如何使用 PrintDialog（或等效项）打印窗口（或屏幕）？

Question

我正在尝试将主窗口打印到打印机和文件（通过使用 PrintDialog）。我尝试了以下三种解决方案，但每种解决方案都存在一些问题（如下所述）。有谁知道一个好的解决方案，或者改进现有的解决方案？

1。 https://social.msdn.microsoft.com/Forums/vstudio/en-US/df305a6c-4546-4665-a9fb-1b190ea47ec6/how-to-print-bitmapsource?forum=wpf

此解决方案会剪切最终文档/打印，因此不会显示整个屏幕。

private void PrintBitmapSource(BitmapSource inBms)
{
    var pd = new PrintDialog();
    var ret = pd.ShowDialog();
    if (ret.Value)
    {
        var dv = new DrawingVisual();
        using (var dc = dv.RenderOpen())
        {
            dc.DrawImage(inBms, new Rect(0, 0, inBms.Width, inBms.Height));
        }
        pd.PrintVisual(dv, "document image");
    }
}

2。 http://www.a2zdotnet.com/View.aspx?id=66#.VcMld_ntlBc

这个解决方案创建了一个完整的打印，但有一些奇怪的伪影，它似乎混合了调整大小之前和之后的元素。同时调整屏幕大小。

PrintDialog printDlg = new System.Windows.Controls.PrintDialog();
if (printDlg.ShowDialog() == true)
{
    //get selected printer capabilities
    System.Printing.PrintCapabilities capabilities = printDlg.PrintQueue.GetPrintCapabilities(printDlg.PrintTicket);

    //get scale of the print wrt to screen of WPF visual
 double scale = Math.Min(capabilities.PageImageableArea.ExtentWidth / this.ActualWidth, capabilities.PageImageableArea.ExtentHeight /
                this.ActualHeight);

    //Transform the Visual to scale
    this.LayoutTransform = new ScaleTransform(scale, scale);

    //get the size of the printer page
    Size sz = new Size(capabilities.PageImageableArea.ExtentWidth, capabilities.PageImageableArea.ExtentHeight);

    //update the layout of the visual to the printer page size.
    this.Measure(sz);
    this.Arrange(new Rect(new Point(capabilities.PageImageableArea.OriginWidth, capabilities.PageImageableArea.OriginHeight), sz));

    //now print the visual to printer to fit on the one page.
    printDlg.PrintVisual(this, "First Fit to Page WPF Print"); 
}

3。 将 PageMediaSize 设置为屏幕分辨率（硬编码用于测试目的）。

这个解决方案几乎是完美的，但右侧有一个黑色区域，但在这个黑色区域的顶部正确显示了一些元素。看起来黑色区域从解决方案 #1 的中断处开始。

var pd = new System.Windows.Controls.PrintDialog();
var ret = pd.ShowDialog();
if (ret.Value)
{
    pd.PrintTicket.PageMediaSize = new PageMediaSize(1920, 1080);
    pd.PrintTicket.PageOrientation = System.Printing.PageOrientation.Landscape;
    pd.PrintVisual(ApplicationGlobal.MainWindow as Window, "testprint");
}

Answer 1

这是一个使用RenderTargetBitmap将继承自FrameworkElement的控件保存到位图图像文件的示例：

private void SaveFrameworkElementToBitmap(FrameworkElement gridinput, string filepath)
{
    gridinput.Measure(new System.Windows.Size(double.PositiveInfinity, double.PositiveInfinity));
    int grid1Width = (int)Math.Round(gridinput.ActualWidth);
    int grid1Height = (int)Math.Round(gridinput.ActualHeight);
    grid1Width = grid1Width == 0 ? 1 : grid1Width;
    grid1Height = grid1Height == 0 ? 1 : grid1Height;

