ITextSharp - get image at a particular location - image

Question

What I need to do is extract a 2D DataMatrix (bitmap) bar code and read it. I can make this work however, I have to loop through all the images on every page. This is taking a long time when I have 1000’s of pages, so I was wondering if it was possible to define a location(rectangle)of where the image(barcode) was and just extract that image?
The bar code is always i the same location.
note: I'm using Spire.Barcode from e-IceBlue
Thank you for any help.
CODE RenderFilter snippet:
public class MyRegionTextRenderFilter : RenderFilter {
/** the region to allow text from */
private RectangleJ filterRect;
public PdfImageObject image;
/**
* Constructs a filter
* #param filterRect the rectangle to filter text against. Note that this is a java.awt.Rectangle !
*/
public MyRegionTextRenderFilter(RectangleJ filterRect) {
this.filterRect = filterRect;
}
/**
* Constructs a filter
* #param filterRect the rectangle to filter text against.
*/
public MyRegionTextRenderFilter(iTextSharp.text.Rectangle filterRect)
{
this.filterRect = new RectangleJ(filterRect);
}
/**
* #see com.itextpdf.text.pdf.parser.RenderFilter#allowText(com.itextpdf.text.pdf.parser.TextRenderInfo)
*/
public override bool AllowImage(ImageRenderInfo renderInfo)
{
var matrix = renderInfo.GetImageCTM();
float left = matrix[6];
float top = matrix[7];
float width = matrix[0];
float height = matrix[4];
return filterRect.IntersectsLine(left, top, width, height);
}
}
Code calling :
RectangleJ rect = new RectangleJ(518.0f, 18.0f, 23.0f, 23.0f);
PdfReaderContentParser parser2 = new PdfReaderContentParser(pdfReader);
RenderFilter[] renderFilter = new RenderFilter[1];
renderFilter[0] = new MyRegionTextRenderFilter(rect);
FilteredTextRenderListener listener2 = new FilteredTextRenderListener(new LocationTextExtractionStrategy(), renderFilter);
parser2.ProcessContent(3, listener2);

Answer 1

The parser namespace of iText(Sharp) allows filtering of information digested by an IRenderListener implementation by using a RenderFilter:
public abstract class RenderFilter {
/**
* #param renderInfo
* #return true if the text render operation should be performed
*/
public virtual bool AllowText(TextRenderInfo renderInfo){
return true;
}
/**
*
* #param renderInfo
* #return true is the image render operation should be performed
*/
public virtual bool AllowImage(ImageRenderInfo renderInfo){
return true;
}
}
For filtering by area there already is a textual render filter, the RegionTextRenderFilter.
For your task simply copy it and add an AllowImage(ImageRenderInfo renderInfo) implementation similar to the existing AllowText(TextRenderInfo renderInfo) method.