ImageFactory.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * 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 "ImageFactory.h"

#include <algorithm>

#include "mozilla/Likely.h"

#include "nsIFileChannel.h"
#include "nsIFile.h"
#include "nsMimeTypes.h"
#include "nsIRequest.h"

#include "MultipartImage.h"
#include "RasterImage.h"
#include "VectorImage.h"
#include "Image.h"
#include "nsMediaFragmentURIParser.h"
#include "nsContentUtils.h"

#include "mozilla/StaticPrefs_image.h"

namespace mozilla {
namespace image {

/*static*/
void ImageFactory::Initialize() {}

static uint32_t ComputeImageFlags(nsIURI* uri, const nsCString& aMimeType,
                                  bool isMultiPart) {
  // We default to the static globals.
  bool isDiscardable = StaticPrefs::image_mem_discardable();
  bool doDecodeImmediately = StaticPrefs::image_decode_immediately_enabled();

  // We want UI to be as snappy as possible and not to flicker. Disable
  // discarding for chrome URLS.
  if (uri->SchemeIs("chrome")) {
    isDiscardable = false;
  }

  // We don't want resources like the "loading" icon to be discardable either.
  if (uri->SchemeIs("resource")) {
    isDiscardable = false;
  }

  // For multipart/x-mixed-replace, we basically want a direct channel to the
  // decoder. Disable everything for this case.
  if (isMultiPart) {
    isDiscardable = false;
  }

  // We have all the information we need.
  uint32_t imageFlags = Image::INIT_FLAG_NONE;
  if (isDiscardable) {
    imageFlags |= Image::INIT_FLAG_DISCARDABLE;
  }
  if (doDecodeImmediately) {
    imageFlags |= Image::INIT_FLAG_DECODE_IMMEDIATELY;
  }
  if (isMultiPart) {
    imageFlags |= Image::INIT_FLAG_TRANSIENT;
  }

  // Synchronously decode metadata (including size) if we have a data URI since
  // the data is immediately available.
  if (uri->SchemeIs("data")) {
    imageFlags |= Image::INIT_FLAG_SYNC_LOAD;
  }

  return imageFlags;
}

#ifdef DEBUG
static void NotifyImageLoading(nsIURI* aURI) {
  if (!NS_IsMainThread()) {
    nsCOMPtr<nsIURI> uri(aURI);
    nsCOMPtr<nsIRunnable> ev = NS_NewRunnableFunction(
        "NotifyImageLoading", [uri]() -> void { NotifyImageLoading(uri); });
    SystemGroup::Dispatch(TaskCategory::Other, ev.forget());
    return;
  }

  nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
  NS_WARNING_ASSERTION(obs, "Can't get an observer service handle");
  if (obs) {
    nsAutoCString spec;
    aURI->GetSpec(spec);
    obs->NotifyObservers(nullptr, "image-loading",
                         NS_ConvertUTF8toUTF16(spec).get());
  }
}
#endif

/* static */
already_AddRefed<Image> ImageFactory::CreateImage(
    nsIRequest* aRequest, ProgressTracker* aProgressTracker,
    const nsCString& aMimeType, nsIURI* aURI, bool aIsMultiPart,
    uint32_t aInnerWindowId) {
  // Compute the image's initialization flags.
  uint32_t imageFlags = ComputeImageFlags(aURI, aMimeType, aIsMultiPart);

#ifdef DEBUG
  // Record the image load for startup performance testing.
  if (aURI->SchemeIs("resource") || aURI->SchemeIs("chrome")) {
    NotifyImageLoading(aURI);
  }
#endif

  // Select the type of image to create based on MIME type.
  if (aMimeType.EqualsLiteral(IMAGE_SVG_XML)) {
    return CreateVectorImage(aRequest, aProgressTracker, aMimeType, aURI,
                             imageFlags, aInnerWindowId);
  } else {
    return CreateRasterImage(aRequest, aProgressTracker, aMimeType, aURI,
                             imageFlags, aInnerWindowId);
  }
}

// Marks an image as having an error before returning it.
template <typename T>
static already_AddRefed<Image> BadImage(const char* aMessage,
                                        RefPtr<T>& aImage) {
  aImage->SetHasError();
  return aImage.forget();
}

/* static */
already_AddRefed<Image> ImageFactory::CreateAnonymousImage(
    const nsCString& aMimeType, uint32_t aSizeHint /* = 0 */) {
  nsresult rv;

  RefPtr<RasterImage> newImage = new RasterImage();

