itextsharp：如何找到矩形的填充颜色
我按照ItextSharp示例获取图形结构，使用代码获取矩形坐标：
class VectorGraphicsListener : IExtRenderListener { public void ModifyPath(PathConstructionRenderInfo renderInfo) { if (renderInfo.Operation == PathConstructionRenderInfo.RECT) { float x = renderInfo.SegmentData[0]; float y = renderInfo.SegmentData[1]; float w = renderInfo.SegmentData[2]; float h = renderInfo.SegmentData[3]; ... 我尝试了renderInfo.GetFillColor（）; 但是没有这样的方法。
我想获得额外的矩形属性：
像矩形填充颜色，（一些类似于DIV样式=“背景：蓝色;边框：黑色;”标签在HTML中）我是如何得到它的？
TextRenderInfo具有您要查找的PathConstructionRenderInfo方法。
你从哪里得到这个例子的？ 您可能使用的版本与使用的版本文档不同。
本文解释了您需要做什么，但它提供的Java源代码应该很容易移植到C＃： http ： //techqa.info/programming/question/41728853/how-to-extract-the-color-of-一个矩形function于A-PDF， -附-iText的
为了总结相关部分，它使用GraphicsState来获取填充颜色。 要实现这一点，您需要使用PdfReaderContentParser解析所有PDF内容，并将派生的PdfReaderContentParser传递给processContent方法，如下所示（取自上面的Java代码）：
PdfReader pdfReader = new PdfReader(resource); ExtRenderListener extRenderListener = new ExtRenderListener(); for (int page = 1; page <= pdfReader.getNumberOfPages(); page++) { PdfReaderContentParser parser = new PdfReaderContentParser(pdfReader); parser.processContent(page, extRenderListener); }
ExtRenderListener将需要覆盖renderPath：
public override Path renderPath(PathPaintingRenderInfo renderInfo) { Field gsField = PathPaintingRenderInfo.class.getDeclaredField("gs"); gsField.setAccessible(true); GraphicsState graphicsState = (GraphicsState) gsField.get(renderInfo); if ((renderInfo.getOperation() & PathPaintingRenderInfo.FILL) != 0) { var fillColor = graphicsState.getFillColor(); bool filledRect= false; for (PathConstructionRenderInfo pathConstructionRenderInfo in pathInfos) { if(pathConstructionRenderInfo.getOperation()==PathConstructionRenderInfo.RECT) { filledRect=true; break; } if (filledRect && fillColor!=null) Console.WriteLine("{0},{1},{2}", fillColor.getRed(), fillColor.getGreen(), fillColor.getBlue()); } } }
亚历山大在他的回答中发布了一个链接，是我在这里关于堆栈溢出的早期回答的副本。
因此，我只是将该答案（使用iText / Java）的代码移植到iTextSharp / C＃：
自定义IExtRenderListener实现
class ExtRenderListener : IExtRenderListener { public void BeginTextBlock() { } public void RenderText(TextRenderInfo renderInfo) { } public void EndTextBlock() { } public void RenderImage(ImageRenderInfo renderInfo) { } public void ModifyPath(PathConstructionRenderInfo renderInfo) { pathInfos.Add(renderInfo); } public iTextSharp.text.pdf.parser.Path RenderPath(PathPaintingRenderInfo renderInfo) { GraphicsState graphicsState = getGraphicsState(renderInfo); Matrix ctm = graphicsState.GetCtm(); if ((renderInfo.Operation & PathPaintingRenderInfo.FILL) != 0) { Console.Write("FILL ({0}) ", toString(graphicsState.FillColor)); if ((renderInfo.Operation & PathPaintingRenderInfo.STROKE) != 0) Console.Write("and "); } if ((renderInfo.Operation & PathPaintingRenderInfo.STROKE) != 0) { Console.Write("STROKE ({0}) ", toString(graphicsState.StrokeColor)); } Console.Write("the path "); foreach (PathConstructionRenderInfo pathConstructionRenderInfo in pathInfos) { switch (pathConstructionRenderInfo.Operation) { case PathConstructionRenderInfo.MOVETO: Console.Write("move to {0} ", toString(transform(ctm, pathConstructionRenderInfo.SegmentData))); break; case PathConstructionRenderInfo.CLOSE: