Question

使用Itextsharp的MVC3 VB.NET应用程序。我有一段生成pdf文件的代码，一切看起来都不错，但是我希望将该pdf文件中的线条颜色替换为2种颜色，以便看到它的人很容易理解这些值。有没有办法根据字体大小将整行的背景颜色设置为设定的颜色？我将使用的功能如下：

    For Each _reg_ In _reg
                Dim _registrant As reg_info = _reg_
                If y_line1 <= 30 Then
                    doc.NewPage()
                    _Page = _Page + 1
                    y_line1 = 670
                End If

                If y_line1 = 670 Then
                    cb.BeginText()
                    cb.SetFontAndSize(BF_Times, 6)
                    cb.ShowTextAligned(PdfContentByte.ALIGN_LEFT, _datePrinted + "  " + _timePrinted, 500, 770, 0)
                    cb.ShowTextAligned(PdfContentByte.ALIGN_RIGHT, "Page Number" + " " + _Page, 600, 770, 0)
                    cb.SetFontAndSize(BF_Times, 8)
                    cb.ShowTextAligned(PdfContentByte.ALIGN_CENTER, _reportHead + " Overrides ", 304, 720, 0)
                    cb.ShowTextAligned(PdfContentByte.ALIGN_LEFT, "First Name", 20, 700, 0)
                    cb.ShowTextAligned(PdfContentByte.ALIGN_LEFT, "Last Name", 80, 700, 0)
                    cb.ShowTextAligned(PdfContentByte.ALIGN_LEFT, "Last Four", 160, 700, 0)
                    cb.ShowTextAligned(PdfContentByte.ALIGN_LEFT, "Email Address", 300, 700, 0)

                    cb.EndText()
                End If

                cb.BeginText()
                cb.SetFontAndSize(BF_Times, 8)
                cb.ShowTextAligned(PdfContentByte.ALIGN_LEFT, _registrant.first_name, 20, y_line1, 0)
                cb.ShowTextAligned(PdfContentByte.ALIGN_LEFT, _registrant.last_name, 80, y_line1, 0)
                cb.ShowTextAligned(PdfContentByte.ALIGN_LEFT, _registrant.last_four_social, 160, y_line1, 0)
                cb.ShowTextAligned(PdfContentByte.ALIGN_LEFT, _registrant.email, 300, y_line1, 0)
                _total += 1
                cb.EndText()
                y_line1 = y_line1 - 15
            Next

我考虑过使用y_line1设置线条的背景颜色，并使用模数来确定颜色应该是灰色还是白色。但我发现在任何地方都没有关于如何设置整行背景颜色的代码示例..任何想法????

Answer 1

PDF规范中没有与文本相关的“背景颜色”概念。任何看起来像背景颜色的东西，甚至是桌子，都只是在矩形（或其他形状）上绘制的文字。

要绘制矩形，只需在Rectangle对象上调用PdfContentByte方法即可。它需要左下角x，y和宽度和高度。颜色取决于之前对其中一种颜色填充的调用，例如SetColorFill()。

使用原始画布时，建议您也使用SaveState()和RestoreState()。由于填充命令在对象之间共享但意味着不同的东西，这些可以帮助避免混淆。 SaveState()设置一个标记，允许您在调用RestoreState()时撤消所有图形状态更改。

下面的代码是一个完整的VB.Net 2010 WinForms应用程序，针对iTextSharp 5.1.2.0展示了上述内容。它在桌面上创建一个示例文件，其中一行文本重复7次。每条线在两种背景颜色之间来回切换。此外，它在文本行周围绘制笔划以模拟边框。

Option Strict On
Option Explicit On

Imports System.IO
Imports iTextSharp.text
Imports iTextSharp.text.pdf

Public Class Form1

    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        ''//Test file that we'll create
        Dim TestFile = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "TestFile.pdf")
        ''//Test String that we'll repeat
        Dim TestString = "It was the best of times..."
        ''//Create an array of our test string
        Dim TestArray = {TestString, TestString, TestString, TestString, TestString, TestString, TestString}

        ''//Create our generic font
        Dim BF_Times = BaseFont.CreateFont(BaseFont.TIMES_BOLD, BaseFont.CP1250, BaseFont.NOT_EMBEDDED)

        ''//Standard PDF setup, change as needed for your stream type
        Using FS As New FileStream(TestFile, FileMode.Create, FileAccess.Write, FileShare.None)
            Using Doc As New Document(PageSize.LETTER)
                Using writer = PdfWriter.GetInstance(Doc, FS)
                    Doc.Open()

                    ''//Grab the raw content object
                    Dim cb = writer.DirectContent
                    ''//Set our starter Y coordinate
                    Dim y = 670
                    ''//Loop through our string collection
                    For I = 0 To (TestArray.Count - 1)
                        ''//Store the current graphics state so that we can unwind it later
                        cb.SaveState()
                        ''//Set the fill color based on eve/odd
                        cb.SetColorFill(If(I Mod 2 = 0, BaseColor.GREEN, BaseColor.BLUE))
                        ''//Optional, set a border
                        cb.SetColorStroke(BaseColor.BLACK)
                        ''//Draw a rectangle. NOTE: I'm subtracting 5 from the y to account for padding
                        cb.Rectangle(0, y - 5, Doc.PageSize.Width, 15)
                        ''//Draw the rectangle with a border. NOTE: Use cb.Fill() to draw without the border
                        cb.FillStroke()
                        ''//Unwind the graphics state
                        cb.RestoreState()

                        ''//Flag to begin text
                        cb.BeginText()
                        ''//Set the font
                        cb.SetFontAndSize(BF_Times, 6)
                        ''//Write some text
                        cb.ShowTextAligned(PdfContentByte.ALIGN_LEFT, TestArray(I), 0, y, 0)
                        ''//Done writing text
                        cb.EndText()

                        ''//Decrease the y accordingly
                        y -= 15
                    Next


                    Doc.Close()
                End Using
            End Using
        End Using

        Me.Close()
    End Sub
End Class

设置contentbyte itextsharp的背景颜色

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