Use Cairo 1.10 blend operators to render feBlend

(bzr r12600)

1 files changed, 30 insertions, 134 deletions

diff --git a/src/display/nr-filter-blend.cpp b/src/display/nr-filter-blend.cpp
index a08191f67..bff7405b7 100644
--- a/src/display/nr-filter-blend.cpp
+++ b/src/display/nr-filter-blend.cpp
@@ -1,6 +1,6 @@
-/*
+/** @file
  * SVG feBlend renderer
- *
+ *//*
  * "This filter composites two objects together using commonly used
  * imaging software blending modes. It performs a pixel-wise combination
  * of two input images." 
@@ -9,6 +9,7 @@
  * Authors:
  *   Niko Kiirala <niko@kiirala.com>
  *   Jasper van de Gronde <th.v.d.gronde@hccnet.nl>
+ *   Krzysztof Kosiński <tweenk.pl@gmail.com>
  *
  * Copyright (C) 2007-2008 authors
  *
@@ -30,20 +31,6 @@
 namespace Inkscape {
 namespace Filters {
 
-/*
- * From http://www.w3.org/TR/SVG11/filters.html#feBlend
- *
- * For all feBlend modes, the result opacity is computed as follows:
- * qr = 1 - (1-qa)*(1-qb)
- *
- * For the compositing formulas below, the following definitions apply:
- * cr = Result color (RGB) - premultiplied
- * qa = Opacity value at a given pixel for image A
- * qb = Opacity value at a given pixel for image B
- * ca = Color (RGB) at a given pixel for image A - premultiplied
- * cb = Color (RGB) at a given pixel for image B - premultiplied
- */
-
 FilterBlend::FilterBlend() 
     : _blend_mode(BLEND_NORMAL),
       _input2(NR_FILTER_SLOT_NOT_SET)
@@ -56,91 +43,6 @@ FilterPrimitive * FilterBlend::create() {
 FilterBlend::~FilterBlend()
 {}
 
-// cr = (1-qa)*cb + (1-qb)*ca + ca*cb
-struct BlendMultiply {
-    guint32 operator()(guint32 in1, guint32 in2)
-    {
-        EXTRACT_ARGB32(in1, aa, ra, ga, ba)
-        EXTRACT_ARGB32(in2, ab, rb, gb, bb)
-
-        guint32 ao = 255*255 - (255-aa)*(255-ab);        ao = (ao + 127) / 255;
-        guint32 ro = (255-aa)*rb + (255-ab)*ra + ra*rb;  ro = (ro + 127) / 255;
-        guint32 go = (255-aa)*gb + (255-ab)*ga + ga*gb;  go = (go + 127) / 255;
-        guint32 bo = (255-aa)*bb + (255-ab)*ba + ba*bb;  bo = (bo + 127) / 255;
-
-        ASSEMBLE_ARGB32(pxout, ao, ro, go, bo)
-        return pxout;
-    }
-};
-
-// cr = cb + ca - ca * cb
-struct BlendScreen {
-    guint32 operator()(guint32 in1, guint32 in2)
-    {
-        EXTRACT_ARGB32(in1, aa, ra, ga, ba)
-        EXTRACT_ARGB32(in2, ab, rb, gb, bb)
-
-        guint32 ao = 255*255 - (255-aa)*(255-ab);    ao = (ao + 127) / 255;
-        guint32 ro = 255*(rb + ra) - ra * rb;        ro = (ro + 127) / 255;
-        guint32 go = 255*(gb + ga) - ga * gb;        go = (go + 127) / 255;
-        guint32 bo = 255*(bb + ba) - ba * bb;        bo = (bo + 127) / 255;
-
-        ASSEMBLE_ARGB32(pxout, ao, ro, go, bo)
-        return pxout;
-    }
-};
-
-// cr = Min ((1 - qa) * cb + ca, (1 - qb) * ca + cb)
-struct BlendDarken {
-    guint32 operator()(guint32 in1, guint32 in2)
-    {
-        EXTRACT_ARGB32(in1, aa, ra, ga, ba)
-        EXTRACT_ARGB32(in2, ab, rb, gb, bb)
-
-        guint32 ao = 255*255 - (255-aa)*(255-ab);                           ao = (ao + 127) / 255;
-        guint32 ro = std::min((255-aa)*rb + 255*ra, (255-ab)*ra + 255*rb);  ro = (ro + 127) / 255;
-        guint32 go = std::min((255-aa)*gb + 255*ga, (255-ab)*ga + 255*gb);  go = (go + 127) / 255;
-        guint32 bo = std::min((255-aa)*bb + 255*ba, (255-ab)*ba + 255*bb);  bo = (bo + 127) / 255;
-
-        ASSEMBLE_ARGB32(pxout, ao, ro, go, bo)
-        return pxout;
-    }
-};
-
-// cr = Max ((1 - qa) * cb + ca, (1 - qb) * ca + cb)
-struct BlendLighten {
-    guint32 operator()(guint32 in1, guint32 in2)
-    {
-        EXTRACT_ARGB32(in1, aa, ra, ga, ba)
-        EXTRACT_ARGB32(in2, ab, rb, gb, bb)
-
-        guint32 ao = 255*255 - (255-aa)*(255-ab);                           ao = (ao + 127) / 255;
-        guint32 ro = std::max((255-aa)*rb + 255*ra, (255-ab)*ra + 255*rb);  ro = (ro + 127) / 255;
-        guint32 go = std::max((255-aa)*gb + 255*ga, (255-ab)*ga + 255*gb);  go = (go + 127) / 255;
-        guint32 bo = std::max((255-aa)*bb + 255*ba, (255-ab)*ba + 255*bb);  bo = (bo + 127) / 255;
-
-        ASSEMBLE_ARGB32(pxout, ao, ro, go, bo)
-        return pxout;
-    }
-};
-
-/*
-struct BlendAlpha
-static inline void blend_alpha(guint32 in1, guint32 in2, guint32 *out)
-{
-    EXTRACT_ARGB32(in1, a1, a2, a3, a4);
-    EXTRACT_ARGB32(in2, b1, b2, b3, b4);
-
-    guint32 o1 = 255*255 - (255-a1)*(255-b1);  o1 = (o1+127) / 255;
-    guint32 o2 = 255*255 - (255-a2)*(255-b2);  o2 = (o2+127) / 255;
-    guint32 o3 = 255*255 - (255-a3)*(255-b3);  o3 = (o3+127) / 255;
-    guint32 o4 = 255*255 - (255-a4)*(255-b4);  o4 = (o4+127) / 255;
-
-    ASSEMBLE_ARGB32(pxout, o1, o2, o3, o4);
-    *out = pxout;
-}
-*/
-
 void FilterBlend::render_cairo(FilterSlot &slot)
 {
     cairo_surface_t *input1 = slot.getcairo(_input);
@@ -161,41 +63,35 @@ void FilterBlend::render_cairo(FilterSlot &slot)
     cairo_surface_t *out = ink_cairo_surface_create_output(input1, input2);
     set_cairo_surface_ci( out, ci_fp );
 
