saving WPF InkCanvas to a JPG - image is getting c

问题:

I have a WPF InkCanvas control I'm using to capture a signature in my application. The control looks like this - it's 700x300

alt text http://img156.imageshack.us/img156/7885/inkcanvas.jpg

However, when I save it as a JPG, the resulting image looks like this, also 700x300

alt text http://img210.imageshack.us/img210/5668/saved.jpg

The code I'm using to save

            sigPath = System.IO.Path.GetTempFileName();

            MemoryStream ms = new MemoryStream();
            FileStream fs = new FileStream(sigPath, FileMode.Create);

            RenderTargetBitmap rtb = new RenderTargetBitmap((int)inkSig.Width, (int)inkSig.Height, 96d, 96d, PixelFormats.Default);
            rtb.Render(inkSig);
            JpegBitmapEncoder encoder = new JpegBitmapEncoder();
            encoder.Frames.Add(BitmapFrame.Create(rtb));

            encoder.Save(fs);
            fs.Close();

This is the XAML I'm using:

<Window x:Class="Consent.Client.SigPanel"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Background="Transparent" Topmost="True" AllowsTransparency="True"
Title="SigPanel" Left="0" Top="0" Height="1024" Width="768" WindowStyle ="None" ShowInTaskbar="False" ResizeMode="NoResize" WindowStartupLocation="CenterScreen" >

<Border BorderThickness="1" BorderBrush="Black" Background='#FFFFFFFF' x:Name='DocumentRoot' Width='750' Height='400' CornerRadius='10'>
    <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
        <TextBlock Name="txtLabel" FontSize="24" HorizontalAlignment="Center" >Label</TextBlock>
        <InkCanvas Opacity="1" Background="Beige" Name="inkSig" Width="700" Height="300" />

        <StackPanel HorizontalAlignment="Center" Orientation="Horizontal">
            <Button FontSize="24" Margin="10" Width="150" Name="btnSave" Click="btnSave_Click">Save</Button>
            <Button FontSize="24" Margin="10" Width="150" Name="btnCancel" Click="btnCancel_Click">Cancel</Button>
            <Button FontSize="24" Margin="10" Width="150" Name="btnClear" Click="btnClear_Click">Clear</Button>
        </StackPanel>
    </StackPanel>
</Border>

In the past this worked perfectly. I can't figure out what changed that is causing the image to shift when it is saved.

回答1:

Aha! The problem is the TextBlock txtLabel that is directly above the InkCanvas. When you remove that the black line disappears.

As for why that is happening, I'm not entirely sure yet.

回答2:

I had same problem i did this way.. It worked here..

    private void Button_Click(object sender, RoutedEventArgs e)
    {           
        double width = inkSig.ActualWidth;
        double height = inkSig.ActualHeight;
        RenderTargetBitmap bmpCopied = new RenderTargetBitmap((int)Math.Round(width), (int)Math.Round(height), 96, 96, PixelFormats.Default);
        DrawingVisual dv = new DrawingVisual();
        using (DrawingContext dc = dv.RenderOpen())
        {
            VisualBrush vb = new VisualBrush(inkSig);
            dc.DrawRectangle(vb, null, new Rect(new System.Windows.Point(), new System.Windows.Size(width, height)));
        }
        bmpCopied.Render(dv);
        System.Drawing.Bitmap bitmap;
        using (MemoryStream outStream = new MemoryStream())
        {
            // from System.Media.BitmapImage to System.Drawing.Bitmap 
            BitmapEncoder enc = new BmpBitmapEncoder();
            enc.Frames.Add(BitmapFrame.Create(bmpCopied));
            enc.Save(outStream);
            bitmap = new System.Drawing.Bitmap(outStream);
        }

        EncoderParameter qualityParam =
     new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 85L);

        // Jpeg image codec
        ImageCodecInfo jpegCodec = getEncoderInfo("image/jpeg");

        if (jpegCodec == null)
            return;

        EncoderParameters encoderParams = new EncoderParameters(1);
        encoderParams.Param[0] = qualityParam;
        Bitmap btm = new Bitmap(bitmap);
        bitmap.Dispose();
        btm.Save("C:\\Users\\Pd\\Desktop\\dfe12.jpg", jpegCodec, encoderParams);
        btm.Dispose(); 
    }

    private ImageCodecInfo getEncoderInfo(string mimeType)
    {
        // Get image codecs for all image formats
        ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();

        // Find the correct image codec
        for (int i = 0; i < codecs.Length; i++)
            if (codecs[i].MimeType == mimeType)
                return codecs[i];
        return null;
    } 

回答3:

My class save image

     using System;
     using System.IO;
     using System.Windows;
     using System.Windows.Controls;
     using System.Windows.Media;
     using System.Windows.Media.Imaging;

     public void ExportToJpeg(String path,  InkCanvas surface)
    {
        double
                x1 = surface.Margin.Left,
                x2 = surface.Margin.Top,
                x3 = surface.Margin.Right,
                x4 = surface.Margin.Bottom;

        if (path == null) return;

        surface.Margin = new Thickness(0, 0, 0, 0);

      Size size = new Size(surface.Width, surface.Height);
   surface.Measure(size);
   surface.Arrange(new Rect(size));

         RenderTargetBitmap renderBitmap =
          new RenderTargetBitmap(
            (int)size.Width,
            (int)size.Height,
            96,
            96,
            PixelFormats.Default);
      renderBitmap.Render(surface);
      using (FileStream fs = File.Open(path, FileMode.Create))
        {
         JpegBitmapEncoder encoder = new JpegBitmapEncoder();
            encoder.Frames.Add(BitmapFrame.Create(renderBitmap));
            encoder.Save(fs);
        }
      surface.Margin = new Thickness(x1, x2, x3, x4);
    }

回答4:

Jason i solvo this problem. Sorry my English. i am Russian. You need set property inkCanvas.Margin is 0,0,0,0 that surface.Margin = new Thickness(0, 0, 0, 0); after saving set margin in you posicion

exaple: i nave

surface.Margin = new Thickness(0, 0, 0, 0); http://img189.imageshack.us/img189/7499/mynewimage.png

回答5:

and surface.Margin = new Thickness(55,40,96,5); http://img519.imageshack.us/img519/7499/mynewimage.png

回答6:

  var size = new Size(inkCanvas.ActualWidth, inkCanvas.ActualHeight);
    inkCanvas.Margin = new Thickness(0, 0, 0, 0);

    inkCanvas.Measure(size);
    inkCanvas.Arrange(new Rect(size));
    var encoder = new PngBitmapEncoder();
    var bitmapTarget = new RenderTargetBitmap((int)size.Width, (int)size.Height, 96, 96, PixelFormats.Default);
    bitmapTarget.Render(inkCanvas);
    encoder.Frames.Add(BitmapFrame.Create(bitmapTarget));
    encoder.Save(ms); 

回答7:

I've been looking all over the net for an answer to this problem and tried most opinions without any joy. Then I tried this and it worked!

<Canvas x:Name="editCanvas" Background="Transparent" ClipToBounds="True">
        <InkCanvas EditingMode="Select" x:Name="inkCanvas"  Background="Transparent" Height="562" Width="866">

        </InkCanvas>
</Canvas>