DXR will be turned off on Tuesday, December 29th. It will redirect to Searchfox.
See the announcement on Discourse.

DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Implementation

Mercurial (6863f516ba38)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213
/* -*- 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/. */

// A class that handles style system image loads (other image loads are handled
// by the nodes in the content tree).

#ifndef mozilla_css_ImageLoader_h___
#define mozilla_css_ImageLoader_h___

#include "mozilla/CORSMode.h"
#include "nsClassHashtable.h"
#include "nsHashKeys.h"
#include "nsIFrame.h"
#include "nsIReflowCallback.h"
#include "nsTArray.h"
#include "imgIRequest.h"
#include "imgINotificationObserver.h"
#include "mozilla/Attributes.h"
#include "mozilla/net/ReferrerPolicy.h"

class imgIContainer;
class nsIFrame;
class nsPresContext;
class nsIURI;
class nsIPrincipal;

namespace mozilla {
namespace dom {
class Document;
}

namespace css {

struct URLValue;

/**
 * NOTE: All methods must be called from the main thread unless otherwise
 * specified.
 */
class ImageLoader final : public imgINotificationObserver {
 public:
  static void Init();
  static void Shutdown();

  // We also associate flags alongside frames in the request-to-frames hashmap.
  // These are used for special handling of events for requests.
  typedef uint32_t FrameFlags;
  enum {
    REQUEST_REQUIRES_REFLOW = 1u << 0,
    REQUEST_HAS_BLOCKED_ONLOAD = 1u << 1,
  };

  explicit ImageLoader(dom::Document* aDocument)
      : mDocument(aDocument), mInClone(false) {
    MOZ_ASSERT(mDocument);
  }

  NS_DECL_ISUPPORTS
  NS_DECL_IMGINOTIFICATIONOBSERVER

  void DropDocumentReference();

  imgRequestProxy* RegisterCSSImage(URLValue* aImage);

  void AssociateRequestToFrame(imgIRequest* aRequest, nsIFrame* aFrame,
                               FrameFlags aFlags);

  void DisassociateRequestFromFrame(imgIRequest* aRequest, nsIFrame* aFrame);

  void DropRequestsForFrame(nsIFrame* aFrame);

  void SetAnimationMode(uint16_t aMode);

  // The prescontext for this ImageLoader's document. We need it to be passed
  // in because this can be called during presentation destruction after the
  // presshell pointer on the document has been cleared.
  void ClearFrames(nsPresContext* aPresContext);

  static void LoadImage(URLValue* aImage, dom::Document* aLoadingDoc);

  // Cancels the image load for the given css::URLValue and deregisters
  // it from any ImageLoaders it was registered with.
  //
  // May be called from any thread.
  static void DeregisterCSSImageFromAllLoaders(URLValue* aImage);

  void FlushUseCounters();

 private:
  // This callback is used to unblock document onload after a reflow
  // triggered from an image load.
  struct ImageReflowCallback final : public nsIReflowCallback {
    RefPtr<ImageLoader> mLoader;
    WeakFrame mFrame;
    nsCOMPtr<imgIRequest> const mRequest;

    ImageReflowCallback(ImageLoader* aLoader, nsIFrame* aFrame,
                        imgIRequest* aRequest)
        : mLoader(aLoader), mFrame(aFrame), mRequest(aRequest) {}

    bool ReflowFinished() override;
    void ReflowCallbackCanceled() override;
  };

  ~ImageLoader() {}

  // We need to be able to look up the frames associated with a request (for
  // delivering notifications) and the requests associated with a frame (when
  // the frame goes away). Thus we maintain hashtables going both ways.  These
  // should always be in sync.

  struct FrameWithFlags {
    explicit FrameWithFlags(nsIFrame* aFrame) : mFrame(aFrame), mFlags(0) {
      MOZ_ASSERT(mFrame);
    }
    nsIFrame* const mFrame;
    FrameFlags mFlags;
  };

