author Steve Fink <>
Sun, 25 Sep 2022 18:14:15 +0000
changeset 636414 43c2ed80ba049f83b4da8549c6a5779275876a6d
parent 623963 dbb5202d0c0fed4caa1b68297f163bfd4b2a71c2
permissions -rw-r--r--
Bug 1790149 - Fix spelling of perfherder-data.json output file for awsy r=perftest-reviewers,sparky Differential Revision:

/* -*- 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 */


#include "mozilla/Maybe.h"
#include "mozilla/SVGContextPaint.h"
#include "mozilla/SVGPreserveAspectRatio.h"
#include "Units.h"

class nsIFrame;

namespace mozilla {

enum class ColorScheme : uint8_t;
class ComputedStyle;

// SVG image-specific rendering context. For imgIContainer::Draw.
// Used to pass information such as
//  - viewport and color-scheme information from CSS, and
//  - overridden attributes from an SVG <image> element
// to the image's internal SVG document when it's drawn.
class SVGImageContext {
  SVGImageContext() = default;

   * Currently it seems that the aViewportSize parameter ends up being used
   * for different things by different pieces of code, and probably in some
   * cases being used incorrectly (specifically in the case of pixel snapping
   * under the nsLayoutUtils::Draw*Image() methods).  An unfortunate result of
   * the messy code is that aViewportSize is currently a Maybe<T> since it
   * is difficult to create a utility function that consumers can use up
   * front to get the "correct" viewport size (i.e. which for compatibility
   * with the current code (bugs and all) would mean the size including all
   * the snapping and resizing magic that happens in various places under the
   * nsLayoutUtils::Draw*Image() methods on the way to DrawImageInternal
   * creating |fallbackContext|).  Using Maybe<T> allows code to pass Nothing()
   * in order to get the size that's created for |fallbackContext|.  At some
   * point we need to clean this code up, make our abstractions clear, create
   * that utility and stop using Maybe for this parameter.
  explicit SVGImageContext(
      const Maybe<CSSIntSize>& aViewportSize,
      const Maybe<SVGPreserveAspectRatio>& aPreserveAspectRatio = Nothing(),
      const Maybe<ColorScheme>& aColorScheme = Nothing())
      : mViewportSize(aViewportSize),
        mColorScheme(aColorScheme) {}

  static void MaybeStoreContextPaint(SVGImageContext& aContext,
                                     nsIFrame* aFromFrame,
                                     imgIContainer* aImgContainer);

  static void MaybeStoreContextPaint(SVGImageContext& aContext,
                                     const nsPresContext&, const ComputedStyle&,

  const Maybe<CSSIntSize>& GetViewportSize() const { return mViewportSize; }

  void SetViewportSize(const Maybe<CSSIntSize>& aSize) {
    mViewportSize = aSize;

  const Maybe<ColorScheme>& GetColorScheme() const { return mColorScheme; }

  void SetColorScheme(const Maybe<ColorScheme>& aScheme) {
    mColorScheme = aScheme;

  const Maybe<SVGPreserveAspectRatio>& GetPreserveAspectRatio() const {
    return mPreserveAspectRatio;

  void SetPreserveAspectRatio(const Maybe<SVGPreserveAspectRatio>& aPAR) {
    mPreserveAspectRatio = aPAR;

  const SVGEmbeddingContextPaint* GetContextPaint() const {
    return mContextPaint.get();

  void ClearContextPaint() { mContextPaint = nullptr; }

  bool operator==(const SVGImageContext& aOther) const {
    bool contextPaintIsEqual =
        // neither have context paint, or they have the same object:
        (mContextPaint == aOther.mContextPaint) ||
        // or both have context paint that are different but equivalent objects:
        (mContextPaint && aOther.mContextPaint &&
         *mContextPaint == *aOther.mContextPaint);

    return contextPaintIsEqual && mViewportSize == aOther.mViewportSize &&
           mPreserveAspectRatio == aOther.mPreserveAspectRatio &&
           mColorScheme == aOther.mColorScheme;

  bool operator!=(const SVGImageContext& aOther) const {
    return !(*this == aOther);

  PLDHashNumber Hash() const {
    PLDHashNumber hash = 0;
    if (mContextPaint) {
      hash = HashGeneric(hash, mContextPaint->Hash());
    return HashGeneric(hash,,

  static PLDHashNumber HashSize(const CSSIntSize& aSize) {
    return HashGeneric(aSize.width, aSize.height);
  static PLDHashNumber HashPAR(const SVGPreserveAspectRatio& aPAR) {
    return aPAR.Hash();
  static PLDHashNumber HashColorScheme(ColorScheme aScheme) {
    return HashGeneric(uint8_t(aScheme));

  // NOTE: When adding new member-vars, remember to update Hash() & operator==.
  RefPtr<SVGEmbeddingContextPaint> mContextPaint;
  Maybe<CSSIntSize> mViewportSize;
  Maybe<SVGPreserveAspectRatio> mPreserveAspectRatio;
  Maybe<ColorScheme> mColorScheme;

}  // namespace mozilla