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 (2cd3752963fc)

VCS Links

ResponsiveImageCandidate

ResponsiveImageSelector

eCandidateType

Macros

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
/* -*- 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/. */

#ifndef mozilla_dom_responsiveimageselector_h__
#define mozilla_dom_responsiveimageselector_h__

#include "nsAutoPtr.h"
#include "nsISupports.h"
#include "nsIContent.h"
#include "nsString.h"
#include "nsCycleCollectionParticipant.h"

class nsMediaQuery;
class nsCSSValue;

namespace mozilla {
namespace dom {

class ResponsiveImageCandidate;

class ResponsiveImageSelector
{
  friend class ResponsiveImageCandidate;
public:
  NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(ResponsiveImageSelector)
  NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(ResponsiveImageSelector)

  explicit ResponsiveImageSelector(nsIContent* aContent);
  explicit ResponsiveImageSelector(nsIDocument* aDocument);

  // NOTE ABOUT CURRENT SELECTION
  //
  // The best candidate is selected lazily when GetSelectedImage*() is
  // called, or when SelectImage() is called explicitly. This result
  // is then cached until either invalidated by further Set*() calls,
  // or explicitly by replaced by SelectImage(aReselect = true).
  //
  // Because the selected image depends on external variants like
  // viewport size and device pixel ratio, the time at which image
  // selection occurs can affect the result.


  // Given a srcset string, parse and replace current candidates (does not
  // replace default source)
  bool SetCandidatesFromSourceSet(const nsAString & aSrcSet);

  // Fill the source sizes from a valid sizes descriptor. Returns false if
  // descriptor is invalid.
  bool SetSizesFromDescriptor(const nsAString & aSizesDescriptor);

  // Set the default source, treated as the least-precedence 1.0 density source.
  void SetDefaultSource(const nsAString& aURLString);

  uint32_t NumCandidates(bool aIncludeDefault = true);

  // If this was created for a specific content. May be null if we were only
  // created for a document.
  nsIContent *Content();

  // The document we were created for, or the owner document of the content if
  // we were created for a specific nsIContent.
  nsIDocument *Document();

  // Get the url and density for the selected best candidate. These
  // implicitly cause an image to be selected if necessary.
  already_AddRefed<nsIURI> GetSelectedImageURL();
  // Returns false if there is no selected image
  bool GetSelectedImageURLSpec(nsAString& aResult);
  double GetSelectedImageDensity();

  // Runs image selection now if necessary. If an image has already
  // been choosen, takes no action unless aReselect is true.
  //
  // aReselect - Always re-run selection, replacing the previously
  //             choosen image.
  // return - true if the selected image result changed.
  bool SelectImage(bool aReselect = false);

protected:
  virtual ~ResponsiveImageSelector();

private:
  // Append a candidate unless its selector is duplicated by a higher priority
  // candidate
  void AppendCandidateIfUnique(const ResponsiveImageCandidate &aCandidate);

  // Append a default candidate with this URL if necessary. Does not check if
  // the array already contains one, use SetDefaultSource instead.
  void MaybeAppendDefaultCandidate();

  // Get index of selected candidate, triggering selection if necessary.
  int GetSelectedCandidateIndex();

  // Forget currently selected candidate. (See "NOTE ABOUT CURRENT SELECTION"
  // above.)
  void ClearSelectedCandidate();

  // Compute a density from a Candidate width. Returns false if sizes were not
  // specified for this selector.
  //
  // aContext is the presContext to use for current viewport sizing, null will
  // use the associated content's context.
  bool ComputeFinalWidthForCurrentViewport(double* aWidth);

  nsCOMPtr<nsINode> mOwnerNode;
  // The cached URL for default candidate.
  nsString mDefaultSourceURL;
  // If this array contains an eCandidateType_Default, it should be the last
  // element, such that the Setters can preserve/replace it respectively.
  nsTArray<ResponsiveImageCandidate> mCandidates;
  int mSelectedCandidateIndex;
  // The cached resolved URL for mSelectedCandidateIndex, such that we only
  // resolve the absolute URL at selection time
  nsCOMPtr<nsIURI> mSelectedCandidateURL;

  nsTArray< nsAutoPtr<nsMediaQuery> > mSizeQueries;
  nsTArray<nsCSSValue> mSizeValues;
};

class ResponsiveImageCandidate {
public:
  ResponsiveImageCandidate();
  ResponsiveImageCandidate(const nsAString& aURLString, double aDensity);

  void SetURLSpec(const nsAString& aURLString);
  // Set this as a default-candidate. This behaves the same as density 1.0, but
  // has a differing type such that it can be replaced by subsequent
  // SetDefaultSource calls.
  void SetParameterDefault();

  // Set this candidate as a by-density candidate with specified density.
  void SetParameterAsDensity(double aDensity);
  void SetParameterAsComputedWidth(int32_t aWidth);

  void SetParameterInvalid();

  // Consume descriptors from a string defined by aIter and aIterEnd, adjusts
  // aIter to the end of data consumed.
  // Returns false if descriptors string is invalid, but still parses to the end
  // of descriptors microsyntax.
  bool ConsumeDescriptors(nsAString::const_iterator& aIter,
                          const nsAString::const_iterator& aIterEnd);

  // Check if our parameter (which does not include the url) is identical
  bool HasSameParameter(const ResponsiveImageCandidate & aOther) const;

  const nsAString& URLString() const;

  // Compute and return the density relative to a selector.
  double Density(ResponsiveImageSelector *aSelector) const;
  // If the width is already known. Useful when iterating over candidates to
  // avoid having each call re-compute the width.
  double Density(double aMatchingWidth) const;

  // If this selector is computed from the selector's matching width.
  bool IsComputedFromWidth() const;

  enum eCandidateType {
    eCandidateType_Invalid,
    eCandidateType_Density,
    // Treated as 1.0 density, but a separate type so we can update the
    // responsive candidates and default separately
    eCandidateType_Default,
    eCandidateType_ComputedFromWidth
  };

  eCandidateType Type() const { return mType; }

private:

  nsString mURLString;
  eCandidateType mType;
  union {
    double mDensity;
    int32_t mWidth;
  } mValue;
};

} // namespace dom
} // namespace mozilla

#endif // mozilla_dom_responsiveimageselector_h__