    RenderTargetBitmap rtbmp = new RenderTargetBitmap(grid1Width, grid1Height, 96d, 96d, PixelFormats.Default);
    rtbmp.Render(gridinput);
    BmpBitmapEncoder encoder = new BmpBitmapEncoder();
    encoder.Frames.Add(BitmapFrame.Create(rtbmp));
    FileStream gridbmpfilestrm = File.Create(filepath);
    encoder.Save(gridbmpfilestrm);
    gridbmpfilestrm.Close();
    rtbmp.Clear();
}

Answer 2

这是一个可以打印 FrameworkElement 的方法的实现。您需要在项目上设置允许不安全代码属性。

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

public void Print(FrameworkElement objectToPrint)
{
    PrintDialog printDialog = new PrintDialog();
    if ((bool)printDialog.ShowDialog().GetValueOrDefault())
    {
        Mouse.OverrideCursor = Cursors.Wait;
        System.Printing.PrintCapabilities capabilities =
            printDialog.PrintQueue.GetPrintCapabilities(printDialog.PrintTicket);
        double dpiScale = 300.0 / 96.0;
        FixedDocument document = new FixedDocument();
        try
        {
            // Change the layout of the UI Control to match the width of the printer page
            objectToPrint.Width = capabilities.PageImageableArea.ExtentWidth;
            objectToPrint.UpdateLayout();
            objectToPrint.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
            Size size = new Size(capabilities.PageImageableArea.ExtentWidth, objectToPrint.DesiredSize.Height);
            objectToPrint.Measure(size);
            size = new Size(capabilities.PageImageableArea.ExtentWidth, objectToPrint.DesiredSize.Height);
            objectToPrint.Measure(size);
            objectToPrint.Arrange(new Rect(size));

            // Convert the UI control into a bitmap at 300 dpi
            double dpiX = 300;
            double dpiY = 300;
            RenderTargetBitmap bmp =
                new RenderTargetBitmap(
                    Convert.ToInt32(capabilities.PageImageableArea.ExtentWidth * dpiScale),
                    Convert.ToInt32(objectToPrint.ActualHeight * dpiScale),
                    dpiX,
                    dpiY,
                    PixelFormats.Pbgra32);
            bmp.Render(objectToPrint);

            // Convert the RenderTargetBitmap into a bitmap we can more readily use
            PngBitmapEncoder png = new PngBitmapEncoder();
            png.Frames.Add(BitmapFrame.Create(bmp));
            System.Drawing.Bitmap bmp2;
            using (MemoryStream memoryStream = new MemoryStream())
            {
                png.Save(memoryStream);
                bmp2 = new System.Drawing.Bitmap(memoryStream);
            }
            document.DocumentPaginator.PageSize = new Size(
                printDialog.PrintableAreaWidth,
                printDialog.PrintableAreaHeight);

            // break the bitmap down into pages
            int pageBreak = 0;
            int previousPageBreak = 0;
            int pageHeight = Convert.ToInt32(capabilities.PageImageableArea.ExtentHeight * dpiScale);
            while (pageBreak < bmp2.Height - pageHeight)
            {
                pageBreak += pageHeight; // Where we thing the end of the page should be

                // Keep moving up a row until we find a good place to break the page
                while (!IsRowGoodBreakingPoint(bmp2, pageBreak)) pageBreak--;

                PageContent pageContent = this.GeneratePageContent(
                    bmp2,
                    previousPageBreak,
                    pageBreak,
                    document.DocumentPaginator.PageSize.Width,
                    document.DocumentPaginator.PageSize.Height,
                    capabilities);
                document.Pages.Add(pageContent);
                previousPageBreak = pageBreak;
            }

