1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "ui/app_list/pagination_controller.h" 6 7 #include "ui/app_list/pagination_model.h" 8 #include "ui/events/event.h" 9 #include "ui/gfx/geometry/rect.h" 10 #include "ui/gfx/geometry/vector2d.h" 11 12 namespace app_list { 13 14 namespace { 15 16 // Constants for dealing with scroll events. 17 const int kMinScrollToSwitchPage = 20; 18 const int kMinHorizVelocityToSwitchPage = 800; 19 20 const double kFinishTransitionThreshold = 0.33; 21 22 } // namespace 23 24 PaginationController::PaginationController(PaginationModel* model, 25 ScrollAxis scroll_axis) 26 : pagination_model_(model), scroll_axis_(scroll_axis) { 27 } 28 29 bool PaginationController::OnScroll(const gfx::Vector2d& offset) { 30 int offset_magnitude; 31 if (scroll_axis_ == SCROLL_AXIS_HORIZONTAL) { 32 // If the view scrolls horizontally, both horizontal and vertical scroll 33 // events are valid (since most mouse wheels only have vertical scrolling). 34 offset_magnitude = 35 abs(offset.x()) > abs(offset.y()) ? offset.x() : offset.y(); 36 } else { 37 // If the view scrolls vertically, only vertical scroll events are valid. 38 offset_magnitude = offset.y(); 39 } 40 41 if (abs(offset_magnitude) > kMinScrollToSwitchPage) { 42 if (!pagination_model_->has_transition()) { 43 pagination_model_->SelectPageRelative(offset_magnitude > 0 ? -1 : 1, 44 true); 45 } 46 return true; 47 } 48 49 return false; 50 } 51 52 bool PaginationController::OnGestureEvent(const ui::GestureEvent& event, 53 const gfx::Rect& bounds) { 54 const ui::GestureEventDetails& details = event.details(); 55 switch (event.type()) { 56 case ui::ET_GESTURE_SCROLL_BEGIN: 57 pagination_model_->StartScroll(); 58 return true; 59 case ui::ET_GESTURE_SCROLL_UPDATE: { 60 float scroll = scroll_axis_ == SCROLL_AXIS_HORIZONTAL 61 ? details.scroll_x() 62 : details.scroll_y(); 63 int width = scroll_axis_ == SCROLL_AXIS_HORIZONTAL ? bounds.width() 64 : bounds.height(); 65 // scroll > 0 means moving contents right or down. That is, transitioning 66 // to the previous page. 67 pagination_model_->UpdateScroll(scroll / width); 68 return true; 69 } 70 case ui::ET_GESTURE_SCROLL_END: 71 pagination_model_->EndScroll(pagination_model_->transition().progress < 72 kFinishTransitionThreshold); 73 return true; 74 case ui::ET_SCROLL_FLING_START: { 75 float velocity = scroll_axis_ == SCROLL_AXIS_HORIZONTAL 76 ? details.velocity_x() 77 : details.velocity_y(); 78 pagination_model_->EndScroll(true); 79 if (fabs(velocity) > kMinHorizVelocityToSwitchPage) 80 pagination_model_->SelectPageRelative(velocity < 0 ? 1 : -1, true); 81 return true; 82 } 83 default: 84 return false; 85 } 86 } 87 88 } // namespace app_list 89