Keep block pagination struts after layout, and store them before any type of break.

third_party/WebKit/Source/core/layout/PaginationTest.cpp

+// Copyright 2015 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 "config.h"
+#include "core/layout/LayoutBlockFlow.h"
+#include "core/layout/LayoutMultiColumnFlowThread.h"
+
+#include "core/layout/LayoutTestHelper.h"
+#include <gtest/gtest.h>
+
+namespace blink {
+
+class PaginationStrutTest : public RenderingTest {
+public:
+    int strutForBox(const char* blockId)
+    {
+        Node* node = document().getElementById(blockId);
+        if (!node || !node->layoutObject() || !node->layoutObject()->isBox())
+            return std::numeric_limits<int>::min();
+        LayoutBox* box = toLayoutBox(node->layoutObject());
+        return box->paginationStrut().toInt();
+    }
+
+    int strutForLine(const char* containerId, int lineIndex)
+    {
+        Node* node = document().getElementById(containerId);
+        if (!node || !node->layoutObject() || !node->layoutObject()->isLayoutBlockFlow())
+            return std::numeric_limits<int>::min();
+        LayoutBlockFlow* block = toLayoutBlockFlow(node->layoutObject());
+        if (block->multiColumnFlowThread())
+            block = block->multiColumnFlowThread();
+        for (RootInlineBox* line = block->firstRootBox(); line; line = line->nextRootBox(), lineIndex--) {
+            if (lineIndex)
+                continue;
+            return line->paginationStrut().toInt();
+        }
+        return std::numeric_limits<int>::min();
+    }
+};
+
+TEST_F(PaginationStrutTest, LineWithStrut)
+{
+    setBodyInnerHTML(
+        "<div id='paged' style='overflow:-webkit-paged-y; height:200px; line-height:150px;'>"
+        "    line1<br>"
+        "    line2<br>"
+        "</div>");
+    EXPECT_EQ(0, strutForLine("paged", 0));
+    EXPECT_EQ(50, strutForLine("paged", 1));
+}
+
+TEST_F(PaginationStrutTest, BlockWithStrut)
+{
+    setBodyInnerHTML(
+        "<div style='overflow:-webkit-paged-y; height:200px; line-height:150px;'>"
+        "    <div id='block1'>line1</div>"
+        "    <div id='block2'>line2</div>"
+        "</div>");
+    EXPECT_EQ(0, strutForBox("block1"));
+    EXPECT_EQ(0, strutForLine("block1", 0));
+    EXPECT_EQ(50, strutForBox("block2"));
+    EXPECT_EQ(0, strutForLine("block2", 0));
+}
+
+TEST_F(PaginationStrutTest, FloatWithStrut)
+{
+    setBodyInnerHTML(
+        "<div style='overflow:-webkit-paged-y; height:200px; line-height:150px;'>"
+        "    <div style='height:120px;'></div>"
+        "    <div id='float' style='float:left;'>line</div>"
+        "</div>");
+    EXPECT_EQ(80, strutForBox("float"));
+    EXPECT_EQ(0, strutForLine("float", 0));
+}
+
+TEST_F(PaginationStrutTest, UnbreakableBlockWithStrut)
+{
+    setBodyInnerHTML(
+        "<style>img { display:block; width:100px; height:150px; outline:4px solid blue; padding:0; border:none; margin:0; }</style>"
+        "<div style='overflow:-webkit-paged-y; height:200px;'>"
+        "    <img id='img1'>"
+        "    <img id='img2'>"
+        "</div>");
+    EXPECT_EQ(0, strutForBox("img1"));
+    EXPECT_EQ(50, strutForBox("img2"));
+}
+
+TEST_F(PaginationStrutTest, BreakBefore)
+{
+    setBodyInnerHTML(
+        "<div style='overflow:-webkit-paged-y; height:400px; line-height:50px;'>"
+        "    <div id='block1'>line1</div>"
+        "    <div id='block2' style='-webkit-column-break-before:always;'>line2</div>"
+        "</div>");
+    EXPECT_EQ(0, strutForBox("block1"));
+    EXPECT_EQ(0, strutForLine("block1", 0));
+    EXPECT_EQ(350, strutForBox("block2"));
+    EXPECT_EQ(0, strutForLine("block2", 0));
+}
+
+TEST_F(PaginationStrutTest, BlockWithStrutPropagatedFromInnerBlock)
+{
+    setBodyInnerHTML(
+        "<div style='overflow:-webkit-paged-y; height:200px; line-height:150px;'>"
+        "    <div id='block1'>line1</div>"
+        "    <div id='block2' style='padding-top:2px;'>"
+        "        <div id='innerBlock' style='padding-top:2px;'>line2</div>"
+        "    </div>"
+        "</div>");
+    EXPECT_EQ(0, strutForBox("block1"));
+    EXPECT_EQ(0, strutForLine("block1", 0));
+    EXPECT_EQ(50, strutForBox("block2"));
+    EXPECT_EQ(0, strutForBox("innerBlock"));
+    EXPECT_EQ(0, strutForLine("innerBlock", 0));
+}
+
+TEST_F(PaginationStrutTest, BlockWithStrutPropagatedFromUnbreakableInnerBlock)
+{
+    setBodyInnerHTML(
+        "<div style='overflow:-webkit-paged-y; height:400px; line-height:150px;'>"
+        "    <div id='block1'>line1</div>"
+        "    <div id='block2' style='padding-top:2px;'>"
+        "        <div id='innerBlock' style='padding-top:2px; -webkit-column-break-inside:avoid;'>"
+        "            line2<br>"
+        "            line3<br>"
+        "        </div>"
+        "    </div>"
+        "</div>");
+    EXPECT_EQ(0, strutForBox("block1"));
+    EXPECT_EQ(0, strutForLine("block1", 0));
+    EXPECT_EQ(250, strutForBox("block2"));
+    EXPECT_EQ(0, strutForBox("innerBlock"));
+    EXPECT_EQ(0, strutForLine("innerBlock", 0));
+    EXPECT_EQ(0, strutForLine("innerBlock", 1));
+}
+
+TEST_F(PaginationStrutTest, InnerBlockWithBreakBefore)
+{
+    setBodyInnerHTML(
+        "<div style='overflow:-webkit-paged-y; height:200px; line-height:150px;'>"
+        "    <div id='block1'>line1</div>"
+        "    <div id='block2' style='padding-top:2px;'>"
+        "        <div id='innerBlock' style='padding-top:2px; -webkit-column-break-before:always;'>line2</div>"
+        "    </div>"
+        "</div>");
+    EXPECT_EQ(0, strutForBox("block1"));
+    EXPECT_EQ(0, strutForLine("block1", 0));
+    EXPECT_EQ(0, strutForBox("block2"));
+    EXPECT_EQ(48, strutForBox("innerBlock"));
+    EXPECT_EQ(0, strutForLine("innerBlock", 0));
+}
+
+} // namespace blink