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183 lines
6.4 KiB
C
183 lines
6.4 KiB
C
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_dom_responsiveimageselector_h__
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#define mozilla_dom_responsiveimageselector_h__
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#include "nsISupports.h"
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#include "nsIContent.h"
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#include "nsString.h"
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#include "nsCycleCollectionParticipant.h"
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class nsMediaQuery;
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class nsCSSValue;
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namespace mozilla {
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namespace dom {
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class ResponsiveImageCandidate;
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class ResponsiveImageSelector
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{
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friend class ResponsiveImageCandidate;
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public:
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NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(ResponsiveImageSelector)
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NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(ResponsiveImageSelector)
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explicit ResponsiveImageSelector(nsIContent* aContent);
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explicit ResponsiveImageSelector(nsIDocument* aDocument);
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// NOTE ABOUT CURRENT SELECTION
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//
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// The best candidate is selected lazily when GetSelectedImage*() is
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// called, or when SelectImage() is called explicitly. This result
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// is then cached until either invalidated by further Set*() calls,
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// or explicitly by replaced by SelectImage(aReselect = true).
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//
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// Because the selected image depends on external variants like
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// viewport size and device pixel ratio, the time at which image
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// selection occurs can affect the result.
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// Given a srcset string, parse and replace current candidates (does not
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// replace default source)
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bool SetCandidatesFromSourceSet(const nsAString & aSrcSet);
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// Fill the source sizes from a valid sizes descriptor. Returns false if
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// descriptor is invalid.
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bool SetSizesFromDescriptor(const nsAString & aSizesDescriptor);
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// Set the default source, treated as the least-precedence 1.0 density source.
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void SetDefaultSource(const nsAString& aURLString);
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uint32_t NumCandidates(bool aIncludeDefault = true);
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// If this was created for a specific content. May be null if we were only
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// created for a document.
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nsIContent *Content();
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// The document we were created for, or the owner document of the content if
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// we were created for a specific nsIContent.
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nsIDocument *Document();
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// Get the url and density for the selected best candidate. These
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// implicitly cause an image to be selected if necessary.
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already_AddRefed<nsIURI> GetSelectedImageURL();
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// Returns false if there is no selected image
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bool GetSelectedImageURLSpec(nsAString& aResult);
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double GetSelectedImageDensity();
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// Runs image selection now if necessary. If an image has already
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// been choosen, takes no action unless aReselect is true.
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//
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// aReselect - Always re-run selection, replacing the previously
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// choosen image.
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// return - true if the selected image result changed.
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bool SelectImage(bool aReselect = false);
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protected:
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virtual ~ResponsiveImageSelector();
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private:
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// Append a candidate unless its selector is duplicated by a higher priority
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// candidate
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void AppendCandidateIfUnique(const ResponsiveImageCandidate &aCandidate);
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// Append a default candidate with this URL. Does not check if the array
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// already contains one, use SetDefaultSource instead.
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void AppendDefaultCandidate(const nsAString& aURLString);
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// Get index of selected candidate, triggering selection if necessary.
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int GetSelectedCandidateIndex();
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// Forget currently selected candidate. (See "NOTE ABOUT CURRENT SELECTION"
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// above.)
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void ClearSelectedCandidate();
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// Compute a density from a Candidate width. Returns false if sizes were not
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// specified for this selector.
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//
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// aContext is the presContext to use for current viewport sizing, null will
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// use the associated content's context.
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bool ComputeFinalWidthForCurrentViewport(int32_t *aWidth);
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nsCOMPtr<nsINode> mOwnerNode;
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// If this array contains an eCandidateType_Default, it should be the last
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// element, such that the Setters can preserve/replace it respectively.
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nsTArray<ResponsiveImageCandidate> mCandidates;
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int mSelectedCandidateIndex;
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// The cached resolved URL for mSelectedCandidateIndex, such that we only
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// resolve the absolute URL at selection time
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nsCOMPtr<nsIURI> mSelectedCandidateURL;
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nsTArray< nsAutoPtr<nsMediaQuery> > mSizeQueries;
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nsTArray<nsCSSValue> mSizeValues;
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};
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class ResponsiveImageCandidate {
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public:
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ResponsiveImageCandidate();
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ResponsiveImageCandidate(const nsAString& aURLString, double aDensity);
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void SetURLSpec(const nsAString& aURLString);
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// Set this as a default-candidate. This behaves the same as density 1.0, but
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// has a differing type such that it can be replaced by subsequent
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// SetDefaultSource calls.
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void SetParameterDefault();
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// Set this candidate as a by-density candidate with specified density.
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void SetParameterAsDensity(double aDensity);
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void SetParameterAsComputedWidth(int32_t aWidth);
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void SetParameterInvalid();
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// Consume descriptors from a string defined by aIter and aIterEnd, adjusts
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// aIter to the end of data consumed.
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// Returns false if descriptors string is invalid, but still parses to the end
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// of descriptors microsyntax.
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bool ConsumeDescriptors(nsAString::const_iterator& aIter,
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const nsAString::const_iterator& aIterEnd);
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// Check if our parameter (which does not include the url) is identical
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bool HasSameParameter(const ResponsiveImageCandidate & aOther) const;
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const nsAString& URLString() const;
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// Compute and return the density relative to a selector.
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double Density(ResponsiveImageSelector *aSelector) const;
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// If the width is already known. Useful when iterating over candidates to
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// avoid having each call re-compute the width.
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double Density(int32_t aMatchingWidth) const;
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// If this selector is computed from the selector's matching width.
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bool IsComputedFromWidth() const;
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enum eCandidateType {
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eCandidateType_Invalid,
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eCandidateType_Density,
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// Treated as 1.0 density, but a separate type so we can update the
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// responsive candidates and default separately
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eCandidateType_Default,
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eCandidateType_ComputedFromWidth
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};
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eCandidateType Type() const { return mType; }
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private:
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nsString mURLString;
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eCandidateType mType;
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union {
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double mDensity;
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int32_t mWidth;
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} mValue;
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};
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} // namespace dom
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} // namespace mozilla
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#endif // mozilla_dom_responsiveimageselector_h__
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