Round expected page size in LocalFrameView::ForceLayoutForPagination

This fixes a regression after https://crrev.com/c/1861035 that caused a web page to require more printed pages due to an inconsistency of rounding directions. We used to implicitly round the rect returned by LayoutView::DocumentRect(), as it used to return a snapped-to-int rect. Now that we've started returning a PhysicalRect, it gets to ResizePageRectsKeepingRatio() as is and gets truncated there. So let's round sizes explicitly before passing to ResizePageRectsKeepingRatio(). BUG=650768, b/142742179 Change-Id: I55a9df6977f464452fc4878517796717761c5b07 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1867126 Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org> Commit-Queue: Andrey Kosyakov <caseq@chromium.org> Cr-Commit-Position: refs/heads/master@{#709153}
marcosholgado · Oct 24, 2019 · 950533a · 950533a
1 parent da9f549
commit 950533a
Show file tree

Hide file tree

Showing 3 changed files with 66 additions and 2 deletions.
diff --git a/headless/lib/headless_web_contents_browsertest.cc b/headless/lib/headless_web_contents_browsertest.cc
@@ -415,6 +415,52 @@ class HeadlessWebContentsPDFStreamTest
 };
 
 HEADLESS_ASYNC_DEVTOOLED_TEST_F(HeadlessWebContentsPDFStreamTest);
+
+class HeadlessWebContentsPDFPageSizeRoundingTest
+    : public HeadlessAsyncDevTooledBrowserTest,
+      public page::Observer {
+ public:
+  void RunDevTooledTest() override {
+    EXPECT_TRUE(embedded_test_server()->Start());
+
+    devtools_client_->GetPage()->AddObserver(this);
+
+    base::RunLoop run_loop(base::RunLoop::Type::kNestableTasksAllowed);
+    devtools_client_->GetPage()->Enable(run_loop.QuitClosure());
+    run_loop.Run();
+
+    devtools_client_->GetPage()->Navigate(
+        embedded_test_server()->GetURL("/red_square.html").spec());
+  }
+
+  void OnLoadEventFired(const page::LoadEventFiredParams&) override {
+    devtools_client_->GetPage()->GetExperimental()->PrintToPDF(
+        page::PrintToPDFParams::Builder()
+            .SetPrintBackground(true)
+            .SetPaperHeight(41)
+            .SetPaperWidth(41)
+            .SetMarginTop(0)
+            .SetMarginBottom(0)
+            .SetMarginLeft(0)
+            .SetMarginRight(0)
+            .Build(),
+        base::BindOnce(
+            &HeadlessWebContentsPDFPageSizeRoundingTest::OnPDFCreated,
+            base::Unretained(this)));
+  }
+
+  void OnPDFCreated(std::unique_ptr<page::PrintToPDFResult> result) {
+    protocol::Binary pdf_data = result->GetData();
+    EXPECT_GT(pdf_data.size(), 0U);
+    auto pdf_span = base::make_span(pdf_data.data(), pdf_data.size());
+    int num_pages;
+    EXPECT_TRUE(chrome_pdf::GetPDFDocInfo(pdf_span, &num_pages, nullptr));
+    EXPECT_THAT(num_pages, testing::Eq(1));
+    FinishAsynchronousTest();
+  }
+};
+
+HEADLESS_ASYNC_DEVTOOLED_TEST_F(HeadlessWebContentsPDFPageSizeRoundingTest);
 #endif
 
 class HeadlessWebContentsSecurityTest

diff --git a/headless/test/data/red_square.html b/headless/test/data/red_square.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<style>
+@page {
+  margin: 0;
+  size: 53.984375px 53.984375px;
+}
+* {
+  margin: 0;
+}
+div {
+  background: red;
+  width: 53.984375px;
+  height: 53.984375px;
+}
+</style>
+<div></div>
diff --git a/third_party/blink/renderer/core/frame/local_frame_view.cc b/third_party/blink/renderer/core/frame/local_frame_view.cc
@@ -2991,10 +2991,12 @@ void LocalFrameView::ForceLayoutForPagination(
                                        ? document_rect.Width()
                                        : document_rect.Height();
     if (doc_logical_width > page_logical_width) {
+      // ResizePageRectsKeepingRatio would truncate the expected page size,
+      // while we want it rounded -- so make sure it's rounded here.
       FloatSize expected_page_size(
-          std::min<float>(document_rect.Width().ToFloat(),
+          std::min<float>(document_rect.Width().Round(),
                           page_size.Width() * maximum_shrink_factor),
-          std::min<float>(document_rect.Height().ToFloat(),
+          std::min<float>(document_rect.Height().Round(),
                           page_size.Height() * maximum_shrink_factor));
       FloatSize max_page_size = frame_->ResizePageRectsKeepingRatio(
           FloatSize(original_page_size.Width(), original_page_size.Height()),