mozart: Add a simple tiling view manager.

examples/ui/tile/tile_view.cc

+// Copyright 2013 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 "examples/ui/tile/tile_view.h"
+#include "mojo/services/surfaces/cpp/surfaces_utils.h"
+#include "mojo/services/surfaces/interfaces/quads.mojom.h"
+
+namespace examples {
+
+TileView::TileView(mojo::ApplicationImpl* app_impl,
+                   const std::vector<std::string>& view_urls,
+                   const mojo::ui::ViewProvider::CreateViewCallback& callback)
+    : app_impl_(app_impl),
+      view_urls_(view_urls),
+      callback_(callback),
+      binding_(this),
+      surface_id_namespace_(0),
+      pending_child_layout_count_(0),
+      frame_pending_(false),
+      weak_ptr_factory_(this) {
+  app_impl_->ConnectToService("mojo:surfaces_service", &surfaces_);
+  app_impl_->ConnectToService("mojo:view_manager_service", &view_manager_);
+
+  surfaces_->GetIdNamespace(base::Bind(&TileView::OnSurfaceIdNamespaceAvailable,
+                                       base::Unretained(this)));
+}
+
+TileView::~TileView() {}
+
+void TileView::OnSurfaceIdNamespaceAvailable(uint32_t id_namespace) {
+  surface_id_namespace_ = id_namespace;
+  InitView();
+}
+
+void TileView::InitView() {
+  // Register the view.
+  mojo::ui::ViewPtr view;
+  binding_.Bind(mojo::GetProxy(&view));
+  view_manager_->RegisterView(view.Pass(), mojo::GetProxy(&view_host_),
+                              callback_);
+
+  // Connect to all child views.
+  uint32_t child_key = 0;
+  for (auto url : view_urls_) {

[qsr, 2015/10/27 09:01:27]

const auto& ?

[jeffbrown, 2015/10/27 22:54:24]

Done.

+    // Start connecting to the view provider.
+    mojo::ui::ViewProviderPtr provider;
+    app_impl_->ConnectToService(url, &provider);
+    provider.set_connection_error_handler(
+        base::Bind(&TileView::OnChildConnectionError, base::Unretained(this),
+                   child_key, url));
+
+    // Create the view.
+    // We include the provider reference in the callback so that the
+    // binding will be kept alive until the callback completes.
+    LOG(INFO) << "Connecting to view: child_key=" << child_key
+              << ", url=" << url;
+    provider->CreateView(
+        nullptr, nullptr,
+        base::Bind(&TileView::OnChildCreated, base::Unretained(this), child_key,
+                   url, base::Passed(provider.Pass())));
+    child_key++;
+  }
+}
+
+void TileView::OnChildConnectionError(uint32_t child_key,
+                                      const std::string& url) {
+  LOG(ERROR) << "Could not connect to view: child_key=" << child_key
+             << ", url=" << url;
+}
+
+void TileView::OnChildCreated(uint32_t child_key,
+                              const std::string& url,
+                              mojo::ui::ViewProviderPtr provider,
+                              mojo::ui::ViewTokenPtr token) {
+  DCHECK(views_.find(child_key) == views_.end());
+  LOG(INFO) << "View created: child_key=" << child_key << ", url=" << url;
+
+  view_host_->AddChild(child_key, token.Pass());
+  views_.emplace(
+      std::make_pair(child_key, std::unique_ptr<ViewData>(new ViewData(url))));

[jamesr, 2015/10/27 22:58:27]

there's a school of thought that C++ code using smart pointers should never
invoke 'new' or 'delete' by hand, it should always use the wrappers. if you buy
into that school, you would write this

mojo::util::MakeUnique<ViewData>(url)

which has the advantage of being slightly terser than what you wrote.

[jeffbrown, 2015/10/27 23:24:19]

Feels weird to depend on an EDK header here so I'll just wait for c++14.

