Adding synthetic touch/mouse drag [Part1]

content/browser/renderer_host/input/synthetic_smooth_move_gesture.cc

Index: content/browser/renderer_host/input/synthetic_smooth_move_gesture.cc
diff --git a/content/browser/renderer_host/input/synthetic_smooth_scroll_gesture.cc b/content/browser/renderer_host/input/synthetic_smooth_move_gesture.cc
similarity index 37%
copy from content/browser/renderer_host/input/synthetic_smooth_scroll_gesture.cc
copy to content/browser/renderer_host/input/synthetic_smooth_move_gesture.cc
index 59f4af31fd891bafa6b19d6532dd1855a0f4d499..cdece1da45ec0884536c2f3c7702911e53924961 100644
--- a/content/browser/renderer_host/input/synthetic_smooth_scroll_gesture.cc
+++ b/content/browser/renderer_host/input/synthetic_smooth_move_gesture.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "content/browser/renderer_host/input/synthetic_smooth_scroll_gesture.h"
+#include "content/browser/renderer_host/input/synthetic_smooth_move_gesture.h"
 
 #include "base/logging.h"
 #include "ui/gfx/geometry/point_f.h"
@@ -29,31 +29,36 @@ gfx::Vector2dF ProjectScalarOntoVector(
 
 }  // namespace
 
-SyntheticSmoothScrollGesture::SyntheticSmoothScrollGesture(
-    const SyntheticSmoothScrollGestureParams& params)
-    : params_(params),
-      gesture_source_type_(SyntheticGestureParams::DEFAULT_INPUT),
-      state_(SETUP) {}
+SyntheticSmoothMoveGesture::SyntheticSmoothMoveGesture(
+    InputType gesture_source_type,

[Sami, 2015/02/19 11:59:05]

input_type would be a better name for this parameter.

[ssid, 2015/02/20 10:58:54]

Done.

+    gfx::PointF start_point,
+    std::vector<gfx::Vector2d> move_distances,
+    int speed_in_pixels_s,
+    bool prevent_fling)
+    : current_move_segment_start_position_(start_point),
+      gesture_source_type_(gesture_source_type),
+      state_(SETUP),
+      move_distances_(move_distances),
+      speed_in_pixels_s_(speed_in_pixels_s),
+      prevent_fling_(prevent_fling) {
+}
 
-SyntheticSmoothScrollGesture::~SyntheticSmoothScrollGesture() {}
+SyntheticSmoothMoveGesture::~SyntheticSmoothMoveGesture() {}
 
-SyntheticGesture::Result SyntheticSmoothScrollGesture::ForwardInputEvents(
+SyntheticGesture::Result SyntheticSmoothMoveGesture::ForwardInputEvents(
     const base::TimeTicks& timestamp, SyntheticGestureTarget* target) {
   if (state_ == SETUP) {
-    gesture_source_type_ = params_.gesture_source_type;
-    if (gesture_source_type_ == SyntheticGestureParams::DEFAULT_INPUT)
-      gesture_source_type_ = target->GetDefaultSyntheticGestureSourceType();
-
     state_ = STARTED;
-    current_scroll_segment_ = -1;
-    current_scroll_segment_stop_time_ = timestamp;
+    current_move_segment_ = -1;
+    current_move_segment_stop_time_ = timestamp;
   }
 
-  DCHECK_NE(gesture_source_type_, SyntheticGestureParams::DEFAULT_INPUT);
-  if (gesture_source_type_ == SyntheticGestureParams::TOUCH_INPUT)
+  if (gesture_source_type_ == TOUCH_INPUT)

[Sami, 2015/02/19 11:59:05]

I think this would be a little neater as a switch statement.

[ssid, 2015/02/20 10:58:54]

Done.

