Bug 1426194 - Part 1: Correspond to the keyframes which have same offset. r=pbro

The problem with this bug was that it did not correspond to animations that
have multiple keyframes with the same offset.

In summary graph, although we were changing the resolution for the graph
creation by the distance of offset between keyframes, as the calculation of
resolution between keyframes with equivalent offset was infinite, generation
was not completed and it was in a state of freezing.
In here, in case of zero distance of offsets, we make avoiding to affect to
changing the resolution.

In addition, the detail graph did not display correctly.
For example, there is an animation below.

div.animate(
  [
    {
      offset: 0,
      opacity: 1,
    },
    {
      offset: 0.5,
      opacity: 0.5,
    },
    {
      offset: 0.5,
      opacity: 0.1,
    },
    {
      offset: 1,
      opacity: 1,
    },
  ],
  1000
);

In this animation, opacity changes from 1 to 0.5 during 0 - 499ms, from 0.1 to 1
after 500ms.
So, opacity at offset 0.5 behaves 0.5 during 0 - 499ms, 0.1 after 500ms.
Since current animation inspector creates the graph with computed value of the
time of offset, the opacity of offset 0.5 always is 0.1 in the example,
was not correct.
As a solution, same to the actual animation work, create the graph between each
keyframes with range that from start keyframe offset time to just before the
time of end keyframe offset time.
Also, in same offsets, connects between just before the time of the offset time
and the offset time.
So, in the example, we separate as below, then calculate the each coordinates,
then combine as graph shape.

1: 0 ~ 499.999ms
2: 499.999 ~ 500ms (same offsets)
3: 500 ~ 999.999ms
4: 1000ms

MozReview-Commit-ID: p4Cn2N9iFt

--HG--
extra : rebase_source : 0f175fa0b7a3c882171e59a6e4a94bb4802e96d2

devtools/client/animationinspector/components/keyframes.js

@@ -166,13 +166,16 @@ function renderEasingHint(parentEl, segments, helper) {
     const startKeyframe = keyframes[i];
     const endKeyframe = keyframes[i + 1];
     const endTime = endKeyframe.offset * duration;
-
     const keyframeSegments = [];
+
     for (; indexOfSegments < segments.length; indexOfSegments++) {
       const segment = segments[indexOfSegments];
       keyframeSegments.push(segment);
 
-      if (segment.x === endTime) {
+      if (startKeyframe.offset === endKeyframe.offset) {
+        keyframeSegments.push(segments[++indexOfSegments]);
+        break;
+      } else if (segment.x === endTime) {
         break;
       }
     }

devtools/client/animationinspector/graph-helper.js

@@ -265,20 +265,30 @@ ProgressGraphHelper.prototype = {
     for (let i = 0; i < this.devtoolsKeyframes.length - 1; i++) {
       const startKeyframe = this.devtoolsKeyframes[i];
       const endKeyframe = this.devtoolsKeyframes[i + 1];
+      const startTime = startKeyframe.offset * duration;
+      const endTime = endKeyframe.offset * duration;
 
-      let threshold = getPreferredProgressThreshold(startKeyframe.easing);
-      if (threshold !== DEFAULT_MIN_PROGRESS_THRESHOLD) {
-        // We should consider the keyframe's duration.
-        threshold *= (endKeyframe.offset - startKeyframe.offset);
+      if (startKeyframe.offset === endKeyframe.offset) {
+        const startSegment = this.getSegment(startTime - BOUND_EXCLUDING_TIME);
+        startSegment.x = startTime;
+        const endSegment = this.getSegment(endTime);
+        segments.push(startSegment, endSegment);
+      } else {
+        let threshold = getPreferredProgressThreshold(startKeyframe.easing);
+
+        if (threshold !== DEFAULT_MIN_PROGRESS_THRESHOLD) {
+          // We should consider the keyframe's duration.
+          threshold *= (endKeyframe.offset - startKeyframe.offset);
+        }
+
+        segments.push(...createPathSegments(startTime, endTime - BOUND_EXCLUDING_TIME,
+                                            minSegmentDuration, threshold, this));
       }
-
-      const startTime = parseFloat((startKeyframe.offset * duration).toFixed(3));
-      const endTime = parseFloat((endKeyframe.offset * duration).toFixed(3));
-
-      segments.push(...createPathSegments(startTime, endTime,
-                                          minSegmentDuration, threshold, this));
     }
 
+    const lastKeyframe = this.devtoolsKeyframes[this.devtoolsKeyframes.length - 1];
+    const lastTime = lastKeyframe.offset * duration;
+    segments.push(this.getSegment(lastTime));
     return segments;
   },
 
@@ -385,7 +395,7 @@ SummaryGraphHelper.prototype = {
       // include the easing in keyframes as well. Although the computed timing progress
       // is not affected by the easing in keyframes at all, computed value reflects that.
       frames = keyframes.map(keyframe => {
-        if (previousOffset) {
+        if (previousOffset && previousOffset != keyframe.offset) {
           const interval = keyframe.offset - previousOffset;
           durationResolution = Math.max(durationResolution, Math.ceil(1 / interval));
         }

devtools/client/animationinspector/test/head.js

@@ -596,9 +596,13 @@ function isPassingThrough(pathSegList, x, y) {
  * @return <stop> element.
  */
 function findStopElement(svgEl, offset) {
-  return [...svgEl.querySelectorAll("stop")].find(stopEl => {
-    return stopEl.getAttribute("offset") == offset;
-  });
+  for (const stopEl of svgEl.querySelectorAll("stop")) {
+    if (offset <= parseFloat(stopEl.getAttribute("offset"))) {
+      return stopEl;
+    }
+  }
+
+  return null;
 }
 
 /*