Update the UI examples.

examples/ui/pdf_viewer/pdf_viewer.cc

Index: examples/ui/pdf_viewer/pdf_viewer.cc
diff --git a/examples/ui/pdf_viewer/pdf_viewer.cc b/examples/ui/pdf_viewer/pdf_viewer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6e5c0699cbc26652fbd0d1d0b47ce28563ae425d
--- /dev/null
+++ b/examples/ui/pdf_viewer/pdf_viewer.cc
@@ -0,0 +1,297 @@
+// 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 <memory>
+#include <string>
+
+#include "base/bind.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "mojo/application/application_runner_chromium.h"
+#include "mojo/data_pipe_utils/data_pipe_utils.h"
+#include "mojo/public/c/system/main.h"
+#include "mojo/ui/content_viewer_app.h"
+#include "mojo/ui/ganesh_view.h"
+#include "mojo/ui/input_handler.h"
+#include "third_party/pdfium/fpdfsdk/include/fpdf_ext.h"
+#include "third_party/pdfium/fpdfsdk/include/fpdfview.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "third_party/skia/include/core/SkData.h"
+#include "third_party/skia/include/core/SkImage.h"
+#include "third_party/skia/include/core/SkImageInfo.h"
+#include "third_party/skia/include/core/SkSurface.h"
+#include "v8/include/v8.h"
+
+namespace examples {
+
+constexpr uint32_t kContentImageResourceId = 1;
+constexpr uint32_t kRootNodeId = mojo::gfx::composition::kSceneRootNodeId;
+
+class PDFLibrary;
+
+class PDFDocument {
+ public:
+  PDFDocument(const std::shared_ptr<PDFLibrary>& pdf_library,
+              FPDF_DOCUMENT doc,
+              const std::string& data)
+      : pdf_library_(pdf_library),
+        doc_(doc),
+        data_(data),
+        page_count_(FPDF_GetPageCount(doc_)) {}
+
+  ~PDFDocument() { FPDF_CloseDocument(doc_); }
+
+  uint32_t page_count() { return page_count_; }
+
+  skia::RefPtr<SkImage> DrawPage(int page_index) {
+    FPDF_PAGE page = FPDF_LoadPage(doc_, page_index);
+    int width = static_cast<int>(FPDF_GetPageWidth(page));
+    int height = static_cast<int>(FPDF_GetPageHeight(page));
+    int stride = width * 4;
+
+    skia::RefPtr<SkData> pixels =
+        skia::AdoptRef(SkData::NewUninitialized(stride * height));
+    DCHECK(pixels);
+
+    FPDF_BITMAP bitmap = FPDFBitmap_CreateEx(width, height, FPDFBitmap_BGRA,
+                                             pixels->writable_data(), stride);
+    FPDFBitmap_FillRect(bitmap, 0, 0, width, height, 0xFFFFFFFF);
+    FPDF_RenderPageBitmap(bitmap, page, 0, 0, width, height, 0, 0);
+    FPDFBitmap_Destroy(bitmap);
+
+    FPDF_ClosePage(page);
+
+    SkImageInfo info = SkImageInfo::Make(width, height, kBGRA_8888_SkColorType,
+                                         kOpaque_SkAlphaType);
+    return skia::AdoptRef(SkImage::NewRasterData(info, pixels.get(), stride));
+  }
+
+ private:
+  std::shared_ptr<PDFLibrary> pdf_library_;
+  FPDF_DOCUMENT doc_;
+  std::string data_;
+  uint32_t page_count_;
+};
+
+class PDFLibrary : public std::enable_shared_from_this<PDFLibrary> {
+ public:
+  PDFLibrary() {
+    v8::V8::InitializeICU();
+    FPDF_InitLibrary();
+  }
+
+  ~PDFLibrary() { FPDF_DestroyLibrary(); }
+
+  std::shared_ptr<PDFDocument> Decode(mojo::URLResponsePtr response) {
+    std::string data;
+    mojo::common::BlockingCopyToString(response->body.Pass(), &data);
+    if (data.length() >= static_cast<size_t>(std::numeric_limits<int>::max()))
+      return nullptr;
+
+    FPDF_DOCUMENT doc = FPDF_LoadMemDocument(
+        data.data(), static_cast<int>(data.length()), nullptr);
+    if (!doc)
+      return nullptr;
+
+    return std::make_shared<PDFDocument>(shared_from_this(), doc, data);
+  }
+};
+
+class PDFDocumentView : public mojo::ui::GaneshView,
+                        public mojo::ui::InputListener {
+ public:
+  PDFDocumentView(
+      mojo::ApplicationImpl* app_impl,
+      const std::shared_ptr<PDFDocument>& pdf_document,
+      const mojo::ui::ViewProvider::CreateViewCallback& create_view_callback)
+      : GaneshView(app_impl, "PDFDocumentViewer", create_view_callback),
+        pdf_document_(pdf_document),
+        input_handler_(view_service_provider(), this) {
+    DCHECK(pdf_document_);
+  }
+
+  ~PDFDocumentView() override {}
+
+ private:
+  // |View|:
+  void OnLayout(mojo::ui::ViewLayoutParamsPtr layout_params,
+                mojo::Array<uint32_t> children_needing_layout,
+                const OnLayoutCallback& callback) override {
+    size_.width = layout_params->constraints->max_width;
+    size_.height = layout_params->constraints->max_height;
+
+    auto info = mojo::ui::ViewLayoutResult::New();
+    info->size = size_.Clone();
+    callback.Run(info.Pass());
+
+    UpdateScene();

