通用Windows 8.1中的用户签名应用程序

Question

是否有任何能够在Windows 8.1移动设备上签名文档的能力？像用户可以用手或手写笔绘制签名的画布。是否有任何XAML控制这个任务或其他东西？

Answer 1

我一直在为这一天的最好的一段而努力。看来，内置墨曾经是在Windows Phone 7和8.0可被拉出8.1

我使用的技术在文章中通过克里斯W¯¯指出，以使该可控制控制添加到页面的XAML并处理其他所有内容。

神奇的是在WritableBitmap和PointerPressed和PointerMoved方法中。

using Windows.Foundation; 
using Windows.UI; 
using Windows.UI.Xaml; 
using Windows.UI.Xaml.Controls; 
using Windows.UI.Xaml.Input; 
using Windows.UI.Xaml.Media; 
using Windows.UI.Xaml.Media.Imaging; 

namespace ProofOfConcept.App.Controls 
{ 
    public class SignatureCaptureControl : Canvas 
    { 
     private WriteableBitmap _writeableBitmap; 

     private Point _currentPoint; 
     private Point _oldPoint; 

     public SignatureCaptureControl() 
     { 
      _writeableBitmap = new WriteableBitmap(300, 130); 
      PointerPressed += SignatureCaptureControl_PointerPressed; 
      PointerMoved += SignatureCaptureControl_PointerMoved; 
     } 

     private void SignatureCaptureControl_PointerPressed(object sender, PointerRoutedEventArgs e) 
     { 
      _currentPoint = e.GetCurrentPoint(this).Position; 
      _oldPoint = _currentPoint; 
     } 

     void SignatureCaptureControl_PointerMoved(object sender, PointerRoutedEventArgs e) 
     { 
      _currentPoint = e.GetCurrentPoint(this).Position; 
      _writeableBitmap.DrawLine((int)_currentPoint.X, (int)_currentPoint.Y, (int)_oldPoint.X, (int)_oldPoint.Y, PenColor); 
      this.InvalidateArrange(); 
      _oldPoint = _currentPoint; 
     } 

     public void ClearSignature() 
     { 
      _writeableBitmap.Clear(); 
     } 

    } 

} 

使用下面所述的控制将显示一个300x130白盒作为手指或指示笔拖过它，这将画线。

<Border Background="White"> 
    <controls:SignatureCaptureControl Height="130" Width="300"/> 
</Border> 

要获得的图像出我们必须提取从WritableBitmap的像素数据，然后对其进行编码为位图/ GIF/JPEG/PNG /等。

public Task<byte[]> ReadAsPngImageAsync() 
{ 
    return ReadImageFromWritableBitmapAsync(_writeableBitmap, Windows.Graphics.Imaging.BitmapEncoder.PngEncoderId); 
} 


internal static async Task<byte[]> ReadImageFromWritableBitmapAsync(Windows.UI.Xaml.Media.Imaging.WriteableBitmap writeableBitmap, Guid encoderId) 
{ 
    var rawPixels = await ConvertBitmapToByteArrayAsync(writeableBitmap); 
    var encodedPixels = await EncodePixels(rawPixels, encoderId, (uint)writeableBitmap.PixelWidth, (uint)writeableBitmap.PixelHeight); 
    return encodedPixels; 
} 

private static async Task<byte[]> ConvertBitmapToByteArrayAsync(Windows.UI.Xaml.Media.Imaging.WriteableBitmap bitmap) 
{ 
    using (var stream = bitmap.PixelBuffer.AsStream()) 
    { 
     var pixels = new byte[(uint)stream.Length]; 
     await stream.ReadAsync(pixels, 0, pixels.Length); 
     return pixels; 
    } 
} 

private static async Task<byte[]> EncodePixels(byte[] signaturePixels, Guid encoderId, uint pixelWidth, uint pixelHeight) 
{ 
    using (var randomAccessStream = new Windows.Storage.Streams.InMemoryRandomAccessStream()) 
    { 
     var encoder = await Windows.Graphics.Imaging.BitmapEncoder.CreateAsync(encoderId, randomAccessStream); 
     encoder.SetPixelData(Windows.Graphics.Imaging.BitmapPixelFormat.Bgra8, Windows.Graphics.Imaging.BitmapAlphaMode.Premultiplied, 
      pixelWidth, pixelHeight, 
      96, 96, signaturePixels); 
     await encoder.FlushAsync(); 

     using (var stream = randomAccessStream.GetInputStreamAt(0)) 
     { 
      var pixels = new byte[(uint)randomAccessStream.Size]; 
      stream.AsStreamForRead().Read(pixels, 0, pixels.Length); 
      return pixels; 
     } 
    } 
} 

现在我们有了代表以标准形式的图像，我们可以简单地将数据保存到本地存储或提交到服务的字节数组。