using System;
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using Android.Views;
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using Android.Content;
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using Android.Widget;
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using Android.Graphics.Drawables;
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namespace Shared
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{
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//已经全面检查了代码
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/// <summary>
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/// 位置布局
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/// </summary>
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public class HorizontalPages : ViewGroup
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{
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/// <summary>
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/// 视图高度
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/// </summary>
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/// <value>The height.</value>
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public override int Height
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{
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get
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{
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return base.Height;
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}
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set
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{
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base.Height = value;
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if (!IsCanRefresh)
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{
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return;
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}
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var layoutParameters = realViewGroup.LayoutParameters;
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layoutParameters.Height = Height;
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realViewGroup.LayoutParameters = layoutParameters;
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}
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}
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/// <summary>
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/// 视图宽度
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/// </summary>
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/// <value>The width.</value>
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public override int Width
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{
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get
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{
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return base.Width;
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}
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set
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{
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base.Width = value;
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if (!IsCanRefresh)
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{
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return;
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}
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var layoutParameters = realViewGroup.LayoutParameters;
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layoutParameters.Width = Width;
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realViewGroup.LayoutParameters = layoutParameters;
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}
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}
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/// <summary>
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/// 页面变化事件
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/// </summary>
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public Action<HorizontalPages, int> PageChange;
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/// <summary>
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/// 构造函数
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/// </summary>
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public HorizontalPages()
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{
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viewGroup = new AndroidFrameLayout(Application.Activity, null);
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realViewGroup = new InnerHorizontalPages(Application.Activity, this) { };
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viewGroup.AddView(realViewGroup);
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}
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int pageIndex;
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/// <summary>
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/// 设置或者获取当前的界面索引
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/// </summary>
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/// <value>The index of the page.</value>
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public int PageIndex
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{
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get
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{
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return (realViewGroup as InnerHorizontalPages).CurrentScreen;
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}
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set
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{
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if (value < 0 || ChildrenCount < value)
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{
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return;
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}
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pageIndex = value;
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if (!IsCanRefresh)
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{
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return;
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}
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(realViewGroup as InnerHorizontalPages).SetSelection(value);
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}
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}
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/// <summary>
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/// 是否允许滑动
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/// </summary>
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/// <value><c>true</c> if scroll enabled; otherwise, <c>false</c>.</value>
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public bool ScrollEnabled
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{
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get
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{
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return (realViewGroup as InnerHorizontalPages).ScrollEnabled;
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}
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set
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{
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(realViewGroup as InnerHorizontalPages).ScrollEnabled = value;
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}
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}
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/// <summary>
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/// 增加子控件
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/// </summary>
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/// <param name="view">View.</param>
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public override void AddChidren(View view)
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{
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view.Parent = this;
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viewList.Add(view);
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realViewGroup.AddView(view.AndroidView);
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if (!IsCanRefresh)
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{
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return;
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}
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view.Refresh();
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if (view is ViewGroup)
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{
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var tempViewGroup = (ViewGroup)view;
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for (int i = 0; i < tempViewGroup.ChildrenCount; i++)
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{
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tempViewGroup.GetChildren(i).Refresh();
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}
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}
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}
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/// <summary>
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/// 移除当前控件
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/// </summary>
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/// <param name="view">View.</param>
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internal override void Remove(View view)
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{
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if (view == null)
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{
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return;
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}
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var index = viewList.FindIndex(obj => obj == view);
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if (index < 0)
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{
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return;
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}
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viewList.Remove(view);
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(realViewGroup as InnerHorizontalPages).RemoveViewAt(index);
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view.Parent = null;
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}
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/// <summary>
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/// 移除所有的控件
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/// </summary>
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public override void RemoveAll()
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{
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while (0 < viewList.Count)
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{
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GetChildren(0)?.RemoveFromParent();
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}
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(realViewGroup as InnerHorizontalPages).SetSelection(0);
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}
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/// <summary>
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/// 根据索引移除控件
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/// </summary>
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/// <param name="index">Index.</param>
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public override void RemoveAt(int index)
