Add support for converting cc::FilterOperations into an SkImageFilter

cc/output/filter_operation.cc

Index: cc/output/filter_operation.cc
diff --git a/cc/output/filter_operation.cc b/cc/output/filter_operation.cc
index e8a08804632c12c9ba550d6abfcb771464352b66..73e315e96704de9093ef47d52c6c9e9bcea82aaa 100644
--- a/cc/output/filter_operation.cc
+++ b/cc/output/filter_operation.cc
@@ -21,6 +21,8 @@ bool FilterOperation::operator==(const FilterOperation& other) const {
            drop_shadow_offset_ == other.drop_shadow_offset_ &&
            drop_shadow_color_ == other.drop_shadow_color_;
   }
+  if (type_ == REFERENCE)
+    return image_filter_.get() == other.image_filter_.get();
   return amount_ == other.amount_;
 }
 
@@ -32,6 +34,7 @@ FilterOperation::FilterOperation(FilterType type, float amount)
       zoom_inset_(0) {
   DCHECK_NE(type_, DROP_SHADOW);
   DCHECK_NE(type_, COLOR_MATRIX);
+  DCHECK_NE(type_, REFERENCE);
   memset(matrix_, 0, sizeof(matrix_));
 }
 
@@ -68,6 +71,33 @@ FilterOperation::FilterOperation(FilterType type, float amount, int inset)
   memset(matrix_, 0, sizeof(matrix_));
 }
 
+FilterOperation::FilterOperation(
+    FilterType type,
+    const skia::RefPtr<SkImageFilter>& image_filter)
+    : type_(type),
+      amount_(0),
+      drop_shadow_offset_(0, 0),
+      drop_shadow_color_(0),
+      image_filter_(image_filter),
+      zoom_inset_(0) {
+  DCHECK_EQ(type_, REFERENCE);
+  DCHECK(image_filter.get());
+  memset(matrix_, 0, sizeof(matrix_));
+}
+
+FilterOperation::FilterOperation(const FilterOperation& other)
+    : type_(other.type_),
+      amount_(other.amount_),
+      drop_shadow_offset_(other.drop_shadow_offset_),
+      drop_shadow_color_(other.drop_shadow_color_),
+      image_filter_(other.image_filter_),
+      zoom_inset_(other.zoom_inset_) {
+  memcpy(matrix_, other.matrix_, sizeof(matrix_));
+}
+
+FilterOperation::~FilterOperation() {
+}
+
 // TODO(ajuma): Define a version of ui::Tween::ValueBetween for floats, and use
 // that instead.
 static float BlendFloats(float from, float to, double progress) {
@@ -147,6 +177,9 @@ static FilterOperation CreateNoOpFilter(FilterOperation::FilterType type) {
       return FilterOperation::CreateZoomFilter(1.f, 0);
     case FilterOperation::SATURATING_BRIGHTNESS:
       return FilterOperation::CreateSaturatingBrightnessFilter(0.f);
+    case FilterOperation::REFERENCE:
+      NOTREACHED();

[danakj, 2013/09/09 22:04:50]

Can't create an image filter that does nothing?

[ajuma, 2013/09/10 21:17:58]

Done.

+      return FilterOperation::CreateEmptyFilter();
   }
   NOTREACHED();
   return FilterOperation::CreateEmptyFilter();
@@ -172,6 +205,7 @@ static float ClampAmountForFilterType(float amount,
     case FilterOperation::SATURATING_BRIGHTNESS:
       return amount;
     case FilterOperation::COLOR_MATRIX:
+    case FilterOperation::REFERENCE:
       NOTREACHED();
       return amount;
   }
@@ -188,6 +222,14 @@ FilterOperation FilterOperation::Blend(const FilterOperation* from,
   if (!from && !to)
     return blended_filter;
 
+  if ((from && from->type() == FilterOperation::REFERENCE) ||

[danakj, 2013/09/09 22:04:50]

If the two types differ, you might get the |to| or |from| operation. But line
236 says you shouldn't. It seems like implementing CreateNoOpFilter would help
keep this function more clear and consistent, allowing you to move this stuff
down further after the earlyouts.

[ajuma, 2013/09/10 21:17:58]

Done.

+      (to && to->type() == FilterOperation::REFERENCE)) {
+    if (progress > 0.5)
+      return to ? *to : blended_filter;
+    else
+      return from ? *from : blended_filter;
+  }
+
   const FilterOperation& from_op = from ? *from : CreateNoOpFilter(to->type());
   const FilterOperation& to_op = to ? *to : CreateNoOpFilter(from->type());
 
@@ -250,6 +292,8 @@ scoped_ptr<base::Value> FilterOperation::AsValue() const {
       value->SetDouble("amount", amount_);
       value->SetDouble("inset", zoom_inset_);
       break;
+    case FilterOperation::REFERENCE:
+      break;

[danakj, 2013/09/09 22:04:50]

Is there any data about the filter you can give here? How about countInputs()?
And canFilterImageGPU()?

[ajuma, 2013/09/10 21:17:58]

Done.

   }
   return value.PassAs<base::Value>();
 }