背水一战 Windows 10 (75) - 控件(控件基类): FrameworkElement - 基础知识, 相关事件, HorizontalAlignm
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2022-03-21 21:05:14
背水一战 Windows 10 之 控件(控件基类 - FrameworkElement): 基础知识, 相关事件, HorizontalAlignment 和 VerticalAlignment ......
[源码下载]
作者:webabcd
介绍
背水一战 Windows 10 之 控件(控件基类 - FrameworkElement)
示例
1、演示 FrameworkElement 的基础知识
Controls/BaseControl/FrameworkElementDemo/Demo1.xaml
<Page x:Class="Windows10.Controls.BaseControl.FrameworkElementDemo.Demo1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:Windows10.Controls.BaseControl.FrameworkElementDemo" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"> <Grid Background="Orange"> <StackPanel Name="stackPanel" Background="Blue" Margin="100"> <TextBlock Name="lblMsg" Margin="5" /> </StackPanel> </Grid> </Page>
Controls/BaseControl/FrameworkElementDemo/Demo1.xaml.cs
/* * FrameworkElement - FrameworkElement(继承自 UIElement, 请参见 /Controls/BaseControl/UIElementDemo/) * MinWidth, MinHeight - 最小宽高,默认值为 0 * MaxWidth, MaxHeight - 最大宽高,默认值为 double.PositiveInfinity * Width, Height - 宽高,默认值为 NaN * ActualWidth, ActualHeight - 实际宽高,来自 UIElement 的 RenderSize 属性(uwp 的 layout 是一个递归系统,更多说明请参见 /MyControls/MyControl2.cs) * Margin - Margin * 它是一个 Thickness 类型的对象,在 C# 端就构造这个对象即可 * 在 xaml 端设置的话,其规则为“左,上,右,下”或“左右,上下”或“左上右下”,可以用逗号分隔也可以用空格分隔 * Name - 名字 * FindName() - 查找当前页面的指定名字的对象 * Parent - 获取当前对象的父对象 * Tag - 用于保存任意对象 * Language - 设置或获取当前元素及其所有子元素的语言信息(没什么实际效果,就是一个标记而已) * BaseUri - 获取当前对象所在的 xaml 页面的 uri 地址 * DataContext - 数据上下文(参见 /Bind/DataContextChanged.xaml) * RequestedTheme - 主题(参见 /Resource/ThemeResourceDemo.xaml.cs) * Resources - 资源字典(参见 /Resource/ResourceDictionaryDemo.xaml) * Style - 样式(参见 /Controls/UI/Style.xaml) * GetBindingExpression() - 获取指定属性的绑定信息(参见 /Bind/UpdateSourceTrigger.xaml.cs) * SetBinding() - 设置绑定信息(参见 /Bind/BindingElement.xaml.cs) * * * 本例用于演示 FrameworkElement 的基础知识 */ using System; using Windows.UI.Xaml; using Windows.UI.Xaml.Controls; namespace Windows10.Controls.BaseControl.FrameworkElementDemo { public sealed partial class Demo1 : Page { public Demo1() { this.InitializeComponent(); this.Loaded += Demo1_Loaded; } private void Demo1_Loaded(object sender, RoutedEventArgs e) { stackPanel.MinWidth = 0; stackPanel.MinHeight = 0; stackPanel.MaxWidth = double.PositiveInfinity; stackPanel.MaxHeight = double.PositiveInfinity; lblMsg.Text += $"stackPanel.ActualWidth:{stackPanel.ActualWidth}, stackPanel.ActualHeight:{stackPanel.ActualHeight}"; lblMsg.Text += Environment.NewLine; if (this.FindName("lblMsg") as TextBlock == lblMsg) { lblMsg.Text += "this.FindName(\"lblMsg\") as TextBlock == lblMsg"; lblMsg.Text += Environment.NewLine; } if (lblMsg.Parent as StackPanel == stackPanel) { lblMsg.Text += "lblMsg.Parent as StackPanel == stackPanel"; lblMsg.Text += Environment.NewLine; } lblMsg.Text += "BaseUri:" + this.BaseUri; lblMsg.Text += Environment.NewLine; lblMsg.Tag = "i am webabcd"; lblMsg.Text += "lblMsg.Tag:" + lblMsg.Tag; lblMsg.Text += Environment.NewLine; } } }
