Bug 1325193 - Get underlying style value in the case where the last segment is missing keyframe for accumulation of iteration composite. r=birtles

Both of tests in this patch fail and cause lots of assertions without this fix.

MozReview-Commit-ID: CFrWSlM0Us5

dom/animation/KeyframeEffectReadOnly.cpp

@@ -347,6 +347,34 @@ KeyframeEffectReadOnly::CompositeValue(
   return StyleAnimationValue();
 }
 
+StyleAnimationValue
+KeyframeEffectReadOnly::GetUnderlyingStyle(
+  nsCSSPropertyID aProperty,
+  const RefPtr<AnimValuesStyleRule>& aAnimationRule)
+{
+  StyleAnimationValue result;
+
+  if (aAnimationRule->HasValue(aProperty)) {
+    // If we have already composed style for the property, we use the style
+    // as the underlying style.
+    DebugOnly<bool> success = aAnimationRule->GetValue(aProperty, result);
+    MOZ_ASSERT(success, "AnimValuesStyleRule::GetValue should not fail");
+  } else {
+    // If we are composing with composite operation that is not 'replace'
+    // and we have not composed style for the property yet, we have to get
+    // the base style for the property.
+    RefPtr<nsStyleContext> styleContext = GetTargetStyleContext();
+    result = EffectCompositor::GetBaseStyle(aProperty,
+                                            styleContext,
+                                            *mTarget->mElement,
+                                            mTarget->mPseudoType);
+    MOZ_ASSERT(!result.IsNull(), "The base style should be set");
+    SetNeedsBaseStyle(aProperty);
+  }
+
+  return result;
+}
+
 StyleAnimationValue
 KeyframeEffectReadOnly::CompositeValue(
   nsCSSPropertyID aProperty,
@@ -374,23 +402,7 @@ KeyframeEffectReadOnly::CompositeValue(
              aCompositeOperation == CompositeOperation::Add,
              "InputValue should be null only if additive composite");
 
-  if (aAnimationRule->HasValue(aProperty)) {
-    // If we have already composed style for the property, we use the style
-    // as the underlying style.
-    DebugOnly<bool> success = aAnimationRule->GetValue(aProperty, result);
-    MOZ_ASSERT(success, "AnimValuesStyleRule::GetValue should not fail");
-  } else {
-    // If we are composing with composite operation that is not 'replace'
-    // and we have not composed style for the property yet, we have to get
-    // the base style for the property.
-    RefPtr<nsStyleContext> styleContext = GetTargetStyleContext();
-    result = EffectCompositor::GetBaseStyle(aProperty,
-                                            styleContext,
-                                            *mTarget->mElement,
-                                            mTarget->mPseudoType);
-    MOZ_ASSERT(!result.IsNull(), "The base style should be set");
-    SetNeedsBaseStyle(aProperty);
-  }
+  result = GetUnderlyingStyle(aProperty, aAnimationRule);
 
   return CompositeValue(aProperty,
                         aValueToComposite,
@@ -533,14 +545,17 @@ KeyframeEffectReadOnly::ComposeStyle(
         prop.mSegments.LastElement();
       // FIXME: Bug 1293492: Add a utility function to calculate both of
       // below StyleAnimationValues.
+      StyleAnimationValue lastValue = lastSegment.mToValue.IsNull()
+        ? GetUnderlyingStyle(prop.mProperty, aStyleRule)
+        : lastSegment.mToValue;
       fromValue =
         StyleAnimationValue::Accumulate(prop.mProperty,
-                                        lastSegment.mToValue,
+                                        lastValue,
                                         Move(fromValue),
                                         computedTiming.mCurrentIteration);
       toValue =
         StyleAnimationValue::Accumulate(prop.mProperty,
-                                        lastSegment.mToValue,
+                                        lastValue,
                                         Move(toValue),
                                         computedTiming.mCurrentIteration);
     }

dom/animation/KeyframeEffectReadOnly.h

@@ -423,6 +423,11 @@ protected:
     const StyleAnimationValue& aValueToComposite,
     CompositeOperation aCompositeOperation);
 
+  // Returns underlying style animation value for |aProperty|.
+  StyleAnimationValue GetUnderlyingStyle(
+    nsCSSPropertyID aProperty,
+    const RefPtr<AnimValuesStyleRule>& aAnimationRule);
+
   // Set a bit in mNeedsBaseStyleSet if |aProperty| can be run on the
   // compositor.
   void SetNeedsBaseStyle(nsCSSPropertyID aProperty);

dom/animation/test/style/file_missing-keyframe-on-compositor.html

@@ -490,6 +490,26 @@ promise_test(t => {
 }, 'Transform value for animation with no keyframe at offset 0 and with ' +
    'positive delay');
 
+promise_test(t => {
+  useTestRefreshMode(t);
+
+  var div = addDiv(t, { style: 'transform: translateX(100px)' });
+
+  div.animate([{ offset: 0, transform: 'translateX(200px)'}],
+              { duration: 100 * MS_PER_SEC,
+                iterationStart: 1,
+                iterationComposite: 'accumulate' });
+
+  return waitForPaintsFlushed().then(() => {
+    var transform =
+      SpecialPowers.DOMWindowUtils.getOMTAStyle(div, 'transform');
+    assert_matrix_equals(transform, 'matrix(1, 0, 0, 1, 300, 0)',
+      'Transform value for animation with no keyframe at offset 1 and its ' +
+      'iterationComposite is accumulate');
+  });
+}, 'Transform value for animation with no keyframe at offset 1 and its ' +
+   'iterationComposite is accumulate');
+
 done();
 </script>
 </body>

dom/animation/test/style/file_missing-keyframe.html

@@ -85,10 +85,24 @@ test(t => {
                                                  // (200px + 200px) * 0.5
   assert_equals(getComputedStyle(div).marginLeft, '200px',
                 'The margin-left value at 50% should be additive value of ' +
-                'of the transition and animation');
+                'the transition and animation');
 }, 'margin-left value at 50% for an animation with no keyframe at offset 1 ' +
    'is that of transition');
 
+test(t => {
+  var div = addDiv(t, { style: 'margin-left: 100px' });
+
+  var animation = div.animate([{ offset: 0, marginLeft: '200px' }],
+                              { duration: 100 * MS_PER_SEC,
+                                iterationStart: 1,
+                                iterationComposite: 'accumulate' });
+
+  assert_equals(getComputedStyle(div).marginLeft, '300px',
+                'The margin-left value should be additive value of the ' +
+                'accumulation of the initial value onto the base value ');
+}, 'margin-left value for an animation with no keyframe at offset 1 and its ' +
+   'iterationComposite is accumulate');
+
 done();
 </script>
 </body>

gfx/layers/composite/AsyncCompositionManager.cpp

@@ -613,12 +613,16 @@ SampleValue(float aPortion, const Animation& aAnimation,
     // below StyleAnimationValues.
     startValue =
       StyleAnimationValue::Accumulate(aAnimation.property(),
-                                      aLastValue,
+                                      aLastValue.IsNull()
+                                        ? aUnderlyingValue
+                                        : aLastValue,
                                       Move(startValue),
                                       aCurrentIteration);
     endValue =
       StyleAnimationValue::Accumulate(aAnimation.property(),
-                                      aLastValue,
+                                      aLastValue.IsNull()
+                                        ? aUnderlyingValue
+                                        : aLastValue,
                                       Move(endValue),
                                       aCurrentIteration);
   }