背水一战 Windows 10 (52) - 控件（集合类）: ItemsControl - 自定义 ItemsControl, 自定义 ContentPresenter

<Page
    x:Class="Windows10.Controls.CollectionControl.ItemsControlDemo.MyItemsControlDemo"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:Windows10.Controls.CollectionControl.ItemsControlDemo"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Page.Resources>
        <DataTemplate x:Key="ItemTemplate">
            <Grid Background="{Binding ColorValue}">
                <Grid Background="Black" VerticalAlignment="Top" Opacity="0.7">
                    <TextBlock Text="{Binding ColorName}" />
                </Grid>
            </Grid>
        </DataTemplate>
        <Style x:Key="ItemContainerStyle" TargetType="GridViewItem">
            <Setter Property="VerticalContentAlignment" Value="Stretch" />
            <Setter Property="HorizontalContentAlignment" Value="Stretch" />
            <Setter Property="Margin" Value="0" />
            <Setter Property="Padding" Value="0" />
        </Style>
        <ItemsPanelTemplate x:Key="ItemsPanel">
            <VariableSizedWrapGrid MaximumRowsOrColumns="8" Orientation="Horizontal" ItemWidth="100" ItemHeight="100"  />
        </ItemsPanelTemplate>

    </Page.Resources>

    <Grid Background="Transparent" Margin="10 0 10 10">
        <!--
            使用 MyGridView 控件，其重写了 GridView 的 PrepareContainerForItemOverride() 方法，详见 MyGridView.cs
        -->
        <local:MyGridView x:Name="gridView" Width="812" VerticalAlignment="Top" HorizontalAlignment="Left"
                          ItemTemplate="{StaticResource ItemTemplate}"
                          ItemContainerStyle="{StaticResource ItemContainerStyle}"
                          ItemsPanel="{StaticResource ItemsPanel}" 
                          IsItemClickEnabled="False" 
                          SelectionMode="None">
        </local:MyGridView>
    </Grid>
</Page>

/*
 * ItemsControl - 集合控件（继承自 Control, 请参见 /Controls/BaseControl/ControlDemo/）
 *     protected virtual void PrepareContainerForItemOverride(DependencyObject element, object item); - 为 item 准备 container 时
 *         element - item 的 container
 *         item - item
 *         
 * 
 * 本例用于演示如何使 GirdView 中的每个 item 占用不同大小的空间
 * 1、布局控件要使用 VariableSizedWrapGrid（利用其 RowSpan 和 ColumnSpan 来实现 item 占用不同大小的空间），需要注意的是其并非是虚拟化布局控件
 * 2、自定义 GridView，并重写 ItemsControl 的 protected override void PrepareContainerForItemOverride(DependencyObject element, object item) 方法
 *    然后设置每个 item 的 VariableSizedWrapGrid.RowSpan 和 VariableSizedWrapGrid.ColumnSpan
 */

using System;
using System.Collections.Generic;
using System.Linq;
using Windows.UI;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Media;
using System.Reflection;

namespace Windows10.Controls.CollectionControl.ItemsControlDemo
{
    public sealed partial class MyItemsControlDemo : Page
    {
        public MyItemsControlDemo()
        {
            this.InitializeComponent();
   
            BindData();
        }

        private void BindData()
        {
            Random random = new Random();

            // 获取 Windows.UI.Colors 的全部数据
            Type type = typeof(Colors);
            List<ColorModel> colors = type.GetRuntimeProperties() // GetRuntimeProperties() 在 System.Reflection 命名空间下
                .Select(c => new ColorModel
                {
                    ColorName = c.Name,
                    ColorValue = new SolidColorBrush((Color)c.GetValue(null)),
                    ColSpan = random.Next(1, 3), // 此对象所占网格的列合并数
                    RowSpan = random.Next(1, 3) // 此对象所占网格的行合并数
                })
                .ToList();

            // 绑定数据
            gridView.ItemsSource = colors;
        }
    }


    /// <summary>
    /// 用于数据绑定的对象
    /// </summary>
    public class ColorModel
    {
        public string ColorName { get; set; }
        public SolidColorBrush ColorValue { get; set; }

        // 此对象所占的网格的列合并数
        public int ColSpan { get; set; }
        // 此对象所占的网格的行合并数
        public int RowSpan { get; set; }
    }


    /// <summary>
    /// 自定义 GridView，重写 ItemsControl 的 protected override void PrepareContainerForItemOverride(DependencyObject element, object item) 方法
    /// 用于指定 GridView 的每个 item 所占网格的列合并数和行合并数
    /// </summary>
    public class MyGridView : GridView
    {
        protected override void PrepareContainerForItemOverride(DependencyObject element, object item)
        {
            try
            {
                // 设置每个 item 的 VariableSizedWrapGrid.RowSpan 和 VariableSizedWrapGrid.ColumnSpan, 从而实现每个 item 占用不同大小的空间
                // 仅为演示用，由于这里的 ColSpan 和 RowSpan 都是随机计算的，所以可能会出现空白空间

                dynamic dynamicItem = item;
                element.SetValue(VariableSizedWrapGrid.ColumnSpanProperty, dynamicItem.ColSpan);
                element.SetValue(VariableSizedWrapGrid.RowSpanProperty, dynamicItem.RowSpan);
            }
            catch (Exception ex)
            {
                var ignore = ex;