+
+  // Don't need the view provider anymore now that we have created the view
+  // so stop watching for errors.
+  provider.set_connection_error_handler(base::Closure());

[qsr, 2015/10/27 09:01:27]

Why is this needed? The provider will be deleted as soon as this function ends.

[jeffbrown, 2015/10/27 22:54:24]

Good point, this is redundant.

+}
+
+void TileView::OnChildUnavailable(uint32_t child_key,
+                                  const OnChildUnavailableCallback& callback) {
+  auto it = views_.find(child_key);
+  DCHECK(it != views_.end());
+  LOG(ERROR) << "View died unexpectedly: child_key=" << child_key
+             << ", url=" << it->second->url();
+
+  std::unique_ptr<ViewData> view_data = std::move(it->second);
+  views_.erase(it);
+
+  view_host_->RemoveChild(child_key);
+
+  if (view_data->layout_pending) {
+    DCHECK(pending_child_layout_count_);
+    pending_child_layout_count_--;
+    FinishLayout();
+  }
+
+  callback.Run();
+}
+
+void TileView::OnLayout(mojo::ui::ViewLayoutParamsPtr layout_params,
+                        mojo::Array<uint32_t> children_needing_layout,
+                        const OnLayoutCallback& callback) {
+  // Create a new surface the first time or if the size has changed.
+  mojo::Size new_size;
+  new_size.width = layout_params->constraints->max_width;
+  new_size.height = layout_params->constraints->max_height;
+  if (!surface_id_ || !size_.Equals(new_size)) {
+    if (!surface_id_) {
+      surface_id_ = mojo::SurfaceId::New();
+      surface_id_->id_namespace = surface_id_namespace_;
+    } else {
+      surfaces_->DestroySurface(surface_id_->local);
+    }
+    surface_id_->local++;
+    size_ = new_size;
+    surfaces_->CreateSurface(surface_id_->local);
+  }
+
+  // Wipe out cached layout information for children needing layout.
+  for (uint32_t child_key : children_needing_layout) {
+    auto view_it = views_.find(child_key);
+    if (view_it != views_.end())
+      view_it->second->layout_info.reset();
+  }
+
+  // Layout all children in a row.
+  if (!views_.empty()) {
+    uint32_t index = 0;
+    uint32_t base_width = new_size.width / views_.size();
+    uint32_t excess_width = new_size.width % views_.size();
+    uint32_t x = 0;
+    for (auto it = views_.begin(); it != views_.end(); ++it, ++index) {
+      ViewData* view_data = it->second.get();
+      DCHECK(!view_data->layout_pending);
+
+      // Distribute any excess width among the leading children.
+      uint32_t child_width = base_width;
+      if (excess_width) {
+        child_width++;
+        excess_width--;
+      }
+      uint32_t child_height = new_size.height;
+      uint32_t child_x = x;
+      x += child_width;
+
+      view_data->layout_bounds.x = child_x;
+      view_data->layout_bounds.y = 0;
+      view_data->layout_bounds.width = child_width;
+      view_data->layout_bounds.height = child_height;
+
+      mojo::ui::ViewLayoutParamsPtr params = mojo::ui::ViewLayoutParams::New();
+      params->constraints = mojo::ui::BoxConstraints::New();
+      params->constraints->min_width = child_width;
+      params->constraints->max_width = child_width;
+      params->constraints->min_height = child_height;
+      params->constraints->max_height = child_height;
+      params->device_pixel_ratio = layout_params->device_pixel_ratio;
+
+      if (view_data->layout_info && view_data->layout_params.Equals(params))
+        continue;  // no layout work to do
+
+      pending_child_layout_count_++;
+      view_data->layout_pending = true;
+      view_data->layout_params = params.Clone();