     ForwardTouchInputEvents(timestamp, target);
-  else if (gesture_source_type_ == SyntheticGestureParams::MOUSE_INPUT)
-    ForwardMouseInputEvents(timestamp, target);
+  else if (gesture_source_type_ == MOUSE_CLICK)
+    ForwardMouseClickInputEvents(timestamp, target);
+  else if (gesture_source_type_ == MOUSE_WHEEL)
+    ForwardMouseWheelInputEvents(timestamp, target);
   else
     return SyntheticGesture::GESTURE_SOURCE_TYPE_NOT_IMPLEMENTED;
 
@@ -61,18 +66,17 @@ SyntheticGesture::Result SyntheticSmoothScrollGesture::ForwardInputEvents(
                           : SyntheticGesture::GESTURE_RUNNING;
 }
 
-void SyntheticSmoothScrollGesture::ForwardTouchInputEvents(
+void SyntheticSmoothMoveGesture::ForwardTouchInputEvents(
     const base::TimeTicks& timestamp, SyntheticGestureTarget* target) {
   base::TimeTicks event_timestamp = timestamp;
   switch (state_) {
     case STARTED:
-      if (ScrollIsNoOp()) {
+      if (MoveIsNoOp()) {

[picksi, 2015/02/19 11:50:18]

As discussed, switch statements that contain code can explode in size. If
possible please pull each case statement's block of code out into its own
function.

[ssid, 2015/02/20 10:58:54]

This cleanup can be done in the next CL :). which can also include making the
input for scroll as float numbers.

         state_ = DONE;
         break;
       }
       AddTouchSlopToFirstDistance(target);

[Sami, 2015/02/19 11:59:05]

I think we need to make this configurable too, since a touch drag shouldn't
include slop.

[ssid, 2015/02/20 10:58:54]

Done.

-      ComputeNextScrollSegment();
-      current_scroll_segment_start_position_ = params_.anchor;
+      ComputeNextMoveSegment();
       PressTouchPoint(target, event_timestamp);
       state_ = MOVING;
       break;
@@ -81,12 +85,12 @@ void SyntheticSmoothScrollGesture::ForwardTouchInputEvents(
       gfx::Vector2dF delta = GetPositionDeltaAtTime(event_timestamp);
       MoveTouchPoint(target, delta, event_timestamp);
 
-      if (FinishedCurrentScrollSegment(event_timestamp)) {
-        if (!IsLastScrollSegment()) {
-          current_scroll_segment_start_position_ +=
-              params_.distances[current_scroll_segment_];
-          ComputeNextScrollSegment();
-        } else if (params_.prevent_fling) {
+      if (FinishedCurrentMoveSegment(event_timestamp)) {
+        if (!IsLastMoveSegment()) {
+          current_move_segment_start_position_ +=
+              move_distances_[current_move_segment_];
+          ComputeNextMoveSegment();
+        } else if (prevent_fling_) {
           state_ = STOPPING;
         } else {
           ReleaseTouchPoint(target, event_timestamp);
@@ -95,9 +99,9 @@ void SyntheticSmoothScrollGesture::ForwardTouchInputEvents(
       }
     } break;
     case STOPPING:
-      if (timestamp - current_scroll_segment_stop_time_ >=
+      if (timestamp - current_move_segment_stop_time_ >=
           target->PointerAssumedStoppedTime()) {
-        event_timestamp = current_scroll_segment_stop_time_ +
+        event_timestamp = current_move_segment_stop_time_ +
                           target->PointerAssumedStoppedTime();
         ReleaseTouchPoint(target, event_timestamp);
         state_ = DONE;
@@ -105,24 +109,24 @@ void SyntheticSmoothScrollGesture::ForwardTouchInputEvents(
       break;
     case SETUP:
       NOTREACHED()
-          << "State STARTED invalid for synthetic scroll using touch input.";
+          << "State SETUP invalid for synthetic scroll using touch input.";
     case DONE:
       NOTREACHED()
           << "State DONE invalid for synthetic scroll using touch input.";
   }
 }
 
