Drop all timeline seeks outside of the seekable range.

Source/core/html/shadow/MediaControlElements.cpp

Index: Source/core/html/shadow/MediaControlElements.cpp
diff --git a/Source/core/html/shadow/MediaControlElements.cpp b/Source/core/html/shadow/MediaControlElements.cpp
index 2439bb62e1be659462f2a824b329da9646fcf7fd..d0ab0dfc2dc79baef3ef0019049bb51fa975192f 100644
--- a/Source/core/html/shadow/MediaControlElements.cpp
+++ b/Source/core/html/shadow/MediaControlElements.cpp
@@ -37,6 +37,7 @@
 #include "core/frame/LocalFrame.h"
 #include "core/html/HTMLVideoElement.h"
 #include "core/html/MediaController.h"
+#include "core/html/TimeRanges.h"
 #include "core/html/shadow/MediaControls.h"
 #include "core/html/track/TextTrack.h"
 #include "core/html/track/vtt/VTTRegionList.h"
@@ -57,6 +58,14 @@ static const AtomicString& getMediaControlTimeRemainingDisplayElementShadowPseud
 // This is the duration from mediaControls.css
 static const double fadeOutDuration = 0.3;
 
+// Snap seeks to the nearest seekable() range if they're <= this percentage of the duration apart.
+// I.e., if the seekable() range is [4s, 5s] and the duration 10s, clicks on the timeline >= 3s or <= 6s
+// would snap to 4 and 5 respectively.  Clicks outside of those ranges would be dropped.
+//
+// This ensures accidental clicks don't cause annoying timeline jumps, or worse, restart the entire
+// playback process when only a seek to zero is available.
+static const double snapPercentageForSeeks = 10 / 100.0;

[philipj_slow, 2014/10/01 11:14:22]

This is 0.1 and not a percentage :)

+
 static bool isUserInteractionEvent(Event* event)
 {
     const AtomicString& type = event->type();
@@ -418,10 +427,21 @@ void MediaControlTimelineElement::defaultEventHandler(Event* event)
     if (event->type() == EventTypeNames::input) {
         // FIXME: This will need to take the timeline offset into consideration
         // once that concept is supported, see https://crbug.com/312699
-        if (mediaElement().controller())
+        if (mediaElement().controller()) {
             mediaElement().controller()->setCurrentTime(time);

[philipj_slow, 2014/10/01 11:14:22]

Should the same rule not apply to a media element slaved to a controller?
MediaController::seekable() also returns TimeRanges, so it shouldn't be too
messy to deal with both.

[DaleCurtis, 2014/10/14 18:06:26]

Done.

[philipj_slow, 2014/10/16 18:52:51]

We appear to have miscommunicated :) I mean that the MediaController::seekable()
is also checked in the else branch. My rule of thumb is that a MediaController
with only a single HTMLMediaElement should behave like the HTMLMediaElement
itself, which can be done in this case.

[DaleCurtis, 2014/10/16 19:51:50]

Sorry I still don't understand. :| Are you saying I should check if a media
controller only represents a single element and call it directly in that case?
If so, how can I tell if the controller only represents one element?

The new code always uses the controller if it's present, otherwise it uses the
media element directly.

[philipj_slow, 2014/10/16 20:03:18]

Oops, sloppy reading on my part! You've already done what I asked for, I just
didn't notice because I was expecting the indentation level to change. Sorry.

-        else
-            mediaElement().setCurrentTime(time, IGNORE_EXCEPTION);
+        } else {
+            // Only pass through seeks that are within the seekable range or close enough that we're sure
+            // the user didn't make an accidental click.
+            RefPtrWillBeRawPtr<TimeRanges> seekableRanges = mediaElement().seekable();
+            if (seekableRanges->contain(time)) {
+                mediaElement().setCurrentTime(time, IGNORE_EXCEPTION);
+            } else {
+                const double duration = getFloatingPointAttribute(maxAttr);

[philipj_slow, 2014/10/01 11:14:22]

It took me a while to realize that the duration is in fact stored in the max
attribute, going directly to mediaElement().duration() would be more clear I
think.

+                const double nearestTime = seekableRanges->nearest(time, mediaElement().currentTime());
+                if (duration && std::abs(time - nearestTime) / duration <= snapPercentageForSeeks)
+                    mediaElement().setCurrentTime(time, IGNORE_EXCEPTION);
+            }
+        }
     }
 
     RenderSlider* slider = toRenderSlider(renderer());