如何在C＃的Windows Metro Style应用程序的屏幕上绘图？

Question

我只是希望用户能够使用某种指针在屏幕上绘图。

我已经有代码工作，捕获指针的位置，但我无法弄清楚如何将像素或形状或任何东西放在屏幕上。

我找到了这个有用的教程：
http://www.dotnetspeaks.com/DisplayArticle.aspx?ID=137

我一直在看这里的文档：
http://msdn.microsoft.com/en-us/library/windows/apps/hh465055(v=VS.85).aspx

到目前为止没有运气。 =（本教程适用于Windows Phone 7，所以它有点不同。= \\ Help，please？=）

这就是我到目前为止所拥有的。

绘图部分：

    private void Image_PointerPressed(object sender, PointerEventArgs e)
    {
        Debug.WriteLine("Image_PointerPressed");
        isTracing = true;
    }

    private void Image_PointerReleased(object sender, PointerEventArgs e)
    {
        Debug.WriteLine("Image_PointerReleased");
        isTracing = false;
    }

    private void Image_PointerMoved(object sender, PointerEventArgs e)
    {
        Debug.WriteLine("Image_PointerMoved");
        Debug.WriteLine(e.GetCurrentPoint(this).Position);
        if (isTracing)
        {
            Debug.WriteLine("isTracing");

            Point pos = e.GetCurrentPoint(this).Position;
            Color color = Colors.Green;
            Line line = new Line() { X1 = pos.X, X2 = pos.X + 1, Y1 = pos.Y, Y2 = pos.Y + 1 };
            line.Stroke = new SolidColorBrush(color);
            line.StrokeThickness = 15;
            //// So how do I draw this line onto the screen?? ////

        }

    }

作为参考，代码中的其他内容：

using System;
    using System.Collections.Generic;
    using System.Diagnostics;
    using System.IO;
    using System.Linq;
    using System.Threading.Tasks;
    using Multimedia.FFmpeg;
    using Windows.Foundation;
    using Windows.Storage;
    using Windows.Storage.Pickers;
    using Windows.Storage.Streams;
    using Windows.UI.Xaml;
    using Windows.UI.Xaml.Controls;
    using Windows.UI.Xaml.Shapes;
    using Windows.UI.Xaml.Media;
    using Windows.UI.Xaml.Input;
    using Windows.UI.Input;

    bool isTracing = false;

Answer 1

简写：

• 将Line s和Rectangle s添加到面板
• 直接操作位图
• 在JavaScript / HTML项目中使用HTML5 Canvas元素
• 用C ++ / DirectX编写整个内容

Metro / XAML无法覆盖OnRender()方法等。 您可以选择将现有图形元素（例如，从Shapes命名空间 ）添加到Canvas或其他Panel，或者直接操作位图中的像素并将该位图推送到Image元素中。

Metro / C＃仅具有保留模式图形绘制，这意味着它将呈现的唯一内容是已添加到视图层次结构中的对象。 您正在寻找的是某种即时模式图形绘制，例如

myCanvas.DrawLine( fromPoint, toPoint );

这可以使用HTML5的Canvas对象在JavaScript / HTML项目中完成。 遗憾的是，这是我倾向于这样一个项目的方式。 不幸的是，微软没有为XAML项目提供立即模式元素，但事实就是如此。 C ++ / DirectX也是进行自定义绘图的一个选项，但需要对应用程序中正在执行的所有其他操作进行大量修改。

Answer 2

这是一个很好的代码示例，介绍如何使用XAML形状执行此操作。

http://www.codeproject.com/Articles/416878/Metro-Paint

Answer 3

你的代码中的主要问题是你没有附加任何XAML元素的行，我建议你把它做到Canvas元素，更像是这样：

newCanvas.Children.Add(line);

另一种方法是使用Modern Components Drawing Library ，它适用于WinRT，使用.NET Graphics类调用并直接在XAML Canvas上绘制，请注意，如果要将图像保存为位图，则可能还需要使用WritableBitmapEx ，因为XAML Canvas无法渲染到位图。

Answer 4

此示例项目具有在C＃/ XAML中为Win 8 Store应用程序在屏幕上绘制的代码：

http://code.msdn.microsoft.com/windowsapps/Drawing-on-a-Canvas-with-33510ae6

这是相关的C＃文件：

using System; 
using System.Collections.Generic; 
using System.IO; 
using System.Linq; 
using Windows.Devices.Input; 
using Windows.Foundation; 
using Windows.Foundation.Collections; 
using Windows.UI; 
using Windows.UI.Input; 
using Windows.UI.Input.Inking; //we need to add this name space in order to have many functions  
using Windows.UI.Xaml; 
using Windows.UI.Xaml.Controls; 
using Windows.UI.Xaml.Controls.Primitives; 
using Windows.UI.Xaml.Data; 
using Windows.UI.Xaml.Input; 
using Windows.UI.Xaml.Media; 
using Windows.UI.Xaml.Navigation; 
using Windows.UI.Xaml.Shapes; 
// The Blank Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=234238 

namespace DrawingOnCanvasWithInkPen 
{ 
/// <summary> 
/// An empty page that can be used on its own or navigated to within a Frame. 
/// </summary> 
public sealed partial class MainPage : Page 
{ 
    InkManager _inkKhaled = new Windows.UI.Input.Inking.InkManager(); 
    private uint _penID; 
    private uint _touchID; 
    private Point _previousContactPt; 
    private Point currentContactPt; 
    private double x1; 
    private double y1; 
    private double x2; 
    private double y2; 


    public MainPage() 
    { 
        this.InitializeComponent(); 