-void SyntheticSmoothScrollGesture::ForwardMouseInputEvents(
+void SyntheticSmoothMoveGesture::ForwardMouseWheelInputEvents(
     const base::TimeTicks& timestamp, SyntheticGestureTarget* target) {
   switch (state_) {
     case STARTED:
-      if (ScrollIsNoOp()) {
+      if (MoveIsNoOp()) {
         state_ = DONE;
         break;
       }
-      ComputeNextScrollSegment();
+      ComputeNextMoveSegment();
       state_ = MOVING;
-      // Fall through to forward the first event.
+    // Fall through to forward the first event.
     case MOVING: {
       // Even though WebMouseWheelEvents take floating point deltas,
       // internally the scroll position is stored as an integer. We therefore
@@ -130,19 +134,19 @@ void SyntheticSmoothScrollGesture::ForwardMouseInputEvents(
       // internal scrolling state. This ensures that when the gesture has
       // finished we've scrolled exactly the specified distance.
       base::TimeTicks event_timestamp = ClampTimestamp(timestamp);
-      gfx::Vector2dF current_scroll_segment_total_delta =
+      gfx::Vector2dF current_move_segment_total_delta =
           GetPositionDeltaAtTime(event_timestamp);
       gfx::Vector2d delta_discrete =
-          FloorTowardZero(current_scroll_segment_total_delta -
-                          current_scroll_segment_total_delta_discrete_);
+          FloorTowardZero(current_move_segment_total_delta -
+                          current_move_segment_total_delta_discrete_);
       ForwardMouseWheelEvent(target, delta_discrete, event_timestamp);
-      current_scroll_segment_total_delta_discrete_ += delta_discrete;
+      current_move_segment_total_delta_discrete_ += delta_discrete;
 
-      if (FinishedCurrentScrollSegment(event_timestamp)) {
-        if (!IsLastScrollSegment()) {
-          current_scroll_segment_total_delta_discrete_ = gfx::Vector2d();
-          ComputeNextScrollSegment();
-          ForwardMouseInputEvents(timestamp, target);
+      if (FinishedCurrentMoveSegment(event_timestamp)) {
+        if (!IsLastMoveSegment()) {
+          current_move_segment_total_delta_discrete_ = gfx::Vector2d();
+          ComputeNextMoveSegment();
+          ForwardMouseWheelInputEvents(timestamp, target);
         } else {
           state_ = DONE;
         }
@@ -150,121 +154,198 @@ void SyntheticSmoothScrollGesture::ForwardMouseInputEvents(
     } break;
     case SETUP:
       NOTREACHED()
-          << "State STARTED invalid for synthetic scroll using touch input.";
+          << "State SETUP invalid for synthetic scroll using mouse "
+             "wheel input.";
     case STOPPING:
       NOTREACHED()
-          << "State STOPPING invalid for synthetic scroll using touch input.";
+          << "State STOPPING invalid for synthetic scroll using mouse "
+             "wheel input.";
     case DONE:
       NOTREACHED()
-          << "State DONE invalid for synthetic scroll using touch input.";
+          << "State DONE invalid for synthetic scroll using mouse wheel input.";
+  }
+}
+
+void SyntheticSmoothMoveGesture::ForwardMouseClickInputEvents(
+    const base::TimeTicks& timestamp,
+    SyntheticGestureTarget* target) {
+  base::TimeTicks event_timestamp = timestamp;
+  switch (state_) {
+    case STARTED:
+      if (MoveIsNoOp()) {
+        state_ = DONE;
+        break;
+      }
+      ComputeNextMoveSegment();
+      PressMousePoint(target, event_timestamp);
+      state_ = MOVING;
+    // Fall through to forward the first event.

[Sami, 2015/02/19 11:59:05]

Thanks for adding this comment.

