[freetype2] GSoC-2019-moazin 2e9e841 28/32: Let FT handle the memory management for rendering port's state

[Moazin Khatti]

branch: GSoC-2019-moazin
commit 2e9e84193d4948c15fed042ff8d6787775d82f42
Author: Moazin Khatti <address@hidden>
Commit: Moazin Khatti <address@hidden>

    Let FT handle the memory management for rendering port's state
    and the image buffer.
    
    State has been moved inside the library structure. A new hook
    function has been added to query the size needed for the state
    structure and this allocation is performed by FT. Memory alloc.
    for the image buffer is also being done by FT so that it can later
    free it easily.
    
    * include/freetype/svgrenderer.h: Small doc fixes. Addition of two
    new hooks. `SVG_Lib_Get_State_Size' and `SVG_Lib_Get_Buffer_Size'.
    
    * src/base/ftglyph.c (FT_Glyph_To_Bitmap): Small bug fix. Memory
    was being initialized before library.
    
    * src/base/ftobjs.c (FT_Set_Svg_Hooks): Adjust the code for new
    hook functions.
    
    * src/svg/ftsvg.c: Adjust the code for new hook functions. Perform
    all memory allocations needed by the rendering port from FreeType
    side.
    
    * src/svg/svgtypes.c: Add the new hooks in the hook structure.
---
 include/freetype/svgrenderer.h | 82 ++++++++++++++++++++++++++++++++++++------
 src/base/ftglyph.c             |  3 +-
 src/base/ftobjs.c              | 17 ++++++---
 src/svg/ftsvg.c                | 56 +++++++++++++++++++----------
 src/svg/svgtypes.c             |  3 ++
 5 files changed, 126 insertions(+), 35 deletions(-)

diff --git a/include/freetype/svgrenderer.h b/include/freetype/svgrenderer.h
index e6c9aa4..2f6e83f 100644
--- a/include/freetype/svgrenderer.h
+++ b/include/freetype/svgrenderer.h
@@ -80,15 +80,63 @@ FT_BEGIN_HEADER
    *   A callback used to render the glyph loaded in the slot.
    *
    * @input:
-   *   svg_doc::
-   *     A pointer to the svg document
+   *   slot ::
+   *     The whole glyph slot object.
+   *
+   *   outline_bbox ::
+   *     The bounding box of the glyph in font units. So that the renderer
+   *     may not need to calculate it again.
    *
    * @return:
    *   FreeType error code.  0 means success.
    */
 
   typedef FT_Error
-  (*SVG_Lib_Render)( FT_GlyphSlot  slot );
+  (*SVG_Lib_Render)( FT_GlyphSlot  slot,
+                     FT_BBox  outline_bbox);
+
+  /**************************************************************************
+   *
+   * @functype:
+   *   SVG_Lib_Get_State_Size
+   *
+   * @description:
+   *   A callback which is called to query the size of the state stucture.
+   *   This is used for allocating the state structure in library.
+   *
+   * @return:
+   *   Size of the state structure in bytes.
+   */
+
+  typedef FT_UInt
+  (*SVG_Lib_Get_State_Size)( );
+
+  /**************************************************************************
+   *
+   * @functype:
+   *   SVG_Lib_Get_Buffer_Size
+   *
+   * @description:
+   *   A callback which is called to get the size of the image buffer needed.
+   *   This buffer will ultimately be populated by `SVG_Lib_Render' hook.
+   *
+   * @input:
+   *   slot ::
+   *     The glyph slot which has the SVG document loaded as well as other
+   *     info.
+   *
+   *   bbox ::
+   *     The bbox in font units. This is required for the rendering port to
+   *     predict the final size of the image buffer.
+   *
+   * @return:
+   *   Size of the state structure in bytes.
+   *
+   */
+
+  typedef FT_ULong
+  (*SVG_Lib_Get_Buffer_Size)( FT_GlyphSlot  slot,
+                              FT_BBox       bbox );
 