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{
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if (viewList.Count - 1 < index || index < 0)
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{
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return;
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}
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GetChildren(index)?.RemoveFromParent();
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}
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/// <summary>
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/// page的外边距
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/// </summary>
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public int RowPadding
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{
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get
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{
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return (realViewGroup as InnerHorizontalPages).Padding;
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}
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set
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{
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(realViewGroup as InnerHorizontalPages).Padding = value;
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}
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}
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/// <summary>
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/// 两个Page之间的距离
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/// </summary>
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public int PagePadding
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{
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get
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{
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return (realViewGroup as InnerHorizontalPages).Padding - (realViewGroup as InnerHorizontalPages).PagePadding;
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}
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set
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{
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(realViewGroup as InnerHorizontalPages).PagePadding = (realViewGroup as InnerHorizontalPages).Padding - value;
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}
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}
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}
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public class InnerHorizontalPages : Android.Widget.FrameLayout
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{
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public bool ScrollEnabled = true;
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static int snapVelocity = 1000;
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static int invalidScreen = -1;
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static int touchStateRest = 0;
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static int touchStateScrolling = 1;
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/// <summary>
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/// 界面之间的边距
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/// </summary>
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public int Padding = 100;
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public int PagePadding = 50;
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Scroller scroller;
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VelocityTracker mVelocityTracker = VelocityTracker.Obtain();
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int touchState = touchStateRest;
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float lastMotionX;
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float lastMotionY;
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int mTouchSlop;
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int mMaximumVelocity;
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internal int CurrentScreen;
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public override void RemoveViewAt(int index)
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{
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if (index == ChildCount - 1) {
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CurrentScreen--;
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if (CurrentScreen < 0) {
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CurrentScreen = 0;
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}
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}
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base.RemoveViewAt(index);
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//刷新
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snapToDestination();
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}
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Shared.HorizontalPages horizontalPages;
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public InnerHorizontalPages(Context context, Shared.HorizontalPages view) : base(context)
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{
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horizontalPages = view;
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init();
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}
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/// <summary>
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/// 重写这个是为了方便部局，在每个界面之间都多加了一个控件包住
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/// </summary>
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/// <param name="child"></param>
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public override void AddView(Android.Views.View child)
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{
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var innerView = new Android.Widget.FrameLayout(Shared.Application.Activity);
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innerView.SetPadding(Padding, 0, Padding, 0);
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if (1 <= ChildCount)
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{
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innerView.SetX(LayoutParameters.Width * ChildCount - Padding - PagePadding);
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}
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base.AddView(innerView, new Android.Widget.FrameLayout.LayoutParams(LayoutParameters.Width, LayoutParameters.Height) { });
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innerView.AddView(child);
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}
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void init()
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{
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scroller = new Scroller(Context);
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var configuration = ViewConfiguration.Get(Context);
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//最小的滑动距离
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mTouchSlop = configuration.ScaledTouchSlop;
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mMaximumVelocity = configuration.ScaledMaximumFlingVelocity;
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}
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public override void RequestDisallowInterceptTouchEvent(bool disallowIntercept)
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{
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base.RequestDisallowInterceptTouchEvent(disallowIntercept);
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disallowInterceptTouchEvent = disallowIntercept;
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}
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bool disallowInterceptTouchEvent;
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bool isFirst;
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public override bool OnInterceptTouchEvent(MotionEvent ev)
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{
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if (disallowInterceptTouchEvent)
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{
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return false;
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}
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System.Console.WriteLine($"PageLayout->OnInterceptTouchEvent:{Height} {ev.Action}");
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//如果没有子控件或者不允许滑动就返回，不处理当前事件
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if (ChildCount == 0 || !ScrollEnabled)
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return false;
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mVelocityTracker.AddMovement(ev);
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var x = ev.GetX();
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var y = ev.GetY();
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switch (ev.Action)
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{
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//每次点击都执行这里
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case MotionEventActions.Down:
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if (!scroller.IsFinished)
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{
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//如果还在滑动，但是用户重新点击了，就让控件马上停止
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scroller.AbortAnimation();
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snapToDestination(false);
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}
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//记录点击的最新X坐标
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lastMotionX = x;
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lastMotionY = y;
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touchState = scroller.IsFinished ? touchStateRest : touchStateScrolling;
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break;
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//有子控件时执行这里
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case MotionEventActions.Move:
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var deltaX = (int)(lastMotionX - x);
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var deltaY = (int)(lastMotionY - y);
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//当前滑动是否已经超出了设定值
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var xMoved = Math.Abs(deltaX) > mTouchSlop;
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System.Console.WriteLine($"PageLayout->xMoved22:{xMoved } {deltaX}");
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if (xMoved && Math.Abs(deltaY) < Math.Abs(deltaX))
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{
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if (!isFirst)
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{
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touchState = touchStateScrolling;
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}
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isFirst = false;
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System.Console.WriteLine($"PageLayout->xMoved33:{xMoved } {deltaX}");
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}
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if (touchState == touchStateScrolling)
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{
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//记录最新的坐标，因为接下来控件已经滑动了
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lastMotionX = x;
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System.Console.WriteLine($"PageLayout->lastMotionX:{lastMotionX } {touchState}");