+    case MOVING: {
+      base::TimeTicks event_timestamp = ClampTimestamp(timestamp);
+      gfx::Vector2dF delta = GetPositionDeltaAtTime(event_timestamp);
+      MoveMousePoint(target, delta, event_timestamp);
+
+      if (FinishedCurrentMoveSegment(event_timestamp)) {
+        if (!IsLastMoveSegment()) {
+          current_move_segment_start_position_ +=
+              move_distances_[current_move_segment_];
+          ComputeNextMoveSegment();
+        } else {
+          ReleaseMousePoint(target, event_timestamp);
+          state_ = DONE;
+        }
+      }
+    } break;
+    case STOPPING:
+      NOTREACHED()
+          << "State STOPPING invalid for synthetic drag using mouse input.";
+    case SETUP:
+      NOTREACHED()
+          << "State SETUP invalid for synthetic drag using mouse input.";
+    case DONE:
+      NOTREACHED()
+          << "State DONE invalid for synthetic drag using mouse input.";
   }
 }
 

[picksi, 2015/02/19 11:50:18]

Design thought: Is this case statement inside out? The same switch appears in
three functions. Should there be one switch that selects the implementation
inside each case (via a baseclass and some virtuals?), rather than this model? 

[ssid, 2015/02/20 10:58:54]

Each of the switch statements does mostly different things. I think it is better
to have switch at this level rather than a common switch statement, which does
different actions with 3 'if' conditions under each case. The code can become
confusing to understand, for example, if you are looking for what does
forwardEvent for MOUSE_DRAG do, you will need to checkthe parts of switch
statements with corresponding condition for MOUSE_DRAG. What do you think?

[picksi, 2015/02/20 11:51:18]

If/When a later refactor removes the 'case' code out into individual functions
the switch statements will become a lot clearer; at this point it will become
obvious if they are all very similar and need refactoring. Let's wait and see.

-void SyntheticSmoothScrollGesture::ForwardTouchEvent(
+void SyntheticSmoothMoveGesture::ForwardTouchEvent(
     SyntheticGestureTarget* target, const base::TimeTicks& timestamp) {
   touch_event_.timeStampSeconds = ConvertTimestampToSeconds(timestamp);
 
   target->DispatchInputEventToPlatform(touch_event_);
 }
 
-void SyntheticSmoothScrollGesture::ForwardMouseWheelEvent(
+void SyntheticSmoothMoveGesture::ForwardMouseWheelEvent(
     SyntheticGestureTarget* target,
     const gfx::Vector2dF& delta,
     const base::TimeTicks& timestamp) const {
   blink::WebMouseWheelEvent mouse_wheel_event =
       SyntheticWebMouseWheelEventBuilder::Build(delta.x(), delta.y(), 0, false);
 
-  mouse_wheel_event.x = params_.anchor.x();
-  mouse_wheel_event.y = params_.anchor.y();
+  mouse_wheel_event.x = current_move_segment_start_position_.x();
+  mouse_wheel_event.y = current_move_segment_start_position_.y();
 
   mouse_wheel_event.timeStampSeconds = ConvertTimestampToSeconds(timestamp);
 
   target->DispatchInputEventToPlatform(mouse_wheel_event);
 }
 
-void SyntheticSmoothScrollGesture::PressTouchPoint(
+void SyntheticSmoothMoveGesture::PressTouchPoint(
     SyntheticGestureTarget* target, const base::TimeTicks& timestamp) {
-  DCHECK_EQ(current_scroll_segment_, 0);
-  touch_event_.PressPoint(params_.anchor.x(), params_.anchor.y());
+  DCHECK_EQ(current_move_segment_, 0);
+  touch_event_.PressPoint(current_move_segment_start_position_.x(),
+                          current_move_segment_start_position_.y());
   ForwardTouchEvent(target, timestamp);
 }
 
-void SyntheticSmoothScrollGesture::MoveTouchPoint(
+void SyntheticSmoothMoveGesture::MoveTouchPoint(
     SyntheticGestureTarget* target,
     const gfx::Vector2dF& delta,
     const base::TimeTicks& timestamp) {
-  DCHECK_GE(current_scroll_segment_, 0);
-  DCHECK_LT(current_scroll_segment_,
-            static_cast<int>(params_.distances.size()));
-  gfx::PointF touch_position = current_scroll_segment_start_position_ + delta;
+  DCHECK_GE(current_move_segment_, 0);
+  DCHECK_LT(current_move_segment_, static_cast<int>(move_distances_.size()));
+  gfx::PointF touch_position = current_move_segment_start_position_ + delta;
   touch_event_.MovePoint(0, touch_position.x(), touch_position.y());
   ForwardTouchEvent(target, timestamp);
 }
 