2、演示 FrameworkElement 的相关事件
Controls/BaseControl/FrameworkElementDemo/Demo2.xaml
<Page x:Class="Windows10.Controls.BaseControl.FrameworkElementDemo.Demo2" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:Windows10.Controls.BaseControl.FrameworkElementDemo" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"> <Grid Background="Orange"> <StackPanel Name="stackPanel" Background="Blue" Margin="100"> <TextBlock Name="lblMsg" Margin="5" /> </StackPanel> </Grid> </Page>
Controls/BaseControl/FrameworkElementDemo/Demo2.xaml.cs
/* * FrameworkElement - FrameworkElement(继承自 UIElement, 请参见 /Controls/BaseControl/UIElementDemo/) * DataContextChanged - 数据上下文发生改变后触发的事件(参见 /Bind/DataContextChanged.xaml) * Loading - 在 OnNavigatedTo 之后,由外到内触发 Loading 事件 * Loaded - 由内到外触发 Loaded 事件 * Unloaded - 在 OnNavigatedFrom 之后,由外到内触发 Unloaded 事件 * SizeChanged - 在尺寸(ActualWidth 或 ActualHeight)发生变化时触发的事件,位置等发生变化时不会触发 * LayoutUpdated - 布局更新时触发的事件,比如尺寸发生了变化或位置发生了变化等 * * * 本例用于演示 FrameworkElement 的相关事件 */ using System; using System.Diagnostics; using Windows.UI.Xaml; using Windows.UI.Xaml.Controls; using Windows.UI.Xaml.Navigation; namespace Windows10.Controls.BaseControl.FrameworkElementDemo { public sealed partial class Demo2 : Page { public Demo2() { this.InitializeComponent(); this.Loading += page_Loading; this.Loaded += page_Loaded; this.Unloaded += page_Unloaded; stackPanel.Loading += stackPanel_Loading; stackPanel.Loaded += stackPanel_Loaded; stackPanel.Unloaded += stackPanel_Unloaded; lblMsg.Loading += lblMsg_Loading; lblMsg.Loaded += lblMsg_Loaded; lblMsg.Unloaded += lblMsg_Unloaded; lblMsg.SizeChanged += lblMsg_SizeChanged; lblMsg.LayoutUpdated += lblMsg_LayoutUpdated; } protected override void OnNavigatedTo(NavigationEventArgs e) { lblMsg.Text += "OnNavigatedTo"; lblMsg.Text += Environment.NewLine; } protected override void OnNavigatingFrom(NavigatingCancelEventArgs e) { Debug.WriteLine("OnNavigatingFrom"); } protected override void OnNavigatedFrom(NavigationEventArgs e) { Debug.WriteLine("OnNavigatedFrom"); } private void page_Loading(FrameworkElement sender, object args) { lblMsg.Text += "page_Loading"; lblMsg.Text += Environment.NewLine; } private void page_Loaded(object sender, RoutedEventArgs e) { lblMsg.Text += "page_Loaded"; lblMsg.Text += Environment.NewLine; } private void page_Unloaded(object sender, RoutedEventArgs e) { Debug.WriteLine("page_Unloaded"); } private void stackPanel_Loading(FrameworkElement sender, object args) { lblMsg.Text += "stackPanel_Loading"; lblMsg.Text += Environment.NewLine; } private void stackPanel_Loaded(object sender, RoutedEventArgs e) { lblMsg.Text += "stackPanel_Loaded"; lblMsg.Text += Environment.NewLine; } private void stackPanel_Unloaded(object sender, RoutedEventArgs e) { Debug.WriteLine("stackPanel_Unloaded"); } private void lblMsg_Loading(FrameworkElement sender, object args) { lblMsg.Text += "lblMsg_Loading"; lblMsg.Text += Environment.NewLine; } private void