[Android] Composited selection handle rendering

content/browser/renderer_host/input/touch_handle.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// 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/touch_handle.h"
+
+#include <cmath>
+
+namespace content {
+
+namespace {
+
+// Maximum duration of a fade sequence.
+const double kFadeDurationMs = 200;
+
+// Maximum amount of travel for a fade sequence. This avoids handle "ghosting"
+// when the handle is moving rapidly while the fade is active.
+const double kFadeDistanceSquared = 20.f * 20.f;
+
+}  // namespace
+
+// Responsible for rendering a selection or insertion handle for text editing.
+TouchHandle::TouchHandle(TouchHandleClient* client,
+                         TouchHandleOrientation orientation)
+    : drawable_(client->CreateDrawable()),
+      client_(client),
+      orientation_(orientation),
+      deferred_orientation_(TOUCH_HANDLE_ORIENTATION_UNDEFINED),
+      alpha_(0.f),
+      animate_deferred_fade_(false),
+      enabled_(true),
+      is_visible_(false),
+      is_dragging_(false) {
+  DCHECK_NE(orientation, TOUCH_HANDLE_ORIENTATION_UNDEFINED);
+  drawable_->SetEnabled(enabled_);
+  drawable_->SetOrientation(orientation_);
+  drawable_->SetAlpha(alpha_);
+  drawable_->SetVisible(is_visible_);
+  drawable_->SetFocus(position_);
+}
+
+TouchHandle::~TouchHandle() {
+}
+
+void TouchHandle::SetEnabled(bool enabled) {
+  if (enabled_ == enabled)
+    return;
+  if (!enabled) {
+    EndDrag();
+    EndFade();
+  }
+  enabled_ = enabled;
+  drawable_->SetEnabled(enabled);
+}
+
+void TouchHandle::SetVisible(bool visible, AnimationStyle animation_style) {
+  DCHECK(enabled_);
+  if (is_visible_ == visible)
+    return;
+
+  is_visible_ = visible;
+
+  // Handle repositioning may have been deferred while previously invisible.
+  if (visible)
+    drawable_->SetFocus(position_);
+
+  bool animate = animation_style != ANIMATION_NONE;
+  if (is_dragging_) {
+    animate_deferred_fade_ = animate;
+    return;
+  }
+
+  if (animate)
+    BeginFade();
+  else
+    EndFade();
+}
+
+void TouchHandle::SetPosition(const gfx::PointF& position) {
+  DCHECK(enabled_);
+  if (position_ == position)
+    return;
+  position_ = position;
+  // Suppress repositioning a handle while invisible or fading out to prevent it
+  // from "ghosting" outside the visible bounds. The position will be pushed to
+  // the drawable when the handle regains visibility (see |SetVisible()|).
+  if (is_visible_)
+    drawable_->SetFocus(position_);
+}
+
+void TouchHandle::SetOrientation(TouchHandleOrientation orientation) {
+  DCHECK(enabled_);
+  DCHECK_NE(orientation, TOUCH_HANDLE_ORIENTATION_UNDEFINED);
+  if (is_dragging_) {
+    deferred_orientation_ = orientation;
+    return;
+  }
+  DCHECK_EQ(deferred_orientation_, TOUCH_HANDLE_ORIENTATION_UNDEFINED);
+  if (orientation_ == orientation)
+    return;
+
+  orientation_ = orientation;
+  drawable_->SetOrientation(orientation);
+}
+
+bool TouchHandle::WillHandleTouchEvent(const ui::MotionEvent& event) {
+  if (!enabled_)
+    return false;
+
+  if (!is_dragging_ && event.GetAction() != ui::MotionEvent::ACTION_DOWN)
+    return false;
+
+  switch (event.GetAction()) {
+    case ui::MotionEvent::ACTION_DOWN: {
+      gfx::PointF touch_position = gfx::PointF(event.GetX(), event.GetY());
+      if (!is_visible_ || !drawable_->ContainsPoint(touch_position))
+        return false;
+      touch_down_position_ = touch_position;
+      touch_to_focus_offset_ = position_ - touch_down_position_;
+      touch_down_time_ = event.GetEventTime();
+      BeginDrag();
+    } break;
+
+    case ui::MotionEvent::ACTION_MOVE: {
+      gfx::PointF new_position =
+          gfx::PointF(event.GetX(), event.GetY()) + touch_to_focus_offset_;
+      client_->OnHandleDragUpdate(*this, new_position);
+    } break;
+
+    case ui::MotionEvent::ACTION_UP: {
+      // TODO(jdduke): Use the platform touch slop distance and tap delay to
+      // properly detect a tap, crbug.com/394093.