[abarth, 2016/01/10 23:09:31]

I'm surprised there's no token that I get from layout_params that I pass through
when publishing my scene.  I was expecting to get some sort of version number or
something so that my parent and I can coordinate resizes.  Maybe I forgot how
that works.

[jeffbrown, 2016/01/26 08:14:17]

I'll be redoing layout once this gets checked in.  And as you expected, there
will be a version passed in somewhere.

+  }
+
+  // |InputListener|:
+  void OnEvent(mojo::EventPtr event, const OnEventCallback& callback) override {
+    if (event->key_data && (event->action != mojo::EventType::KEY_PRESSED ||
+                            event->key_data->is_char)) {
+      callback.Run(false);
+      return;
+    }
+
+    if ((event->key_data &&
+         event->key_data->windows_key_code == mojo::KeyboardCode::DOWN) ||
+        (event->pointer_data && event->pointer_data->vertical_wheel < 0)) {
+      GotoNextPage();
+      callback.Run(true);
+      return;
+    }
+
+    if ((event->key_data &&
+         event->key_data->windows_key_code == mojo::KeyboardCode::UP) ||
+        (event->pointer_data && event->pointer_data->vertical_wheel > 0)) {
+      GotoPreviousPage();
+      callback.Run(true);
+      return;
+    }
+
+    callback.Run(false);
+  }
+
+  void UpdateScene() {
+    mojo::Rect bounds;
+    bounds.width = size_.width;
+    bounds.height = size_.height;
+
+    auto update = mojo::gfx::composition::SceneUpdate::New();
+    mojo::gfx::composition::ResourcePtr content_resource =
+        ganesh_renderer()->DrawCanvas(
+            size_,
+            base::Bind(&PDFDocumentView::DrawContent, base::Unretained(this)));
+    DCHECK(content_resource);
+    update->resources.insert(kContentImageResourceId, content_resource.Pass());
+
+    auto root_node = mojo::gfx::composition::Node::New();
+    root_node->op = mojo::gfx::composition::NodeOp::New();
+    root_node->op->set_image(mojo::gfx::composition::ImageNodeOp::New());
+    root_node->op->get_image()->content_rect = bounds.Clone();
+    root_node->op->get_image()->image_resource_id = kContentImageResourceId;
+    update->nodes.insert(kRootNodeId, root_node.Pass());
+
+    scene()->Update(update.Pass());
+    scene()->Publish(nullptr);
+  }
+
+  void DrawContent(SkCanvas* canvas) {
+    if (!cached_image_) {
+      cached_image_ = pdf_document_->DrawPage(page_);
+    }
+
+    if (cached_image_) {
+      canvas->clear(SK_ColorBLACK);
+
+      int32_t w, h;
+      if (size_.width * cached_image_->height() <
+          size_.height * cached_image_->width()) {
+        w = size_.width;
+        h = cached_image_->height() * size_.width / cached_image_->width();
+      } else {
+        w = cached_image_->width() * size_.height / cached_image_->height();
+        h = size_.height;
+      }
+      canvas->drawImageRect(
+          cached_image_.get(),
+          SkRect::MakeWH(cached_image_->width(), cached_image_->height()),
+          SkRect::MakeXYWH((size_.width - w) / 2, (size_.height - h) / 2, w, h),
+          nullptr);
+    } else {
+      canvas->clear(SK_ColorBLUE);
+    }
+
+    canvas->flush();
+  }
+
+  void GotoNextPage() {
+    if (page_ + 1 < pdf_document_->page_count()) {
+      page_++;
+      Redraw();
+    }
+  }
+
+  void GotoPreviousPage() {
+    if (page_ > 0) {
+      page_--;
+      Redraw();
+    }
+  }
+
+  void Redraw() {
+    cached_image_.clear();
+    UpdateScene();

