cc: Resource list for headup display

cc/layers/heads_up_display_layer_impl.cc

 // Copyright 2012 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 "cc/layers/heads_up_display_layer_impl.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/debug/trace_event.h"
@@ skipping 63 matching lines @@
       paint_time_graph_(16.0, 48.0),
       fade_step_(0) {}
 
 HeadsUpDisplayLayerImpl::~HeadsUpDisplayLayerImpl() {}
 
 scoped_ptr<LayerImpl> HeadsUpDisplayLayerImpl::CreateLayerImpl(
     LayerTreeImpl* tree_impl) {
   return HeadsUpDisplayLayerImpl::Create(tree_impl, id()).PassAs<LayerImpl>();
 }
 
+void HeadsUpDisplayLayerImpl::AcquireResource(
+    ResourceProvider* resource_provider) {
+  for (ScopedPtrVector<ScopedResource>::iterator it = resources_.begin();
+       it != resources_.end();
+       ++it) {
+    if (!resource_provider->InUseByConsumer((*it)->id())) {
+      resources_.swap(it, resources_.end() - 1);
+      return;
+    }
+  }
+
+  scoped_ptr<ScopedResource> resource =
+      ScopedResource::Create(resource_provider);
+  resource->Allocate(
+      content_bounds(), ResourceProvider::TextureHintImmutable, RGBA_8888);
+  resources_.push_back(resource.Pass());
+}
+
+void HeadsUpDisplayLayerImpl::ReleaseUnmatchedSizeResources(
+    ResourceProvider* resource_provider) {
+  ScopedPtrVector<ScopedResource> to_be_kept;
+  for (ScopedPtrVector<ScopedResource>::iterator it = resources_.begin();
+       it != resources_.end();
+       ++it) {
+    if ((*it)->size() == content_bounds())
+      to_be_kept.push_back(resources_.take(it));

[danakj, 2014/08/27 13:25:01]

i feel like the common case will be that we keep all the resources, which is
also the worst case for this code.

how about instead doing something like this, where in the common case where we
delete nothing, we just iterate and done.

size_t all_count = resources_.size();
size_t deleted_count = 0;
for (size_t i = 0; i < all_count - deleted_count; ++i) {
  if (...want to delete...) {
    resources_.swap(i, end() - deleted_count - 1);
    ++deleted_count;
  }
}
resources_.erase(end() - deleted_count, end());

[JungJik, 2014/08/28 15:55:38]

thanks for the kind explanation.
however for two reasons, I could not apply your explanation.
one is that erase of ScopedPtrVector supports only iterator type params.
the other is that if in the case that begin() and end() - 1 are same and has
different size with others, we could not remove them.
so I made new patch with stl::partition + fix all nits.
please take a look again. thank you in advance.

+  }
+  resources_.clear();
+
+  resources_.insert_and_take(resources_.begin(), to_be_kept);
+}
+
 bool HeadsUpDisplayLayerImpl::WillDraw(DrawMode draw_mode,
                                        ResourceProvider* resource_provider) {
   if (draw_mode == DRAW_MODE_RESOURCELESS_SOFTWARE)
     return false;
 
-  if (!hud_resource_)
-    hud_resource_ = ScopedResource::Create(resource_provider);
+  ReleaseUnmatchedSizeResources(resource_provider);
 

[danakj, 2014/08/27 13:25:01]

nit: drop whitespace

-  // TODO(danakj): The HUD could swap between two textures instead of creating a
-  // texture every frame in ubercompositor.
-  if (hud_resource_->size() != content_bounds() ||
-      (hud_resource_->id() &&
-       resource_provider->InUseByConsumer(hud_resource_->id()))) {
-    hud_resource_->Free();
-  }
-
-  if (!hud_resource_->id()) {
-    hud_resource_->Allocate(
-        content_bounds(), ResourceProvider::TextureHintImmutable, RGBA_8888);
-  }
+  AcquireResource(resource_provider);
 

