WPF程序设计：第四章按钮与其他控件(Buttons and Other Controls)

WPF中，控件（Control）一词的意义，比早期Windows编程的控件，有更特定的含义。

比方说，在WinForms应用程序中，屏幕上出现的一切，都被视为控件。在WPF中，这个词保留给用户交互使用，也就是说，当用户用鼠标或是键盘时，控件一般会对用户提供某种响应（feedback）。前章的TextBlock、Image和Shape元素，都会接收键盘、但是它们都选择忽略，控件会主动监视并处理用户的输入。

Control 类直接继承自 FrameworkElement：

Object

DispatcherObject（abstract）

DependencyObject

Visual（abstract）

UIElement

FrameworkElement

Control

Window 继承自Control，中间还有个ContentControl，你自己知道ContentControl继承自Control，Control是继承自FrameworkElement。Control所定义的property包括Background、BorderBrush、BorderThickness以及和font相关的property，例如FontWeight和FontStretch。（注意的是：虽然TextBlock也具有许多font property，但是TextBlock不是继承自Control。TextBlock的这些property是自己定义的。）

从Control继承而来的类超过了50个，这些类提供给程序员各式各样的控件，包括按钮、列表框（list box）、滚动条（scroll bar）、编辑框（edit field）、菜单(menu)和工具条（toolbar）。这些类都是放在System.Windows.Controls与System.Windows.Controls.Primitives命名空间中的。这些命名空间也包含一些不是继承自Control的类。

最为经典的控件是Button按钮，在WPF中是Button类。Button类有一个Content 的property以及一个名为Click的事件。当用户用鼠标按下按钮，就会发生事件。

实例程序 - 1

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Controls;

namespace PartFour
{
    class ClickTheButton : Window
    {
        [STAThread]
        public static void Main()
        {
            Application app = new Application();
            app.Run(new ClickTheButton());
        }
        public ClickTheButton()
        {
            Title = "Click the Button";
            Button btn = new Button();
            btn.Content = "_Click me, please!";
            btn.Click += new RoutedEventHandler(btn_Click);
            btn.Margin = new Thickness(100);
            btn.Height = 300;
            btn.Width = 300;
            btn.HorizontalContentAlignment = HorizontalAlignment.Left;
            btn.VerticalContentAlignment = VerticalAlignment.Bottom;

            btn.HorizontalAlignment = HorizontalAlignment.Left;
            btn.VerticalAlignment = VerticalAlignment.Bottom;
            Content = btn;
            SizeToContent = SizeToContent.WidthAndHeight;
        }

        void btn_Click(object sender, RoutedEventArgs e)
        {
            MessageBox.Show("The button has been Clicked and all is well.", Title);
        }
    }
}

Button有一个Content property，这一点和Window一样，且并非巧合。这两个类（以及一些其他的类）都是继承自ContentControl的类，也就是定义了Content property的地方。

下面是Control以下的局部类层次图：

Control

ContentControl

ButtonBase（abstract）

Button

Window

Window与Button否有相同的 Content property.

btn.IsDefault = true; 等价于 btn.Focus();按钮作为默认按钮，也就是焦点。

或则让它可以对Escape键有反应，做法如下： btn.IsCancel = true;

实例程序 - 2：

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Media;

namespace PartFour
{
    public class FormatTheButton : Window
    {
        [STAThread]
        public static void Main()
        {
            Application app = new Application();
            app.Run(new FormatTheButton());
        }

        Run runButton;

        public FormatTheButton()
        {
            Title = "Format the Button";

            // 建立一个按钮，将其设置成窗体的Content
            Button btn = new Button();
            btn.HorizontalAlignment = HorizontalAlignment.Center;
            btn.VerticalAlignment = VerticalAlignment.Center;
            btn.MouseEnter += new System.Windows.Input.MouseEventHandler(btn_MouseEnter);
            btn.MouseLeave += new System.Windows.Input.MouseEventHandler(btn_MouseLeave);
            Content = btn;

            // 建立一个Textblock,将它设置成按钮的内容
            TextBlock txtblk = new TextBlock();
            txtblk.FontSize = 24;
            txtblk.TextAlignment = TextAlignment.Center;
            btn.Content = txtblk;

            // 在TextBlock中加入格式文本
            txtblk.Inlines.Add(new Italic(new Run("Click")));
            txtblk.Inlines.Add(" the");
            txtblk.Inlines.Add(runButton = new Run(" Button"));
            txtblk.Inlines.Add(new LineBreak());
            txtblk.Inlines.Add(" to launch the ");
            txtblk.Inlines.Add(new Bold(new Run("rocket")));
        }

        void btn_MouseLeave(object sender, System.Windows.Input.MouseEventArgs e)
        {
            runButton.Foreground = Brushes.Red;
        }

        void btn_MouseEnter(object sender, System.Windows.Input.MouseEventArgs e)
        {
            runButton.Foreground = SystemColors.ControlTextBrush;
        }
    }
}

注意，在该程序中，包含单词"button"的Run对象被存储在一个名为runButton的变量中，当鼠标进入按钮区域时，Run对象的前景色上红色。当鼠标离开按钮区域时，颜色恢复默认值（SystemColors。ControlTextBrush）。

实例程序 - 3：

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Media.Imaging;
using System.Windows.Controls;
using System.Windows.Media;

namespace PartFour
{
    public class ImageTheButton : Window
    {
        [STAThread]
        public static void Main()
        {
            Application app = new Application();
            app.Run(new ImageTheButton());
        }

        public ImageTheButton()
        {
            Title = "Image the Button";

            Uri uri = new Uri(@"D:/MyFace.jpg");

            BitmapImage bitmap = new BitmapImage(uri);
            Image img = new Image();
            img.Source = bitmap;
            img.Stretch = Stretch.None;

            Button btn = new Button();
            btn.Content = img;

            btn.HorizontalAlignment = HorizontalAlignment.Center;
            btn.VerticalAlignment = VerticalAlignment.Center;

            Content = btn;
        }
    }
}

-----

Command property，ButtonBase类和其他的类（包括MenuItem）定义了这个property，对于常见的命名，你会将Button的Command property设置为ApplicationCommands、ComponentCommands、MediaCommands、NavigationCommads或EditingCommands类的静态property。前面4个类属于System.Windows.Input命名空间；后面一个是在System.Windows.Documents命名空间。这些类的静态property是属于RoutedUICommand类型。你可以创建你自己的RoutedUICommand类型的对象。

比方说，如果你想要特定的按钮，以进行一个Paste命名，你可以将Command property设置成：

btn.Command = ApplicationCommands.Paste;

现在，你需要将此特定的Paste命令与事件处理器关联起来。这样的关联方法称为绑定（binding），这是WPF数种binding中的一种.UIElement类定义一个名为CommandBindings（复数）的Property（且Control和Window类继承此property），这是CommanBinding对象的集合（collection）。你可能用窗口的CommandBinding集合：

CommandBindings.Add(new CommandBinding(ApplicationCommands.Paste), PasteOnExecute, PasteCanExecute));

具体可参加如下程序：

实例程序 - 4：

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;

namespace PartFour
{
    public class CommandTheButton : Window
    {
        [STAThread]
        public static void Main()
        {
            Application app = new Application();
            app.Run(new CommandTheButton());
        }

        public CommandTheButton()
        {
            Title = "Command The Button!";

            // 建立按钮，并将其设置成窗体的内容
            Button btn = new Button();
            btn.HorizontalAlignment = HorizontalAlignment.Center;
            btn.VerticalAlignment = VerticalAlignment.Center;
            btn.Command = ApplicationCommands.Paste;
            btn.Content = ApplicationCommands.Paste.Text;
            Content = btn;

            // 将此命令绑定到事件处理器
            CommandBindings.Add(new CommandBinding(ApplicationCommands.Paste, PasteOnExecute, PasteCanExecute));
        }

        void PasteOnExecute(object sender, ExecutedRoutedEventArgs ards)
        {
            Title = Clipboard.GetText();
        }

        void PasteCanExecute(object sender, CanExecuteRoutedEventArgs args)
        {
            args.CanExecute = Clipboard.ContainsText();
        }

        protected override void OnMouseDown(MouseButtonEventArgs e)
        {
            base.OnMouseDown(e);
            Title = "Command The Button!";
        }
    }
}

-------

切换按钮，CheckBox和RadioButton都被认为是"切换"（toggle）按钮，这一点从它们的继承结构就可以轻易看出来：

Control

ContentControl

ButtonBase（abstract）

Button

GridViewColumnHeader

RequestButton

ToggleButton

CheckBox

RadioButton

ToggleButton不是抽象类，所以你可以创建它的对象。它看起来就像一个常规的按钮，不同之处在于，他可以有On和Off切换。

实例程序 - 5：

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Controls.Primitives;

namespace PartFour
{
    public class ToggleTheButton : Window
    {
        [STAThread]
        public static void Main()
        {
            Application app = new Application();
            app.Run(new ToggleTheButton());
        }

        public ToggleTheButton()
        {
            Title="ToggleTheButton";

            ToggleButton btn = new ToggleButton();
            btn.Content = "Can_Resize";

            btn.HorizontalAlignment = HorizontalAlignment.Center;
            btn.VerticalAlignment = VerticalAlignment.Center;

            btn.IsChecked = (ResizeMode == ResizeMode.CanResize);
            btn.Checked += new RoutedEventHandler(btn_Checked);
            btn.Unchecked += new RoutedEventHandler(btn_Checked);
            Content = btn;
        }

        void btn_Checked(object sender, RoutedEventArgs e)
        {
            ToggleButton btn = sender as ToggleButton;
            ResizeMode = (bool)btn.IsChecked ? ResizeMode.CanResize : ResizeMode.NoResize;
        }
    }
}

见下面程序：

实例程序 - 6：

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Controls.Primitives;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Media.Imaging;

namespace PartFour
{
    public class BindTheButton : Window
    {
        [STAThread]
        public static void Main()
        {
            Application app = new Application();
            app.Run(new BindTheButton());
        }

        public BindTheButton()
        {
            Title = "Bind the Button !";
            Topmost = true;
            ToggleButton btn = new ToggleButton();
            btn.Content = "Make_Topmost";
            btn.HorizontalAlignment = HorizontalAlignment.Center;
            btn.VerticalAlignment = VerticalAlignment.Center;
            btn.SetBinding(ToggleButton.IsCheckedProperty, "Topmost");
            btn.DataContext = this;
            Content = btn;

            //Binding bind = new Binding("Topmost");
            //bind.Source = this;
            //btn.SetBinding(ToggleButton.IsCheckedProperty, bind);
            // 这个Binding类让你在定义数据绑定时有更过的选择

            Uri uri = new Uri(@"D:/MyFace.jpg");
            BitmapImage bitmap = new BitmapImage(uri);
            Image img = new Image();
            img.Source = bitmap;

            ToolTip tip = new ToolTip();
            tip.Content = img;//"Toogle the button on to make the window topmost on the desktop";
            btn.ToolTip = tip;

        }
    }
}

-----

TextBox控件：

Control

TextBoxBase（abstract）

TextBox

RichTextBox

实例程序 - 7：

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;

namespace PartFour
{
    class UriDialog : Window
    {
        TextBox txtbox;

        public UriDialog()
        {
            Title = "Enter a URI";
            ShowInTaskbar = false;
            SizeToContent = SizeToContent.WidthAndHeight;
            WindowStyle = WindowStyle.ToolWindow;

            WindowStartupLocation = WindowStartupLocation.CenterOwner;

            txtbox = new TextBox();
            txtbox.Margin = new Thickness(48);
            Content = txtbox;

            txtbox.Focus();
        }

        public string Text
        {
            set {
                txtbox.Text = value;
                txtbox.SelectionStart = txtbox.Text.Length;
            }
            get {
                return txtbox.Text;
            }
        }

        protected override void OnKeyDown(System.Windows.Input.KeyEventArgs e)
        {
            if (e.Key == Key.Enter)
                Close();
        }
    }

    class NavigateTheWeb : Window
    {
        [STAThread]
        public static void Main()
        {
            Application app = new Application();
            app.Run(new NavigateTheWeb ());
        }

        Frame frm;
        public NavigateTheWeb()
        {
            Title = "Navigate the Web";

            frm = new Frame();

            Content = frm;

            Loaded += new RoutedEventHandler(NavigateTheWeb_Loaded);
        }

        void NavigateTheWeb_Loaded(object sender, RoutedEventArgs e)
        {
            UriDialog dlg = new UriDialog();
            dlg.Owner = this;
            dlg.Text = "http://";

            dlg.ShowDialog();

            try
            {
                frm.Source = new Uri(dlg.Text);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, Title);
            }
        }
    }
}

实例程序 - 8：

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.IO;
using System.Windows.Controls;
using System.Windows.Input;

namespace PartFour
{
    class EditSomeText : Window
    {
        [STAThread]
        public static void Main()
        {
            Application app = new Application();
            app.Run(new EditSomeText());
        }

        static string strFileName = @"D:/EditSomeText.txt";
        //Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "EditSomeText/EditSomeText.txt");

        TextBox txtbox;

        public EditSomeText()
        {
            Title = "Edit Some Text";

            // 建立 text box
            txtbox = new TextBox();
            txtbox.AcceptsReturn = true;
            txtbox.TextWrapping = TextWrapping.Wrap;
            txtbox.VerticalScrollBarVisibility = ScrollBarVisibility.Auto;
            txtbox.KeyDown += new System.Windows.Input.KeyEventHandler(txtbox_KeyDown);

            Content = txtbox;

            try
            {
                txtbox.Text = File.ReadAllText(strFileName);
            }
            catch
            {
            }

            txtbox.CaretIndex = txtbox.Text.Length;
            txtbox.Focus();
        }

        void txtbox_KeyDown(object sender, System.Windows.Input.KeyEventArgs e)
        {
            if (e.Key == Key.F5)
            {
                txtbox.SelectedText = DateTime.Now.ToString();
                txtbox.CaretIndex = txtbox.SelectionStart + txtbox.SelectionLength;
            }
        }

        protected override void OnClosing(System.ComponentModel.CancelEventArgs e)
        {
            try
            {
                Directory.CreateDirectory(Path.GetDirectoryName(strFileName));
                File.WriteAllText(strFileName, txtbox.Text);
            }
            catch (Exception ex)
            {
                MessageBoxResult result = MessageBox.Show("sffss" + ex.Message, Title, MessageBoxButton.YesNo, MessageBoxImage.Exclamation);

                e.Cancel = (result == MessageBoxResult.No);
            }
        }
    }
}

WPF程序设计 ：第四章 按钮与其他控件(Buttons and Other Controls)

WPF程序设计：第四章按钮与其他控件(Buttons and Other Controls)