dom/xml/nsXMLPrettyPrinter.cpp

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* 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 "nsXMLPrettyPrinter.h"
#include "nsContentUtils.h"
#include "nsICSSDeclaration.h"
#include "nsIObserver.h"
#include "nsSyncLoadService.h"
#include "nsPIDOMWindow.h"
#include "nsIDOMElement.h"
#include "nsIServiceManager.h"
#include "nsNetUtil.h"
#include "mozilla/dom/Element.h"
#include "nsBindingManager.h"
#include "nsXBLService.h"
#include "nsIScriptSecurityManager.h"
#include "mozilla/Preferences.h"
#include "nsIDocument.h"
#include "nsVariant.h"
#include "mozilla/dom/CustomEvent.h"
#include "mozilla/dom/DocumentFragment.h"
#include "mozilla/dom/txMozillaXSLTProcessor.h"

using namespace mozilla;
using namespace mozilla::dom;

NS_IMPL_ISUPPORTS(nsXMLPrettyPrinter, nsIDocumentObserver, nsIMutationObserver)

nsXMLPrettyPrinter::nsXMLPrettyPrinter()
    : mDocument(nullptr), mUnhookPending(false) {}

nsXMLPrettyPrinter::~nsXMLPrettyPrinter() {
  NS_ASSERTION(!mDocument, "we shouldn't be referencing the document still");
}

nsresult nsXMLPrettyPrinter::PrettyPrint(nsIDocument* aDocument,
                                         bool* aDidPrettyPrint) {
  *aDidPrettyPrint = false;

  // Check for iframe with display:none. Such iframes don't have presshells
  nsCOMPtr<nsIPresShell> shell = aDocument->GetShell();
  if (!shell) {
    return NS_OK;
  }

  // check if we're in an invisible iframe
  nsPIDOMWindowOuter* internalWin = aDocument->GetWindow();
  nsCOMPtr<Element> frameElem;
  if (internalWin) {
    frameElem = internalWin->GetFrameElementInternal();
  }

  if (frameElem) {
    nsCOMPtr<nsICSSDeclaration> computedStyle;
    if (nsIDocument* frameOwnerDoc = frameElem->OwnerDoc()) {
      nsPIDOMWindowOuter* window = frameOwnerDoc->GetDefaultView();
      if (window) {
        nsCOMPtr<nsPIDOMWindowInner> innerWindow =
            window->GetCurrentInnerWindow();

        ErrorResult dummy;
        computedStyle =
            innerWindow->GetComputedStyle(*frameElem, EmptyString(), dummy);
        dummy.SuppressException();
      }
    }

    if (computedStyle) {
      nsAutoString visibility;
      computedStyle->GetPropertyValue(NS_LITERAL_STRING("visibility"),
                                      visibility);
      if (!visibility.EqualsLiteral("visible")) {
        return NS_OK;
      }
    }
  }

  // check the pref
  if (!Preferences::GetBool("layout.xml.prettyprint", true)) {
    return NS_OK;
  }

  // Ok, we should prettyprint. Let's do it!
  *aDidPrettyPrint = true;
  nsresult rv = NS_OK;

  // Load the XSLT
  nsCOMPtr<nsIURI> xslUri;
  rv = NS_NewURI(
      getter_AddRefs(xslUri),
      NS_LITERAL_CSTRING("chrome://global/content/xml/XMLPrettyPrint.xsl"));
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIDOMDocument> xslDocument;
  rv = nsSyncLoadService::LoadDocument(
      xslUri, nsIContentPolicy::TYPE_XSLT, nsContentUtils::GetSystemPrincipal(),
      nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_DATA_IS_NULL, nullptr, true,
      mozilla::net::RP_Unset, getter_AddRefs(xslDocument));
  NS_ENSURE_SUCCESS(rv, rv);

  // Transform the document
  RefPtr<txMozillaXSLTProcessor> transformer = new txMozillaXSLTProcessor();
  ErrorResult err;
  nsCOMPtr<nsIDocument> xslDoc = do_QueryInterface(xslDocument);
  transformer->ImportStylesheet(*xslDoc, err);
  if (NS_WARN_IF(err.Failed())) {
    return err.StealNSResult();
  }

  RefPtr<DocumentFragment> resultFragment =
      transformer->TransformToFragment(*aDocument, *aDocument, err);
  if (NS_WARN_IF(err.Failed())) {
    return err.StealNSResult();
  }

  //
  // Apply the prettprint XBL binding.
  //
  // We take some shortcuts here. In particular, we don't bother invoking the
  // contstructor (since the binding has no constructor), and we don't bother
  // calling LoadBindingDocument because it's a chrome:// URI and thus will get
  // sync loaded no matter what.
  //