+      base::TimeDelta delay = event.GetEventTime() - touch_down_time_;
+      if (delay < base::TimeDelta::FromMilliseconds(180))
+        client_->OnHandleTapped(*this);
+
+      EndDrag();
+    } break;
+
+    case ui::MotionEvent::ACTION_CANCEL:
+      EndDrag();
+      break;
+
+    default:
+      break;
+  };
+  return true;
+}
+
+bool TouchHandle::Animate(base::TimeTicks frame_time) {
+  if (fade_end_time_ == base::TimeTicks())
+    return false;
+
+  DCHECK(enabled_);
+
+  float time_u =
+      1.f - (fade_end_time_ - frame_time).InMillisecondsF() / kFadeDurationMs;
+  float position_u =
+      (position_ - fade_start_position_).LengthSquared() / kFadeDistanceSquared;
+  float u = std::max(time_u, position_u);
+  SetAlpha(is_visible_ ? u : 1.f - u);
+
+  if (u >= 1.f) {
+    EndFade();
+    return false;
+  }
+
+  return true;
+}
+
+void TouchHandle::BeginDrag() {
+  DCHECK(enabled_);
+  if (is_dragging_)
+    return;
+  EndFade();
+  is_dragging_ = true;
+  client_->OnHandleDragBegin(*this);
+}
+
+void TouchHandle::EndDrag() {
+  DCHECK(enabled_);
+  if (!is_dragging_)
+    return;
+
+  is_dragging_ = false;
+  client_->OnHandleDragEnd(*this);
+
+  if (deferred_orientation_ != TOUCH_HANDLE_ORIENTATION_UNDEFINED) {
+    TouchHandleOrientation deferred_orientation = deferred_orientation_;
+    deferred_orientation_ = TOUCH_HANDLE_ORIENTATION_UNDEFINED;
+    SetOrientation(deferred_orientation);
+  }
+
+  if (animate_deferred_fade_) {
+    BeginFade();
+  } else {
+    // As drawable visibility assignment is deferred while dragging, push the
+    // change by forcing fade completion.
+    EndFade();
+  }
+}
+
+void TouchHandle::BeginFade() {
+  DCHECK(enabled_);
+  DCHECK(!is_dragging_);
+  animate_deferred_fade_ = false;
+  const float target_alpha = is_visible_ ? 1.f : 0.f;
+  if (target_alpha == alpha_) {
+    EndFade();
+    return;
+  }
+
+  drawable_->SetVisible(true);
+  fade_end_time_ = base::TimeTicks::Now() +
+                   base::TimeDelta::FromMillisecondsD(
+                       kFadeDurationMs * std::abs(target_alpha - alpha_));
+  fade_start_position_ = position_;
+  client_->SetNeedsAnimate();
+}
+
+void TouchHandle::EndFade() {
+  DCHECK(enabled_);
+  animate_deferred_fade_ = false;
+  fade_end_time_ = base::TimeTicks();
+  SetAlpha(is_visible_ ? 1.f : 0.f);
+  drawable_->SetVisible(is_visible_);
+}
+
+void TouchHandle::SetAlpha(float alpha) {
+  alpha = std::max(0.f, std::min(1.f, alpha));
+  if (alpha_ == alpha)
+    return;
+  alpha_ = alpha;
+  drawable_->SetAlpha(alpha);
+}
+
+}  // namespace content