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SVGImageContext.h (5549B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #ifndef LAYOUT_SVG_SVGIMAGECONTEXT_H_
      8 #define LAYOUT_SVG_SVGIMAGECONTEXT_H_
      9 
     10 #include "Units.h"
     11 #include "mozilla/Maybe.h"
     12 #include "mozilla/SVGContextPaint.h"
     13 #include "mozilla/SVGPreserveAspectRatio.h"
     14 
     15 class nsIFrame;
     16 class nsISVGPaintContext;
     17 
     18 namespace mozilla {
     19 
     20 enum class ColorScheme : uint8_t;
     21 class ComputedStyle;
     22 
     23 // SVG image-specific rendering context. For imgIContainer::Draw.
     24 // Used to pass information such as
     25 //  - viewport and color-scheme information from CSS, and
     26 //  - overridden attributes from an SVG <image> element
     27 // to the image's internal SVG document when it's drawn.
     28 class SVGImageContext {
     29 public:
     30  SVGImageContext() = default;
     31 
     32  /**
     33   * Currently it seems that the aViewportSize parameter ends up being used
     34   * for different things by different pieces of code, and probably in some
     35   * cases being used incorrectly (specifically in the case of pixel snapping
     36   * under the nsLayoutUtils::Draw*Image() methods).  An unfortunate result of
     37   * the messy code is that aViewportSize is currently a Maybe<T> since it
     38   * is difficult to create a utility function that consumers can use up
     39   * front to get the "correct" viewport size (i.e. which for compatibility
     40   * with the current code (bugs and all) would mean the size including all
     41   * the snapping and resizing magic that happens in various places under the
     42   * nsLayoutUtils::Draw*Image() methods on the way to DrawImageInternal
     43   * creating |fallbackContext|).  Using Maybe<T> allows code to pass Nothing()
     44   * in order to get the size that's created for |fallbackContext|.  At some
     45   * point we need to clean this code up, make our abstractions clear, create
     46   * that utility and stop using Maybe for this parameter.
     47   */
     48  explicit SVGImageContext(
     49      const Maybe<CSSIntSize>& aViewportSize,
     50      const Maybe<SVGPreserveAspectRatio>& aPreserveAspectRatio = Nothing(),
     51      const Maybe<ColorScheme>& aColorScheme = Nothing())
     52      : mViewportSize(aViewportSize),
     53        mPreserveAspectRatio(aPreserveAspectRatio),
     54        mColorScheme(aColorScheme) {}
     55 
     56  static void MaybeStoreContextPaint(SVGImageContext& aContext,
     57                                     nsIFrame* aFromFrame,
     58                                     imgIContainer* aImgContainer);
     59 
     60  static void MaybeStoreContextPaint(SVGImageContext& aContext,
     61                                     const nsPresContext&, const ComputedStyle&,
     62                                     imgIContainer*);
     63 
     64  static void MaybeStoreContextPaint(SVGImageContext& aContext,
     65                                     nsISVGPaintContext* aPaintContext,
     66                                     imgIContainer* aImgContainer);
     67 
     68  const Maybe<CSSIntSize>& GetViewportSize() const { return mViewportSize; }
     69 
     70  void SetViewportSize(const Maybe<CSSIntSize>& aSize) {
     71    mViewportSize = aSize;
     72  }
     73 
     74  const Maybe<ColorScheme>& GetColorScheme() const { return mColorScheme; }
     75 
     76  void SetColorScheme(const Maybe<ColorScheme>& aScheme) {
     77    mColorScheme = aScheme;
     78  }
     79 
     80  const Maybe<SVGPreserveAspectRatio>& GetPreserveAspectRatio() const {
     81    return mPreserveAspectRatio;
     82  }
     83 
     84  void SetPreserveAspectRatio(const Maybe<SVGPreserveAspectRatio>& aPAR) {
     85    mPreserveAspectRatio = aPAR;
     86  }
     87 
     88  const SVGEmbeddingContextPaint* GetContextPaint() const {
     89    return mContextPaint.get();
     90  }
     91 
     92  SVGEmbeddingContextPaint* GetOrCreateContextPaint() {
     93    if (!mContextPaint) {
     94      mContextPaint = MakeRefPtr<SVGEmbeddingContextPaint>();
     95    }
     96 
     97    return mContextPaint.get();
     98  }
     99 
    100  void ClearContextPaint() { mContextPaint = nullptr; }
    101 
    102  bool operator==(const SVGImageContext& aOther) const {
    103    bool contextPaintIsEqual =
    104        // neither have context paint, or they have the same object:
    105        (mContextPaint == aOther.mContextPaint) ||
    106        // or both have context paint that are different but equivalent objects:
    107        (mContextPaint && aOther.mContextPaint &&
    108         *mContextPaint == *aOther.mContextPaint);
    109 
    110    return contextPaintIsEqual && mViewportSize == aOther.mViewportSize &&
    111           mPreserveAspectRatio == aOther.mPreserveAspectRatio &&
    112           mColorScheme == aOther.mColorScheme;
    113  }
    114 
    115  bool operator!=(const SVGImageContext&) const = default;
    116 
    117  PLDHashNumber Hash() const {
    118    PLDHashNumber hash = 0;
    119    if (mContextPaint) {
    120      hash = HashGeneric(hash, mContextPaint->Hash());
    121    }
    122    return HashGeneric(hash, mViewportSize.map(HashSize).valueOr(0),
    123                       mPreserveAspectRatio.map(HashPAR).valueOr(0),
    124                       mColorScheme.map(HashColorScheme).valueOr(0));
    125  }
    126 
    127 private:
    128  static PLDHashNumber HashSize(const CSSIntSize& aSize) {
    129    return HashGeneric(aSize.width, aSize.height);
    130  }
    131  static PLDHashNumber HashPAR(const SVGPreserveAspectRatio& aPAR) {
    132    return aPAR.Hash();
    133  }
    134  static PLDHashNumber HashColorScheme(ColorScheme aScheme) {
    135    return HashGeneric(uint8_t(aScheme));
    136  }
    137 
    138  // NOTE: When adding new member-vars, remember to update Hash() & operator==.
    139  RefPtr<SVGEmbeddingContextPaint> mContextPaint;
    140  Maybe<CSSIntSize> mViewportSize;
    141  Maybe<SVGPreserveAspectRatio> mPreserveAspectRatio;
    142  Maybe<ColorScheme> mColorScheme;
    143 };
    144 
    145 }  // namespace mozilla
    146 
    147 #endif  // LAYOUT_SVG_SVGIMAGECONTEXT_H_