Consider 'order' when updating feConvolveMatrix 'target*'

third_party/WebKit/Source/core/svg/SVGFEConvolveMatrixElement.cpp

Index: third_party/WebKit/Source/core/svg/SVGFEConvolveMatrixElement.cpp
diff --git a/third_party/WebKit/Source/core/svg/SVGFEConvolveMatrixElement.cpp b/third_party/WebKit/Source/core/svg/SVGFEConvolveMatrixElement.cpp
index 550d3ddc20c4c39e7e4d4a699c8e7aa0f46daaaa..1cf148867c35219cd2f5fb64fface45d92896f43 100644
--- a/third_party/WebKit/Source/core/svg/SVGFEConvolveMatrixElement.cpp
+++ b/third_party/WebKit/Source/core/svg/SVGFEConvolveMatrixElement.cpp
@@ -118,6 +118,26 @@ DEFINE_TRACE(SVGFEConvolveMatrixElement)
 
 DEFINE_NODE_FACTORY(SVGFEConvolveMatrixElement)
 
+IntSize SVGFEConvolveMatrixElement::matrixOrder() const
+{
+    if (!m_order->isSpecified())
+        return IntSize(3, 3);
+    return IntSize(orderX()->currentValue()->value(), orderY()->currentValue()->value());
+}
+
+IntPoint SVGFEConvolveMatrixElement::targetPoint() const
+{
+    IntSize order = matrixOrder();
+    IntPoint target(m_targetX->currentValue()->value(), m_targetY->currentValue()->value());
+    // The spec says the default value is: targetX = floor ( orderX / 2 ))
+    if (!m_targetX->isSpecified())
+        target.setX(order.width() / 2);

[f(malita), 2016/07/05 15:20:12]

I was worried here about negative half-value treatment (both int coercion and
trunc vs. floor discrepancies).

But, reading the spec, 'order' cannot be negative.  Just to double-check: is the
parser enforcing order.x/y > 0 or do we need to clamp in matrixOrder?

[fs, 2016/07/05 15:29:43]

We verify all the parameters down in FEConvolveMatrix::parametersValid (and
produce transparent black if anything is "out of spec").

+    // The spec says the default value is: targetY = floor ( orderY / 2 ))
+    if (!m_targetY->isSpecified())
+        target.setY(order.height() / 2);
+    return target;
+}
+
 bool SVGFEConvolveMatrixElement::setFilterEffectAttribute(FilterEffect* effect, const QualifiedName& attrName)
 {
     FEConvolveMatrix* convolveMatrix = static_cast<FEConvolveMatrix*>(effect);
@@ -127,10 +147,8 @@ bool SVGFEConvolveMatrixElement::setFilterEffectAttribute(FilterEffect* effect,
         return convolveMatrix->setDivisor(m_divisor->currentValue()->value());
     if (attrName == SVGNames::biasAttr)
         return convolveMatrix->setBias(m_bias->currentValue()->value());
-    if (attrName == SVGNames::targetXAttr)
-        return convolveMatrix->setTargetOffset(IntPoint(m_targetX->currentValue()->value(), m_targetY->currentValue()->value()));
-    if (attrName == SVGNames::targetYAttr)
-        return convolveMatrix->setTargetOffset(IntPoint(m_targetX->currentValue()->value(), m_targetY->currentValue()->value()));
+    if (attrName == SVGNames::targetXAttr || attrName == SVGNames::targetYAttr)
+        return convolveMatrix->setTargetOffset(targetPoint());
     if (attrName == SVGNames::preserveAlphaAttr)
         return convolveMatrix->setPreserveAlpha(m_preserveAlpha->currentValue()->value());
 
@@ -167,23 +185,6 @@ FilterEffect* SVGFEConvolveMatrixElement::build(SVGFilterBuilder* filterBuilder,
     FilterEffect* input1 = filterBuilder->getEffectById(AtomicString(m_in1->currentValue()->value()));
     ASSERT(input1);
 
-    int orderXValue = orderX()->currentValue()->value();
-    int orderYValue = orderY()->currentValue()->value();
-    if (!m_order->isSpecified()) {
-        orderXValue = 3;
-        orderYValue = 3;
-    }
-
-    int targetXValue = m_targetX->currentValue()->value();
-    // The spec says the default value is: targetX = floor ( orderX / 2 ))
-    if (!m_targetX->isSpecified())
-        targetXValue = static_cast<int>(floorf(orderXValue / 2));
-
-    int targetYValue = m_targetY->currentValue()->value();
-    // The spec says the default value is: targetY = floor ( orderY / 2 ))
-    if (!m_targetY->isSpecified())
-        targetYValue = static_cast<int>(floorf(orderYValue / 2));
-
     float divisorValue = m_divisor->currentValue()->value();
     if (!m_divisor->isSpecified()) {
         SVGNumberList* kernelMatrix = m_kernelMatrix->currentValue();
@@ -195,8 +196,8 @@ FilterEffect* SVGFEConvolveMatrixElement::build(SVGFilterBuilder* filterBuilder,
     }
 
     FilterEffect* effect = FEConvolveMatrix::create(filter,
-        IntSize(orderXValue, orderYValue), divisorValue,
-        m_bias->currentValue()->value(), IntPoint(targetXValue, targetYValue), m_edgeMode->currentValue()->enumValue(),
+        matrixOrder(), divisorValue,
+        m_bias->currentValue()->value(), targetPoint(), m_edgeMode->currentValue()->enumValue(),
         m_preserveAlpha->currentValue()->value(), m_kernelMatrix->currentValue()->toFloatVector());
     effect->inputEffects().append(input1);
     return effect;