Handle nested position:sticky elements correctly (compositor)

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMappingTest.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/compositing/CompositedLayerMapping.h"
 
 #include "core/frame/FrameView.h"
 #include "core/layout/LayoutBoxModelObject.h"
 #include "core/layout/LayoutTestHelper.h"
 #include "core/layout/api/LayoutViewItem.h"
@@ skipping 1478 matching lines @@
           ->compositedLayerMapping();
 
   // Box offsets the content by the combination of the shadow offset and blur
   // radius plus an additional pixel of anti-aliasing.
   ASSERT_TRUE(sticky1);
   WebLayerStickyPositionConstraint constraint1 =
       sticky1->mainGraphicsLayer()
           ->contentLayer()
           ->layer()
           ->stickyPositionConstraint();
-  EXPECT_EQ(IntPoint(-11, -11),
-            IntPoint(constraint1.parentRelativeStickyBoxOffset));
+  EXPECT_EQ(FloatPoint(-11, -11),
+            FloatPoint(constraint1.parentRelativeStickyBoxOffset));
 
   // Since the nested div will be squashed into the same composited layer the
   // sticky element is offset by the nested element's offset.
   ASSERT_TRUE(sticky2);
   WebLayerStickyPositionConstraint constraint2 =
       sticky2->mainGraphicsLayer()
           ->contentLayer()
           ->layer()
           ->stickyPositionConstraint();
-  EXPECT_EQ(IntPoint(-50, -50),
-            IntPoint(constraint2.parentRelativeStickyBoxOffset));
+  EXPECT_EQ(FloatPoint(-50, -50),
+            FloatPoint(constraint2.parentRelativeStickyBoxOffset));
 }
 
 TEST_P(CompositedLayerMappingTest, StickyPositionTableCellContentOffset) {
   setBodyInnerHTML(
       "<style>body {height: 2000px; width: 2000px;} "
       "td, th { height: 50px; width: 50px; } "
       "table {border: none; }"
       "#scroller { overflow: auto; will-change: transform; height: 50px; }"
       "#sticky { position: sticky; left: 0; will-change: transform; }"
       "</style>"
       "<div id='scroller'><table cellspacing='0' cellpadding='0'>"
       "    <thead><tr><td></td></tr></thead>"
       "    <tr><td id='sticky'></td></tr>"
       "</table></div>");
   document().view()->updateLifecycleToCompositingCleanPlusScrolling();
 
   CompositedLayerMapping* sticky =
       toLayoutBlock(getLayoutObjectByElementId("sticky"))
           ->layer()
           ->compositedLayerMapping();
 
   ASSERT_TRUE(sticky);
   WebLayerStickyPositionConstraint constraint =
       sticky->mainGraphicsLayer()
           ->contentLayer()
           ->layer()
           ->stickyPositionConstraint();
-  EXPECT_EQ(IntPoint(0, 50),
-            IntPoint(constraint.parentRelativeStickyBoxOffset));
+  EXPECT_EQ(FloatPoint(0, 50),
+            FloatPoint(constraint.parentRelativeStickyBoxOffset));
 }
 
 TEST_P(CompositedLayerMappingTest, StickyPositionEnclosingLayersContentOffset) {
   setBodyInnerHTML(
       "<style>.composited { will-change: transform; }"
       "#scroller { overflow: auto; height: 200px; width: 200px; }"
       ".container { height: 500px; }"
       ".innerPadding { height: 10px; }"
       "#sticky { position: sticky; top: 25px; height: 50px; }</style>"
       "<div id='scroller' class='composited'>"
       "<div class='composited container'>"
       "  <div class='composited container'>"
       "    <div class='innerPadding'></div>"
       "    <div id='sticky' class='composited'></div>"
       "  </div></div></div>");
 
   PaintLayer* stickyLayer =
       toLayoutBox(getLayoutObjectByElementId("sticky"))->layer();
   CompositedLayerMapping* stickyMapping = stickyLayer->compositedLayerMapping();
   ASSERT_TRUE(stickyMapping);
 
   WebLayerStickyPositionConstraint constraint =
       stickyMapping->mainGraphicsLayer()
           ->contentLayer()
           ->layer()
           ->stickyPositionConstraint();
-  EXPECT_EQ(IntPoint(0, 10),
-            IntPoint(constraint.parentRelativeStickyBoxOffset));
+  EXPECT_EQ(FloatPoint(0, 10),
+            FloatPoint(constraint.parentRelativeStickyBoxOffset));
 
