gecko-dev/image/ImageURL.h

153 lines
4.2 KiB
C++

/* -*- 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/. */
#ifndef mozilla_image_ImageURL_h
#define mozilla_image_ImageURL_h
#include "nsIURI.h"
#include "MainThreadUtils.h"
#include "nsNetUtil.h"
#include "mozilla/HashFunctions.h"
#include "nsHashKeys.h"
#include "nsProxyRelease.h"
namespace mozilla {
namespace image {
class ImageCacheKey;
/** ImageURL
*
* nsStandardURL is not threadsafe, so this class is created to hold only the
* necessary URL data required for image loading and decoding.
*
* Note: Although several APIs have the same or similar prototypes as those
* found in nsIURI/nsStandardURL, the class does not implement nsIURI. This is
* intentional; functionality is limited, and is only useful for imagelib code.
* By not implementing nsIURI, external code cannot unintentionally be given an
* nsIURI pointer with this limited class behind it; instead, conversion to a
* fully implemented nsIURI is required (e.g. through NS_NewURI).
*/
class ImageURL
{
public:
explicit ImageURL(nsIURI* aURI, nsresult& aRv)
: mURI(new nsMainThreadPtrHolder<nsIURI>(aURI))
{
MOZ_ASSERT(NS_IsMainThread(), "Cannot use nsIURI off main thread!");
aRv = aURI->GetSpec(mSpec);
NS_ENSURE_SUCCESS_VOID(aRv);
aRv = aURI->GetScheme(mScheme);
NS_ENSURE_SUCCESS_VOID(aRv);
aRv = aURI->GetRef(mRef);
NS_ENSURE_SUCCESS_VOID(aRv);
}
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ImageURL)
nsresult GetSpec(nsACString& result)
{
result = mSpec;
return NS_OK;
}
/// A weak pointer to the URI spec for this ImageURL. For logging only.
const char* Spec() const { return mSpec.get(); }
enum TruncatedSpecStatus {
FitsInto1k,
TruncatedTo1k
};
TruncatedSpecStatus GetSpecTruncatedTo1k(nsACString& result)
{
static const size_t sMaxTruncatedLength = 1024;
if (sMaxTruncatedLength >= mSpec.Length()) {
result = mSpec;
return FitsInto1k;
}
result = Substring(mSpec, 0, sMaxTruncatedLength);
return TruncatedTo1k;
}
nsresult GetScheme(nsACString& result)
{
result = mScheme;
return NS_OK;
}
nsresult SchemeIs(const char* scheme, bool* result)
{
NS_PRECONDITION(scheme, "scheme is null");
NS_PRECONDITION(result, "result is null");
*result = mScheme.Equals(scheme);
return NS_OK;
}
nsresult GetRef(nsACString& result)
{
result = mRef;
return NS_OK;
}
already_AddRefed<nsIURI> ToIURI()
{
nsCOMPtr<nsIURI> newURI = mURI.get();
return newURI.forget();
}
bool operator==(const ImageURL& aOther) const
{
// Note that we don't need to consider mScheme and mRef, because they're
// already represented in mSpec.
return mSpec == aOther.mSpec;
}
bool HasSameRef(const ImageURL& aOther) const
{
return mRef == aOther.mRef;
}
private:
friend class ImageCacheKey;
uint32_t ComputeHash(const Maybe<uint64_t>& aBlobSerial) const
{
if (aBlobSerial) {
// For blob URIs, we hash the serial number of the underlying blob, so that
// different blob URIs which point to the same blob share a cache entry. We
// also include the ref portion of the URI to support media fragments which
// requires us to create different Image objects even if the source data is
// the same.
return HashGeneric(*aBlobSerial, HashString(mRef));
}
// For non-blob URIs, we hash the URI spec.
return HashString(mSpec);
}
nsMainThreadPtrHandle<nsIURI> mURI;
// Since this is a basic storage class, no duplication of spec parsing is
// included in the functionality. Instead, the class depends upon the
// parsing implementation in the nsIURI class used in object construction.
// This means each field is stored separately, but since only a few are
// required, this small memory tradeoff for threadsafe usage should be ok.
nsAutoCString mSpec;
nsAutoCString mScheme;
nsAutoCString mRef;
~ImageURL() { }
};
} // namespace image
} // namespace mozilla
#endif // mozilla_image_ImageURL_h