-void SyntheticSmoothScrollGesture::ReleaseTouchPoint(
+void SyntheticSmoothMoveGesture::ReleaseTouchPoint(
     SyntheticGestureTarget* target, const base::TimeTicks& timestamp) {
-  DCHECK_EQ(current_scroll_segment_,
-            static_cast<int>(params_.distances.size()) - 1);
+  DCHECK_EQ(current_move_segment_,
+            static_cast<int>(move_distances_.size()) - 1);
   touch_event_.ReleasePoint(0);
   ForwardTouchEvent(target, timestamp);
 }
 
-void SyntheticSmoothScrollGesture::AddTouchSlopToFirstDistance(
+void SyntheticSmoothMoveGesture::PressMousePoint(SyntheticGestureTarget* target,
+                                       const base::TimeTicks& timestamp) {
+  DCHECK(gesture_source_type_ == MOUSE_CLICK);
+  blink::WebMouseEvent mouse_event = SyntheticWebMouseEventBuilder::Build(
+      blink::WebInputEvent::MouseDown, current_move_segment_start_position_.x(),
+      current_move_segment_start_position_.y(), 0);
+  mouse_event.clickCount = 1;
+  mouse_event.timeStampSeconds = ConvertTimestampToSeconds(timestamp);
+  target->DispatchInputEventToPlatform(mouse_event);
+}
+
+void SyntheticSmoothMoveGesture::ReleaseMousePoint(
+    SyntheticGestureTarget* target, const base::TimeTicks& timestamp) {
+  DCHECK(gesture_source_type_ == MOUSE_CLICK);
+  gfx::PointF mouse_position =
+      current_move_segment_start_position_ + GetPositionDeltaAtTime(timestamp);
+  blink::WebMouseEvent mouse_event = SyntheticWebMouseEventBuilder::Build(
+      blink::WebInputEvent::MouseUp, mouse_position.x(), mouse_position.y(), 0);
+  mouse_event.timeStampSeconds = ConvertTimestampToSeconds(timestamp);
+  target->DispatchInputEventToPlatform(mouse_event);
+}
+
+void SyntheticSmoothMoveGesture::MoveMousePoint(SyntheticGestureTarget* target,
+                                           const gfx::Vector2dF& delta,
+                                           const base::TimeTicks& timestamp) {
+  gfx::PointF mouse_position = current_move_segment_start_position_ + delta;
+  DCHECK(gesture_source_type_ == MOUSE_CLICK);
+  blink::WebMouseEvent mouse_event = SyntheticWebMouseEventBuilder::Build(
+      blink::WebInputEvent::MouseMove, mouse_position.x(), mouse_position.y(),
+      0);
+  mouse_event.button = blink::WebMouseEvent::ButtonLeft;
+  mouse_event.timeStampSeconds = ConvertTimestampToSeconds(timestamp);
+  target->DispatchInputEventToPlatform(mouse_event);
+}
+
+void SyntheticSmoothMoveGesture::AddTouchSlopToFirstDistance(
     SyntheticGestureTarget* target) {
-  DCHECK_GE(params_.distances.size(), 1ul);
-  gfx::Vector2d& first_scroll_distance = params_.distances[0];
-  DCHECK_GT(first_scroll_distance.Length(), 0);
-  first_scroll_distance += CeilFromZero(ProjectScalarOntoVector(
-      target->GetTouchSlopInDips(), first_scroll_distance));
+  DCHECK_GE(move_distances_.size(), 1ul);
+  gfx::Vector2d& first_move_distance = move_distances_[0];
+  DCHECK_GT(first_move_distance.Length(), 0);
+  first_move_distance += CeilFromZero(ProjectScalarOntoVector(
+      target->GetTouchSlopInDips(), first_move_distance));
 }
 
