9.14.  Render Pages to PNG

If you want to test formatted text, the only way to do it is to render a PDF page and compare the result with an image of the correctly formatted content. Section 3.20: “Layout - Entire PDF Pages” describes layout-tests using rendered pages. And the utility RenderPdfToImages renders a PDF document page by page into PNG files.

Program Start

:: Render PDF into image files. Each page as a file.

@echo off
set CLASSPATH=./lib/bouncycastle-jdk15on-153/*;%CLASSPATH%
set CLASSPATH=./lib/commons-logging-1.2/*;%CLASSPATH%
set CLASSPATH=./lib/pdfbox-2.0.0/*;%CLASSPATH%
set CLASSPATH=./lib/pdfunit-2016.05/*;%CLASSPATH%

set TOOL=com.pdfunit.tools.RenderPdfToImages
set OUT_DIR=./tmp
set IN_FILE=documentUnderTest.pdf

java  %TOOL%  %IN_FILE%  %OUT_DIR%  %PASSWD%


The input file documentUnderTest.pdf consists of 4 pages with different images and text. The PDF Reader SumatraPDF (http://code.google.com/p/sumatrapdf) shows the first page:


After running the rendering program 4 files are created:


The first of these files looks the same as seen with the PDF Reader:

Internally, PDFUnit uses the same algorithm to render the pages as the rendering program does. So, any difference found by a test is due to a change in the PDF document.