Serialize a subset of WebInputEvents to protobufs.

blimp/common/proto/input.proto

Index: blimp/common/proto/input.proto
diff --git a/blimp/common/proto/input.proto b/blimp/common/proto/input.proto
index 8e793e787c051d33977f39ff6cc796b64cafb9f3..4ef29b53a446e287307e66711acce29375fe8cf2 100644
--- a/blimp/common/proto/input.proto
+++ b/blimp/common/proto/input.proto
@@ -4,8 +4,8 @@
 //
 // Message definitions for the input subprotocol.
 //
-// Current definitions are just placeholders and are NOT final.
-// Feel free to modify this interface as necessary during feature work.
+// The InputMessage protobuf is a serialized representation of the
+// blink::WebInputEvent POD struct.

[Wez, 2015/11/18 02:18:32]

nit: That's an implementation detail of this early implementation, so perhaps
make clear that in general InputMessage will carry web input events, and that
currently we just serialize WebInputEvent data?

[David Trainor- moved to gerrit, 2015/11/18 08:26:30]

Done.

 
 syntax = "proto2";
 
@@ -15,24 +15,123 @@ import "common.proto";
 
 package blimp;
 
-message ClickArgs {
-  optional CoordinatePair target = 1;
+// See blink::WebGestureDevice at
+// third_party/WebKit/public/platform/WebGestureDevice.h.
+enum WebGestureDevice {

[David Trainor- moved to gerrit, 2015/11/19 00:49:43]

Ended up removing this.  We'll only be using Touchscreens for now... no point in
adding the extra field.

+  WebGestureDevice_Uninitialized = 0;
+  WebGestureDevice_Touchpad = 1;

[Wez, 2015/11/18 02:18:32]

nit: TouchPad

[David Trainor- moved to gerrit, 2015/11/18 08:26:30]

oddly they aren't capitalized in the WebKit file.  I prefer capitalizing them
too though :).

+  WebGestureDevice_Touchscreen = 2;

[Wez, 2015/11/18 02:18:32]

nit: TouchScreen

[David Trainor- moved to gerrit, 2015/11/18 08:26:30]

Done.

 }
 
-message DragArgs {
-  optional CoordinatePair origin = 1;
-  optional CoordinatePair destination = 2;
-  optional CoordinatePair elastic_overscroll = 3;
+// See blink::WebGestureEvent at third_party/WebKit/public/web/WebInputEvent.h.
+// The inner messages represent the |data| union structs in WebGestureEvent.
+message GestureArgs {
+  message Tap {
+    optional int32 tap_count = 1;
+    optional float width = 2;
+    optional float height = 3;
+  }
+
+  message TapDown {
+    optional float width = 1;
+    optional float height = 2;
+  }
+
+  message ShowPress {

[Wez, 2015/11/18 02:18:32]

nit: As below; what does this event actually mean - do we really need it?

[David Trainor- moved to gerrit, 2015/11/18 08:26:30]

Mystery!  So we rely on a Chromium class to build WebGestureEvents from
ui::MotionEvents.  I didn't want to make any assumptions on what that could kick
out so I just supported serializing the whole WebGestureEvent class.  I can
prune this down to a smaller subset of WebGestureEvents though.

[David Trainor- moved to gerrit, 2015/11/19 00:49:43]

Got rid of all of the events we didn't explicitly mention we wanted to support
:).

[Rick Byers, 2015/11/20 03:12:53]

ShowPress it the event that triggers link highlighting and the CSS :active state
(shortly after TapDown when there has been no movement, which is when the finger
actually goes down).

+    optional float width = 1;
+    optional float height = 2;
+  }
+
+  message LongPress {

[Wez, 2015/11/18 02:18:32]

nit: Where/when is this used? We omitted it from the protocol design because it
wasn't clear.

[David Trainor- moved to gerrit, 2015/11/18 08:26:30]

I don't know what Blink does with it (although this is a Blink class so I assume
- maybe naively - they support it to some extent!).  I can remove it if we don't
want it for now.