                // 当有异常情况发生时（比如：item 没有 ColSpan 属性或 RowSpan 属性）

                element.SetValue(VariableSizedWrapGrid.ColumnSpanProperty, 1);
                element.SetValue(VariableSizedWrapGrid.RowSpanProperty, 1);
            }
            finally
            {
                base.PrepareContainerForItemOverride(element, item);
            }
        }
    }
}

/*
 * 自定义 ContentPresenter 实现类似 GridViewItemPresenter 和 ListViewItemPresenter 的效果
 */

using System;
using Windows.Foundation;
using Windows.UI;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Media.Animation;
using Windows.UI.Xaml.Shapes;

namespace Windows10.Controls.CollectionControl.ItemsControlDemo
{
    class MyItemPresenter : ContentPresenter
    {
        Panel _container = null; // item 的容器（即在 DataTemplate 中定义的根元素，在示例 MyItemPresenterDemo.xaml 中用的是 Grid）
        Rectangle _pointerOverBorder = null; // 鼠标经过 item 时覆盖在 item 上的 rectangle
        Rectangle _focusVisual = null; // 选中 item 时覆盖在 item 上的 rectangle

        Storyboard _pointerDownStoryboard = null; // 鼠标按下时的动画
        Storyboard _pointerUpStoryboard = null; // 鼠标抬起时的动画

        public MyItemPresenter()
            : base()
        {
            base.Margin = new Thickness(10);
        }

        // override OnApplyTemplate() - 应用控件模板时调用
        protected override void OnApplyTemplate()
        {
            base.OnApplyTemplate();

            _container = (Panel)VisualTreeHelper.GetChild(this, 0);
        }

        // override GoToElementStateCore() - VisualState 转换时调用（此方法仅在自定义 ContentPresenter 并将其应用于 GridView 或 ListView 的 ItemContainerStyle 时才会被调用）
        //     stateName - VisualState 的名字
        //     useTransitions - 是否使用 VisualTransition 过渡效果
        protected override bool GoToElementStateCore(string stateName, bool useTransitions)
        {
            base.GoToElementStateCore(stateName, useTransitions);

            switch (stateName)
            {
                // 正常状态
                case "Normal":
                    HidePointerOverVisuals();
                    HideFocusVisuals();
                    if (useTransitions)
                    {
                        StopPointerDownAnimation();
                    }
                    break;

                // 选中状态
                case "Selected":
                case "PointerFocused":
                    ShowFocusVisuals();
                    if (useTransitions)
                    {
                        StopPointerDownAnimation();
                    }
                    break;

                // 取消选中状态
                case "Unfocused":
                    HideFocusVisuals();
                    break;

                // 鼠标经过状态
                case "PointerOver":
                    ShowPointerOverVisuals();
                    if (useTransitions)
                    {
                        StopPointerDownAnimation();
                    }
                    break;

                // 鼠标点击状态
                case "Pressed":
                case "PressedSelected":
                    if (useTransitions)
                    {
                        StartPointerDownAnimation();
                    }
                    break;

                default: break;
            }

            return true;
        }

        private void StartPointerDownAnimation()
        {
            if (_pointerDownStoryboard == null)
                CreatePointerDownStoryboard();

            _pointerDownStoryboard.Begin();
        }

        private void StopPointerDownAnimation()
        {
            if (_pointerUpStoryboard == null)
                CreatePointerUpStoryboard();

            _pointerUpStoryboard.Begin();
        }

        private void ShowFocusVisuals()
        {
            if (!FocusElementsAreCreated())
                CreateFocusElements();

            _focusVisual.Opacity = 1;
        }

        private void HideFocusVisuals()
        {
            if (FocusElementsAreCreated())
                _focusVisual.Opacity = 0;
        }

        private void ShowPointerOverVisuals()
        {
            if (!PointerOverElementsAreCreated())
                CreatePointerOverElements();

            _pointerOverBorder.Opacity = 1;
        }

        private void HidePointerOverVisuals()
        {
            if (PointerOverElementsAreCreated())
                _pointerOverBorder.Opacity = 0;
        }

        private void CreatePointerDownStoryboard()
        {
            /*
             * 用这种方式为 item 实现鼠标按下的效果会报错（Attempted to read or write protected memory. This is often an indication that other memory is corrupt.），不知道为什么
             * PointerDownThemeAnimation pointerDownAnimation = new PointerDownThemeAnimation();
             * Storyboard.SetTarget(pointerDownAnimation, _container);
             * Storyboard pointerDownStoryboard = new Storyboard();
             * pointerDownStoryboard.Children.Add(pointerDownAnimation);
             */