   // Now scroll the page - this should not affect the parent-relative offset.
   LayoutBoxModelObject* scroller =
       toLayoutBoxModelObject(getLayoutObjectByElementId("scroller"));
   PaintLayerScrollableArea* scrollableArea = scroller->getScrollableArea();
   scrollableArea->scrollToAbsolutePosition(
       FloatPoint(scrollableArea->scrollPosition().x(), 100));
   ASSERT_EQ(100.0, scrollableArea->scrollPosition().y());
 
   stickyLayer->setNeedsCompositingInputsUpdate();
   EXPECT_TRUE(stickyLayer->needsCompositingInputsUpdate());
   document().view()->updateLifecycleToCompositingCleanPlusScrolling();
   EXPECT_FALSE(stickyLayer->needsCompositingInputsUpdate());
 
   constraint = stickyMapping->mainGraphicsLayer()
                    ->contentLayer()
                    ->layer()
                    ->stickyPositionConstraint();
-  EXPECT_EQ(IntPoint(0, 10),
-            IntPoint(constraint.parentRelativeStickyBoxOffset));
+  EXPECT_EQ(FloatPoint(0, 10),
+            FloatPoint(constraint.parentRelativeStickyBoxOffset));
+}
+
+TEST_P(CompositedLayerMappingTest, StickyPositionNestedStickyContentOffset) {
+  setBodyInnerHTML(
+      "<style>.composited { will-change: transform; }"
+      "#scroller { overflow: auto; height: 200px; width: 200px; }"
+      ".container { height: 500px; }"
+      "#outerSticky { position: sticky; top: 0; height: 100px; }"
+      "#middleSticky { position: sticky; top: 10px; height: 50px; }"
+      "#innerSticky { position: sticky; top: 25px; height: 25px; }</style>"
+      "<div id='scroller' class='composited'>"
+      "  <div style='height: 50px'></div>"
+      "  <div class='composited container'>"
+      "    <div style='height: 10px;'></div>"
+      "    <div id='outerSticky' class='composited'>"
+      "      <div id='middleSticky' class='composited'>"
+      "        <div style='height: 5px;'></div>"
+      "        <div id='innerSticky' class='composited'></div>"
+      "      </div>"
+      "    </div>"
+      "  </div>"
+      "</div>");
+
+  PaintLayer* outerSticky =
+      toLayoutBox(getLayoutObjectByElementId("outerSticky"))->layer();
+  PaintLayer* middleSticky =
+      toLayoutBox(getLayoutObjectByElementId("middleSticky"))->layer();
+  PaintLayer* innerSticky =
+      toLayoutBox(getLayoutObjectByElementId("innerSticky"))->layer();
+
+  WebLayerStickyPositionConstraint outerStickyConstraint =
+      outerSticky->compositedLayerMapping()
+          ->mainGraphicsLayer()
+          ->contentLayer()
+          ->layer()
+          ->stickyPositionConstraint();
+  WebLayerStickyPositionConstraint middleStickyConstraint =
+      middleSticky->compositedLayerMapping()
+          ->mainGraphicsLayer()
+          ->contentLayer()
+          ->layer()
+          ->stickyPositionConstraint();
+  WebLayerStickyPositionConstraint innerStickyConstraint =
+      innerSticky->compositedLayerMapping()
+          ->mainGraphicsLayer()
+          ->contentLayer()
+          ->layer()
+          ->stickyPositionConstraint();
+
+  EXPECT_EQ(FloatPoint(0, 10),
+            FloatPoint(outerStickyConstraint.parentRelativeStickyBoxOffset));
+  EXPECT_EQ(FloatPoint(0, 0),
+            FloatPoint(middleStickyConstraint.parentRelativeStickyBoxOffset));
+  EXPECT_EQ(FloatPoint(0, 5),
+            FloatPoint(innerStickyConstraint.parentRelativeStickyBoxOffset));
+
+  // Scroll the content to engage the sticky elements.
+  LayoutBoxModelObject* scroller =
+      toLayoutBoxModelObject(getLayoutObjectByElementId("scroller"));
+  PaintLayerScrollableArea* scrollableArea = scroller->getScrollableArea();
+  scrollableArea->scrollToAbsolutePosition(
+      FloatPoint(scrollableArea->scrollPosition().x(), 110));
+  ASSERT_EQ(110.0, scrollableArea->scrollPosition().y());
+
+  outerSticky->setNeedsCompositingInputsUpdate();
+  middleSticky->setNeedsCompositingInputsUpdate();
+  innerSticky->setNeedsCompositingInputsUpdate();
+
+  document().view()->updateLifecycleToCompositingCleanPlusScrolling();
+
+  outerStickyConstraint = outerSticky->compositedLayerMapping()
+                              ->mainGraphicsLayer()
+                              ->contentLayer()
+                              ->layer()
+                              ->stickyPositionConstraint();
+  middleStickyConstraint = middleSticky->compositedLayerMapping()
+                               ->mainGraphicsLayer()
+                               ->contentLayer()
+                               ->layer()
+                               ->stickyPositionConstraint();
+  innerStickyConstraint = innerSticky->compositedLayerMapping()
+                              ->mainGraphicsLayer()
+                              ->contentLayer()
+                              ->layer()
+                              ->stickyPositionConstraint();
+
+  // After scrolling and despite ancestor sticky changes, the offset relative to
+  // the parent layer should remain constant.
+  EXPECT_EQ(FloatPoint(0, 10),
+            FloatPoint(outerStickyConstraint.parentRelativeStickyBoxOffset));
+  EXPECT_EQ(FloatPoint(0, 0),
+            FloatPoint(middleStickyConstraint.parentRelativeStickyBoxOffset));
+  EXPECT_EQ(FloatPoint(0, 5),
+            FloatPoint(innerStickyConstraint.parentRelativeStickyBoxOffset));
 }
 
 }  // namespace blink