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//当前事件自己处理了，子控制不需要处理当前这事件
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return true;
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}
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break;
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case MotionEventActions.Cancel:
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touchState = touchStateRest;
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mVelocityTracker.Clear();
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break;
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}
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return false;
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}
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public override bool OnTouchEvent(MotionEvent e)
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{
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if (disallowInterceptTouchEvent)
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{
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return false;
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}
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System.Console.WriteLine($"PageLayout->OnTouchEvent:{Height} {e.Action}");
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if (ChildCount == 0 || !ScrollEnabled)
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return false;
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mVelocityTracker.AddMovement(e);
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var x = e.GetX();
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var y = e.GetY();
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switch (e.Action)
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{
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case MotionEventActions.Move:
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var deltaX = (int)(lastMotionX - x);
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var deltaY = (int)(lastMotionY - y);
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//当前滑动是否已经超出了设定值
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var xMoved = Math.Abs(deltaX) > mTouchSlop;
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System.Console.WriteLine($"PageLayout->xMoved:{xMoved } {deltaX}");
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if (xMoved && Math.Abs(deltaY) < Math.Abs(deltaX))
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{
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if (!isFirst)
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{
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touchState = touchStateScrolling;
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}
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isFirst = false;
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}
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if (touchState == touchStateScrolling)
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{
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lastMotionX = x;
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return true;
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}
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break;
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case MotionEventActions.Up:
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if (touchState == touchStateScrolling)
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{
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mVelocityTracker.ComputeCurrentVelocity(1000, mMaximumVelocity);
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var velocityX = mVelocityTracker.XVelocity;
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if (velocityX > snapVelocity && CurrentScreen > 0)
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{
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// 显示左边界面
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snapToScreen(CurrentScreen - 1);
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}
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else if (velocityX < -snapVelocity && CurrentScreen < ChildCount - 1)
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{
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// 显示右边界面
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snapToScreen(CurrentScreen + 1);
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}
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}
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touchState = touchStateRest;
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mVelocityTracker.Clear();
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break;
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case MotionEventActions.Cancel:
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touchState = touchStateRest;
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mVelocityTracker.Clear();
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break;
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}
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return true;
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}
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/// <summary>
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/// 滑动到指定的界面
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/// </summary>
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void snapToDestination(bool isDelay = true)
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{
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var whichScreen = (ScrollX + (MeasuredWidth / 2)) / MeasuredWidth;
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snapToScreen(whichScreen, isDelay);
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}
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/// <summary>
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/// 滑动到指定界面
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/// </summary>
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/// <param name="whichScreen">Which screen.</param>
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void snapToScreen(int whichScreen, bool isDelay = true)
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{
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if (!scroller.IsFinished)
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{
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scroller.AbortAnimation();
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}
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var beforePosition = CurrentScreen;
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whichScreen = Math.Max(0, Math.Min(whichScreen, ChildCount - 1));
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CurrentScreen = whichScreen;
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//还原这个控件之前的位置
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var newX = CurrentScreen * MeasuredWidth;
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var delta = newX - ScrollX;
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scroller.StartScroll(ScrollX, 0, delta, 0, isDelay ? 800 : 0);
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Invalidate();
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refreshPage();
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if (beforePosition != CurrentScreen)
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{
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horizontalPages.PageChange?.Invoke(horizontalPages, CurrentScreen);
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}
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}
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void refreshPage()
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{
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GetChildAt(CurrentScreen).SetX(LayoutParameters.Width * CurrentScreen);
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if (0 <= CurrentScreen - 1)
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{
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//让上一个界面向右出来一点
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GetChildAt(CurrentScreen - 1).SetX(LayoutParameters.Width * (CurrentScreen - 1) + Padding + PagePadding);
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}
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if (CurrentScreen + 1 <= ChildCount - 1)
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{
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//让下一个界面向左出来一点
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GetChildAt(CurrentScreen + 1).SetX(LayoutParameters.Width * (CurrentScreen + 1) - Padding - PagePadding);
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}
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}
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public override void ComputeScroll()
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{
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if (scroller.ComputeScrollOffset())
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{
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ScrollTo(scroller.CurrX, scroller.CurrY);
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PostInvalidate();
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}
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else if (CurrentScreen != invalidScreen)
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{
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//mCurrentScreen = Math.Max(0, Math.Min(mNextScreen, ChildCount - 1));
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//mNextScreen = invalidScreen;
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//postViewSwitched(mLastScrollDirection);
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}
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}
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public void SetSelection(int position)
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{
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if (position < 0)
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{
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return;
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}
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scroller.ForceFinished(true);
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position = Math.Min(position, ChildCount - 1);
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snapToScreen(position, false);
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}
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public override bool DispatchTouchEvent(MotionEvent e)
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{
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//System.Console.WriteLine($"PageLayout->DispatchTouchEvent:{Height} {e.Action}");
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if (e.Action == MotionEventActions.Down)
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{
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//还原中断
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RequestDisallowInterceptTouchEvent(false);
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isFirst = true;
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}
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return base.DispatchTouchEvent(e);
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}
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}
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}
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