal->color_layers->layers;
 
-          FT_Int  idx;
+            do
+            {
+              FT_Int32  load_flags = slot->internal->load_flags;
 
 
-          for ( idx = 0;
-                idx < slot->internal->color_layers->num_layers;
-                idx++ )
-          {
-            FT_Int32  load_flags;
+              /* disable the `FT_LOAD_COLOR' flag to avoid recursion */
+              /* right here in this function                         */
+              load_flags &= ~FT_LOAD_COLOR;
 
+              /* render into the new `face->glyph' glyph slot */
+              load_flags |=  FT_LOAD_RENDER;
 
-            load_flags  = slot->internal->color_layers->load_flags
-                          & ~FT_LOAD_COLOR;
-            load_flags |= FT_LOAD_RENDER;
+              error = FT_Load_Glyph( face, glyph_index, load_flags );
+              if ( error )
+                break;
 
-            error = FT_Load_Glyph( face,
-                                   glyph_layers[idx].glyph_index,
-                                   load_flags );
-            if ( error )
-              break;
+              /* blend new `face->glyph' into old `slot'; */
+              /* at the first call, `slot' is still empty */
+              error = sfnt->colr_blend( ttface,
+                                        color_index,
+                                        slot,
+                                        face->glyph );
+              if ( error )
+                break;
 
-            error = sfnt->colr_blend( ttface,
-                                      glyph_layers[idx].color_index,
-                                      slot,
-                                      face->glyph );
-            if ( error )
-              break;
+            } while ( ( glyph_index =
+                          FT_Get_Color_Glyph_Layer( face,
+                                                    base_glyph,
+                                                    &color_index,
+                                                    &iterator ) ) != 0 );
+
+            if ( !error )
+              slot->format = FT_GLYPH_FORMAT_BITMAP;
+
+            /* this call also restores `slot' as the glyph slot */
+            FT_Done_GlyphSlot( face->glyph );
           }
 
           if ( !error )
-            slot->format = FT_GLYPH_FORMAT_BITMAP;
+            return error;
 
-          FT_Done_GlyphSlot( face->glyph );
+          /* Failed to do the colored layer.  Draw outline instead. */
+          slot->format = FT_GLYPH_FORMAT_OUTLINE;
         }
-
-        if ( !error )
-          return error;
-
-        /* Failed to do the colored layer.  Draw outline instead. */
-        slot->format = FT_GLYPH_FORMAT_OUTLINE;
       }
 
       {
@@ -5467,31 +5473,6 @@
 
   /* documentation is in freetype.h */
 
-  FT_EXPORT_DEF( FT_Error )
-  FT_Get_GlyphLayers( FT_GlyphSlot     glyph,
-                      FT_UShort       *anum_layers,
-                      FT_Glyph_Layer  *alayers )
-  {
-    if ( !glyph )
-      return FT_THROW( Invalid_Argument );
-
-    if ( glyph->internal->color_layers )
-    {
-      *anum_layers = glyph->internal->color_layers->num_layers;
-      *alayers     = glyph->internal->color_layers->layers;
-    }
-    else
-    {
-      *anum_layers = 0;
-      *alayers     = NULL;
-    }
-
-    return FT_Err_Ok;
-  }
-
-
-  /* documentation is in freetype.h */
-
   FT_EXPORT_DEF( FT_UInt )
   FT_Get_Color_Glyph_Layer( FT_Face            face,
                             FT_UInt            base_glyph,
diff --git a/src/sfnt/sfdriver.c b/src/sfnt/sfdriver.c
index e1f481802..cd2d8091b 100644
--- a/src/sfnt/sfdriver.c
+++ b/src/sfnt/sfdriver.c
@@ -1268,8 +1268,6 @@
                             /* TT_Free_Table_Func      free_colr       */
     PUT_COLOR_LAYERS( tt_face_palette_set ),
                             /* TT_Set_Palette_Func     set_palette     */
-    PUT_COLOR_LAYERS( tt_face_load_colr_layers ),
-                            /* TT_Load_Colr_Layer_Func load_colr_layer */
     PUT_COLOR_LAYERS( tt_face_get_colr_layer ),
                             /* TT_Get_Colr_Layer_Func  get_colr_layer  */
     PUT_COLOR_LAYERS( tt_face_colr_blend_layer ),
diff --git a/src/sfnt/ttcolr.c b/src/sfnt/ttcolr.c
index 323f0ca51..7e44d42ad 100644
--- a/src/sfnt/ttcolr.c
+++ b/src/sfnt/ttcolr.c
@@ -207,74 +207,6 @@
   }
 
