SnipperImages(Silverlight DEMO)控件设计之Slider和ColorSlider

     在上一篇文章中，介绍了CheckBox控件的开发方式，包括xaml和控件逻辑(cs代码控制xaml中UI元素)。
本文所要介绍的Slider控件在xaml上与CheckBox复杂度相似，比较底。而控件逻辑相对要复杂不少，这些
逻辑会在本文中进行介绍。

     好了，开始今天的正文。

     首先看一下这个演示页，如下：

　　注：因为我从网上所获得的源码中Slider控件并没有全部开发完，起码在上面所示的垂直Slider只是粗

略的定义了xaml（其中某些值还有错误），而CS代码就少得更多了。本人在原有代码基础上，完成了垂直

Slider的开发，并修正了原有的CS代码中的BUG。

      而该控件的xaml代码如下所示(Slider.xaml)：

<ControlTemplate xmlns="http://schemas.microsoft.com/client/2007"
                 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
  <Grid x:Name="Part_Root" Width="200" Height="24">
    <Canvas x:Name="Part_Border" Background="Transparent">
        <Line x:Name='Part_Line' StrokeThickness="1" Stroke="Blue" X1="4" X2="196" Y1="12"
              Y2="12"/>
        <Path x:Name='Part_ThumbHorizontal' Canvas.Top='3' Data='M0,0 L16,0 L8,18z' Fill='Silver'
              Stroke='Black'/>
        <Path x:Name='Part_ThumbVertical' Canvas.Left='3' Visibility="Collapsed"
              Data='M0,0 L18,8 L0,16z' Fill='Silver' Stroke='Black'/>
    </Canvas>
  </Grid>
</ControlTemplate>

    从上面代码可以看出，Slider由四个主要元素组成：

　　　Part_Border：用于绘制背景色(如ColorSlider控件的背景色)

Part_Line：用于绘制滑动的中线

Part_ThumbHorizontal：用于绘制水平滑块

Part_ThumbVertical：用于绘制垂直滑块

　　下面这张图标识了各元素在控件中的对应位置和关系：

 

      对应上图，下面是ColorSlider的xaml代码：

<ControlTemplate xmlns="http://schemas.microsoft.com/client/2007"
                 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
<Grid x:Name="Part_Root" Width='200' Height='24'>
    <Canvas x:Name='Part_Border'>
      <Canvas.Background>
        <LinearGradientBrush x:Name="GradientBrush"  StartPoint="0,0" EndPoint="1,0">
          <GradientStop Color="#FF000000" Offset="0"/>
          <GradientStop Color="#FFFF0000" Offset="0.143"/>
          <GradientStop Color="#FF00FF00" Offset="0.286"/>
          <GradientStop Color="#FF0000FF" Offset="0.429"/>
          <GradientStop Color="#FF00FFFF" Offset="0.571"/>
          <GradientStop Color="#FFFF00FF" Offset="0.714"/>
          <GradientStop Color="#FFFFFF00" Offset="0.857"/>
          <GradientStop Color="#FFFFFFFF" Offset="1"/>
        </LinearGradientBrush>
      </Canvas.Background>
      <Line x:Name='Part_Line' StrokeThickness="1" Stroke="Blue" X1="4" X2="196" Y1="12" Y2="12"/>
      <Path x:Name='Part_ThumbHorizontal' Canvas.Top='3' Data='M0,0 L16,0 L8,18z' Fill='Silver'
      　　　　　　　Stroke='Black'/>
      <Path x:Name='Part_ThumbVertical' Canvas.Left='3' Visibility="Collapsed"
      　　　　　　　Data='M0,0 L18,8 L0,16z' Fill='Silver' Stroke='Black'/>
   </Canvas>
  </Grid>
</ControlTemplate>

      说完了xaml，下面开始介绍cs控件逻辑代码。

      首先要说的是一个枚举类型，用于标识滑动方向(垂直或水平):

/// <summary>
/// 滑动条方向类型
/// </summary>
public enum SliderOrientation
{
    /// <summary>
    /// 垂直
    /// </summary>
    Vertical,
    /// <summary>
    /// 水平
    /// </summary>
    Horizontal
}

