dom/animation/KeyframeUtils.h

   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 file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_KeyframeUtils_h
   8 #define mozilla_KeyframeUtils_h
   9
  10 #include "mozilla/KeyframeEffectParams.h"  // For CompositeOperation
  11 #include "nsCSSPropertyID.h"
  12 #include "nsTArrayForwardDeclare.h"  // For nsTArray
  13 #include "js/RootingAPI.h"           // For JS::Handle
  14
  15 struct JSContext;
  16 class JSObject;
  17
  18 namespace mozilla {
  19 struct AnimatedPropertyID;
  20 struct AnimationProperty;
  21 class ComputedStyle;
  22
  23 enum class PseudoStyleType : uint8_t;
  24 class ErrorResult;
  25 struct Keyframe;
  26 struct PropertyStyleAnimationValuePair;
  27
  28 namespace dom {
  29 class Document;
  30 class Element;
  31 }  // namespace dom
  32 }  // namespace mozilla
  33
  34 namespace mozilla {
  35
  36 // Represents the set of property-value pairs on a Keyframe converted to
  37 // computed values.
  38 using ComputedKeyframeValues = nsTArray<PropertyStyleAnimationValuePair>;
  39
  40 /**
  41  * Utility methods for processing keyframes.
  42  */
  43 class KeyframeUtils {
  44  public:
  45   /**
  46    * Converts a JS value representing a property-indexed keyframe or a sequence
  47    * of keyframes to an array of Keyframe objects.
  48    *
  49    * @param aCx The JSContext that corresponds to |aFrames|.
  50    * @param aDocument The document to use when parsing CSS properties.
  51    * @param aFrames The JS value, provided as an optional IDL |object?| value,
  52    *   that is the keyframe list specification.
  53    * @param aContext Information about who is trying to get keyframes from the
  54    *   object, for use in error reporting.  This must be be a non-null
  55    *   pointer representing a null-terminated ASCII string.
  56    * @param aRv (out) Out-param to hold any error returned by this function.
  57    *   Must be initially empty.
  58    * @return The set of processed keyframes. If an error occurs, aRv will be
  59    *   filled-in with the appropriate error code and an empty array will be
  60    *   returned.
  61    */
  62   static nsTArray<Keyframe> GetKeyframesFromObject(
  63       JSContext* aCx, dom::Document* aDocument, JS::Handle<JSObject*> aFrames,
  64       const char* aContext, ErrorResult& aRv);
  65
  66   /**
  67    * Calculate the computed offset of keyframes by evenly distributing keyframes
  68    * with a missing offset.
  69    *
  70    * @see
  71    * https://drafts.csswg.org/web-animations/#calculating-computed-keyframes
  72    *
  73    * @param aKeyframes The set of keyframes to adjust.
  74    */
  75   static void DistributeKeyframes(nsTArray<Keyframe>& aKeyframes);
  76
  77   /**
  78    * Converts an array of Keyframe objects into an array of AnimationProperty
  79    * objects. This involves creating an array of computed values for each
  80    * longhand property and determining the offset and timing function to use
  81    * for each value.
  82    *
  83    * @param aKeyframes The input keyframes.
  84    * @param aElement The context element.
  85    * @param aStyle The computed style values.
  86    * @param aEffectComposite The composite operation specified on the effect.
  87    *   For any keyframes in |aKeyframes| that do not specify a composite
  88    *   operation, this value will be used.
  89    * @return The set of animation properties. If an error occurs, the returned
  90    *   array will be empty.
  91    */
  92   static nsTArray<AnimationProperty> GetAnimationPropertiesFromKeyframes(
  93       const nsTArray<Keyframe>& aKeyframes, dom::Element* aElement,
  94       const PseudoStyleRequest& aPseudoRequest, const ComputedStyle* aStyle,
  95       dom::CompositeOperation aEffectComposite);
  96
  97   /**
  98    * Check if the property or, for shorthands, one or more of
  99    * its subproperties, is animatable.
 100    *
 101    * @param aProperty The property to check.
 102    * @param aBackend  The style backend, Servo or Gecko, that should determine
 103    *                  if the property is animatable or not.
 104    * @return true if |aProperty| is animatable.
 105    */
 106   static bool IsAnimatableProperty(const AnimatedPropertyID& aProperty);
 107 };
 108
 109 }  // namespace mozilla
 110
 111 #endif  // mozilla_KeyframeUtils_h