gecko-dev/gfx/vr/VRDisplayPresentation.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "VRDisplayPresentation.h"
#include "mozilla/dom/DocGroup.h"
#include "mozilla/dom/Document.h"
#include "mozilla/dom/XRWebGLLayer.h"
#include "mozilla/Unused.h"
#include "VRDisplayClient.h"
#include "VRLayerChild.h"

using namespace mozilla;
using namespace mozilla::gfx;

VRDisplayPresentation::VRDisplayPresentation(
    VRDisplayClient* aDisplayClient,
    const nsTArray<mozilla::dom::VRLayer>& aLayers, uint32_t aGroup)
    : mDisplayClient(aDisplayClient),
      mDOMLayers(aLayers.Clone()),
      mGroup(aGroup) {
  CreateLayers();
}

void VRDisplayPresentation::UpdateLayers(
    const nsTArray<mozilla::dom::VRLayer>& aLayers) {
  mDOMLayers = aLayers.Clone();
  CreateLayers();
}

void VRDisplayPresentation::UpdateXRWebGLLayer(dom::XRWebGLLayer* aLayer) {
  VRManagerChild* manager = VRManagerChild::Get();
  if (!manager) {
    // This should not happen, but let's log it and avoid a crash in case
    // of regression.
    NS_WARNING("VRManagerChild::Get returned null!");
    return;
  }

  dom::HTMLCanvasElement* canvasElement = aLayer->GetCanvas();
  nsCOMPtr<nsISerialEventTarget> target =
      canvasElement->OwnerDoc()->EventTargetFor(TaskCategory::Other);

  if (mLayers.Length() == 0) {
    // WebXR uses a single layer for now.
    RefPtr<VRLayerChild> vrLayer =
        static_cast<VRLayerChild*>(manager->CreateVRLayer(
            mDisplayClient->GetDisplayInfo().GetDisplayID(), target, mGroup));
    mLayers.AppendElement(vrLayer);
  }
  RefPtr<VRLayerChild> vrLayer = mLayers[0];

  Rect leftBounds(0.0, 0.0, 0.5, 1.0);
  Rect rightBounds(0.5, 0.0, 0.5, 1.0);

  vrLayer->Initialize(canvasElement, leftBounds, rightBounds);
  vrLayer->SetXRFramebuffer(aLayer->GetFramebuffer());
}

uint32_t VRDisplayPresentation::GetGroup() const { return mGroup; }

void VRDisplayPresentation::CreateLayers() {
  VRManagerChild* manager = VRManagerChild::Get();
  if (!manager) {
    // This should not happen, but let's log it and avoid a crash in case
    // of regression.
    NS_WARNING("VRManagerChild::Get returned null!");
    return;
  }

  unsigned int iLayer = 0;
  for (dom::VRLayer& layer : mDOMLayers) {
    dom::HTMLCanvasElement* canvasElement = layer.mSource;
    if (!canvasElement) {
      /// XXX In the future we will support WebVR in WebWorkers here
      continue;
    }

    Rect leftBounds(0.0, 0.0, 0.5, 1.0);
    if (layer.mLeftBounds.Length() == 4) {
      leftBounds.SetRect(layer.mLeftBounds[0], layer.mLeftBounds[1],
                         layer.mLeftBounds[2], layer.mLeftBounds[3]);
    } else if (layer.mLeftBounds.Length() != 0) {
      /**
       * We ignore layers with an incorrect number of values.
       * In the future, VRDisplay.requestPresent may throw in
       * this case.  See https://github.com/w3c/webvr/issues/71
       */
      continue;
    }

    Rect rightBounds(0.5, 0.0, 0.5, 1.0);
    if (layer.mRightBounds.Length() == 4) {
      rightBounds.SetRect(layer.mRightBounds[0], layer.mRightBounds[1],
                          layer.mRightBounds[2], layer.mRightBounds[3]);
    } else if (layer.mRightBounds.Length() != 0) {
      /**
       * We ignore layers with an incorrect number of values.
       * In the future, VRDisplay.requestPresent may throw in
       * this case.  See https://github.com/w3c/webvr/issues/71
       */
      continue;
    }

    nsCOMPtr<nsISerialEventTarget> target =
        canvasElement->OwnerDoc()->EventTargetFor(TaskCategory::Other);

    if (mLayers.Length() <= iLayer) {
      // Not enough layers, let's add one
      RefPtr<VRLayerChild> vrLayer =
          static_cast<VRLayerChild*>(manager->CreateVRLayer(
              mDisplayClient->GetDisplayInfo().GetDisplayID(), target, mGroup));
      if (!vrLayer) {
        NS_WARNING("CreateVRLayer returned null!");
        continue;
      }
      vrLayer->Initialize(canvasElement, leftBounds, rightBounds);
      mLayers.AppendElement(vrLayer);
    } else {
      // We already have a layer, let's update it
      mLayers[iLayer]->Initialize(canvasElement, leftBounds, rightBounds);
    }
    iLayer++;
  }

  // Truncate any excess layers that weren't included in the updated list
  mLayers.SetLength(iLayer);
}

void VRDisplayPresentation::DestroyLayers() {
  for (VRLayerChild* layer : mLayers) {
    if (layer->IsIPCOpen()) {
      Unused << layer->SendDestroy();
    }
  }
  mLayers.Clear();
}

void VRDisplayPresentation::GetDOMLayers(nsTArray<dom::VRLayer>& result) {
  result = mDOMLayers.Clone();
}

VRDisplayPresentation::~VRDisplayPresentation() {
  DestroyLayers();
  mDisplayClient->PresentationDestroyed();
}

void VRDisplayPresentation::SubmitFrame() {
  // Currently only one layer supported, submit only the first
  if (mLayers.Length() >= 1) {
    VRLayerChild* layer = mLayers.ElementAt(0);
    layer->SubmitFrame(mDisplayClient->GetDisplayInfo());
  }
}