      而控件的核心代码如下(有关我修改或添加的部分已通过注释说明)：

/// <summary>
/// 滑动条控制类
/// </summary>
[TemplatePart(Name = "Part_Root", Type = typeof(Panel))]
[TemplatePart(Name = "Part_Border", Type = typeof(FrameworkElement))]
[TemplatePart(Name = "Part_ThumbHorizontal", Type = typeof(FrameworkElement))]
[TemplatePart(Name = "Part_ThumbVertical", Type = typeof(FrameworkElement))]
[TemplatePart(Name = "Part_Line", Type = typeof(FrameworkElement))]
public partial class Slider : Control
{
    public Slider()
    {
        string xaml = ResourceHelper.GetTemplate(this.GetType());
        ControlTemplate template = (ControlTemplate)XamlReader.Load(xaml);
        this.Template = template;
        this.ApplyTemplate();
    }

    public event EventHandler ValueChanged;

    /// <summary>
    /// 值改变时
    /// </summary>
    protected void OnValueChanged()
    {
        if (ValueChanged != null)
        {
            //执行绑定代码
            ValueChanged(this, new EventArgs());
        }
    }

    /// <summary>
    /// 绑定模板元素及相应事件
    /// </summary>
    public override void OnApplyTemplate()
    {
        Part_Root = (Panel)GetTemplateChild("Part_Root");
        Part_Line = (Line)GetTemplateChild("Part_Line");
        Part_ThumbHorizontal = (FrameworkElement)GetTemplateChild("Part_ThumbHorizontal");
        Part_ThumbVertical = (FrameworkElement)GetTemplateChild("Part_ThumbVertical");
        Part_Border = (FrameworkElement)GetTemplateChild("Part_Border");

        Part_ThumbHorizontal.MouseLeftButtonDown += new MouseButtonEventHandler(Part_Thumb_MouseLeftButtonDown);
        Part_ThumbHorizontal.MouseMove += new MouseEventHandler(Part_Thumb_MouseMove);
        Part_ThumbHorizontal.MouseLeftButtonUp += new MouseButtonEventHandler(Part_Thumb_MouseLeftButtonUp);
        Part_ThumbVertical.MouseLeftButtonDown += new MouseButtonEventHandler(Part_Thumb_MouseLeftButtonDown);
        Part_ThumbVertical.MouseMove += new MouseEventHandler(Part_Thumb_MouseMove);
        Part_ThumbVertical.MouseLeftButtonUp += new MouseButtonEventHandler(Part_Thumb_MouseLeftButtonUp);
        Part_Root.MouseLeave += new MouseEventHandler(Part_Root_MouseLeave);
        Part_Root.MouseEnter += new MouseEventHandler(Part_Root_MouseEnter);
        Part_Border.MouseLeftButtonDown += new MouseButtonEventHandler(Part_Border_MouseLeftButtonDown);           
    }

    /// <summary>
    /// 当鼠标在滑动条(不是滑块)上点击时，将滑块设置到鼠标点击位置
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    void Part_Border_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        //当不是滑块时
        if (e.Source != Part_ThumbHorizontal && e.Source != Part_ThumbVertical)
        {
            Point newPos = e.GetPosition(Part_Root);
            {
                if (_orientation == SliderOrientation.Horizontal)
                {
                    Part_ThumbHorizontal.SetValue(Canvas.LeftProperty, Math.Min(newPos.X,
                    　　　　　Part_Border.ActualWidth - Part_ThumbHorizontal.ActualWidth));
                }
                else
                {
                    Part_ThumbVertical.SetValue(Canvas.TopProperty, Math.Min(newPos.Y,
                    　　　　　Part_Border.ActualHeight - Part_ThumbVertical.ActualHeight));
                }
                this.OnValueChanged();
            }
        }
    }
    /// <summary>
    /// 鼠标进入滑动条区域
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    void Part_Root_MouseEnter(object sender, MouseEventArgs e)
    {
        if (hasCapture)
        {
            if (_orientation == SliderOrientation.Horizontal)
            {
                Part_ThumbHorizontal.CaptureMouse();
            }
            else
            {
                Part_ThumbVertical.CaptureMouse();
            }
        }
        else
        {
            _mouseDownValue = -1;
        }
    }

