Avoid unnecessary style recalc for subtree of focused element.

Source/core/css/AffectedByFocusTest.cpp

Index: Source/core/css/AffectedByFocusTest.cpp
diff --git a/Source/core/css/AffectedByFocusTest.cpp b/Source/core/css/AffectedByFocusTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..671a6bed401ddee24c39e835039f9e76f3c1018a
--- /dev/null
+++ b/Source/core/css/AffectedByFocusTest.cpp
@@ -0,0 +1,215 @@
+/*
+ * Copyright (c) 2014, Opera Software ASA. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Opera Software ASA nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "HTMLNames.h"
+#include "core/dom/Element.h"
+#include "core/dom/ElementTraversal.h"
+#include "core/frame/FrameView.h"
+#include "core/html/HTMLDocument.h"
+#include "core/html/HTMLElement.h"
+#include "core/testing/DummyPageHolder.h"
+#include <gtest/gtest.h>
+
+using namespace WebCore;
+using namespace HTMLNames;
+
+namespace {
+
+class AffectedByFocusTest : public ::testing::Test {
+
+protected:
+
+    struct ElementResult {
+        const WebCore::QualifiedName tag;
+        bool affectedBy;
+        bool childrenAffectedBy;
+    };
+
+    virtual void SetUp() OVERRIDE;
+
+    HTMLDocument& document() const { return *m_document; }
+
+    void setHtmlInnerHTML(const char* htmlContent);
+
+    void checkElements(ElementResult expected[], unsigned expectedCount) const;
+
+private:
+    OwnPtr<DummyPageHolder> m_dummyPageHolder;
+
+    HTMLDocument* m_document;
+};
+
+void AffectedByFocusTest::SetUp()
+{
+    m_dummyPageHolder = DummyPageHolder::create(IntSize(800, 600));
+    m_document = toHTMLDocument(&m_dummyPageHolder->document());
+    ASSERT(m_document);
+}
+
+void AffectedByFocusTest::setHtmlInnerHTML(const char* htmlContent)
+{
+    document().documentElement()->setInnerHTML(String::fromUTF8(htmlContent), ASSERT_NO_EXCEPTION);
+    document().view()->updateLayoutAndStyleIfNeededRecursive();
+}
+
+void AffectedByFocusTest::checkElements(ElementResult expected[], unsigned expectedCount) const
+{
+    unsigned i = 0;
+    Element* elm = document().body();
+
+    for (; elm && i < 5; elm = ElementTraversal::next(*elm), ++i) {
+        ASSERT_TRUE(elm->hasTagName(expected[i].tag));
+        ASSERT(elm->renderStyle());
+        ASSERT_EQ(expected[i].affectedBy, elm->renderStyle()->affectedByFocus());
+        ASSERT_EQ(expected[i].childrenAffectedBy, elm->childrenAffectedByFocus());
+    }
+
+    ASSERT(!elm && i == size);
+}
+
+// A global :focus rule in html.css currently causes every single element to be
+// affectedByFocus. Check that all elements in a document with no :focus rules
+// gets the affectedByFocus set on RenderStyle and not childrenAffectedByFocus.
+TEST_F(AffectedByFocusTest, UAUniversalFocusRule)
+{
+    ElementResult expected[] = {
+        { bodyTag, true, false },
+        { divTag, true, false },
+        { divTag, true, false },
+        { divTag, true, false },
+        { spanTag, true, false }
+    };
+
+    setHtmlInnerHTML("<body>"
+        "<div><div></div></div>"
+        "<div><span></span></div>"
+        "</body>");
+
+    checkElements(expected, sizeof(expected) / sizeof(ElementResult));
+}
+
+// ":focus div" will mark ascendants of all divs with childrenAffectedByFocus.
+TEST_F(AffectedByFocusTest, FocusedAscendant)
+{
+    ElementResult expected[] = {
+        { bodyTag, true, true },
+        { divTag, true, true },
+        { divTag, true, false },
+        { divTag, true, false },
+        { spanTag, true, false }
+    };
+
+    setHtmlInnerHTML("<head>"
+        "<style>:focus div { background-color: pink }</style>"
+        "</head>"
+        "<body>"
+        "<div><div></div></div>"
+        "<div><span></span></div>"
+        "</body>");
+
+    checkElements(expected, sizeof(expected) / sizeof(ElementResult));
+}
+
+// "body:focus div" will mark the body element with childrenAffectedByFocus.
+TEST_F(AffectedByFocusTest, FocusedAscendantWithType)
+{
+    ElementResult expected[] = {
+        { bodyTag, true, true },
+        { divTag, true, false },
+        { divTag, true, false },
+        { divTag, true, false },
+        { spanTag, true, false }
+    };
+
+    setHtmlInnerHTML("<head>"
+        "<style>body:focus div { background-color: pink }</style>"
+        "</head>"
+        "<body>"
+        "<div><div></div></div>"
+        "<div><span></span></div>"
+        "</body>");
+
+    checkElements(expected, sizeof(expected) / sizeof(ElementResult));
+}
+
+// ":not(body):focus div" should not mark the body element with childrenAffectedByFocus.
+// Note that currently ":focus:not(body)" does not do the same. Then the :focus is
+// checked and the childrenAffectedByFocus flag set before the negated type selector
+// is found.
+TEST_F(AffectedByFocusTest, FocusedAscendantWithNegatedType)
+{
+    ElementResult expected[] = {
+        { bodyTag, true, false },
+        { divTag, true, true },
+        { divTag, true, false },
+        { divTag, true, false },
+        { spanTag, true, false }
+    };
+
+    setHtmlInnerHTML("<head>"
+        "<style>:not(body):focus div { background-color: pink }</style>"
+        "</head>"
+        "<body>"
+        "<div><div></div></div>"
+        "<div><span></span></div>"
+        "</body>");
+
+    checkElements(expected, sizeof(expected) / sizeof(ElementResult));
+}
+
+// Checking current behavior for ":focus + div", but this is a BUG or at best
+// sub-optimal. The focused element will also in this case get childrenAffectedByFocus
+// even if it's really a sibling. Effectively, the whole sub-tree of the focused
+// element will have styles recalculated even though none of the children are
+// affected. There are other mechanisms that makes sure the sibling also gets its
+// styles recalculated.
+TEST_F(AffectedByFocusTest, FocusedSibling)
+{
+    ElementResult expected[] = {
+        { bodyTag, true, false },
+        { divTag, true, true },
+        { spanTag, true, false },
+        { divTag, true, false }
+    };
+
+    setHtmlInnerHTML("<head>"
+        "<style>:focus + div { background-color: pink }</style>"
+        "</head>"
+        "<body>"
+        "<div>"
+        "  <span></span>"
+        "</div>"
+        "<div></div>"
+        "</body>");
+
+    checkElements(expected, sizeof(expected) / sizeof(ElementResult));
+}
+
+} // namespace