Fix mask rendering to use luminance-to-alpha

(bzr r9508.1.49)

3 files changed, 48 insertions, 20 deletions

diff --git a/src/display/cairo-templates.h b/src/display/cairo-templates.h
index 78fdff664..3c8a6fea3 100644
--- a/src/display/cairo-templates.h
+++ b/src/display/cairo-templates.h
@@ -24,6 +24,7 @@ static const int OPENMP_THRESHOLD = 2048;
 #include <glib.h>
 #include <math.h>
 #include "display/nr-3dutils.h"
+#include "display/cairo-utils.h"
 
 /**
  * @brief Blend two surfaces using the supplied functor.
@@ -200,6 +201,30 @@ void ink_cairo_surface_filter(cairo_surface_t *in, cairo_surface_t *out, Filter
     int num_threads = prefs->getIntLimited("/options/threading/numthreads", omp_get_num_procs(), 1, 256);
     #endif
 
+    // this is provided just in case, to avoid problems with strict aliasing rules
+    if (in == out) {
+        if (bppin == 4) {
+            #if HAVE_OPENMP
+            #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
+            #endif
+            for (int i = 0; i < limit; ++i) {
+                *(in_data + i) = filter(*(in_data + i));
+            }
+        } else {
+            #if HAVE_OPENMP
+            #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
+            #endif
+            for (int i = 0; i < limit; ++i) {
+                guint8 *in_p = reinterpret_cast<guint8*>(in_data) + i;
+                guint32 in_px = *in_p; in_px <<= 24;
+                guint32 out_px = filter(in_px);
+                *in_p = out_px >> 24;
+            }
+        }
+        cairo_surface_mark_dirty(out);
+        return;
+    }
+
     if (bppin == 4) {
         if (bppout == 4) {
             // bppin == 4, bppout == 4
@@ -661,6 +686,22 @@ pxclamp(gint32 v, gint32 low, gint32 high) {
 #define ASSEMBLE_ARGB32(px,a,r,g,b) \
     guint32 px = (a << 24) | (r << 16) | (g << 8) | b;
 
+// this is also used for masks, so it resides in this header
+struct ColorMatrixLuminanceToAlpha {
+    guint32 operator()(guint32 in) {
+        // original computation in double: r*0.2125 + g*0.7154 + b*0.0721
+        EXTRACT_ARGB32(in, a, r, g, b)
+        // unpremultiply color values
+        if (a != 0) {
+            r = unpremul_alpha(r, a);
+            g = unpremul_alpha(g, a);
+            b = unpremul_alpha(b, a);
+        }
+        guint32 ao = r*54 + g*182 + b*18;
+        return ((ao + 127) / 255) << 24;
+    }
+};
+
 #endif
 /*
   Local Variables:
diff --git a/src/display/nr-arena-item.cpp b/src/display/nr-arena-item.cpp
index 0bdbd12ae..9b76c4ff7 100644
--- a/src/display/nr-arena-item.cpp
+++ b/src/display/nr-arena-item.cpp
@@ -20,6 +20,7 @@
 #include <cairomm/cairomm.h>
 
 #include "display/cairo-utils.h"
+#include "display/cairo-templates.h"
 #include "nr-arena.h"
 #include "nr-arena-item.h"
 #include "gc-core.h"
@@ -433,7 +434,7 @@ nr_arena_item_invoke_render (cairo_t *ct, NRArenaItem *item, NRRectL const *area
 
     // render mask on the intermediate context and store it
     if (item->mask) {
-        maskgroup.push_with_content(CAIRO_CONTENT_ALPHA);
+        maskgroup.push_with_content(CAIRO_CONTENT_COLOR_ALPHA);
         // handle opacity of a masked object by composing it with the mask
         // this uses 1/4 the memory of composing it with full rendering
         if (needs_opacity) {
@@ -449,12 +450,13 @@ nr_arena_item_invoke_render (cairo_t *ct, NRArenaItem *item, NRRectL const *area
             cct.paint_with_alpha(opacity);
         }
         mask = maskgroup.popmm();
+        // convert luminance to alpha
+        cairo_pattern_t *p = mask->cobj();
+        cairo_surface_t *s;
+        cairo_pattern_get_surface(p, &s);
+        ink_cairo_surface_filter(s, s, ColorMatrixLuminanceToAlpha());
     }
 
-    /*if (mask) {
-        drawgroup.push();
-    }*/
-
     // render the object (possibly to the intermediate surface)
     state = NR_ARENA_ITEM_VIRTUAL (item, render) (this_ct, item, this_area, pb, flags);
     if (state & NR_ARENA_ITEM_STATE_INVALID) {
diff --git a/src/display/nr-filter-colormatrix.cpp b/src/display/nr-filter-colormatrix.cpp
index 7ab606182..d77898180 100644
--- a/src/display/nr-filter-colormatrix.cpp
+++ b/src/display/nr-filter-colormatrix.cpp
@@ -135,21 +135,6 @@ private:
     gint32 _v[9];
 };
 
-struct ColorMatrixLuminanceToAlpha {
-    guint32 operator()(guint32 in) {
-        // original computation in double: r*0.2125 + g*0.7154 + b*0.0721
-        EXTRACT_ARGB32(in, a, r, g, b)
-        // unpremultiply color values
-        if (a != 0) {
-            r = unpremul_alpha(r, a);
-            g = unpremul_alpha(g, a);
-            b = unpremul_alpha(b, a);
-        }
-        guint32 ao = r*54 + g*182 + b*18;
-        return ((ao + 127) / 255) << 24;
-    }
-};
-
 void FilterColorMatrix::render_cairo(FilterSlot &slot)
 {
     cairo_surface_t *input = slot.getcairo(_input);