    /// <summary>
    /// 鼠标离开滑动条区域
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    void Part_Root_MouseLeave(object sender, MouseEventArgs e)
    {
        if (_orientation == SliderOrientation.Horizontal)
        {
            Part_ThumbHorizontal.ReleaseMouseCapture();
        }
        else
        {
            Part_ThumbVertical.ReleaseMouseCapture();
        }
    }
    /// <summary>
    /// 鼠标按下滑动块
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    void Part_Thumb_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        FrameworkElement thumb = (FrameworkElement)sender;
        //在当前滑动块上设置“鼠标捕获”
        thumb.CaptureMouse();
        hasCapture = true;
        _thumbMouseDown = e.GetPosition(Part_Root);
        
        if (_orientation == SliderOrientation.Horizontal)//当为水平方向时
        {
            //获取滑动块的“左”值属性
            _mouseDownValue = (double)thumb.GetValue(Canvas.LeftProperty);
        }
        else
        {
            //获取滑动块的“顶”值属性
            _mouseDownValue = (double)thumb.GetValue(Canvas.TopProperty);
        }
    }

    /// <summary>
    /// 鼠标拖动滑动块移动
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    void Part_Thumb_MouseMove(object sender, MouseEventArgs e)
    {
        FrameworkElement thumb = (FrameworkElement)sender;
        Point newPos = e.GetPosition(Part_Root);
        if (_orientation == SliderOrientation.Horizontal)
        {
            double newX = newPos.X - _thumbMouseDown.X + _mouseDownValue;
            if (_mouseDownValue != -1 &&
                newX <= Part_Border.ActualWidth - 8 &&
                newX >= -8)
            {
                thumb.SetValue(Canvas.LeftProperty, newX);//仅在水平方向上移动
                this.OnValueChanged();
            }
        }
        else
        {
            double newY = newPos.Y - _thumbMouseDown.Y + _mouseDownValue;
            if (_mouseDownValue != -1 &&
                newY <= Part_Border.ActualHeight - 8 &&
                newY >= -8)
            {
                thumb.SetValue(Canvas.TopProperty, newY);//仅在垂直方向上移动
                this.OnValueChanged();
            }
        }
    }

    /// <summary>
    /// 鼠标拖动结束
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    void Part_Thumb_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
    {
        FrameworkElement thumb = (FrameworkElement)sender;
        _mouseDownValue = -1;
        thumb.ReleaseMouseCapture();
        hasCapture = false;
    }

    /// <summary>
    /// 设置滑动条的宽
    /// </summary>
    public double SliderWidth
    {
        get { return Part_Root.Width; }
        set
        {
            if (_orientation == SliderOrientation.Horizontal)
            {
                //水平方向上设置
                Part_Line.X2 = value;
                Part_Root.Width = value;
            }
            else
            {
                //获取Slider.xaml中的相应属性配置
                Part_Line.X1 = Part_Line.X2 = value / 2d;
                Part_ThumbVertical.SetValue(Canvas.LeftProperty, value / 2d - Part_ThumbVertical.ActualWidth / 2d);
            }
        }
    }

    /// <summary>
    /// 设置滑动条的高度
    /// </summary>
    public double SliderHeight
    {
        get { return Part_Root.Height; }
        set
        {
            if (_orientation == SliderOrientation.Horizontal)
            {
                //获取Slider.xaml中的相应属性配置
                Part_Line.Y1 = Part_Line.Y2 = value / 2d;
                Part_ThumbHorizontal.SetValue(Canvas.TopProperty, value / 2d - Part_ThumbHorizontal.ActualHeight / 2d);
            }
            else
            {
                //垂直方向上设置
                Part_Line.Y2 = value;
                Part_Root.Height = value;
            }
        }
    }