            DoubleAnimation da1 = new DoubleAnimation()
            {
                To = 0.9,
                Duration = TimeSpan.FromMilliseconds(100)
            };
            DoubleAnimation da2 = new DoubleAnimation()
            {
                To = 0.9,
                Duration = TimeSpan.FromMilliseconds(100)
            };
            Storyboard.SetTarget(da1, _container);
            Storyboard.SetTargetProperty(da1, "(UIElement.RenderTransform).(TransformGroup.Children)[0].(ScaleTransform.ScaleX)");
            Storyboard.SetTarget(da2, _container);
            Storyboard.SetTargetProperty(da2, "(UIElement.RenderTransform).(TransformGroup.Children)[0].(ScaleTransform.ScaleY)");
            if (!(_container.RenderTransform is TransformGroup))
            {
                TransformGroup Group = new TransformGroup();
                Group.Children.Add(new ScaleTransform());
                _container.RenderTransform = Group;
                _container.RenderTransformOrigin = new Point(0.5, 0.5);
            }

            _pointerDownStoryboard = new Storyboard();
            _pointerDownStoryboard.Children.Add(da1);
            _pointerDownStoryboard.Children.Add(da2);
            _pointerDownStoryboard.Begin();
        }

        private void CreatePointerUpStoryboard()
        {
            DoubleAnimation da1 = new DoubleAnimation()
            {
                To = 1,
                Duration = TimeSpan.FromMilliseconds(100)
            };
            DoubleAnimation da2 = new DoubleAnimation()
            {
                To = 1,
                Duration = TimeSpan.FromMilliseconds(100)
            };
            Storyboard.SetTarget(da1, _container);
            Storyboard.SetTargetProperty(da1, "(UIElement.RenderTransform).(TransformGroup.Children)[0].(ScaleTransform.ScaleX)");
            Storyboard.SetTarget(da2, _container);
            Storyboard.SetTargetProperty(da2, "(UIElement.RenderTransform).(TransformGroup.Children)[0].(ScaleTransform.ScaleY)");
            if (!(_container.RenderTransform is TransformGroup))
            {
                TransformGroup Group = new TransformGroup();
                Group.Children.Add(new ScaleTransform());
                _container.RenderTransform = Group;
                _container.RenderTransformOrigin = new Point(0.5, 0.5);
            }

            _pointerUpStoryboard = new Storyboard();
            _pointerUpStoryboard.Children.Add(da1);
            _pointerUpStoryboard.Children.Add(da2);
            _pointerUpStoryboard.Begin();
        }

        private void CreatePointerOverElements()
        {
            _pointerOverBorder = new Rectangle();
            _pointerOverBorder.IsHitTestVisible = false;
            _pointerOverBorder.Opacity = 0;
            // 这里把颜色写死了，仅为演示用，实际写的时候要摘出来写成依赖属性
            _pointerOverBorder.Fill = new SolidColorBrush(Color.FromArgb(0x50, 0x50, 0x50, 0x50));

            _container.Children.Insert(_container.Children.Count, _pointerOverBorder);
        }

        private void CreateFocusElements()
        {
            _focusVisual = new Rectangle();
            _focusVisual.IsHitTestVisible = false;
            _focusVisual.Height = 10;
            _focusVisual.VerticalAlignment = VerticalAlignment.Bottom;
            // 这里把颜色写死了，仅为演示用，实际写的时候要摘出来写成依赖属性
            _focusVisual.Fill = new SolidColorBrush(Color.FromArgb(0xff, 0xff, 0x0, 0x0));

            _container.Children.Insert(0, _focusVisual);
        }

        private bool FocusElementsAreCreated()
        {
            return _focusVisual != null;
        }

        private bool PointerOverElementsAreCreated()
        {
            return _pointerOverBorder != null;
        }
    }
}

<Page
    x:Class="Windows10.Controls.CollectionControl.ItemsControlDemo.MyItemPresenterDemo"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:Windows10.Controls.CollectionControl.ItemsControlDemo"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Page.Resources>
        <Style x:Key="MyGridViewItemPresenterTemplate" TargetType="GridViewItem">
            <Setter Property="Background" Value="Transparent"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="GridViewItem">
                        <!--
                            自定义 ContentPresenter 实现类似 GridViewItemPresenter 和 ListViewItemPresenter 的效果
                        -->
                        <local:MyItemPresenter />
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </Page.Resources>

    <Grid Background="Transparent">
        <GridView x:Name="gridView" SelectionMode="Single" Margin="10 0 10 10" 
                  ItemContainerStyle="{StaticResource MyGridViewItemPresenterTemplate}">
            <GridView.ItemTemplate>
                <DataTemplate>
                    <Grid Height="100" Width="100" Background="Blue">
                        <TextBlock x:Name="lblName" Text="{Binding Name}" Foreground="Yellow" />
                    </Grid>
                </DataTemplate>
            </GridView.ItemTemplate>
        </GridView>
    </Grid>
</Page>

/*
 * 本例用于演示如何自定义 ContentPresenter 实现类似 GridViewItemPresenter 和 ListViewItemPresenter 的效果
 */

using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation;
using Windows10.Common;

namespace Windows10.Controls.CollectionControl.ItemsControlDemo
{
    public sealed partial class MyItemPresenterDemo : Page
    {
        public MyItemPresenterDemo()
        {
            this.InitializeComponent();
        }

        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            gridView.ItemsSource = TestData.GetEmployees();
        }
    }
}