WPF + Windows7 Multi-touch (Part 3)

目前在WPF中使用Multi-touch功能,必須透過P/Invoke的方式呼叫Win32 Touch API的功能(可參考這篇文章 : WPF + Windows7 Multi-touch (Part 2) ), 或是可以直接使用微軟提供的Windows 7 Multitouch .NET Interop Sample Library, 它提供 WPF 與 WinForms 3.5 SP1 要開發Multi-Touch 程式所需的功能, 不過利用上述這些方法開發觸控功能時, 還是有稍嫌複雜, 也不是很直覺.

因此在WPF 4.0 已經將一些觸控功能放到UIElement, UIElement3D和ContentElement中,
在 Beta 1中, 將支援高階操作的觸控功能(Manipulation), 如下所示:

• ManipulationStarted
• ManipulationDelta
• ManipulationInertiaStarting
• ManipulationCompleted
• ManipulationBoundaryFeedback

而在Beta 2 中, 除了原本高階操作的觸控功能(Manipulation)外, 還提供的Touch相關的event,如下所示:

• PreviewTouchDown
• TouchDown
• PreviewTouchMove
• TouchMove
• PreviewTouchUp
• TouchUp
• GotTouchCapture
• LostTouchCapture
• TouchEnter
• TouchLeave

下面我們將利用WPF 4.0 Beta2 Touch功能, 撰寫一個顯示目前觸控點的應用程式, 其步驟如下:

軟體和硬體需求

• IDE -安裝Visual Studio 2010 Beta 2
  
• OS 版本 - Windows 7 Ultimate Editions
• 硬體設備 - 準備一台具有多點觸控的螢幕或電腦

程式碼如下:

XAML檔的部份:

<Window x:Class="WPFTouchPoint.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="800" Width="800"
    TouchDown="Window_TouchDown"
    TouchMove="Window_TouchMove"
    TouchUp="Window_TouchUp">
<Canvas Background="Black">
    <Ellipse
        Canvas.Left="0"
        Canvas.Top="0"
        Name="Touch1"
        Stroke="Black"
        Height="60"
        Width="60"
        Fill="LightGreen"
        Visibility="Hidden">
        <Ellipse.BitmapEffect>
            <DropShadowBitmapEffect ShadowDepth="10"
                                    Direction="270"
                                    Color="White"
                                    Opacity="0.5"
                                    Softness="0.25"/>
        </Ellipse.BitmapEffect>
    </Ellipse>

    <Ellipse
        Canvas.Left="0"
        Canvas.Top="0"
        Name="Touch2"
        Stroke="Black"
        Height="60"
        Width="60"
        Fill="LightBlue"
        Visibility="Hidden">
        <Ellipse.BitmapEffect>
            <dropshadowbitmapeffect shadowdepth="10" direction="270" color="White"
            opacity="0.5" softness="0.25">
       </dropshadowbitmapeffect>
     </Ellipse>
  </Canvas>
 </Window>

C#檔的部分:

namespace WPFTouchPoint
{
/// 

/// Interaction logic for MainWindow.xaml
/// 
public partial class MainWindow : Window
{

    private int Touch1ID = 0;    // id for first touch contact
    private int Touch2ID = 0;    // id for second touch contact

    public MainWindow()
    {
        InitializeComponent();
    }


    private void Window_TouchDown(object sender, TouchEventArgs e)
    {
        TouchPoint p = e.GetTouchPoint(this);

        if (Touch1ID == 0)
        {
           // Show the touch point
           Touch1.Visibility = Visibility.Visible;

           Touch1ID = e.TouchDevice.Id;

           // move the ellipse to the given location
           Touch1.SetValue(Canvas.LeftProperty, p.Position.X - Touch1.Width / 2);
           Touch1.SetValue(Canvas.TopProperty, p.Position.Y - Touch1.Height / 2);
        }
        else if (Touch2ID == 0)
        {
           Touch2.Visibility = Visibility.Visible;

           Touch2ID = e.TouchDevice.Id;
           // move the ellipse to the given location
           Touch2.SetValue(Canvas.LeftProperty, p.Position.X - Touch2.Width / 2);
           Touch2.SetValue(Canvas.TopProperty, p.Position.Y - Touch2.Height / 2);
        }

    }

    private void Window_TouchMove(object sender, TouchEventArgs e)
    {
        TouchPoint p = e.GetTouchPoint(this);
        // determine which contact this belongs to
        if (Touch1ID == e.TouchDevice.Id)
        {
           Touch1.SetValue(Canvas.LeftProperty, p.Position.X - Touch1.Width / 2);
           Touch1.SetValue(Canvas.TopProperty, p.Position.Y - Touch1.Height / 2);
        }
        else if (Touch2ID == e.TouchDevice.Id)
        {
           Touch2.SetValue(Canvas.LeftProperty, p.Position.X - Touch2.Width / 2);
           Touch2.SetValue(Canvas.TopProperty, p.Position.Y - Touch2.Height / 2);
        }
    }

    private void Window_TouchUp(object sender, TouchEventArgs e)
    {
        if (e.TouchDevice.Id == Touch1ID)
        {
            Touch1.Visibility = Visibility.Hidden;

            Touch1ID = 0;
        }
        else if (e.TouchDevice.Id == Touch2ID)
        {
            Touch2.Visibility = Visibility.Hidden;

            Touch2ID = 0;
        }

    }
}
}

顯示結果如下所示:


[圖 1] Multi-touch points in WPF4.0 Beta 2


不過目前這些觸控功能在Beta版還是有很多bug, 可參考這些文章測試出來的結果:
Multi-touch in WPF4.0 Beta2

WPF 4, Beta 2 expands multi-touch API but is buggy


參考文章:
Windows 7: Experimenting with Multi-Touch on Windows 7 ( Part 5 )

Windows using Multi-touch using WPF

Multi-touch in WPF4.0 and VS2010

Introduction to WPF 4 Multitouch

Walkthrough: Creating Your First Touch Application

What's New in WPF Version 4