ref: 216270327d180b8f8edab11ba2a8469a1a62c2c3
parent: cd6ff28a1798fa2c5b881e2018ef1951f0d4245c
author: Anuj Verma <[email protected]>
date: Mon Aug 17 07:40:57 EDT 2020
[sdf] Add common elements for 'sdf' and 'bsdf' renderers. * src/sdf/ftsdfrend.h (SDF_Rendere_Module, ft_sdf_renderer_class, ft_bitmap_sdf_renderer_class): New structures. * src/sdf/ftsdfcommon.h (DEFAULT_SPREAD, MIN_SPREAD_MAX_SPREAD, USE_SQUARED_DISTANCES): New macros. (FT_INT_26D6, FT_INT_16D16, FT_26D6_16D16): New macros. (FT_CALL, VECTOR_LENGTH_16D16): New macros. (FT_26D6_Vec, FT_16D16_Vec, FT_16D16, FT_26D6, FT_6D10, FT_CBox): New typedefs. (square_root): New macro. * src/sdf/ftsdferrs.h: Add module error setup.
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,20 @@
+2020-08-17 Anuj Verma <[email protected]>
+
+ [sdf] Add common elements for 'sdf' and 'bsdf' renderers.
+
+ * src/sdf/ftsdfrend.h (SDF_Rendere_Module, ft_sdf_renderer_class,
+ ft_bitmap_sdf_renderer_class): New structures.
+
+ * src/sdf/ftsdfcommon.h (DEFAULT_SPREAD, MIN_SPREAD_MAX_SPREAD,
+ USE_SQUARED_DISTANCES): New macros.
+ (FT_INT_26D6, FT_INT_16D16, FT_26D6_16D16): New macros.
+ (FT_CALL, VECTOR_LENGTH_16D16): New macros.
+ (FT_26D6_Vec, FT_16D16_Vec, FT_16D16, FT_26D6, FT_6D10, FT_CBox):
+ New typedefs.
+ (square_root): New macro.
+
+ * src/sdf/ftsdferrs.h: Add module error setup.
+
2020-08-16 Anuj Verma <[email protected]>
[sdf] Add files for new 'sdf' module.
--- a/src/sdf/ftsdfcommon.h
+++ b/src/sdf/ftsdfcommon.h
@@ -1,7 +1,150 @@
+ /****************************************************
+ *
+ * This file contains common functions and properties
+ * for both the 'sdf' and 'bsdf' renderers.
+ *
+ */
+
#ifndef FTSDFCOMMON_H_
#define FTSDFCOMMON_H_
+#include <ft2build.h>
+#include FT_CONFIG_CONFIG_H
+#include <freetype/freetype.h>
+
+
+FT_BEGIN_HEADER
+
+
+ /**************************************************************************
+ *
+ * default values (cannot be set individually for each renderer)
+ *
+ */
+
+ /* default spread value */
+#define DEFAULT_SPREAD 8
+ /* minimum spread supported by the renderer */
+#define MIN_SPREAD 2
+ /* maximum spread supported by the renderer */
+#define MAX_SPREAD 32
+
+
+ /**************************************************************************
+ *
+ * common definitions (cannot be set individually for each renderer)
+ *
+ */
+
+ /* If this macro is set to 1 the rasterizer uses squared distances for */
+ /* computation. It can greatly improve the performance but there is a */
+ /* chance of overflow and artifacts. You can safely use it up to a */
+ /* pixel size of 128. */
+#ifndef USE_SQUARED_DISTANCES
+#define USE_SQUARED_DISTANCES 0
+#endif
+
+
+ /**************************************************************************
+ *
+ * common macros
+ *
+ */
+
+ /* convert int to 26.6 fixed-point */
+#define FT_INT_26D6( x ) ( x * 64 )
+ /* convert int to 16.16 fixed-point */
+#define FT_INT_16D16( x ) ( x * 65536 )
+ /* convert 26.6 to 16.16 fixed-point */
+#define FT_26D6_16D16( x ) ( x * 1024 )
+
+
+ /* Convenience macro to call a function; it */
+ /* jumps to label `Exit` if an error occurs. */
+#define FT_CALL( x ) do \
+ { \+ error = ( x ); \
+ if ( error != FT_Err_Ok ) \
+ goto Exit; \
+ } while ( 0 )
+
+
+ /*
+ * The macro `VECTOR_LENGTH_16D16` computes either squared distances or
+ * actual distances, depending on the value of `USE_SQUARED_DISTANCES`.
+ *
+ * By using squared distances the performance can be greatly improved but
+ * there is a risk of overflow.
