exo: Allow updating cc::Surface viewport and crop state independently.

components/exo/surface.cc

 // Copyright 2015 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/exo/surface.h"
 
 #include <utility>
 
 #include "base/callback_helpers.h"
 #include "base/logging.h"
@@ skipping 370 matching lines @@
 
   DCHECK(ListContainsEntry(pending_sub_surfaces_, sub_surface));
   pending_sub_surfaces_.splice(
       sibling_it, pending_sub_surfaces_,
       FindListEntry(pending_sub_surfaces_, sub_surface));
 }
 
 void Surface::SetViewport(const gfx::Size& viewport) {
   TRACE_EVENT1("exo", "Surface::SetViewport", "viewport", viewport.ToString());
 
+  if (pending_viewport_ == viewport)
+    return;
+
   pending_viewport_ = viewport;
+  changed_viewport_or_crop_ = true;
 }
 
 void Surface::SetCrop(const gfx::RectF& crop) {
   TRACE_EVENT1("exo", "Surface::SetCrop", "crop", crop.ToString());
 
+  if (pending_crop_ == crop)
+    return;
+
   pending_crop_ = crop;
+  changed_viewport_or_crop_ = true;
 }
 
 void Surface::SetOnlyVisibleOnSecureOutput(bool only_visible_on_secure_output) {
   TRACE_EVENT1("exo", "Surface::SetOnlyVisibleOnSecureOutput",
                "only_visible_on_secure_output", only_visible_on_secure_output);
 
   pending_only_visible_on_secure_output_ = only_visible_on_secure_output;
 }
 
 void Surface::SetBlendMode(SkXfermode::Mode blend_mode) {
@@ skipping 97 matching lines @@
   // fills-bounds-opaquely.
   layer()->SetFillsBoundsOpaquely(
       pending_blend_mode_ == SkXfermode::kSrc_Mode ||
       pending_opaque_region_.contains(
           gfx::RectToSkIRect(gfx::Rect(layer()->size()))));
 }
 
 void Surface::CommitSurfaceContents() {
   // We update contents if Attach() has been called since last commit.
   if (has_pending_contents_) {
-    has_pending_contents_ = false;
-
     current_buffer_ = pending_buffer_;
     pending_buffer_.reset();
+  }
+
+  if (has_pending_contents_ || changed_viewport_or_crop_) {
+    has_pending_contents_ = false;
+    changed_viewport_or_crop_ = false;
 
     bool secure_output_only = pending_only_visible_on_secure_output_;
     pending_only_visible_on_secure_output_ = false;
 
     cc::TextureMailbox texture_mailbox;
     std::unique_ptr<cc::SingleReleaseCallback> texture_mailbox_release_callback;
     if (current_buffer_) {
       texture_mailbox_release_callback = current_buffer_->ProduceTextureMailbox(

[reveman, 2016/06/02 21:48:29]

It's considered a client error to commit the same buffer when already used.
ProduceTextureMailbox changes the behavior of buffer and logs warnings when this
happens. It looks like this will now happen when a client is just changing the
viewport or crop state. Can we change this state without having to produce a new
texture mailbox somehow?

           &texture_mailbox, secure_output_only, false);
     }
 
     cc::SurfaceId old_surface_id = surface_id_;
     surface_id_ = factory_owner_->id_allocator_->GenerateId();
     factory_owner_->surface_factory_->Create(surface_id_);
 
     gfx::Size buffer_size = texture_mailbox.size_in_pixels();
     gfx::SizeF scaled_buffer_size(
         gfx::ScaleSize(gfx::SizeF(buffer_size), 1.0f / pending_buffer_scale_));
@@ skipping 327 matching lines @@
 void Surface::WillDraw(cc::SurfaceId id) {
   while (!active_frame_callbacks_.empty()) {
     active_frame_callbacks_.front().Run(base::TimeTicks::Now());
     active_frame_callbacks_.pop_front();
   }
 }
 
 bool Surface::use_surface_layer_ = false;
 
 }  // namespace exo