[Rick Byers, 2015/11/20 03:12:53]

LongPress is used to trigger text selection and context menus 

+    optional float width = 1;
+    optional float height = 2;
+  }
+
+  message TwoFingerTap {
+    optional float first_finger_width = 1;
+    optional float first_finger_height = 2;
+  }
+
+  message ScrollBegin {
+    optional float delta_x_hint = 1;
+    optional float delta_y_hint = 2;
+    optional bool target_viewport = 3;
+  }
+
+  message ScrollUpdate {
+    optional float delta_x = 1;
+    optional float delta_y = 2;
+    optional float velocity_x = 3;
+    optional float velocity_y = 4;
+    optional bool previous_update_in_sequence_prevented = 5;
+    optional bool prevent_propagation = 6;
+    optional bool inertial = 7;
+  }
+
+  message FlingStart {
+    optional float velocity_x = 1;
+    optional float velocity_y = 2;
+    optional bool target_viewport = 3;
+  }
+
+  message FlingCancel {
+    optional bool prevent_boosting = 1;
+  }
+
+  message PinchUpdate {
+    optional bool zoom_disabled = 1;
+    optional float scale = 2;
+  }
+
+  optional int64 x = 1;
+  optional int64 y = 2;
+  optional int64 global_x = 3;
+  optional int64 global_y = 4;
+  optional WebGestureDevice source_device = 5;
+
+  // Purposely omitting WebGestureEvent::resendingPluginId.
+
+  // Tap represents GestureTap, GestureTapUnconfirmed, and GestureDoubleTap.
+  optional Tap tap = 1000;
+  optional TapDown tap_down = 1001;
+  optional ShowPress show_press = 1002;
+  optional LongPress long_press = 1003;
+  optional TwoFingerTap two_finger_tap = 1004;
+  optional ScrollBegin scroll_begin = 1005;
+  optional ScrollUpdate scroll_update = 1006;
+  optional FlingStart fling_start = 1007;
+  optional FlingCancel fling_cancel = 1008;
+  optional PinchUpdate pinch_update = 1009;
 }
 
+// See blink::WebInputEvent at third_party/WebKit/public/web/WebInputEvent.h.
 message InputMessage {
   enum Type {
-    CLICK = 1;
-    DRAG = 2;
+    Type_Undefined = -1;
+
+    // TODO(dtrainor): Support other types of WebInputEvents in the future?
+    Type_GestureScrollBegin = 1;
+    Type_GestureScrollEnd = 2;
+    Type_GestureScrollUpdate = 3;
+    Type_GestureFlingStart = 4;
+    Type_GestureFlingCancel = 5;
+    Type_GestureShowPress = 6;
+    Type_GestureTap = 7;
+    Type_GestureTapUnconfirmed = 8;
+    Type_GestureTapDown = 9;
+    Type_GestureTapCancel = 10;
+    Type_GestureDoubleTap = 11;
+    Type_GestureTwoFingerTap = 12;
+    Type_GestureLongPress = 13;
+    Type_GestureLongTap = 14;
+    Type_GesturePinchBegin = 15;
+    Type_GesturePinchEnd = 16;
+    Type_GesturePinchUpdate = 17;
   }
+
   optional Type type = 1;
+  optional double timestamp_seconds = 2;

[Wez, 2015/11/18 02:18:32]

What is this relative to..?

[David Trainor- moved to gerrit, 2015/11/18 08:26:30]

Currently it is the time the event happened relative to the amount time the
device has been running.  I'll add a comment.

 
-  optional ClickArgs click = 1000;
-  optional DragArgs drag = 1001;
+  optional GestureArgs gesture = 1000;

[Wez, 2015/11/18 02:18:32]

Why give this such a high index? That just means it'll take more space to encode
on the wire, for no reason!

The original idea was to have the message-specific args as discrete optional
sub-messages within the top-level message, e.g:

optional GestureTapDown
optional GestureTap

etc

[David Trainor- moved to gerrit, 2015/11/18 08:26:30]

That seemed to be the standard we've been using across most of the blimp protos
I've seen.  I can drop this though.  That's a good point.
All of the gestures share some extra data (see GestureArgs common fields).  But
each gesture type has some additional data it adds.  I split this out because if
we ever support touch events or key events we'd have TouchArgs and KeyArgs which
would have whatever those need as well.

 }