iTextSharp 提取每个字符并获取矩形

Question

我想逐个字符地解析整个 PDF，并能够获取该 PDF 文档上该字符的 ASCII 值、字体和矩形，稍后我可以将其用于另存为位图。我尝试使用 PdfTextExtractor.GetTextFromPage 但它以字符串形式给出了 PDF 中的整个文本。

Answer 1

与 iTextSharp 捆绑在一起的文本提取策略（特别是 PdfTextExtractor.GetTextFromPage 默认使用的 LocationTextExtractionStrategy 重载没有策略参数）只允许直接访问收集的纯文本，而不是位置。

克里斯·哈斯`MyLocationTextExtractionStrategy`

@Chris Haas 在 his old answer here 中介绍了 LocationTextExtractionStrategy

的以下扩展

public class MyLocationTextExtractionStrategy : LocationTextExtractionStrategy {
    //Hold each coordinate
    public List<RectAndText> myPoints = new List<RectAndText>();

    //Automatically called for each chunk of text in the PDF
    public override void RenderText(TextRenderInfo renderInfo) {
        base.RenderText(renderInfo);

        //Get the bounding box for the chunk of text
        var bottomLeft = renderInfo.GetDescentLine().GetStartPoint();
        var topRight = renderInfo.GetAscentLine().GetEndPoint();

        //Create a rectangle from it
        var rect = new iTextSharp.text.Rectangle(
                                                bottomLeft[Vector.I1],
                                                bottomLeft[Vector.I2],
                                                topRight[Vector.I1],
                                                topRight[Vector.I2]
                                                );

        //Add this to our main collection
        this.myPoints.Add(new RectAndText(rect, renderInfo.GetText()));
    }
}

它利用了这个助手 class

//Helper class that stores our rectangle and text
public class RectAndText {
    public iTextSharp.text.Rectangle Rect;
    public String Text;
    public RectAndText(iTextSharp.text.Rectangle rect, String text) {
        this.Rect = rect;
        this.Text = text;
    }
}

此策略使文本块及其封闭矩形在 public 成员 List<RectAndText> myPoints 中可用，您可以像这样访问它：

//Create an instance of our strategy
var t = new MyLocationTextExtractionStrategy();

//Parse page 1 of the document above
using (var r = new PdfReader(testFile)) {
    var ex = PdfTextExtractor.GetTextFromPage(r, 1, t);
}

//Loop through each chunk found
foreach (var p in t.myPoints) {
    Console.WriteLine(string.Format("Found text {0} at {1}x{2}", p.Text, p.Rect.Left, p.Rect.Bottom));
}

对于您的任务逐个字符解析整个 PDF 并能够获取该字符的 ASCII 值、字体和矩形这里只有两个细节是错误的：

这样返回的文本块可能包含多个字符
未提供字体信息。

因此，我们必须稍微调整一下：

一个新的`CharLocationTextExtractionStrategy`

除了 MyLocationTextExtractionStrategy class 之外，CharLocationTextExtractionStrategy 按字形拆分输入并提供字体名称：

public class CharLocationTextExtractionStrategy : LocationTextExtractionStrategy
{
    //Hold each coordinate
    public List<RectAndTextAndFont> myPoints = new List<RectAndTextAndFont>();

    //Automatically called for each chunk of text in the PDF
    public override void RenderText(TextRenderInfo wholeRenderInfo)
    {
        base.RenderText(wholeRenderInfo);

        foreach (TextRenderInfo renderInfo in wholeRenderInfo.GetCharacterRenderInfos())
        {
            //Get the bounding box for the chunk of text
            var bottomLeft = renderInfo.GetDescentLine().GetStartPoint();
            var topRight = renderInfo.GetAscentLine().GetEndPoint();

            //Create a rectangle from it
            var rect = new iTextSharp.text.Rectangle(
                                                    bottomLeft[Vector.I1],
                                                    bottomLeft[Vector.I2],
                                                    topRight[Vector.I1],
                                                    topRight[Vector.I2]
                                                    );

            //Add this to our main collection
            this.myPoints.Add(new RectAndTextAndFont(rect, renderInfo.GetText(), renderInfo.GetFont().PostscriptFontName));
        }
    }
}

//Helper class that stores our rectangle, text, and font
public class RectAndTextAndFont
{
    public iTextSharp.text.Rectangle Rect;
    public String Text;
    public String Font;
    public RectAndTextAndFont(iTextSharp.text.Rectangle rect, String text, String font)
    {
        this.Rect = rect;
        this.Text = text;
        this.Font = font;
    }
}

像这样使用这个策略

CharLocationTextExtractionStrategy strategy = new CharLocationTextExtractionStrategy();

using (var pdfReader = new PdfReader(testFile))
{
    PdfTextExtractor.GetTextFromPage(pdfReader, 1, strategy);
}

foreach (var p in strategy.myPoints)
{
    Console.WriteLine(string.Format("<{0}> in {3} at {1}x{2}", p.Text, p.Rect.Left, p.Rect.Bottom, p.Font));
}

您按字符和包括字体获取信息。

iTextSharp 提取每个字符并获取矩形

iTextSharp extract each character and getRectangle

itextsharp

pdf-extraction

克里斯·哈斯`MyLocationTextExtractionStrategy`

一个新的`CharLocationTextExtractionStrategy`

iTextSharp 提取每个字符并获取矩形

iTextSharp extract each character and getRectangle

itextsharp

pdf-extraction

克里斯·哈斯MyLocationTextExtractionStrategy

一个新的CharLocationTextExtractionStrategy

克里斯·哈斯`MyLocationTextExtractionStrategy`

一个新的`CharLocationTextExtractionStrategy`