From 9422570f4e099a834fc43619f7b2a7eb6b442e25 Mon Sep 17 00:00:00 2001

From: Tom Hughes <tom@compton.nu>

Date: Sun, 19 May 2013 15:31:01 +0100

Subject: [PATCH 06/15] Implement grain-merge blending mode (GIMP)

---

 include/agg_pixfmt_rgba.h | 42 ++++++++++++++++++++++++++++++++++++++++--

 1 file changed, 40 insertions(+), 2 deletions(-)

diff --git a/include/agg_pixfmt_rgba.h b/include/agg_pixfmt_rgba.h

index 79d10dc..f576ce4 100644

--- a/include/agg_pixfmt_rgba.h

+++ b/include/agg_pixfmt_rgba.h

@@ -1401,9 +1401,46 @@ namespace agg

         }

     };

+    //================================================comp_op_rgba_grain_merge

+    template <typename ColorT, typename Order> struct comp_op_rgba_grain_merge

+    {

+        typedef ColorT color_type;

+        typedef Order order_type;

+        typedef typename color_type::value_type value_type;

+        typedef typename color_type::calc_type calc_type;

+        typedef typename color_type::long_type long_type;

+        enum base_scale_e

+        {

+            base_shift = color_type::base_shift,

+            base_mask  = color_type::base_mask

+        };

+        // E = I + M - 128

+        static AGG_INLINE void blend_pix(value_type* p,

+                                         unsigned sr, unsigned sg, unsigned sb,

+                                         unsigned sa, unsigned cover)

+        {

-

+            if(cover < 255)

+            {

+                sr = (sr * cover + 255) >> 8;

+                sg = (sg * cover + 255) >> 8;

+                sb = (sb * cover + 255) >> 8;

+                sa = (sa * cover + 255) >> 8;

+            }

+            if(sa)

+            {

+                calc_type da = p[Order::A];

+                int dr = sr + p[Order::R] - 128;

+                int dg = sg + p[Order::G] - 128;

+                int db = sb + p[Order::B] - 128;

+                p[Order::R] = (value_type)(dr < 0 ? 0 : (dr > 255 ? 255 : dr));

+                p[Order::G] = (value_type)(dg < 0 ? 0 : (dg > 255 ? 255 : dg));

+                p[Order::B] = (value_type)(db < 0 ? 0 : (db > 255 ? 255 : db));

+                p[Order::A] = (value_type)(sa + da - ((sa * da + base_mask) >> base_shift));

+            }

+        }

+    };

     //======================================================comp_op_table_rgba

     template<class ColorT, class Order> struct comp_op_table_rgba

@@ -1451,6 +1488,7 @@ namespace agg

         comp_op_rgba_contrast   <ColorT,Order>::blend_pix,

         comp_op_rgba_invert     <ColorT,Order>::blend_pix,

         comp_op_rgba_invert_rgb <ColorT,Order>::blend_pix,

+        comp_op_rgba_grain_merge<ColorT,Order>::blend_pix,

         0

     };

@@ -1486,6 +1524,7 @@ namespace agg

         comp_op_contrast,      //----comp_op_contrast

         comp_op_invert,        //----comp_op_invert

         comp_op_invert_rgb,    //----comp_op_invert_rgb

+        comp_op_grain_merge,   //----comp_op_grain_merge

         end_of_comp_op_e

     };

@@ -2908,4 +2947,3 @@ namespace agg

 }

 #endif

-

-- 

1.8.1.4