lblMsg_Loaded(object sender, RoutedEventArgs e) { lblMsg.Text += "lblMsg_Loaded"; lblMsg.Text += Environment.NewLine; } private void lblMsg_Unloaded(object sender, RoutedEventArgs e) { Debug.WriteLine("lblMsg_Unloaded"); } private void lblMsg_SizeChanged(object sender, SizeChangedEventArgs e) { Debug.WriteLine($"lblMsg_SizeChanged, PreviousSize:{e.PreviousSize}, NewSize:{e.NewSize}"); // 注:如果在这里又改变了 lblMsg 的尺寸的话,则会发生循环调用,编译时会出现“Layout cycle detected. Layout could not complete.”错误 } private void lblMsg_LayoutUpdated(object sender, object e) { Debug.WriteLine("lblMsg_LayoutUpdated"); // 注:如果在这里又改变了 lblMsg 的布局的话,则会发生循环调用,编译时会出现“Layout cycle detected. Layout could not complete.”错误 } } }
3、演示 FrameworkElement 的 HorizontalAlignment 和 VerticalAlignment 的应用
Controls/BaseControl/FrameworkElementDemo/Demo3.xaml
<Page x:Class="Windows10.Controls.BaseControl.FrameworkElementDemo.Demo3" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:Windows10.Controls.BaseControl.FrameworkElementDemo" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"> <Grid Background="Orange"> <StackPanel Name="stackPanel" Background="Blue" Margin="100" VerticalAlignment="Stretch"> <ComboBox Name="cmbHorizontalAlignment" PlaceholderText="HorizontalAlignment" SelectionChanged="cmbHorizontalAlignment_SelectionChanged" Margin="5"> <ComboBoxItem>Left</ComboBoxItem> <ComboBoxItem>Center</ComboBoxItem> <ComboBoxItem>Right</ComboBoxItem> <ComboBoxItem IsSelected="True">Stretch</ComboBoxItem> </ComboBox> <ComboBox Name="cmbVerticalAlignment" PlaceholderText="VerticalAlignment" SelectionChanged="cmbVerticalAlignment_SelectionChanged" Margin="5"> <ComboBoxItem>Top</ComboBoxItem> <ComboBoxItem>Center</ComboBoxItem> <ComboBoxItem>Bottom</ComboBoxItem> <ComboBoxItem IsSelected="True">Stretch</ComboBoxItem> </ComboBox> </StackPanel> </Grid> </Page>
Controls/BaseControl/FrameworkElementDemo/Demo3.xaml.cs
/* * FrameworkElement - FrameworkElement(继承自 UIElement, 请参见 /Controls/BaseControl/UIElementDemo/) * HorizontalAlignment - 水平对齐方式(Left, Center, Right, Stretch) * VerticalAlignment - 垂直对齐方式(Top, Center, Bottom, Stretch) * * * 本例用于演示 FrameworkElement 的 HorizontalAlignment 和 VerticalAlignment 的应用 */ using System; using Windows.UI.Xaml; using Windows.UI.Xaml.Controls; namespace Windows10.Controls.BaseControl.FrameworkElementDemo { public sealed partial class Demo3 : Page { public Demo3() { this.InitializeComponent(); } private void cmbHorizontalAlignment_SelectionChanged(object sender, SelectionChangedEventArgs e) { stackPanel.HorizontalAlignment = (HorizontalAlignment)Enum.Parse(typeof(HorizontalAlignment), (e.AddedItems[0] as ComboBoxItem).Content.ToString()); } private void cmbVerticalAlignment_SelectionChanged(object sender, SelectionChangedEventArgs e) { stackPanel.VerticalAlignment = (VerticalAlignment)Enum.Parse(typeof(VerticalAlignment), (e.AddedItems[0] as ComboBoxItem).Content.ToString()); } } }
OK
[源码下载]
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