Surfaceless OutputSurface implementation.

content/browser/compositor/buffered_output_surface.cc

+// 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 "content/browser/compositor/buffered_output_surface.h"
+
+#include "content/common/gpu/client/context_provider_command_buffer.h"
+#include "gpu/GLES2/gl2extchromium.h"
+#include "gpu/command_buffer/client/gles2_interface.h"
+
+namespace content {
+
+BufferedOutputSurface::BufferedOutputSurface(
+    scoped_refptr<cc::ContextProvider> context_provider,
+    unsigned int internalformat)
+    : context_provider_(context_provider),
+      fbo_(0),
+      depth_rb_(0),
+      tex_id_(0),
+      internalformat_(internalformat),
+      current_surface_(0),
+      last_surface_(0),
+      in_flight_surface_(0) {
+  Initialize();
+}
+
+BufferedOutputSurface::~BufferedOutputSurface() {
+  FreeAllSurfaces();
+
+  gpu::gles2::GLES2Interface* gl = context_provider_->ContextGL();
+  if (fbo_)
+    gl->DeleteFramebuffers(1, &fbo_);
+  if (depth_rb_)
+    gl->DeleteRenderbuffers(1, &depth_rb_);
+  if (tex_id_)
+    gl->DeleteTextures(1, &tex_id_);
+}
+
+void BufferedOutputSurface::Initialize() {
+  gpu::gles2::GLES2Interface* gl = context_provider_->ContextGL();
+  gl->GenFramebuffers(1, &fbo_);
+  gl->GenRenderbuffers(1, &depth_rb_);
+  gl->GenTextures(1, &tex_id_);
+  DCHECK(fbo_);
+  DCHECK(depth_rb_);
+  DCHECK(tex_id_);
+}
+
+void BufferedOutputSurface::BindFramebuffer() {
+  if (!current_surface_)
+    current_surface_ = GetNextSurface();
+
+  gpu::gles2::GLES2Interface* gl = context_provider_->ContextGL();
+  gl->BindFramebuffer(GL_FRAMEBUFFER, fbo_);
+  gl->BindTexture(GL_TEXTURE_2D, tex_id_);
+  gl->BindTexImage2DCHROMIUM(GL_TEXTURE_2D, current_surface_);

[alexst (slow to review), 2014/09/10 17:37:08]

I looked at the implementation, and this has a non-trivial cost. It reshuffles a
bunch of internal stuff and calls glEGLImageTargetTexture2DOES. I would prefer
we have a one to one mapping of texture_id to image_id to avoid calling into egl
unnecessarily. I don't we it makes tracking that much more complicated, you just
keep a pair instead of an int.

[achaulk, 2014/09/10 18:56:07]

Done.

+  gl->FramebufferTexture2D(
+      GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, tex_id_, 0);
+}
+
+void BufferedOutputSurface::SwapBuffers() {
+  if (last_surface_) {
+    if (in_flight_surface_) {

[alexst (slow to review), 2014/09/10 17:37:08]

Let's move this to bind.

[achaulk, 2014/09/10 18:56:07]

We can't. Multiply calling bind is probably allowed, so we can't just advance on
every call, we need something else to push surfaces along the path

+      // This is a case where a frame has been issued (bind/swap), and a second
+      // frame has been issued before receiving the PageFlipComplete for the
+      // first frame. We are now quad-buffering.
+      DCHECK(false);

[alexst (slow to review), 2014/09/10 17:37:08]

LOG(FATAL) << why we crashed

+      context_provider_->ContextGL()->DestroyImageCHROMIUM(in_flight_surface_);
+    } else {
+      in_flight_surface_ = last_surface_;
+    }
+  }
+  last_surface_ = current_surface_;
+  current_surface_ = 0;
+}
+
+void BufferedOutputSurface::Reshape(const gfx::Size& size, float scale_factor) {
+  if (size == size_)
+    return;
+  size_ = size;
+  FreeAllSurfaces();
+
+  if (size_.width() == 0 || size_.height() == 0)
+    return;  // Nothing to do.
+  gpu::gles2::GLES2Interface* gl = context_provider_->ContextGL();
+  gl->BindFramebuffer(GL_FRAMEBUFFER, fbo_);
+  gl->BindRenderbuffer(GL_RENDERBUFFER, depth_rb_);
+  gl->RenderbufferStorage(
+      GL_RENDERBUFFER, GL_DEPTH_COMPONENT24_OES, size_.width(), size_.height());
+  gl->FramebufferRenderbuffer(
+      GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depth_rb_);
+}
+
+void BufferedOutputSurface::PageFlipComplete() {
+  if (in_flight_surface_) {
+    available_surfaces_.push_back(in_flight_surface_);
+    in_flight_surface_ = 0;
+  }
+}
+
+void BufferedOutputSurface::FreeAllSurfaces() {
+  unsigned int bound_surface =
+      current_surface_ ? current_surface_ : last_surface_;
+  gpu::gles2::GLES2Interface* gl = context_provider_->ContextGL();
+  if (bound_surface) {
+    gl->BindTexture(GL_TEXTURE_2D, tex_id_);
+    gl->ReleaseTexImage2DCHROMIUM(GL_TEXTURE_2D, bound_surface);
+  }
+  FreeSurface(&in_flight_surface_);
+  FreeSurface(&last_surface_);
+  FreeSurface(&current_surface_);
+  for (size_t i = 0; i < available_surfaces_.size(); i++)
+    gl->DestroyImageCHROMIUM(available_surfaces_[i]);
+  available_surfaces_.clear();
+}
+
+void BufferedOutputSurface::FreeSurface(unsigned int* surface) {
+  if (*surface) {
+    context_provider_->ContextGL()->DestroyImageCHROMIUM(*surface);
+    *surface = 0;
+  }
+}
+
+unsigned int BufferedOutputSurface::GetNextSurface() {
+  if (!available_surfaces_.empty()) {
+    unsigned int id = available_surfaces_.back();
+    available_surfaces_.pop_back();
+    return id;
+  }
+
+  unsigned int id = context_provider_->ContextGL()->CreateImageCHROMIUM(
+      size_.width(),
+      size_.height(),
+      internalformat_,
+      GL_IMAGE_SCANOUT_CHROMIUM);
+  DCHECK(id);
+  return id;
+}
+
+}  // namespace content