+      view_data->layout_info.reset();
+
+      view_host_->LayoutChild(it->first, params.Pass(),
+                              base::Bind(&TileView::OnChildLayoutFinished,
+                                         base::Unretained(this), it->first));
+    }
+  }
+
+  // Store the callback until layout of all children is finished.
+  pending_layout_callback_ = callback;
+  FinishLayout();
+}
+
+void TileView::OnChildLayoutFinished(
+    uint32_t child_key,
+    mojo::ui::ViewLayoutInfoPtr child_layout_info) {
+  auto it = views_.find(child_key);
+  if (it != views_.end()) {
+    ViewData* view_data = it->second.get();
+    DCHECK(view_data->layout_pending);
+    DCHECK(pending_child_layout_count_);
+    pending_child_layout_count_--;
+    view_data->layout_pending = false;
+    view_data->layout_info = child_layout_info.Pass();
+    FinishLayout();
+  }
+}
+
+void TileView::FinishLayout() {
+  if (frame_pending_ || pending_layout_callback_.is_null())
+    return;
+
+  // Wait until all children have laid out.
+  // TODO(jeffbrown): There should be a timeout on this.
+  if (pending_child_layout_count_)
+    return;
+
+  // Produce a new frame.
+  mojo::FramePtr frame = mojo::Frame::New();
+  frame->resources.resize(0u);
+
+  mojo::Rect bounds;
+  bounds.width = size_.width;
+  bounds.height = size_.height;
+  mojo::PassPtr pass = mojo::CreateDefaultPass(1, bounds);
+  pass->shared_quad_states.resize(0u);
+  pass->quads.resize(0u);
+
+  for (auto it = views_.cbegin(); it != views_.cend(); it++) {
+    const ViewData& view_data = *(it->second.get());
+
+    mojo::QuadPtr quad = mojo::Quad::New();
+    quad->rect = view_data.layout_bounds.Clone();
+    quad->rect->x = 0;
+    quad->rect->y = 0;
+    quad->opaque_rect = quad->rect.Clone();
+    quad->visible_rect = quad->rect.Clone();
+    quad->shared_quad_state_index = pass->shared_quad_states.size();
+
+    mojo::Size size;
+    size.width = view_data.layout_bounds.width;
+    size.height = view_data.layout_bounds.height;
+
+    mojo::SharedQuadStatePtr quad_state = mojo::CreateDefaultSQS(size);
+    quad_state->content_to_target_transform->matrix[3] =
+        view_data.layout_bounds.x;
+    pass->shared_quad_states.push_back(quad_state.Pass());
+
+    if (it->second->layout_info) {
+      quad->material = mojo::Material::SURFACE_CONTENT;
+      quad->surface_quad_state = mojo::SurfaceQuadState::New();
+      quad->surface_quad_state->surface =
+          view_data.layout_info->surface_id.Clone();
+    } else {
+      quad->material = mojo::Material::SOLID_COLOR;
+      quad->solid_color_quad_state = mojo::SolidColorQuadState::New();
+      quad->solid_color_quad_state->color = mojo::Color::New();
+      quad->solid_color_quad_state->color->rgba = 0xffff00ff;
+    }
+
+    pass->quads.push_back(quad.Pass());
+  }
+
+  frame->passes.push_back(pass.Pass());
+
+  frame_pending_ = true;
+  surfaces_->SubmitFrame(
+      surface_id_->local, frame.Pass(),
+      base::Bind(&TileView::OnFrameSubmitted, base::Unretained(this)));
+
+  // Submit the new layout information.
+  mojo::ui::ViewLayoutInfoPtr info = mojo::ui::ViewLayoutInfo::New();
+  info->size = size_.Clone();
+  info->surface_id = surface_id_->Clone();
+  pending_layout_callback_.Run(info.Pass());
+  pending_layout_callback_.reset();
+}
+
+void TileView::OnFrameSubmitted() {
+  DCHECK(frame_pending_);
+
+  frame_pending_ = false;
+  FinishLayout();
+}
+
+TileView::ViewData::ViewData(const std::string& url)
+    : layout_pending(false), url_(url) {}
+
+TileView::ViewData::~ViewData() {}
+
+}  // namespace examples