-gfx::Vector2dF SyntheticSmoothScrollGesture::GetPositionDeltaAtTime(
+gfx::Vector2dF SyntheticSmoothMoveGesture::GetPositionDeltaAtTime(
     const base::TimeTicks& timestamp) const {
   // Make sure the final delta is correct. Using the computation below can lead
   // to issues with floating point precision.
-  if (FinishedCurrentScrollSegment(timestamp))
-    return params_.distances[current_scroll_segment_];
+  if (FinishedCurrentMoveSegment(timestamp))
+    return move_distances_[current_move_segment_];
 
   float delta_length =
-      params_.speed_in_pixels_s *
-      (timestamp - current_scroll_segment_start_time_).InSecondsF();
+      speed_in_pixels_s_ *
+      (timestamp - current_move_segment_start_time_).InSecondsF();
   return ProjectScalarOntoVector(delta_length,
-                                 params_.distances[current_scroll_segment_]);
+                                 move_distances_[current_move_segment_]);
 }
 
-void SyntheticSmoothScrollGesture::ComputeNextScrollSegment() {
-  current_scroll_segment_++;
-  DCHECK_LT(current_scroll_segment_,
-            static_cast<int>(params_.distances.size()));
+void SyntheticSmoothMoveGesture::ComputeNextMoveSegment() {
+  current_move_segment_++;

[picksi, 2015/02/19 11:50:18]

Nit/Comment: FYI This feels dangerous to me! It would be much neater to have a
class that you pass a time and it figures out which segment that time lies in
and returns the correct position. Stepping through segments is error prone &
assumes that time always travels forward (!).

+  DCHECK_LT(current_move_segment_,
+            static_cast<int>(move_distances_.size()));
   int64 total_duration_in_us = static_cast<int64>(
-      1e6 * (params_.distances[current_scroll_segment_].Length() /
-             params_.speed_in_pixels_s));
+      1e6 *
+      (move_distances_[current_move_segment_].Length() / speed_in_pixels_s_));
   DCHECK_GT(total_duration_in_us, 0);
-  current_scroll_segment_start_time_ = current_scroll_segment_stop_time_;
-  current_scroll_segment_stop_time_ =
-      current_scroll_segment_start_time_ +
+  current_move_segment_start_time_ = current_move_segment_stop_time_;
+  current_move_segment_stop_time_ =
+      current_move_segment_start_time_ +
       base::TimeDelta::FromMicroseconds(total_duration_in_us);
 }
 
-base::TimeTicks SyntheticSmoothScrollGesture::ClampTimestamp(
+base::TimeTicks SyntheticSmoothMoveGesture::ClampTimestamp(
     const base::TimeTicks& timestamp) const {
-  return std::min(timestamp, current_scroll_segment_stop_time_);
+  return std::min(timestamp, current_move_segment_stop_time_);
 }
 
-bool SyntheticSmoothScrollGesture::FinishedCurrentScrollSegment(
+bool SyntheticSmoothMoveGesture::FinishedCurrentMoveSegment(
     const base::TimeTicks& timestamp) const {
-  return timestamp >= current_scroll_segment_stop_time_;
+  return timestamp >= current_move_segment_stop_time_;
 }
 
-bool SyntheticSmoothScrollGesture::IsLastScrollSegment() const {
-  DCHECK_LT(current_scroll_segment_,
-            static_cast<int>(params_.distances.size()));
-  return current_scroll_segment_ ==
-         static_cast<int>(params_.distances.size()) - 1;
+bool SyntheticSmoothMoveGesture::IsLastMoveSegment() const {
+  DCHECK_LT(current_move_segment_, static_cast<int>(move_distances_.size()));
+  return current_move_segment_ == static_cast<int>(move_distances_.size()) - 1;
 }
 
-bool SyntheticSmoothScrollGesture::ScrollIsNoOp() const {
-  return params_.distances.size() == 0 || params_.distances[0].IsZero();
+bool SyntheticSmoothMoveGesture::MoveIsNoOp() const {
+  return move_distances_.size() == 0 || move_distances_[0].IsZero();
 }
 
 }  // namespace content