  // Grab the XBL service.
  nsXBLService* xblService = nsXBLService::GetInstance();
  NS_ENSURE_TRUE(xblService, NS_ERROR_NOT_AVAILABLE);

  // Compute the binding URI.
  nsCOMPtr<nsIURI> bindingUri;
  rv = NS_NewURI(
      getter_AddRefs(bindingUri),
      NS_LITERAL_STRING(
          "chrome://global/content/xml/XMLPrettyPrint.xml#prettyprint"));
  NS_ENSURE_SUCCESS(rv, rv);

  // Compute the bound element.
  RefPtr<Element> rootElement = aDocument->GetRootElement();
  NS_ENSURE_TRUE(rootElement, NS_ERROR_UNEXPECTED);

  // Grab the system principal.
  nsCOMPtr<nsIPrincipal> sysPrincipal;
  nsContentUtils::GetSecurityManager()->GetSystemPrincipal(
      getter_AddRefs(sysPrincipal));

  // Destroy any existing frames before we unbind anonymous content.
  // Note that the shell might be Destroy'ed by now (see bug 1415541).
  if (!shell->IsDestroying()) {
    shell->DestroyFramesForAndRestyle(rootElement);
  }

  // Load the bindings.
  RefPtr<nsXBLBinding> unused;
  bool ignored;
  rv = xblService->LoadBindings(rootElement, bindingUri, sysPrincipal,
                                getter_AddRefs(unused), &ignored);
  NS_ENSURE_SUCCESS(rv, rv);

  // Fire an event at the bound element to pass it |resultFragment|.
  RefPtr<CustomEvent> event =
      NS_NewDOMCustomEvent(rootElement, nullptr, nullptr);
  MOZ_ASSERT(event);
  nsCOMPtr<nsIWritableVariant> resultFragmentVariant = new nsVariant();
  rv = resultFragmentVariant->SetAsISupports(ToSupports(resultFragment.get()));
  MOZ_ASSERT(NS_SUCCEEDED(rv));
  rv = event->InitCustomEvent(NS_LITERAL_STRING("prettyprint-dom-created"),
                              /* bubbles = */ false, /* cancelable = */ false,
                              /* detail = */ resultFragmentVariant);
  NS_ENSURE_SUCCESS(rv, rv);
  event->SetTrusted(true);
  bool dummy;
  rv = rootElement->DispatchEvent(event, &dummy);
  NS_ENSURE_SUCCESS(rv, rv);

  // Observe the document so we know when to switch to "normal" view
  aDocument->AddObserver(this);
  mDocument = aDocument;

  NS_ADDREF_THIS();

  return NS_OK;
}

void nsXMLPrettyPrinter::MaybeUnhook(nsIContent* aContent) {
  // If there either aContent is null (the document-node was modified) or
  // there isn't a binding parent we know it's non-anonymous content.
  if ((!aContent || !aContent->GetBindingParent()) && !mUnhookPending) {
    // Can't blindly to mUnhookPending after AddScriptRunner,
    // since AddScriptRunner _could_ in theory run us
    // synchronously
    mUnhookPending = true;
    nsContentUtils::AddScriptRunner(NewRunnableMethod(
        "nsXMLPrettyPrinter::Unhook", this, &nsXMLPrettyPrinter::Unhook));
  }
}

void nsXMLPrettyPrinter::Unhook() {
  mDocument->RemoveObserver(this);
  nsCOMPtr<Element> element = mDocument->GetDocumentElement();

  if (element) {
    mDocument->BindingManager()->ClearBinding(element);
  }

  mDocument = nullptr;

  NS_RELEASE_THIS();
}

void nsXMLPrettyPrinter::AttributeChanged(Element* aElement,
                                          int32_t aNameSpaceID,
                                          nsAtom* aAttribute, int32_t aModType,
                                          const nsAttrValue* aOldValue) {
  MaybeUnhook(aElement);
}

void nsXMLPrettyPrinter::ContentAppended(nsIContent* aFirstNewContent) {
  MaybeUnhook(aFirstNewContent->GetParent());
}

void nsXMLPrettyPrinter::ContentInserted(nsIContent* aChild) {
  MaybeUnhook(aChild->GetParent());
}

void nsXMLPrettyPrinter::ContentRemoved(nsIContent* aChild,
                                        nsIContent* aPreviousSibling) {
  MaybeUnhook(aChild->GetParent());
}

void nsXMLPrettyPrinter::NodeWillBeDestroyed(const nsINode* aNode) {
  mDocument = nullptr;
  NS_RELEASE_THIS();
}

nsresult NS_NewXMLPrettyPrinter(nsXMLPrettyPrinter** aPrinter) {
  *aPrinter = new nsXMLPrettyPrinter;
  NS_ADDREF(*aPrinter);
  return NS_OK;
}