Add PDF compositor service

components/printing/service/pdf_compositor_impl.cc

Index: components/printing/service/pdf_compositor_impl.cc
diff --git a/components/printing/service/pdf_compositor_impl.cc b/components/printing/service/pdf_compositor_impl.cc
new file mode 100644
index 0000000000000000000000000000000000000000..11908a36bc48c59b8f08fe2ebeeb08600fb063f0
--- /dev/null
+++ b/components/printing/service/pdf_compositor_impl.cc
@@ -0,0 +1,127 @@
+// Copyright 2017 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 "components/printing/service/pdf_compositor_impl.h"
+
+#include <utility>
+#include <vector>
+
+#include "base/logging.h"
+#include "base/memory/shared_memory.h"
+#include "base/memory/shared_memory_handle.h"
+#include "base/time/time.h"
+#include "mojo/public/cpp/system/platform_handle.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "third_party/skia/include/core/SkDocument.h"
+#include "third_party/skia/include/core/SkSize.h"
+#include "third_party/skia/include/core/SkStream.h"
+#include "third_party/skia/include/core/SkTime.h"
+#include "third_party/skia/include/core/SkTypes.h"
+#include "third_party/skia/src/utils/SkMultiPictureDocument.h"

[hal.canary, 2017/04/24 19:13:17]

FYI: I am trying to get this API blessed: https://review.skia.org/11138

[Wei Li, 2017/04/27 05:34:16]

Acknowledged.

+
+namespace {
+
+SkTime::DateTime TimeToSkTime(base::Time time) {

[Lei Zhang, 2017/04/22 00:12:26]

Do we want to reuse the existing code in printing/pdf_metafile_skia.cc somehow?

[Wei Li, 2017/04/27 05:34:16]

Done.

+  base::Time::Exploded exploded;
+  time.UTCExplode(&exploded);
+  SkTime::DateTime skdate;
+  skdate.fTimeZoneMinutes = 0;
+  skdate.fYear = exploded.year;
+  skdate.fMonth = exploded.month;
+  skdate.fDayOfWeek = exploded.day_of_week;
+  skdate.fDay = exploded.day_of_month;
+  skdate.fHour = exploded.hour;
+  skdate.fMinute = exploded.minute;
+  skdate.fSecond = exploded.second;
+  return skdate;
+}
+
+sk_sp<SkDocument> MakePdfDocument(const std::string& creator,
+                                  SkWStream* wStream) {
+  SkDocument::PDFMetadata metadata;
+  SkTime::DateTime now = TimeToSkTime(base::Time::Now());
+  metadata.fCreation.fEnabled = true;
+  metadata.fCreation.fDateTime = now;
+  metadata.fModified.fEnabled = true;
+  metadata.fModified.fDateTime = now;
+  metadata.fCreator = creator.empty()
+                          ? SkString("Chromium")
+                          : SkString(creator.c_str(), creator.size());
+  return SkDocument::MakePDF(wStream, SK_ScalarDefaultRasterDPI, metadata,
+                             nullptr, false);
+}
+
+}  // namespace
+
+namespace printing {
+
+PdfCompositorImpl::PdfCompositorImpl(
+    const std::string& creator,
+    std::unique_ptr<service_manager::ServiceContextRef> service_ref)
+    : service_ref_(std::move(service_ref)), creator_(creator) {}
+
+PdfCompositorImpl::~PdfCompositorImpl() = default;
+
+void PdfCompositorImpl::CompositePdf(
+    mojo::ScopedSharedBufferHandle sk_handle,
+    const mojom::PdfCompositor::CompositePdfCallback& callback) {
+  DCHECK(sk_handle.is_valid());
+
+  base::SharedMemoryHandle memory_handle;
+  size_t memory_size = 0;
+  bool read_only_flag = false;
+
+  const MojoResult result = mojo::UnwrapSharedMemoryHandle(
+      std::move(sk_handle), &memory_handle, &memory_size, &read_only_flag);
+  DCHECK_EQ(MOJO_RESULT_OK, result);
+  DCHECK_GT(memory_size, 0u);
+
+  std::unique_ptr<base::SharedMemory> shm =
+      base::MakeUnique<base::SharedMemory>(memory_handle, true);
+  if (!shm->Map(memory_size)) {
+    DLOG(ERROR) << "OnBufferCreated: Map failed.";

[Lei Zhang, 2017/04/22 00:12:26]

Do we need to run |callback| here and anywhere else below where we fail?

[Wei Li, 2017/04/27 05:34:16]

Done.

+    return;
+  }
+
+  if (shm->mapped_size() == 0) {
+    callback.Run(mojo::ScopedSharedBufferHandle());
+    return;
+  }
+
+  SkMemoryStream stream(shm->memory(), memory_size);
+  int page_count = SkMultiPictureDocumentReadPageCount(&stream);
+  if (!page_count) {
+    DLOG(ERROR) << "No page is read.";
+    return;
+  }
+
+  std::vector<SkDocumentPage> pages(page_count);
+  if (!SkMultiPictureDocumentRead(&stream, pages.data(), page_count)) {
+    DLOG(ERROR) << "Page read error.";
+    return;
+  }
+
+  SkDynamicMemoryWStream wstream;
+  sk_sp<SkDocument> doc =
+      MakePdfDocument(creator_.size() ? creator_ : "Chromium", &wstream);
+
+  for (const auto& page : pages) {
+    SkCanvas* canvas = doc->beginPage(page.fSize.width(), page.fSize.height());
+    canvas->drawPicture(page.fPicture);
+    doc->endPage();
+  }
+  doc->close();
+
+  mojo::ScopedSharedBufferHandle buffer =
+      mojo::SharedBufferHandle::Create(wstream.bytesWritten());
+  DCHECK(buffer.is_valid());
+
+  mojo::ScopedSharedBufferMapping mapping = buffer->Map(wstream.bytesWritten());
+  DCHECK(mapping);
+  wstream.copyTo(mapping.get());

[hal.canary, 2017/04/24 19:13:17]

`wstream.copyToAndReset(mapping.get());`
is the new way of doing this:  it frees memory as it goes and may save physical
memory use.

[Wei Li, 2017/04/27 05:34:16]

Done.

+
+  callback.Run(std::move(buffer));
+}
+
+}  // namespace printing