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件：
http://msdn.microsoft.com/en-us/library/windows/apps/hh465055(v=VS.85).aspx
到目前为止没有运气。 =（该教程适用于Windows Phone 7，所以它有点不同。= \ Help，please？=）
这就是我到目前为止所做的。
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?? ////
}
}
供参考，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;
答案 0 :(得分：7)
简短形式：
Line和Rectangle添加到面板 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 namespace）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＃只有保留模式的图形绘制，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's Canvas object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，但需要对您在应用程序中执行的所有其他操作进行大量修改。
答案 1 :(得分：2)
以下是有关如何使用XAML形状执行此操作的优秀代码示例。
答案 2 :(得分：0)
您应该将Line添加到UI元素，例如Canvas。
答案 3 :(得分：0)
你的代码中的主要问题是你没有附加任何XAML元素的行，我建议你去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，则可能需要也使用WritableBitmapEx，因为XAML Canvas无法呈现给位图。
答案 4 :(得分：0)
此示例项目包含在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
以下是相关的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即可使用它。