[abarth, 2016/01/10 23:09:31]

I was expecting some sort of "invalidate and wait for the choreographer" pattern
here.  If I spam the keyboard, does this mean a re-raster the PDF multiple times
per vsync?

[jeffbrown, 2016/01/26 08:14:17]

Good point.  Let's add that.

+  }
+
+  std::shared_ptr<PDFDocument> pdf_document_;
+  uint32_t page_ = 0u;
+  skia::RefPtr<SkImage> cached_image_;
+
+  mojo::Size size_;
+  mojo::ui::InputHandler input_handler_;
+
+  DISALLOW_COPY_AND_ASSIGN(PDFDocumentView);
+};
+
+class PDFContentViewProviderApp : public mojo::ui::ViewProviderApp {
+ public:
+  PDFContentViewProviderApp(const std::shared_ptr<PDFLibrary>& pdf_library,
+                            const std::shared_ptr<PDFDocument>& pdf_document)
+      : pdf_library_(pdf_library), pdf_document_(pdf_document) {
+    DCHECK(pdf_library_);
+    DCHECK(pdf_document_);
+  }
+
+  ~PDFContentViewProviderApp() override {}
+
+  bool CreateView(
+      const std::string& connection_url,
+      mojo::InterfaceRequest<mojo::ServiceProvider> services,
+      mojo::ServiceProviderPtr exposed_services,
+      const mojo::ui::ViewProvider::CreateViewCallback& callback) override {
+    new PDFDocumentView(app_impl(), pdf_document_, callback);
+    return true;
+  }
+
+ private:
+  std::shared_ptr<PDFLibrary> pdf_library_;
+  std::shared_ptr<PDFDocument> pdf_document_;
+
+  DISALLOW_COPY_AND_ASSIGN(PDFContentViewProviderApp);
+};
+
+class PDFContentViewerApp : public mojo::ui::ContentViewerApp {
+ public:
+  PDFContentViewerApp() : pdf_library_(std::make_shared<PDFLibrary>()) {}
+
+  ~PDFContentViewerApp() override {}
+
+  mojo::ui::ViewProviderApp* LoadContent(
+      const std::string& content_handler_url,
+      mojo::URLResponsePtr response) override {
+    std::shared_ptr<PDFDocument> pdf_document =
+        pdf_library_->Decode(response.Pass());
+    if (!pdf_document) {
+      LOG(ERROR) << "Could not decode PDFDocument.";
+      return nullptr;
+    }
+
+    return new PDFContentViewProviderApp(pdf_library_, pdf_document);
+  }
+
+ private:
+  std::shared_ptr<PDFLibrary> pdf_library_;
+
+  DISALLOW_COPY_AND_ASSIGN(PDFContentViewerApp);
+};
+
+}  // namespace examples
+
+MojoResult MojoMain(MojoHandle application_request) {
+  mojo::ApplicationRunnerChromium runner(new examples::PDFContentViewerApp());
+  return runner.Run(application_request);
+}