        MyCanvas.PointerPressed += new PointerEventHandler(MyCanvas_PointerPressed); 
        MyCanvas.PointerMoved += new PointerEventHandler(MyCanvas_PointerMoved); 
        MyCanvas.PointerReleased += new PointerEventHandler(MyCanvas_PointerReleased); 
        MyCanvas.PointerExited += new PointerEventHandler(MyCanvas_PointerReleased); 
    } 


    #region PointerEvents 
    private void MyCanvas_PointerReleased(object sender, PointerRoutedEventArgs e) 
    { 
        if (e.Pointer.PointerId == _penID) 
        { 
            Windows.UI.Input.PointerPoint pt = e.GetCurrentPoint(MyCanvas); 

            // Pass the pointer information to the InkManager.  
            _inkKhaled.ProcessPointerUp(pt); 
        } 

        else if (e.Pointer.PointerId == _touchID) 
        { 
            // Process touch input 
        } 

        _touchID = 0; 
        _penID = 0; 

        // Call an application-defined function to render the ink strokes. 


        e.Handled = true; 
    } 

    private void MyCanvas_PointerMoved(object sender, PointerRoutedEventArgs e) 
    { 
        if (e.Pointer.PointerId == _penID) 
        { 
            PointerPoint pt = e.GetCurrentPoint(MyCanvas); 

            // Render a red line on the canvas as the pointer moves.  
            // Distance() is an application-defined function that tests 
            // whether the pointer has moved far enough to justify  
            // drawing a new line. 
            currentContactPt = pt.Position; 
            x1 = _previousContactPt.X; 
            y1 = _previousContactPt.Y; 
            x2 = currentContactPt.X; 
            y2 = currentContactPt.Y; 

            if (Distance(x1, y1, x2, y2) > 2.0) // We need to developp this method now  
            { 
                Line line = new Line() 
                { 
                    X1 = x1, 
                    Y1 = y1, 
                    X2 = x2, 
                    Y2 = y2, 
                    StrokeThickness = 4.0, 
                    Stroke = new SolidColorBrush(Colors.Green) 
                }; 

                _previousContactPt = currentContactPt; 

                // Draw the line on the canvas by adding the Line object as 
                // a child of the Canvas object. 
                MyCanvas.Children.Add(line); 

                // Pass the pointer information to the InkManager. 
                _inkKhaled.ProcessPointerUpdate(pt); 
            } 
        } 

        else if (e.Pointer.PointerId == _touchID) 
        { 
            // Process touch input 
        } 

    } 

    private double Distance(double x1, double y1, double x2, double y2) 
    { 
        double d = 0; 
        d = Math.Sqrt(Math.Pow((x2 - x1), 2) + Math.Pow((y2 - y1), 2)); 
        return d; 
    } 

    private void MyCanvas_PointerPressed(object sender, PointerRoutedEventArgs e) 
    { 
        // Get information about the pointer location. 
        PointerPoint pt = e.GetCurrentPoint(MyCanvas); 
        _previousContactPt = pt.Position; 

        // Accept input only from a pen or mouse with the left button pressed.  
        PointerDeviceType pointerDevType = e.Pointer.PointerDeviceType; 
        if (pointerDevType == PointerDeviceType.Pen || 
                pointerDevType == PointerDeviceType.Mouse && 
                pt.Properties.IsLeftButtonPressed) 
        { 
            // Pass the pointer information to the InkManager. 
            _inkKhaled.ProcessPointerDown(pt); 
            _penID = pt.PointerId; 

            e.Handled = true; 
        } 

        else if (pointerDevType == PointerDeviceType.Touch) 
        { 
            // Process touch input 
        } 
    } 

    #endregion 

    /// <summary> 
    /// Invoked when this page is about to be displayed in a Frame. 
    /// </summary> 
    /// <param name="e">Event data that describes how this page was reached.  The Parameter 
    /// property is typically used to configure the page.</param> 
    protected override void OnNavigatedTo(NavigationEventArgs e) 
    { 
    } 
} 

}

和xaml文件：

<Page 

x:Class="DrawingOnCanvasWithInkPen.MainPage" 
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
xmlns:local="using:DrawingOnCanvasWithInkPen" 
xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
mc:Ignorable="d"> 

<Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}"> 
    <Canvas Name="MyCanvas" Background="White" HorizontalAlignment="Left" Height="513" Margin="83,102,0,0" VerticalAlignment="Top" Width="1056"/> 

</Grid> 

在目前的状态下，它只处理笔或鼠标输入 - 但我也只需稍作修改就可以触摸它。

Answer 5

您应该将Line添加到UI元素（如Canvas）。