 
-  FT_LOCAL_DEF( FT_Error )
-  tt_face_load_colr_layers( TT_Face          face,
-                            FT_UInt          glyph_id,
-                            FT_Glyph_Layer  *ret_layers,
-                            FT_UShort*       ret_num_layers )
-  {
-    FT_Error   error;
-    FT_Memory  memory = face->root.memory;
-
-    Colr*  colr = (Colr*)face->colr;
-
-    BaseGlyphRecord  glyph_record;
-    FT_Glyph_Layer   layers = NULL;
-    int              layer_idx;
-    FT_Byte*         layer_record_ptr;
-
-
-    if ( !ret_layers || !ret_num_layers )
-      return FT_THROW( Invalid_Argument );
-
-    if ( !find_base_glyph_record( colr->base_glyphs,
-                                  colr->num_base_glyphs,
-                                  glyph_id,
-                                  &glyph_record ) )
-    {
-      *ret_layers     = NULL;
-      *ret_num_layers = 0;
-
-      return FT_Err_Ok;
-    }
-
-    /* Load all colors for the glyphs; this would be stored in the slot. */
-    layer_record_ptr = colr->layers +
-                       glyph_record.first_layer_index * LAYER_SIZE;
-
-    if ( FT_NEW_ARRAY( layers, glyph_record.num_layers ) )
-      goto Error;
-
-    for ( layer_idx = 0; layer_idx < glyph_record.num_layers; layer_idx++ )
-    {
-      FT_UShort  gid                 = FT_NEXT_USHORT( layer_record_ptr );
-      FT_UShort  palette_entry_index = FT_NEXT_USHORT( layer_record_ptr );
-
-
-      if ( palette_entry_index != 0xFFFF                                 &&
-           palette_entry_index >= face->palette_data.num_palette_entries )
-      {
-        error = FT_THROW( Invalid_Table );
-        goto Error;
-      }
-
-      layers[layer_idx].color_index = palette_entry_index;
-      layers[layer_idx].glyph_index = gid;
-    }
-
-    *ret_layers     = layers;
-    *ret_num_layers = glyph_record.num_layers;
-
-    return FT_Err_Ok;
-
-  Error:
-    if ( layers )
-      FT_FREE( layers );
-
-    return error;
-  }
-
-
   FT_LOCAL_DEF( FT_UInt )
   tt_face_get_colr_layer( TT_Face            face,
                           FT_UInt            base_glyph,
diff --git a/src/sfnt/ttcolr.h b/src/sfnt/ttcolr.h
index 480fd6770..983ab831e 100644
--- a/src/sfnt/ttcolr.h
+++ b/src/sfnt/ttcolr.h
@@ -36,12 +36,6 @@ FT_BEGIN_HEADER
   FT_LOCAL( void )
   tt_face_free_colr( TT_Face  face );
 
-  FT_LOCAL( FT_Error )
-  tt_face_load_colr_layers( TT_Face          face,
-                            FT_UInt          glyph_id,
-                            FT_Glyph_Layer  *ret_layers,
-                            FT_UShort*       ret_num_layers );
-
   FT_LOCAL( FT_UInt )
   tt_face_get_colr_layer( TT_Face            face,
                           FT_UInt            base_glyph,
diff --git a/src/truetype/ttgload.c b/src/truetype/ttgload.c
index c5e96e687..f0f6a0602 100644
--- a/src/truetype/ttgload.c
+++ b/src/truetype/ttgload.c
@@ -2904,39 +2904,6 @@
          size->metrics->y_ppem < 24         )
       glyph->outline.flags |= FT_OUTLINE_HIGH_PRECISION;
 
-    /* The outline based algorithm took care of metrics. */
-    /* Read additional color info if requested.          */
-    if ( ( load_flags & FT_LOAD_COLOR ) &&
-         ( (TT_Face)glyph->face )->colr )
-    {
-      TT_Face       face   = (TT_Face)glyph->face;
-      FT_Memory     memory = face->root.memory;
-      SFNT_Service  sfnt   = (SFNT_Service)face->sfnt;
-
-      FT_Glyph_Layer  glyph_layers;
-      FT_UShort       num_glyph_layers;
-
-
-      error = sfnt->load_colr_layer( face,
-                                     glyph_index,
-                                     &glyph_layers,
-                                     &num_glyph_layers );
-      if ( error )
-        return error;
-
-      if ( !glyph->internal->color_layers )
-      {
-        if ( FT_NEW( glyph->internal->color_layers ) )
-          return error;
-      }
-
-      FT_FREE( glyph->internal->color_layers->layers );
-
-      glyph->internal->color_layers->layers     = glyph_layers;
-      glyph->internal->color_layers->num_layers = num_glyph_layers;
-      glyph->internal->color_layers->load_flags = load_flags;
-    }
-
   Exit:
 #ifdef FT_DEBUG_LEVEL_TRACE
     if ( error )