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
PaginationController(PaginationModel * model,ScrollAxis scroll_axis)24 PaginationController::PaginationController(PaginationModel* model,
25 ScrollAxis scroll_axis)
26 : pagination_model_(model), scroll_axis_(scroll_axis) {
27 }
28
OnScroll(const gfx::Vector2d & offset)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
OnGestureEvent(const ui::GestureEvent & event,const gfx::Rect & bounds)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