+ */
+#if USE_SQUARED_DISTANCES
+#define VECTOR_LENGTH_16D16( v ) ( FT_MulFix( v.x, v.x ) + \
+ FT_MulFix( v.y, v.y ) )
+#else
+#define VECTOR_LENGTH_16D16( v ) FT_Vector_Length( &v )
+#endif
+
+
+ /**************************************************************************
+ *
+ * common typedefs
+ *
+ */
+
+ typedef FT_Vector FT_26D6_Vec; /* with 26.6 fixed-point components */
+ typedef FT_Vector FT_16D16_Vec; /* with 16.16 fixed-point components */
+
+ typedef FT_Fixed FT_16D16; /* 16.16 fixed-point representation */
+ typedef FT_Fixed FT_26D6; /* 26.6 fixed-point representation */
+ typedef FT_Short FT_6D10; /* 6.10 fixed-point representation */
+
+ typedef FT_BBox FT_CBox; /* control box of a curve */
+
+
+ /**************************************************************************
+ *
+ * common functions
+ *
+ */
+
+ /*
+ * Original algorithm:
+ *
+ * https://github.com/chmike/fpsqrt
+ *
+ * Use this to compute the square root of a 16.16 fixed point number.
+ */
+ static FT_16D16
+ square_root( FT_16D16 val )
+ {+ FT_ULong t, q, b, r;
+
+
+ r = val;
+ b = 0x40000000L;
+ q = 0;
+
+ while ( b > 0x40L )
+ {+ t = q + b;
+
+ if ( r >= t )
+ {+ r -= t;
+ q = t + b;
+ }
+
+ r <<= 1;
+ b >>= 1;
+ }
+
+ q >>= 8;
+
+ return q;
+ }
+
+
+FT_END_HEADER
#endif /* FTSDFCOMMON_H_ */
--- a/src/sdf/ftsdferrs.h
+++ b/src/sdf/ftsdferrs.h
@@ -2,6 +2,15 @@
#ifndef FTSDFERRS_H_
#define FTSDFERRS_H_
+#include <freetype/ftmoderr.h>
+
+#undef FTERRORS_H_
+
+#undef FT_ERR_PREFIX
+#define FT_ERR_PREFIX Sdf_Err_
+#define FT_ERR_BASE FT_Mod_Err_Sdf
+
+#include <freetype/fterrors.h>
#endif /* FTSDFERRS_H_ */
--- a/src/sdf/ftsdfrend.h
+++ b/src/sdf/ftsdfrend.h
@@ -2,6 +2,95 @@
#ifndef FTSDFREND_H_
#define FTSDFREND_H_
+#include <freetype/ftrender.h>
+#include <freetype/ftmodapi.h>
+#include <freetype/internal/ftobjs.h>
+
+FT_BEGIN_HEADER
+
+
+ /**************************************************************************
+ *
+ * @struct:
+ * SDF_Renderer_Module
+ *
+ * @description:
+ * This struct extends the native renderer struct `FT_RendererRec`. It
+ * is basically used to store various parameters required by the
+ * renderer and some additional parameters that can be used to tweak the
+ * output of the renderer.
+ *
+ * @fields:
+ * root ::
+ * The native rendere struct.
+ *
+ * spread ::
+ * This is an essential parameter/property required by the renderer.
+ * `spread` defines the maximum unsigned value that is present in the
+ * final SDF output. For the default value check file
+ * `ftsdfcommon.h`.
+ *
+ * flip_sign ::
+ * By default positive values indicate positions inside of contours,
+ * i.e., filled by a contour. If this property is true then that
+ * output will be the opposite of the default, i.e., negative values
+ * indicate positions inside of contours.
+ *
+ * flip_y ::
+ * Setting this parameter to true makes the output image flipped
+ * along the y-axis.
+ *
+ * overlaps ::
+ * Set this to true to generate SDF for glyphs having overlapping
+ * contours. The overlapping support is limited to glyphs that do not
+ * have self-intersecting contours. Also, removing overlaps require a
+ * considerable amount of extra memory; additionally, it will not work
+ * if generating SDF from bitmap.
+ *
+ * @note:
+ * All properties except `overlaps` are valid for both the 'sdf' and
+ * 'bsdf' renderers.
+ */
+ typedef struct SDF_Renderer_Module_
+ {+ FT_RendererRec root;
+ FT_UInt spread;
+ FT_Bool flip_sign;
+ FT_Bool flip_y;
+ FT_Bool overlaps;
+
+ } SDF_Renderer_Module, *SDF_Renderer;
+
+
+ /**************************************************************************
+ *
+ * @renderer:
+ * ft_sdf_renderer_class
+ *
+ * @description:
+ * Renderer to convert @FT_Outline to signed distance fields.
+ *
+ */
+ FT_DECLARE_RENDERER( ft_sdf_renderer_class )
+
+
+ /**************************************************************************
+ *
+ * @renderer:
+ * ft_bitmap_sdf_renderer_class
+ *
+ * @description:
+ * This is not exactly a renderer; it is just a converter that
+ * transforms bitmaps to signed distance fields.
+ *
+ * @note:
+ * This is not a separate module, it is part of the 'sdf' module.
+ *
+ */
+ FT_DECLARE_RENDERER( ft_bitmap_sdf_renderer_class )
+
+
+FT_END_HEADER
#endif /* FTSDFREND_H_ */