获取图像的位置和大小 _图像位置

本文概述

扩展PDFStreamEngine
调用processPage()
覆盖processOperator()
检查图像
打印位置和尺寸

在本教程中, 我们将学习如何从所有页面获取PDF中图像的坐标或位置以及大小。这可以通过使用PDFStreamEngine类执行。此类通过提供回调接口来处理和执行处理PDF文档的操作。
为了获取PDF文档中图像的位置和大小, 我们将扩展PDFStreamEngine类并拦截并实现processOperator()方法。
对于PDF文档中的每个对象, 我们将检查该对象是否为图像对象, 并获取其属性, 例如(X, Y)坐标和大小。为此, 我们可以使用在PDFStreamEngine.processPage(page)中调用的processOperator()方法。
请按照以下步骤获取现有PDF文档中图像的坐标或位置以及尺寸,
扩展PDFStreamEngine 在此, 我们必须首先创建一个Java类, 并使用PDFStreamEngine对其进行扩展。可以在下面的代码中显示。

publicclass GetImageLocationsAndSize extends PDFStreamEngine {......}

调用processPage() 【获取图像的位置和大小】对于PDF文档中的每个页面, 调用方法processPage()。此方法接受页面名称作为参数。可以在以下代码中显示。

for( PDPage page : document.getPages() ){ pageNum++; printer.processPage(page); }

覆盖processOperator() 对于PDF页面中的每个对象, 在processPage()方法中调用processOperator。我们还可以覆盖processOperator()方法。

@Overrideprotectedvoid processOperator( Operator operator, List< COSBase> operands) throws IOException { ...........}

检查图像现在, 我们可以检查已发送到processOperator()方法的对象是否为图像对象。

if( xobjectinstanceof PDImageXObject){PDImageXObject image = (PDImageXObject)xobject; intimageWidth = image.getWidth(); intimageHeight = image.getHeight(); System.out.println("\nImage [" + objectName.getName() + "]"); }

打印位置和尺寸最后, 如果给定的对象是图像对象, 则打印图像的位置和大小。

// position of image in the PDF in terms of user space unitsSystem.out.println("Position in PDF = " + ctmNew.getTranslateX() + ", " + ctmNew.getTranslateY() + " in user space units"); // raw size in pixelsSystem.out.println("Raw image size= " + imageWidth + ", " + imageHeight + " in pixels"); // displayed size in user space unitsSystem.out.println("Displayed size= " + imageXScale + ", " + imageYScale + " in user space units");

例-

import org.apache.pdfbox.cos.COSBase; import org.apache.pdfbox.cos.COSName; import org.apache.pdfbox.pdmodel.PDDocument; import org.apache.pdfbox.pdmodel.PDPage; import org.apache.pdfbox.pdmodel.graphics.PDXObject; import org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject; import org.apache.pdfbox.pdmodel.graphics.image.PDImageXObject; import org.apache.pdfbox.util.Matrix; import org.apache.pdfbox.contentstream.operator.DrawObject; import org.apache.pdfbox.contentstream.operator.Operator; import org.apache.pdfbox.contentstream.PDFStreamEngine; import java.io.File; import java.io.IOException; import java.util.List; import org.apache.pdfbox.contentstream.operator.state.Concatenate; import org.apache.pdfbox.contentstream.operator.state.Restore; import org.apache.pdfbox.contentstream.operator.state.Save; import org.apache.pdfbox.contentstream.operator.state.SetGraphicsStateParameters; import org.apache.pdfbox.contentstream.operator.state.SetMatrix; public class GetImageLocationsAndSize extends PDFStreamEngine { public void GetImageLocationsAndSize() throws IOException{// preparing PDFStreamEngineaddOperator(new Concatenate()); addOperator(new DrawObject()); addOperator(new SetGraphicsStateParameters()); addOperator(new Save()); addOperator(new Restore()); addOperator(new SetMatrix()); } publicstaticvoid main(String[] args)throws IOException {PDDocument document = null; String fileName = "/eclipse-workspace/Merge.pdf"; try{ document = PDDocument.load( new File(fileName) ); GetImageLocationsAndSize printer = new GetImageLocationsAndSize(); intpageNum = 0; for( PDPage page : document.getPages() ){ pageNum++; System.out.println( "\n\nProcessing PDF page:" + pageNum +"\n---------------------------------"); printer.processPage(page); }} finally{ if( document != null ){ document.close(); }}} protectedvoid processOperator( Operator operator, List< COSBase> operands) throws IOException{String operation = operator.getName(); if( "Do".equals(operation) ){COSName objectName = (COSName) operands.get( 0 ); // get the PDF objectPDXObject xobject = getResources().getXObject( objectName ); // check if the object is an image object if( xobjectinstanceof PDImageXObject){PDImageXObject image = (PDImageXObject)xobject; intimageWidth = image.getWidth(); intimageHeight = image.getHeight(); System.out.println("\nImage [" + objectName.getName() + "]"); Matrix ctmNew = getGraphicsState().getCurrentTransformationMatrix(); floatimageXScale = ctmNew.getScalingFactorX(); floatimageYScale = ctmNew.getScalingFactorY(); // position of image in the PDF in terms of user space unitsSystem.out.println("position in PDF = " + ctmNew.getTranslateX() + ", " + ctmNew.getTranslateY() + " in user space units"); // raw size in pixelsSystem.out.println("raw image size= " + imageWidth + ", " + imageHeight + " in pixels"); // displayed size in user space unitsSystem.out.println("displayed size= " + imageXScale + ", " + imageYScale + " in user space units"); } elseif(xobjectinstanceof PDFormXObject){PDFormXObject form = (PDFormXObject)xobject; showForm(form); }} else{ super.processOperator( operator, operands ); }}}

输出