    /// <summary>
    /// 获取或设置滑动条的当前值
    /// </summary>
    public double Value
    {
        get
        {
            if (_orientation == SliderOrientation.Horizontal)
            {
                double val = (double)Part_ThumbHorizontal.GetValue(Canvas.LeftProperty) / (Part_Root.ActualWidth - 8);
                val = Math.Max(0d, val);
                val = Math.Min(val, 1d);
                return val;
            }
            else
            {
                double val = (double)Part_ThumbVertical.GetValue(Canvas.TopProperty) / (Part_Root.ActualHeight - 8);
                val = Math.Max(0d, val);
                val = Math.Min(val, 1d);
                return val;
            }
        }
        set
        {
            if (_orientation == SliderOrientation.Horizontal)
            {
                Part_ThumbHorizontal.SetValue(Canvas.LeftProperty, value * (Part_Root.Width - 8));
            }
            else
            {
                Part_ThumbVertical.SetValue(Canvas.TopProperty, value * (Part_Root.Height - 8));
            }
        }
    }

    /// <summary>
    /// 获取或设置滑动条的方向，参见SliderOrientation
    /// </summary>
    public  SliderOrientation Orientation
    {
        get { return _orientation; }
        set
        {
            _orientation = value;
            if (_orientation == SliderOrientation.Horizontal)
            {
                Part_ThumbVertical.Visibility = Visibility.Collapsed;
                Part_ThumbHorizontal.Visibility = Visibility.Visible;
                Part_Line.Y1 = Part_Line.Y2 = Part_Root.Height / 2d;
                Part_Line.X1 = 0d;
                Part_Line.X2 = Part_Root.Width;
            }
            else
            {
                //注：此处代码为本人所加，用于当为垂直方向时，交换Width与Height的值
                double temp = Part_Root.Width;
                Part_Root.Width = Part_Root.Height;
                Part_Root.Height = temp;                    

                Part_ThumbHorizontal.Visibility = Visibility.Collapsed;
                Part_ThumbVertical.Visibility = Visibility.Visible;
                Part_Line.X1 = Part_Line.X2 = Part_Root.Width / 2d;
                Part_Line.Y1 = 0d;
                Part_Line.Y2 = Part_Root.Height;
            }
        }
    }

    #region UI元素声明
    protected Panel Part_Root;
    protected Line Part_Line;
    protected FrameworkElement Part_Border, Part_ThumbVertical, Part_ThumbHorizontal;
    #endregion

    protected Point _thumbMouseDown;
    protected double _mouseDownValue = -1;
    protected bool hasCapture = false;
    protected SliderOrientation _orientation = SliderOrientation.Horizontal;
}

       下面代介绍的是ColorSlider控件的控件逻辑cs文件（详情看注释）：

/// <summary>
/// 颜色滑动条控制
/// </summary>
public partial class ColorSlider : Slider
{
    public ColorSlider()
    {
        string xaml = ResourceHelper.GetTemplate(this.GetType());
        ControlTemplate template = (ControlTemplate)XamlReader.Load(xaml);
        this.Template = template;
        base.ApplyTemplate();
    }
    /// <summary>
    /// 该方法为本人所加，用户当滑动条方向为“垂直”时，重新设置“GradientBrush”的“EndPoint”属性
    /// </summary>
    public new SliderOrientation Orientation
    {
        get { return base.Orientation; }
        set
        {
            base.Orientation = value;
            //当为垂直方向时
            if (value == SliderOrientation.Vertical)
            {
                ((LinearGradientBrush)GetTemplateChild("GradientBrush")).EndPoint = new Point(0, 1);
            }               
        }
    }
    

/// <summary>
/// 获取颜色值
/// </summary>
/// <returns></returns>
    public Color GetColor()
    {
        return this.GetColor(255);
    }

    /// <summary>
    /// 将滑动条值(Value)转换为ARGB 颜色值并返回
    /// </summary>
    /// <param name="alpha">alpha通道，该值介于0到255</param>
    /// <returns>ARGB 颜色值</returns>
    public Color GetColor(byte alpha)
    {
        Color color;
        double value = this.Value;

        // 将滑动条的值转换为 ARGB 颜色值
        if (value < 0.143d)
        {
            color = Color.FromArgb(alpha, (byte)Math.Floor((value * 256d) / 0.143d), 0, 0);
        }
        else if (value < 0.286d)
        {
            color = Color.FromArgb(alpha, (byte)Math.Floor(256d * (0.286d - value) / 0.143d), 
                              (byte)Math.Floor(256d * (value - 0.143d) / 0.143d), 0);
        }
        else if (value < 0.429)
        {
            color = Color.FromArgb(alpha, 0, (byte)Math.Floor(256d * (0.429d - value) / 0.143d), 
                              (byte)Math.Floor(256d * (value - 0.286d) / 0.143d));
        }
        else if (value < 0.571)
        {
            color = Color.FromArgb(alpha, 0, (byte)Math.Floor(256d*(value-0.429d)/0.143d), 255);
        }
        else if (value < 0.714)
        {
            color = Color.FromArgb(alpha, (byte)Math.Floor(256d * (value - 0.571d) / 0.143d), 
                             (byte)Math.Floor(256d * (0.714d - value) / 0.143d), 255);
        }
        else if (value < 0.857)
        {
            color = Color.FromArgb(alpha, 255, (byte)Math.Floor(256d * (value - 0.714d) / 0.143d), 
                             (byte)Math.Floor(256d * (0.857d - value) / 0.143d));
        }
        else
        {
            color = Color.FromArgb(alpha, 255, 255, (byte)Math.Floor(256d * (value - 0.857d) / 0.143d));
        }
        return color;
    }
}

      接着再来看一下如何使用这两个控件（也就是本文第一张图所演示的效果），其page逻辑代码如下：

public partial class Page2 : UserControl
{
 public Page2()
     {
            InitializeComponent();
            
            
            #region Slider测试代码,加载图片并添加演示缩放旋转的Transform

            string baseUri = Application.Current.Host.Source.AbsoluteUri.Substring(0, 
                                    Application.Current.Host.Source.AbsoluteUri.LastIndexOf("/"));
            currentImage.SetValue(Image.SourceProperty, new BitmapImage(
                                     new Uri(String.Concat(baseUri, "/../Images/j0433157.jpg"))));
            TransformGroup transforms = new TransformGroup();
            transforms.Children.Add(new ScaleTransform());
            transforms.Children.Add(new RotateTransform());
            currentImage.RenderTransform = transforms;
            currentImage.RenderTransformOrigin = new Point(0.5, 0.5);

            #endregion

    }

    #region Slider示例代码
    void ColorSlider_ValueChanged(object sender, EventArgs e)
    { 
    　  //水平Slider设置背景色
        SliderPanel.Background = new SolidColorBrush(ColorSlider.GetColor());
    }

    void ColorSlider2_ValueChanged(object sender, EventArgs e)
    {
    　　//垂直Slider设置背景色
        SliderPanel2.Background = new SolidColorBrush(ColorSlider2.GetColor());
    }

    private void opacitySlider_ValueChanged(object sender, EventArgs e)
    {　
    　　//设置图像的Opacity属性
        currentImage.Opacity = 1d - opacitySlider.Value;
    }

    
    private void transformSlider_ValueChanged(object sender, EventArgs e)
    {
    　　//设置旋转属性
        ((RotateTransform)((TransformGroup)currentImage.RenderTransform).Children[1]).Angle = 
                                                     (transformSlider.Value - 0.5d) * 720d;
//设置缩放属性
        ((ScaleTransform)((TransformGroup)currentImage.RenderTransform).Children[0]).ScaleX = 
                                                     transformSlider.Value * 2d;
        ((ScaleTransform)((TransformGroup)currentImage.RenderTransform).Children[0]).ScaleY = 
                                                     transformSlider.Value * 2d;
    }
    #endregion
}

     好了，今天的内容就先到这里了。

     tag:silverlight,slider,colorslider,imagesnipper

     作者:代震军,daizhj

     原文链接:http://www.cnblogs.com/daizhj/archive/2008/09/04/1284228.html

     源码下载，请点击这里:)