-    cairo_content_t ct1 = cairo_surface_get_content(input1);
-    cairo_content_t ct2 = cairo_surface_get_content(input2);
-    if ((ct1 == CAIRO_CONTENT_ALPHA && ct2 == CAIRO_CONTENT_ALPHA)
-        || _blend_mode == BLEND_NORMAL)
-    {
-        ink_cairo_surface_blit(input2, out);
-        cairo_t *out_ct = cairo_create(out);
-        cairo_set_source_surface(out_ct, input1, 0, 0);
-        cairo_paint(out_ct);
-        cairo_destroy(out_ct);
-    } else {
-        // blend mode != normal and at least 1 surface is not pure alpha
-
-        // TODO: convert to Cairo blending operators once we start using the 1.10 series
-        switch (_blend_mode) {
-            case BLEND_MULTIPLY:
-                ink_cairo_surface_blend(input1, input2, out, BlendMultiply());
-                break;
-            case BLEND_SCREEN:
-                ink_cairo_surface_blend(input1, input2, out, BlendScreen());
-                break;
-            case BLEND_DARKEN:
-                ink_cairo_surface_blend(input1, input2, out, BlendDarken());
-                break;
-            case BLEND_LIGHTEN:
-                ink_cairo_surface_blend(input1, input2, out, BlendLighten());
-                break;
-            case BLEND_NORMAL:
-            default:
-                // this was handled before
-                g_assert_not_reached();
-                break;
-        }
+    ink_cairo_surface_blit(input2, out);
+    cairo_t *out_ct = cairo_create(out);
+    cairo_set_source_surface(out_ct, input1, 0, 0);
+
+    // All of the blend modes are implemented in Cairo as of 1.10.
+    // For a detailed description, see:
+    // http://cairographics.org/operators/
+    switch (_blend_mode) {
+    case BLEND_MULTIPLY:
+        cairo_set_operator(out_ct, CAIRO_OPERATOR_MULTIPLY);
+        break;
+    case BLEND_SCREEN:
+        cairo_set_operator(out_ct, CAIRO_OPERATOR_SCREEN);
+        break;
+    case BLEND_DARKEN:
+        cairo_set_operator(out_ct, CAIRO_OPERATOR_DARKEN);
+        break;
+    case BLEND_LIGHTEN:
+        cairo_set_operator(out_ct, CAIRO_OPERATOR_LIGHTEN);
+        break;
+    case BLEND_NORMAL:
+    default:
+        cairo_set_operator(out_ct, CAIRO_OPERATOR_OVER);
+        break;
     }
 
+    cairo_paint(out_ct);
+    cairo_destroy(out_ct);
+
     slot.set(_output, out);
     cairo_surface_destroy(out);
 }