 
   /**************************************************************************
@@ -116,15 +164,25 @@ FT_BEGIN_HEADER
    *     A function pointer of the type `SVG_Lib_Render'. Read the
    *     documentation of `SVG_Lib_Render'.
    *
+   *   get_state_size::
+   *     A function pointer of the type `SVG_Lib_Get_State_Size'. Read the
+   *     documentation of `SVG_Lib_Get_State_Size'.
+   *
+   *   get_buffer_size::
+   *     A function pointer of the type `SVG_Lib_Get_Buffer_Size'. Read the
+   *     documentation of `SVG_Lib_Get_Buffer_Size'.
+   *
    * @return:
    *   FreeType error code.  0 means success.
    */
 
   typedef FT_Error
-  (*SVG_Set_Hooks)( FT_Module       module,
-                    SVG_Lib_Init    init_hook,
-                    SVG_Lib_Free    free_hook,
-                    SVG_Lib_Render  render_hook );
+  (*SVG_Set_Hooks)( FT_Module                module,
+                    SVG_Lib_Init             init_hook,
+                    SVG_Lib_Free             free_hook,
+                    SVG_Lib_Render           render_hook,
+                    SVG_Lib_Get_State_Size   get_state_size,
+                    SVG_Lib_Get_Buffer_Size  get_buffer_size );
 
   /**************************************************************************
    *
@@ -151,10 +209,12 @@ FT_BEGIN_HEADER
 
   /* TODO: to document */
   FT_EXPORT( FT_Error )
-  FT_Set_Svg_Hooks( FT_Library      library,
-                    SVG_Lib_Init    init_hook,
-                    SVG_Lib_Free    free_hook,
-                    SVG_Lib_Render  render_hook );
+  FT_Set_Svg_Hooks( FT_Library               library,
+                    SVG_Lib_Init             init_hook,
+                    SVG_Lib_Free             free_hook,
+                    SVG_Lib_Render           render_hook,
+                    SVG_Lib_Get_State_Size   get_state_size,
+                    SVG_Lib_Get_Buffer_Size  get_buffer_size );
 
   /**************************************************************************
    *
diff --git a/src/base/ftglyph.c b/src/base/ftglyph.c
index ae6480b..8d53281 100644
--- a/src/base/ftglyph.c
+++ b/src/base/ftglyph.c
@@ -716,7 +716,7 @@
     const FT_Glyph_Class*     clazz;
 
     FT_Library                library;
-    FT_Memory                 memory = library->memory;
+    FT_Memory                 memory;
 
 
     /* check argument */
@@ -728,6 +728,7 @@
 
     clazz   = glyph->clazz;
     library = glyph->library;
+    memory = library->memory;
     if ( !library || !clazz )
       goto Bad;
 
diff --git a/src/base/ftobjs.c b/src/base/ftobjs.c
index e4e1532..b72f5f2 100644
--- a/src/base/ftobjs.c
+++ b/src/base/ftobjs.c
@@ -5596,10 +5596,12 @@
   }
 
   FT_EXPORT_DEF( FT_Error )
-  FT_Set_Svg_Hooks( FT_Library      library,
-                    SVG_Lib_Init    init_hook,
-                    SVG_Lib_Free    free_hook,
-                    SVG_Lib_Render  render_hook )
+  FT_Set_Svg_Hooks( FT_Library               library,
+                    SVG_Lib_Init             init_hook,
+                    SVG_Lib_Free             free_hook,
+                    SVG_Lib_Render           render_hook,
+                    SVG_Lib_Get_State_Size   get_state_size,
+                    SVG_Lib_Get_Buffer_Size  get_buffer_size )
   {
     FT_Module               renderer;
     SVG_Renderer_Interface  *svg;
@@ -5612,7 +5614,12 @@
       return FT_THROW( Missing_Module );
 
     svg = (SVG_Renderer_Interface*)renderer->clazz->module_interface;
-    svg->set_hooks(renderer, init_hook, free_hook, render_hook);
+    svg->set_hooks(renderer,
+                   init_hook,
+                   free_hook,
+                   render_hook,
+                   get_state_size,
+                   get_buffer_size );
     return FT_Err_Ok;
   }
 
diff --git a/src/svg/ftsvg.c b/src/svg/ftsvg.c
index 445cf65..bf027c5 100644
--- a/src/svg/ftsvg.c
+++ b/src/svg/ftsvg.c
@@ -17,22 +17,12 @@
 