  RefPtr<ProgressTracker> newTracker = new ProgressTracker();
  newTracker->SetImage(newImage);
  newImage->SetProgressTracker(newTracker);

  rv = newImage->Init(aMimeType.get(), Image::INIT_FLAG_SYNC_LOAD);
  if (NS_FAILED(rv)) {
    return BadImage("RasterImage::Init failed", newImage);
  }

  rv = newImage->SetSourceSizeHint(aSizeHint);
  if (NS_FAILED(rv)) {
    return BadImage("RasterImage::SetSourceSizeHint failed", newImage);
  }

  return newImage.forget();
}

/* static */
already_AddRefed<MultipartImage> ImageFactory::CreateMultipartImage(
    Image* aFirstPart, ProgressTracker* aProgressTracker) {
  MOZ_ASSERT(aFirstPart);
  MOZ_ASSERT(aProgressTracker);

  RefPtr<MultipartImage> newImage = new MultipartImage(aFirstPart);
  aProgressTracker->SetImage(newImage);
  newImage->SetProgressTracker(aProgressTracker);

  newImage->Init();

  return newImage.forget();
}

int32_t SaturateToInt32(int64_t val) {
  if (val > INT_MAX) {
    return INT_MAX;
  }
  if (val < INT_MIN) {
    return INT_MIN;
  }

  return static_cast<int32_t>(val);
}

uint32_t GetContentSize(nsIRequest* aRequest) {
  nsCOMPtr<nsIChannel> channel(do_QueryInterface(aRequest));
  if (channel) {
    int64_t size;
    nsresult rv = channel->GetContentLength(&size);
    if (NS_SUCCEEDED(rv)) {
      return std::max(SaturateToInt32(size), 0);
    }
  }

  // Use the file size as a size hint for file channels.
  nsCOMPtr<nsIFileChannel> fileChannel(do_QueryInterface(aRequest));
  if (fileChannel) {
    nsCOMPtr<nsIFile> file;
    nsresult rv = fileChannel->GetFile(getter_AddRefs(file));
    if (NS_SUCCEEDED(rv)) {
      int64_t filesize;
      rv = file->GetFileSize(&filesize);
      if (NS_SUCCEEDED(rv)) {
        return std::max(SaturateToInt32(filesize), 0);
      }
    }
  }

  // Fallback - neither http nor file. We'll use dynamic allocation.
  return 0;
}

/* static */
already_AddRefed<Image> ImageFactory::CreateRasterImage(
    nsIRequest* aRequest, ProgressTracker* aProgressTracker,
    const nsCString& aMimeType, nsIURI* aURI, uint32_t aImageFlags,
    uint32_t aInnerWindowId) {
  MOZ_ASSERT(aProgressTracker);

  nsresult rv;

  RefPtr<RasterImage> newImage = new RasterImage(aURI);
  aProgressTracker->SetImage(newImage);
  newImage->SetProgressTracker(aProgressTracker);

  rv = newImage->Init(aMimeType.get(), aImageFlags);
  if (NS_FAILED(rv)) {
    return BadImage("RasterImage::Init failed", newImage);
  }

  newImage->SetInnerWindowID(aInnerWindowId);

  rv = newImage->SetSourceSizeHint(GetContentSize(aRequest));
  if (NS_FAILED(rv)) {
    return BadImage("RasterImage::SetSourceSizeHint failed", newImage);
  }

  return newImage.forget();
}

/* static */
already_AddRefed<Image> ImageFactory::CreateVectorImage(
    nsIRequest* aRequest, ProgressTracker* aProgressTracker,
    const nsCString& aMimeType, nsIURI* aURI, uint32_t aImageFlags,
    uint32_t aInnerWindowId) {
  MOZ_ASSERT(aProgressTracker);

  nsresult rv;

  RefPtr<VectorImage> newImage = new VectorImage(aURI);
  aProgressTracker->SetImage(newImage);
  newImage->SetProgressTracker(aProgressTracker);

  rv = newImage->Init(aMimeType.get(), aImageFlags);
  if (NS_FAILED(rv)) {
    return BadImage("VectorImage::Init failed", newImage);
  }

  newImage->SetInnerWindowID(aInnerWindowId);

  rv = newImage->OnStartRequest(aRequest);
  if (NS_FAILED(rv)) {
    return BadImage("VectorImage::OnStartRequest failed", newImage);
  }

  return newImage.forget();
}

}  // namespace image
}  // namespace mozilla