[danakj, 2014/08/27 13:25:01]

nit: drop whitespace

   return LayerImpl::WillDraw(draw_mode, resource_provider);
 }
 
 void HeadsUpDisplayLayerImpl::AppendQuads(
     RenderPass* render_pass,
     const OcclusionTracker<LayerImpl>& occlusion_tracker,
     AppendQuadsData* append_quads_data) {
-  if (!hud_resource_->id())
+  if (!resources_.back()->id())
     return;
 
   SharedQuadState* shared_quad_state =
       render_pass->CreateAndAppendSharedQuadState();
   PopulateSharedQuadState(shared_quad_state);
 
   gfx::Rect quad_rect(content_bounds());
   gfx::Rect opaque_rect(contents_opaque() ? quad_rect : gfx::Rect());
   gfx::Rect visible_quad_rect(quad_rect);
   bool premultiplied_alpha = true;
   gfx::PointF uv_top_left(0.f, 0.f);
   gfx::PointF uv_bottom_right(1.f, 1.f);
   const float vertex_opacity[] = { 1.f, 1.f, 1.f, 1.f };
   bool flipped = false;
   TextureDrawQuad* quad =
       render_pass->CreateAndAppendDrawQuad<TextureDrawQuad>();
   quad->SetNew(shared_quad_state,
                quad_rect,
                opaque_rect,
                visible_quad_rect,
-               hud_resource_->id(),
+               resources_.back()->id(),
                premultiplied_alpha,
                uv_top_left,
                uv_bottom_right,
                SK_ColorTRANSPARENT,
                vertex_opacity,
                flipped);
 }
 
 void HeadsUpDisplayLayerImpl::UpdateHudTexture(
     DrawMode draw_mode,
     ResourceProvider* resource_provider) {
-  if (draw_mode == DRAW_MODE_RESOURCELESS_SOFTWARE || !hud_resource_->id())
+  if (draw_mode == DRAW_MODE_RESOURCELESS_SOFTWARE || !resources_.back()->id())
     return;
 
   SkISize canvas_size;
   if (hud_canvas_)
     canvas_size = hud_canvas_->getDeviceSize();
   else
     canvas_size.set(0, 0);
 
   if (canvas_size.width() != content_bounds().width() ||
       canvas_size.height() != content_bounds().height() || !hud_canvas_) {
@@ skipping 16 matching lines @@
     hud_canvas_->restore();
   }
 
   TRACE_EVENT0("cc", "UploadHudTexture");
   SkImageInfo info;
   size_t row_bytes = 0;
   const void* pixels = hud_canvas_->peekPixels(&info, &row_bytes);
   DCHECK(pixels);
   gfx::Rect content_rect(content_bounds());
   DCHECK(info.colorType() == kN32_SkColorType);
-  resource_provider->SetPixels(hud_resource_->id(),
+  resource_provider->SetPixels(resources_.back()->id(),
                                static_cast<const uint8_t*>(pixels),
                                content_rect,
                                content_rect,
                                gfx::Vector2d());
 }
 
-void HeadsUpDisplayLayerImpl::ReleaseResources() { hud_resource_.reset(); }
+void HeadsUpDisplayLayerImpl::ReleaseResources() {
+  resources_.clear();
+}
 
 void HeadsUpDisplayLayerImpl::UpdateHudContents() {
   const LayerTreeDebugState& debug_state = layer_tree_impl()->debug_state();
 
   // Don't update numbers every frame so text is readable.
   base::TimeTicks now = layer_tree_impl()->CurrentBeginFrameArgs().frame_time;
   if (base::TimeDelta(now - time_of_last_graph_update_).InSecondsF() > 0.25f) {
     time_of_last_graph_update_ = now;
 
     if (debug_state.show_fps_counter) {
@@ skipping 562 matching lines @@
   return "cc::HeadsUpDisplayLayerImpl";
 }
 
 void HeadsUpDisplayLayerImpl::AsValueInto(
     base::debug::TracedValue* dict) const {
   LayerImpl::AsValueInto(dict);
   dict->SetString("layer_name", "Heads Up Display Layer");
 }
 
 }  // namespace cc