 #include <ft2build.h>
 #include FT_SVG_RENDERER_H
+#include FT_BBOX_H
 
 #include <stdio.h>
 
 #include "ftsvg.h"
 
-  /* tmp hook injection */
-  FT_Error
-  tmp_svg_lib_init()
-  {
-    FT_Error  error;
-
-    error = FT_Err_Ok;
-    printf("Init svg\n");
-    return error;
-  }
-
   /* ft_svg_init */
   static FT_Error
   ft_svg_init( SVG_Renderer svg_module )
@@ -46,8 +36,10 @@
   ft_svg_done( SVG_Renderer svg_module )
   {
     FT_Library  library = svg_module->root.root.library;
-    if ( svg_module->loaded = TRUE )
+    FT_Memory   memory  = library->memory;
+    if ( svg_module->loaded == TRUE )
       svg_module->hooks.svg_lib_free( library );
+      FT_FREE( library->svg_renderer_state );
     svg_module->loaded = FALSE;
   }
 
@@ -59,20 +51,45 @@
   {
     SVG_Renderer  svg_renderer = (SVG_Renderer)renderer;
     FT_Library    library      = renderer->root.library;
+    FT_Memory     memory       = library->memory;
+    FT_BBox       outline_bbox;
     FT_Error      error;
+
+    SVG_RendererHooks hooks = svg_renderer->hooks;
+
+    unsigned long  size_image_buffer;
+
     if ( svg_renderer->loaded == FALSE )
     {
-      error = svg_renderer->hooks.svg_lib_init( library );
+      FT_MEM_ALLOC( library->svg_renderer_state,
+                    hooks.svg_lib_get_state_size() );
+      if ( error )
+        return error;
+      error = hooks.svg_lib_init( library );
       svg_renderer->loaded = TRUE;
     }
-    return svg_renderer->hooks.svg_lib_render( slot );
+
+    /* Let's calculate the bounding box in font units here */
+    error = FT_Outline_Get_BBox( &slot->outline, &outline_bbox );
+    if( error != FT_Err_Ok )
+      return error;
+
+    size_image_buffer = hooks.svg_lib_get_buffer_size( slot, outline_bbox );
+
+    FT_MEM_ALLOC( slot->bitmap.buffer, size_image_buffer );
+    if ( error )
+      return error;
+
+    return hooks.svg_lib_render( slot, outline_bbox );
   }
 
   static FT_Error
-  ft_svg_set_hooks( FT_Module       module,
-                    SVG_Lib_Init    init_hook,
-                    SVG_Lib_Free    free_hook,
-                    SVG_Lib_Render  render_hook )
+  ft_svg_set_hooks( FT_Module                module,
+                    SVG_Lib_Init             init_hook,
+                    SVG_Lib_Free             free_hook,
+                    SVG_Lib_Render           render_hook,
+                    SVG_Lib_Get_State_Size   get_state_size,
+                    SVG_Lib_Get_Buffer_Size  get_buffer_size )
   {
     SVG_Renderer  renderer;
 
@@ -81,6 +98,9 @@
     renderer->hooks.svg_lib_free   = free_hook;
     renderer->hooks.svg_lib_render = render_hook;
 
+    renderer->hooks.svg_lib_get_state_size  = get_state_size;
+    renderer->hooks.svg_lib_get_buffer_size = get_buffer_size;
+
     return FT_Err_Ok;
   }
 
diff --git a/src/svg/svgtypes.c b/src/svg/svgtypes.c
index 57e5c01..d393858 100644
--- a/src/svg/svgtypes.c
+++ b/src/svg/svgtypes.c
@@ -27,6 +27,9 @@
     SVG_Lib_Init    svg_lib_init;
     SVG_Lib_Free    svg_lib_free;
     SVG_Lib_Render  svg_lib_render;
+
+    SVG_Lib_Get_State_Size   svg_lib_get_state_size;
+    SVG_Lib_Get_Buffer_Size  svg_lib_get_buffer_size;
   } SVG_RendererHooks;
 
   typedef struct SVG_RendererRec_