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