Avoid floating point when calculating the actual column count.

It's too inaccurate. BUG=502407 R=jchaffraix@chromium.org,leviw@chromium.org Review URL: https://codereview.chromium.org/1285273004 git-svn-id: svn://svn.chromium.org/blink/trunk@200848 bbb929c8-8fbe-4397-9dbb-9b2b20218538

Avoid floating point when calculating the actual column count.
It's too inaccurate. BUG=502407 R=jchaffraix@chromium.org,leviw@chromium.org Review URL: https://codereview.chromium.org/1285273004 git-svn-id: svn://svn.chromium.org/blink/trunk@200848 bbb929c8-8fbe-4397-9dbb-9b2b20218538
4a931c53 · mstensho@opera.com · 405c19c0 · 4a931c53 · 4a931c53 · 4a931c53
Commit 4a931c53 authored Aug 19, 2015 by mstensho@opera.com
3 changed files
--- a/third_party/WebKit/LayoutTests/fast/pagination/short-pages-tall-content-expected.txt
+++ b/third_party/WebKit/LayoutTests/fast/pagination/short-pages-tall-content-expected.txt
+PASS if no crash or assertion failure.
+
+
--- a/third_party/WebKit/LayoutTests/fast/pagination/short-pages-tall-content.html
+++ b/third_party/WebKit/LayoutTests/fast/pagination/short-pages-tall-content.html
+<!DOCTYPE html>
+<script>
+    if (window.testRunner)
+        testRunner.dumpAsText();
+</script>
+<p>PASS if no crash or assertion failure.</p>
+<div style="overflow:-webkit-paged-y; height:27.5px;">
+    <div style="height:12345678901234px;"></div>
+</div>
--- a/third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.cpp
+++ b/third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.cpp
@@ -314,7 +314,10 @@ unsigned MultiColumnFragmentainerGroup::actualColumnCount() const
    if (!flowThreadPortionHeight)
        return 1;

-    unsigned count = ceil(flowThreadPortionHeight.toFloat() / m_columnHeight.toFloat());
+    unsigned count = (flowThreadPortionHeight / m_columnHeight).floor();
+    // flowThreadPortionHeight may be saturated, so detect the remainder manually.
+    if (count * m_columnHeight < flowThreadPortionHeight)
+        count++;
    ASSERT(count >= 1);
    return count;
 }