Console.Write("close {0} ", toString(transform(ctm, pathConstructionRenderInfo.SegmentData))); break; case PathConstructionRenderInfo.CURVE_123: Console.Write("curve123 {0} ", toString(transform(ctm, pathConstructionRenderInfo.SegmentData))); break; case PathConstructionRenderInfo.CURVE_13: Console.Write("curve13 {0} ", toString(transform(ctm, pathConstructionRenderInfo.SegmentData))); break; case PathConstructionRenderInfo.CURVE_23: Console.Write("curve23 {0} ", toString(transform(ctm, pathConstructionRenderInfo.SegmentData))); break; case PathConstructionRenderInfo.LINETO: Console.Write("line to {0} ", toString(transform(ctm, pathConstructionRenderInfo.SegmentData))); break; case PathConstructionRenderInfo.RECT: Console.Write("rectangle {0} ", toString(transform(ctm, expandRectangleCoordinates(pathConstructionRenderInfo.SegmentData)))); break; } } Console.WriteLine(); pathInfos.Clear(); return null; } String toString(IList coordinates) { StringBuilder result = new StringBuilder(); result.Append("[ "); for (int i = 0; i < coordinates.Count; i++) { result.Append(coordinates[i]); result.Append(' '); } result.Append(']'); return result.ToString(); } List transform(Matrix ctm, IList coordinates) { List result = new List (); for (int i = 0; i + 1 < coordinates.Count; i += 2) { Vector vector = new Vector(coordinates[i], coordinates[i + 1], 1); vector = vector.Cross(ctm); result.Add(vector[Vector.I1]); result.Add(vector[Vector.I2]); } return result; } List expandRectangleCoordinates(IList rectangle) { if (rectangle.Count < 4) return new List (); return new List { rectangle[0], rectangle[1], rectangle[0] + rectangle[2], rectangle[1], rectangle[0] + rectangle[2], rectangle[1] + rectangle[3], rectangle[0], rectangle[1] + rectangle[3] }; } String toString(BaseColor baseColor) { if (baseColor == null) return "DEFAULT"; return String.Format("{0},{1},{2}", baseColor.R, baseColor.G, baseColor.B); } GraphicsState getGraphicsState(PathPaintingRenderInfo renderInfo) { System.Reflection.FieldInfo gsField = typeof(PathPaintingRenderInfo).GetField("gs", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance); return (GraphicsState) gsField.GetValue(renderInfo); } public void ClipPath(int rule) { } List pathInfos = new List (); }
检索GraphicsState所需的reflection发生在方法getGraphicsState 。
使用ExtRenderListener类
using (var pdfReader = new PdfReader([FILE TO PARSE])) { IExtRenderListener extRenderListener = new ExtRenderListener(); // Loop through each page of the document for (var page = 1; page <= pdfReader.NumberOfPages; page++) { Console.Write("\nPage {0}\n====\n", page); PdfReaderContentParser parser = new PdfReaderContentParser(pdfReader); parser.ProcessContent(page, extRenderListener); } }
产量
对于以前的问题所涉及的PDF，此代码返回
Page 1 ==== STROKE (0,0,0) the path rectangle [ 88,3 693,69 227,77 693,69 227,77 788 88,3 788 ] STROKE (0,0,0) the path rectangle [ 227,77 693,69 367,24 693,69 367,24 788 227,77 788 ] STROKE (0,0,0) the path rectangle [ 367,23 693,69 506,7 693,69 506,7 788 367,23 788 ] FILL (255,0,0) the path rectangle [ 229,77 695,69 365,37 695,69 365,37 786,09 229,77 786,09 ] STROKE (DEFAULT) the path move to [ 228 810 ] line to [ 338 810 ]
（正如您在坐标输出中观察到的，我当前的语言环境使用逗号作为小数分隔符...）