  // A helper class to compare FrameWithFlags by comparing mFrame and
  // ignoring mFlags.
  class FrameOnlyComparator {
   public:
    bool Equals(const FrameWithFlags& aElem1,
                const FrameWithFlags& aElem2) const {
      return aElem1.mFrame == aElem2.mFrame;
    }

    bool LessThan(const FrameWithFlags& aElem1,
                  const FrameWithFlags& aElem2) const {
      return aElem1.mFrame < aElem2.mFrame;
    }
  };

  typedef nsTArray<FrameWithFlags> FrameSet;
  typedef nsTArray<nsCOMPtr<imgIRequest>> RequestSet;
  typedef nsClassHashtable<nsISupportsHashKey, FrameSet> RequestToFrameMap;
  typedef nsClassHashtable<nsPtrHashKey<nsIFrame>, RequestSet>
      FrameToRequestMap;

  nsPresContext* GetPresContext();

  void RequestPaintIfNeeded(FrameSet* aFrameSet, imgIRequest* aRequest,
                            bool aForcePaint);
  void UnblockOnloadIfNeeded(nsIFrame* aFrame, imgIRequest* aRequest);
  void RequestReflowIfNeeded(FrameSet* aFrameSet, imgIRequest* aRequest);
  void RequestReflowOnFrame(FrameWithFlags* aFwf, imgIRequest* aRequest);

  nsresult OnSizeAvailable(imgIRequest* aRequest, imgIContainer* aImage);
  nsresult OnFrameComplete(imgIRequest* aRequest);
  nsresult OnImageIsAnimated(imgIRequest* aRequest);
  nsresult OnFrameUpdate(imgIRequest* aRequest);
  nsresult OnLoadComplete(imgIRequest* aRequest);

  // Helpers for DropRequestsForFrame / DisassociateRequestFromFrame above.
  void RemoveRequestToFrameMapping(imgIRequest* aRequest, nsIFrame* aFrame);
  void RemoveFrameToRequestMapping(imgIRequest* aRequest, nsIFrame* aFrame);

  // Helper for the public DeregisterCSSImageFromAllLoaders overload above.
  static void DeregisterCSSImageFromAllLoaders(uint64_t aLoadID);

  // A map of imgIRequests to the nsIFrames that are using them.
  RequestToFrameMap mRequestToFrameMap;

  // A map of nsIFrames to the imgIRequests they use.
  FrameToRequestMap mFrameToRequestMap;

  // A weak pointer to our document. Nulled out by DropDocumentReference.
  dom::Document* mDocument;

  // A map of css::URLValues, keyed by their LoadID(), to the imgRequestProxy
  // representing the load of the image for this ImageLoader's document.
  //
  // We use the LoadID() as the key since we can only access mRegisteredImages
  // on the main thread, but css::URLValues might be destroyed from other
  // threads, and we don't want to leave dangling pointers around.
  nsRefPtrHashtable<nsUint64HashKey, imgRequestProxy> mRegisteredImages;

  // Are we cloning?  If so, ignore any notifications we get.
  bool mInClone;

  // Data associated with every css::URLValue object that has had a load
  // started.
  struct ImageTableEntry {
    // Set of all ImageLoaders that have registered this css::URLValue.
    nsTHashtable<nsPtrHashKey<ImageLoader>> mImageLoaders;

    // The "canonical" image request for this css::URLValue.
    //
    // This request is held on to as long as the specified css::URLValue
    // object is, so that any image that has already started loading (or
    // has completed loading) will stay alive even if all computed values
    // referencing the image requesst have gone away.
    RefPtr<imgRequestProxy> mCanonicalRequest;
  };

  // A table of all css::URLValues that have been loaded, keyed by their
  // LoadID(), mapping them to the set of ImageLoaders they have been registered
  // in, and recording their "canonical" image request.
  //
  // We use the LoadID() as the key since we can only access sImages on the
  // main thread, but css::URLValues might be destroyed from other threads,
  // and we don't want to leave dangling pointers around.
  static nsClassHashtable<nsUint64HashKey, ImageTableEntry>* sImages;
};

}  // namespace css
}  // namespace mozilla

#endif /* mozilla_css_ImageLoader_h___ */