[smooth] Turn on LCD filtering during FreeType initialization.

* src/smooth/ftsmooth.c (ft_smooth_init): Enable LCD filtering.

* include/freetype/ftlcdfil.h: Document it, remove patent warnings.
* include/freetype/freetype.h (FT_Render_Mode): Updated.
* include/freetype/config/ftoption.h, devel/ftoption.h
[FT_CONFIG_OPTION_SUBPIXEL_RENDERING]: Do not mention patents.

ChangeLog

@@ -1,3 +1,14 @@
+2020-05-12  Alexei Podtelezhnikov  <apodtele@gmail.com>
+
+	[smooth] Turn on LCD filtering during FreeType initialization.
+
+	* src/smooth/ftsmooth.c (ft_smooth_init): Enable LCD filtering.
+
+	* include/freetype/ftlcdfil.h: Document it, remove patent warnings.
+	* include/freetype/freetype.h (FT_Render_Mode): Updated.
+	* include/freetype/config/ftoption.h, devel/ftoption.h
+	[FT_CONFIG_OPTION_SUBPIXEL_RENDERING]: Do not mention patents.
+
 2020-05-11  Alexei Podtelezhnikov  <apodtele@gmail.com>
 
 	[smooth] Stop using dedicated LCD modules and classes.

devel/ftoption.h

@@ -121,10 +121,8 @@ FT_BEGIN_HEADER
    * mitigate color fringes inherent to this technology, you also need to
    * explicitly set up LCD filtering.
    *
-   * Note that this feature is covered by several Microsoft patents and
-   * should not be activated in any default build of the library.  When this
-   * macro is not defined, FreeType offers alternative LCD rendering
-   * technology that produces excellent output without LCD filtering.
+   * When this macro is not defined, FreeType offers alternative LCD
+   * rendering technology that produces excellent output.
    */
 /* #define FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
 

include/freetype/config/ftoption.h

@@ -121,10 +121,8 @@ FT_BEGIN_HEADER
    * mitigate color fringes inherent to this technology, you also need to
    * explicitly set up LCD filtering.
    *
-   * Note that this feature is covered by several Microsoft patents and
-   * should not be activated in any default build of the library.  When this
-   * macro is not defined, FreeType offers alternative LCD rendering
-   * technology that produces excellent output without LCD filtering.
+   * When this macro is not defined, FreeType offers alternative LCD
+   * rendering technology that produces excellent output.
    */
 /* #define FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
 

include/freetype/freetype.h

@@ -3246,14 +3246,6 @@ FT_BEGIN_HEADER
    *     pixels and use the @FT_PIXEL_MODE_LCD_V mode.
    *
    * @note:
-   *   Should you define `FT_CONFIG_OPTION_SUBPIXEL_RENDERING` in your
-   *   `ftoption.h`, which enables patented ClearType-style rendering, the
-   *   LCD-optimized glyph bitmaps should be filtered to reduce color fringes
-   *   inherent to this technology.  You can either set up LCD filtering with
-   *   @FT_Library_SetLcdFilter or @FT_Face_Properties, or do the filtering
-   *   yourself.  The default FreeType LCD rendering technology does not
-   *   require filtering.
-   *
    *   The selected render mode only affects vector glyphs of a font.
    *   Embedded bitmaps often have a different pixel mode like
    *   @FT_PIXEL_MODE_MONO.  You can use @FT_Bitmap_Convert to transform them

include/freetype/ftlcdfil.h

@@ -47,7 +47,7 @@ FT_BEGIN_HEADER
    * @description:
    *   FreeType provides two alternative subpixel rendering technologies. 
    *   Should you define `FT_CONFIG_OPTION_SUBPIXEL_RENDERING` in your
-   *   `ftoption.h` file, this enables patented ClearType-style rendering. 
+   *   `ftoption.h` file, this enables ClearType-style rendering.
    *   Otherwise, Harmony LCD rendering is enabled.  These technologies are
    *   controlled differently and API described below, although always
    *   available, performs its function when appropriate method is enabled
@@ -177,7 +177,7 @@ FT_BEGIN_HEADER
    *   FT_Library_SetLcdFilter
    *
    * @description:
-   *   This function is used to apply color filtering to LCD decimated
+   *   This function is used to change filter applied to LCD decimated
    *   bitmaps, like the ones used when calling @FT_Render_Glyph with
    *   @FT_RENDER_MODE_LCD or @FT_RENDER_MODE_LCD_V.
    *
@@ -196,15 +196,14 @@ FT_BEGIN_HEADER
    *   FreeType error code.  0~means success.
    *
    * @note:
-   *   This feature is always disabled by default.  Clients must make an
-   *   explicit call to this function with a `filter` value other than
-   *   @FT_LCD_FILTER_NONE in order to enable it.
+   *   Since 2.11 the LCD filtering is enabled with @FT_LCD_FILTER_DEFAULT.
+   *   It is no longer necessary to call this function explicitly except
+   *   to choose a different filter or disable filtering altogether with
+   *   @FT_LCD_FILTER_NONE.
    *
-   *   Due to **PATENTS** covering subpixel rendering, this function doesn't
-   *   do anything except returning `FT_Err_Unimplemented_Feature` if the
-   *   configuration macro `FT_CONFIG_OPTION_SUBPIXEL_RENDERING` is not
-   *   defined in your build of the library, which should correspond to all
-   *   default builds of FreeType.
+   *   This function does nothing but returns `FT_Err_Unimplemented_Feature`
+   *   if the configuration macro `FT_CONFIG_OPTION_SUBPIXEL_RENDERING` is
+   *   not defined in your build of the library.
    *
    * @since:
    *   2.3.0
@@ -235,11 +234,9 @@ FT_BEGIN_HEADER
    *   FreeType error code.  0~means success.
    *
    * @note:
-   *   Due to **PATENTS** covering subpixel rendering, this function doesn't
-   *   do anything except returning `FT_Err_Unimplemented_Feature` if the
-   *   configuration macro `FT_CONFIG_OPTION_SUBPIXEL_RENDERING` is not
-   *   defined in your build of the library, which should correspond to all
-   *   default builds of FreeType.
+   *   This function does nothing but returns `FT_Err_Unimplemented_Feature`
+   *   if the configuration macro `FT_CONFIG_OPTION_SUBPIXEL_RENDERING` is
+   *   not defined in your build of the library.
    *
    *   LCD filter weights can also be set per face using @FT_Face_Properties
    *   with @FT_PARAM_TAG_LCD_FILTER_WEIGHTS.

src/smooth/ftsmooth.c

@@ -44,7 +44,7 @@
     sub[2].x = 21;
     sub[2].y = 0;
 
-#elif 0   /* or else, once ClearType patents expire */
+#else   /* set up default LCD filtering */
 
     FT_Library_SetLcdFilter( render->root.library, FT_LCD_FILTER_DEFAULT );