c# - 如何在 C# 中将长字符串打印到多个页面

Question

我正在尝试使用下面的代码打印一个很长的字符串，但它只在一页中打印了整个文本。有什么简单的方法可以正确打印吗？

string text="the text has like 1000 words";

System.Drawing.Printing.PrintDocument p = new System.Drawing.Printing.PrintDocument();

p.PrintPage += delegate (object sender1, System.Drawing.Printing.PrintPageEventArgs e1)
{
    e1.Graphics.DrawString(text, new System.Drawing.Font("Times New Roman", 12), new System.Drawing.SolidBrush(System.Drawing.Color.Black), new System.Drawing.RectangleF(50, 50, p.DefaultPageSettings.PrintableArea.Width - 50, p.DefaultPageSettings.PrintableArea.Height - 50));

};
try
{
    p.Print();
}
catch (Exception ex)
{
    throw new Exception("Exception Occured While Printing", ex);
}

我试着用 this article 来解决它但是该方法卡在了某个我不知道如何修复的循环中。

Answer 1

您必须记住，只要您告诉它还有更多页面，PrintDocument 就会引发事件PrintPage。您的任务是跟踪打印的内容、接下来需要打印的内容以及是否需要另一页。

有几种方法可以做到这一点。在这种情况下，我选择获取您的 text 的内容，检查它有多少适合当前页面，DrawString 那一点，然后更新我的处理字符串，称为 remainingtext 以便能够重复下一页。完成后，通过将 PrintEvent 参数实例的 HasMorepages 设置为 true 或 false 来决定是否需要下一页。

代码如下:

PrintDocument p = new PrintDocument();

var font = new Font("Times New Roman", 12);
var margins = p.DefaultPageSettings.Margins;
var layoutArea = new RectangleF(
    margins.Left, 
    margins.Top, 
    p.DefaultPageSettings.PrintableArea.Width - (margins.Left + margins.Right ), 
    p.DefaultPageSettings.PrintableArea.Height - (margins.Top + margins.Bottom));
var layoutSize = layoutArea.Size;
layoutSize.Height = layoutSize.Height - font.GetHeight(); // keep lastline visible
var brush = new SolidBrush(Color.Black);

// what still needs to be printed
var remainingText = text;

p.PrintPage += delegate (object sender1, PrintPageEventArgs e1)
{
    int charsFitted, linesFilled;

    // measure how many characters will fit of the remaining text
    var realsize = e1.Graphics.MeasureString(
        remainingText, 
        font, 
        layoutSize, 
        StringFormat.GenericDefault, 
        out charsFitted,  // this will return what we need
        out linesFilled);

    // take from the remainingText what we're going to print on this page
    var fitsOnPage = remainingText.Substring(0, charsFitted);
    // keep what is not printed on this page 
    remainingText = remainingText.Substring(charsFitted).Trim();

    // print what fits on the page
    e1.Graphics.DrawString(
        fitsOnPage, 
        font, 
        brush, 
        layoutArea);

    // if there is still text left, tell the PrintDocument it needs to call 
    // PrintPage again.
    e1.HasMorePages = remainingText.Length > 0;
};
p.Print();

当我连接 PrintPreviewControl 时，结果如下: