Add Aura handles to be used in unified touch selection

ui/touch_selection/touch_handle_drawable_aura.cc

+// Copyright 2015 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 "ui/touch_selection/touch_handle_drawable_aura.h"
+
+#include "ui/aura/window.h"
+#include "ui/aura/window_targeter.h"
+#include "ui/aura_extra/image_window_delegate.h"
+#include "ui/base/cursor/cursor.h"
+#include "ui/base/hit_test.h"
+#include "ui/base/resource/resource_bundle.h"
+#include "ui/events/event.h"
+#include "ui/gfx/canvas.h"
+#include "ui/gfx/geometry/rect_conversions.h"
+#include "ui/resources/grit/ui_resources.h"
+
+namespace ui {
+namespace {
+
+// The distance by which a handle image is offset from the focal point (i.e.
+// text baseline) downwards.
+const int kSelectionHandleVerticalVisualOffset = 2;
+
+// The padding around the selection handle image can be used to extend the
+// handle window so that touch events near the selection handle image are
+// targeted to the selection handle window.
+const int kSelectionHandlePadding = 0;
+
+// Epsilon value used to compare float values to zero.
+const float kEpsilon = 1e-8f;
+
+// Returns the appropriate handle image based on the handle orientation.
+gfx::Image* GetHandleImage(TouchHandleOrientation orientation) {
+  int resource_id = 0;
+  switch (orientation) {
+    case TouchHandleOrientation::LEFT:
+      resource_id = IDR_TEXT_SELECTION_HANDLE_LEFT;
+      break;
+    case TouchHandleOrientation::CENTER:
+      resource_id = IDR_TEXT_SELECTION_HANDLE_CENTER;
+      break;
+    case TouchHandleOrientation::RIGHT:
+      resource_id = IDR_TEXT_SELECTION_HANDLE_RIGHT;
+      break;
+    case TouchHandleOrientation::UNDEFINED:
+      NOTREACHED() << "Invalid touch handle bound type.";
+      return nullptr;
+  };
+  return &ResourceBundle::GetSharedInstance().GetImageNamed(resource_id);
+}
+
+bool IsNearlyZero(float value) {
+  return std::abs(value) < kEpsilon;
+}
+
+}  // namespace
+
+TouchHandleDrawableAura::TouchHandleDrawableAura(aura::Window* parent)
+    : window_delegate_(new aura_extra::ImageWindowDelegate),
+      window_(new aura::Window(window_delegate_)),
+      enabled_(false),
+      alpha_(0),
+      orientation_(TouchHandleOrientation::UNDEFINED) {
+  window_delegate_->set_image_offset(gfx::Vector2d(kSelectionHandlePadding,
+                                                   kSelectionHandlePadding));
+  window_delegate_->set_background_color(SK_ColorTRANSPARENT);
+  window_->SetTransparent(true);
+  window_->Init(LAYER_TEXTURED);
+  window_->set_owned_by_parent(false);
+  window_->set_ignore_events(true);
+  parent->AddChild(window_.get());
+}
+
+TouchHandleDrawableAura::~TouchHandleDrawableAura() {
+}
+
+void TouchHandleDrawableAura::UpdateBounds() {
+  gfx::RectF new_bounds = relative_bounds_;
+  new_bounds.Offset(focal_position_.x(), focal_position_.y());
+  window_->SetBounds(gfx::ToEnclosingRect(new_bounds));
+}
+
+bool TouchHandleDrawableAura::IsVisible() const {
+  return enabled_ && !IsNearlyZero(alpha_);
+}
+
+void TouchHandleDrawableAura::SetEnabled(bool enabled) {
+  if (enabled == enabled_)
+    return;
+
+  enabled_ = enabled;
+  if (IsVisible())
+    window_->Show();
+  else
+    window_->Hide();
+}
+
+void TouchHandleDrawableAura::SetOrientation(
+    TouchHandleOrientation orientation) {
+  if (orientation_ == orientation)
+    return;
+  orientation_ = orientation;
+  gfx::Image* image = GetHandleImage(orientation);
+  window_delegate_->SetImage(*image);
+
+  // Calculate the relative bounds.
+  gfx::Size image_size = image->Size();
+  int window_width = image_size.width() + 2 * kSelectionHandlePadding;
+  int window_height = image_size.height() + 2 * kSelectionHandlePadding;
+  // Due to the shape of the handle images, the window is aligned differently to
+  // the selection bound depending on the orientation.
+  int window_left = 0;
+  switch (orientation) {
+    case TouchHandleOrientation::LEFT:
+      window_left = -image_size.width() - kSelectionHandlePadding;
+      break;
+    case TouchHandleOrientation::RIGHT:
+      window_left = -kSelectionHandlePadding;
+      break;
+    case TouchHandleOrientation::CENTER:
+      window_left = -window_width / 2;
+      break;
+    case TouchHandleOrientation::UNDEFINED:
+      NOTREACHED() << "Undefined handle orientation.";
+      break;
+  };
+  relative_bounds_ = gfx::RectF(
+      window_left,
+      kSelectionHandleVerticalVisualOffset - kSelectionHandlePadding,
+      window_width,
+      window_height);
+  UpdateBounds();
+}
+
+void TouchHandleDrawableAura::SetAlpha(float alpha) {
+  if (alpha == alpha_)
+    return;
+
+  alpha_ = alpha;
+  window_->layer()->SetOpacity(alpha_);
+  if (IsVisible())
+    window_->Show();
+  else
+    window_->Hide();
+}
+
+void TouchHandleDrawableAura::SetFocus(const gfx::PointF& position) {
+  focal_position_ = position;
+  UpdateBounds();
+}
+
+gfx::RectF TouchHandleDrawableAura::GetVisibleBounds() const {
+  gfx::RectF bounds(window_->bounds());
+  bounds.Inset(kSelectionHandlePadding,
+               kSelectionHandlePadding + kSelectionHandleVerticalVisualOffset,
+               kSelectionHandlePadding,
+               kSelectionHandlePadding);
+  return bounds;
+}
+
+}  // namespace ui