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// 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 "ui/app_list/pagination_controller.h"
#include "ui/app_list/pagination_model.h"
#include "ui/events/event.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/vector2d.h"
namespace app_list {
namespace {
// Constants for dealing with scroll events.
const int kMinScrollToSwitchPage = 20;
const int kMinHorizVelocityToSwitchPage = 800;
const double kFinishTransitionThreshold = 0.33;
} // namespace
PaginationController::PaginationController(PaginationModel* model,
ScrollAxis scroll_axis)
: pagination_model_(model), scroll_axis_(scroll_axis) {
}
bool PaginationController::OnScroll(const gfx::Vector2d& offset,
ScrollEventType type) {
int offset_magnitude;
if (scroll_axis_ == SCROLL_AXIS_HORIZONTAL) {
// If the view scrolls horizontally, both horizontal and vertical scroll
// events are valid (since most mouse wheels only have vertical scrolling).
offset_magnitude =
abs(offset.x()) > abs(offset.y()) ? offset.x() : offset.y();
} else {
// If the view scrolls vertically, only vertical scroll events are valid.
offset_magnitude = offset.y();
}
// Do not scroll on very small touchpad events. Mouse wheel events should
// scroll, no matter how small the value change.
if (type == SCROLL_MOUSE_WHEEL ||
abs(offset_magnitude) > kMinScrollToSwitchPage) {
if (!pagination_model_->has_transition()) {
pagination_model_->SelectPageRelative(offset_magnitude > 0 ? -1 : 1,
true);
}
return true;
}
return false;
}
bool PaginationController::OnGestureEvent(const ui::GestureEvent& event,
const gfx::Rect& bounds) {
const ui::GestureEventDetails& details = event.details();
switch (event.type()) {
case ui::ET_GESTURE_SCROLL_BEGIN:
pagination_model_->StartScroll();
return true;
case ui::ET_GESTURE_SCROLL_UPDATE: {
float scroll = scroll_axis_ == SCROLL_AXIS_HORIZONTAL
? details.scroll_x()
: details.scroll_y();
int width = scroll_axis_ == SCROLL_AXIS_HORIZONTAL ? bounds.width()
: bounds.height();
// scroll > 0 means moving contents right or down. That is, transitioning
// to the previous page.
pagination_model_->UpdateScroll(scroll / width);
return true;
}
case ui::ET_GESTURE_SCROLL_END:
pagination_model_->EndScroll(pagination_model_->transition().progress <
kFinishTransitionThreshold);
return true;
case ui::ET_SCROLL_FLING_START: {
float velocity = scroll_axis_ == SCROLL_AXIS_HORIZONTAL
? details.velocity_x()
: details.velocity_y();
pagination_model_->EndScroll(true);
if (fabs(velocity) > kMinHorizVelocityToSwitchPage)
pagination_model_->SelectPageRelative(velocity < 0 ? 1 : -1, true);
return true;
}
default:
return false;
}
}
} // namespace app_list
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