            // Last Page
            PageContent lastPageContent = this.GeneratePageContent(
                bmp2,
                previousPageBreak,
                bmp2.Height,
                document.DocumentPaginator.PageSize.Width,
                document.DocumentPaginator.PageSize.Height,
                capabilities);
            document.Pages.Add(lastPageContent);
        }
        finally
        {
            // Scale UI control back to the original so we don't effect what is on the screen 
            objectToPrint.Width = double.NaN;
            objectToPrint.UpdateLayout();
            objectToPrint.LayoutTransform = new ScaleTransform(1, 1);
            Size size = new Size(
                capabilities.PageImageableArea.ExtentWidth,
                capabilities.PageImageableArea.ExtentHeight);
            objectToPrint.Measure(size);
            objectToPrint.Arrange(
                new Rect(
                    new Point(
                        capabilities.PageImageableArea.OriginWidth,
                        capabilities.PageImageableArea.OriginHeight),
                    size));
            Mouse.OverrideCursor = null;
        }
        printDialog.PrintDocument(document.DocumentPaginator, "Print Document Name");
    }
}

private PageContent GeneratePageContent(System.Drawing.Bitmap bmp, int top,
    int bottom, double pageWidth, double PageHeight,
    System.Printing.PrintCapabilities capabilities)
{
    FixedPage printDocumentPage = new FixedPage();
    printDocumentPage.Width = pageWidth;
    printDocumentPage.Height = PageHeight;

    int newImageHeight = bottom - top;
    System.Drawing.Bitmap bmpPage = bmp.Clone(new System.Drawing.Rectangle(0, top,
            bmp.Width, newImageHeight), System.Drawing.Imaging.PixelFormat.Format32bppArgb);

    // Create a new bitmap for the contents of this page
    Image pageImage = new Image();
    BitmapSource bmpSource =
        System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
            bmpPage.GetHbitmap(),
            IntPtr.Zero,
            System.Windows.Int32Rect.Empty,
            BitmapSizeOptions.FromWidthAndHeight(bmp.Width, newImageHeight));

    pageImage.Source = bmpSource;
    pageImage.VerticalAlignment = VerticalAlignment.Top;

    // Place the bitmap on the page
    printDocumentPage.Children.Add(pageImage);

    PageContent pageContent = new PageContent();
    ((System.Windows.Markup.IAddChild)pageContent).AddChild(printDocumentPage);

    FixedPage.SetLeft(pageImage, capabilities.PageImageableArea.OriginWidth);
    FixedPage.SetTop(pageImage, capabilities.PageImageableArea.OriginHeight);

    pageImage.Width = capabilities.PageImageableArea.ExtentWidth;
    pageImage.Height = capabilities.PageImageableArea.ExtentHeight;
    return pageContent;
}

private bool IsRowGoodBreakingPoint(System.Drawing.Bitmap bmp, int row)
{
    double maxDeviationForEmptyLine = 1627500;
    bool goodBreakingPoint = false;

    if (rowPixelDeviation(bmp, row) < maxDeviationForEmptyLine)
        goodBreakingPoint = true;

    return goodBreakingPoint;
}

private double rowPixelDeviation(System.Drawing.Bitmap bmp, int row)
{
    int count = 0;
    double total = 0;
    double totalVariance = 0;
    double standardDeviation = 0;
    System.Drawing.Imaging.BitmapData bmpData =
        bmp.LockBits(
            new System.Drawing.Rectangle(0, 0, bmp.Width, bmp.Height),
            System.Drawing.Imaging.ImageLockMode.ReadOnly,
            bmp.PixelFormat);
    int stride = bmpData.Stride;
    IntPtr firstPixelInImage = bmpData.Scan0;

    unsafe
    {
        byte* p = (byte*)(void*)firstPixelInImage;
        p += stride * row; // find starting pixel of the specified row
        for (int column = 0; column < bmp.Width; column++)
        {
            count++; //count the pixels

            byte blue = p[0];
            byte green = p[1];
            byte red = p[3];

            int pixelValue = System.Drawing.Color.FromArgb(0, red, green, blue).ToArgb();
            total += pixelValue;
            double average = total / count;
            totalVariance += Math.Pow(pixelValue - average, 2);
            standardDeviation = Math.Sqrt(totalVariance / count);

            // go to next pixel
            p += 3;
        }
    }
    bmp.UnlockBits(bmpData);

    return standardDeviation;
}