Author: tilman
Date: Thu Sep 10 19:33:24 2026
New Revision: 1938083
Log:
PDFBOX-6259: hasBlendMode() now recurses into the resources of form XObjects +
test, by Daniel Persson and Claude Fable 5.1
Added:
pdfbox/branches/2.0/examples/src/test/java/org/apache/pdfbox/examples/rendering/TestPDFRendererBlendMode.java
(contents, props changed)
Modified:
pdfbox/branches/2.0/pdfbox/src/main/java/org/apache/pdfbox/rendering/PDFRenderer.java
Added:
pdfbox/branches/2.0/examples/src/test/java/org/apache/pdfbox/examples/rendering/TestPDFRendererBlendMode.java
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++
pdfbox/branches/2.0/examples/src/test/java/org/apache/pdfbox/examples/rendering/TestPDFRendererBlendMode.java
Thu Sep 10 19:33:24 2026 (r1938083)
@@ -0,0 +1,183 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.pdfbox.rendering;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.awt.image.BufferedImage;
+import java.io.IOException;
+
+import org.apache.pdfbox.pdmodel.PDDocument;
+import org.apache.pdfbox.pdmodel.PDFormContentStream;
+import org.apache.pdfbox.pdmodel.PDPage;
+import org.apache.pdfbox.pdmodel.PDPageContentStream;
+import org.apache.pdfbox.pdmodel.PDResources;
+import org.apache.pdfbox.pdmodel.common.PDRectangle;
+import org.apache.pdfbox.pdmodel.graphics.blend.BlendMode;
+import org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject;
+import org.apache.pdfbox.pdmodel.graphics.state.PDExtendedGraphicsState;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests that blend modes are detected wherever they are used on a page, so
that the page is
+ * rendered on a transparent backdrop and composited onto white afterwards
(PDFBOX-4095). A blend
+ * mode such as ColorBurn or Multiply applied directly onto an opaque white
backdrop would make
+ * the blended content disappear.
+ */
+class TestPDFRendererBlendMode
+{
+ private static final int BLUE = 0xFF0000FF;
+ private static final int WHITE = 0xFFFFFFFF;
+
+ /**
+ * Blend mode set in the resources of the page itself.
+ */
+ @Test
+ void testBlendModeInPageResources() throws IOException
+ {
+ try (PDDocument doc = new PDDocument())
+ {
+ PDPage page = new PDPage(new PDRectangle(200, 200));
+ doc.addPage(page);
+ try (PDPageContentStream cs = new PDPageContentStream(doc, page))
+ {
+ drawBlueSquareWithColorBurn(cs);
+ }
+ assertBlueSquareVisible(doc);
+ }
+ }
+
+ /**
+ * Blend mode set in the resources of a form XObject that is drawn by the
page. The page
+ * resources themselves don't have any blend mode.
+ */
+ @Test
+ void testBlendModeInFormXObject() throws IOException
+ {
+ try (PDDocument doc = new PDDocument())
+ {
+ PDPage page = new PDPage(new PDRectangle(200, 200));
+ doc.addPage(page);
+
+ PDFormXObject form = createForm(doc);
+ try (PDFormContentStream cs = new PDFormContentStream(form))
+ {
+ drawBlueSquareWithColorBurn(cs);
+ }
+ try (PDPageContentStream cs = new PDPageContentStream(doc, page))
+ {
+ cs.drawForm(form);
+ }
+ assertBlueSquareVisible(doc);
+ }
+ }
+
+ /**
+ * Blend mode set in the resources of a form XObject that is nested in
another form XObject,
+ * as done by layout applications placing artwork from illustration
applications.
+ */
+ @Test
+ void testBlendModeInNestedFormXObject() throws IOException
+ {
+ try (PDDocument doc = new PDDocument())
+ {
+ PDPage page = new PDPage(new PDRectangle(200, 200));
+ doc.addPage(page);
+
+ PDFormXObject inner = createForm(doc);
+ try (PDFormContentStream cs = new PDFormContentStream(inner))
+ {
+ drawBlueSquareWithColorBurn(cs);
+ }
+ PDFormXObject outer = createForm(doc);
+ try (PDFormContentStream cs = new PDFormContentStream(outer))
+ {
+ cs.drawForm(inner);
+ }
+ try (PDPageContentStream cs = new PDPageContentStream(doc, page))
+ {
+ cs.drawForm(outer);
+ }
+ assertBlueSquareVisible(doc);
+ }
+ }
+
+ /**
+ * A form XObject referencing itself must not cause endless recursion in
the blend mode
+ * detection.
+ */
+ @Test
+ void testSelfReferencingFormXObject() throws IOException
+ {
+ try (PDDocument doc = new PDDocument())
+ {
+ PDPage page = new PDPage(new PDRectangle(200, 200));
+ doc.addPage(page);
+
+ PDFormXObject form = createForm(doc);
+ form.getResources().add(form);
+ try (PDFormContentStream cs = new PDFormContentStream(form))
+ {
+ cs.setNonStrokingColor(0f, 0f, 1f);
+ cs.addRect(50, 50, 100, 100);
+ cs.fill();
+ }
+ try (PDPageContentStream cs = new PDPageContentStream(doc, page))
+ {
+ cs.drawForm(form);
+ }
+ assertBlueSquareVisible(doc);
+ }
+ }
+
+ private static PDFormXObject createForm(PDDocument doc)
+ {
+ PDFormXObject form = new PDFormXObject(doc);
+ form.setBBox(new PDRectangle(200, 200));
+ form.setResources(new PDResources());
+ return form;
+ }
+
+ private static void drawBlueSquareWithColorBurn(PDPageContentStream cs)
throws IOException
+ {
+ PDExtendedGraphicsState gs = new PDExtendedGraphicsState();
+ gs.setBlendMode(BlendMode.COLOR_BURN);
+ cs.setGraphicsStateParameters(gs);
+ cs.setNonStrokingColor(0f, 0f, 1f);
+ cs.addRect(50, 50, 100, 100);
+ cs.fill();
+ }
+
+ private static void drawBlueSquareWithColorBurn(PDFormContentStream cs)
throws IOException
+ {
+ PDExtendedGraphicsState gs = new PDExtendedGraphicsState();
+ gs.setBlendMode(BlendMode.COLOR_BURN);
+ cs.setGraphicsStateParameters(gs);
+ cs.setNonStrokingColor(0f, 0f, 1f);
+ cs.addRect(50, 50, 100, 100);
+ cs.fill();
+ }
+
+ private static void assertBlueSquareVisible(PDDocument doc) throws
IOException
+ {
+ BufferedImage image = new PDFRenderer(doc).renderImage(0, 1,
ImageType.RGB);
+ assertEquals(BufferedImage.TYPE_INT_RGB, image.getType());
+ assertEquals(BLUE, image.getRGB(100, 100), "blended content must be
visible on white");
+ assertEquals(WHITE, image.getRGB(25, 25), "background must stay
white");
+ }
+}
Modified:
pdfbox/branches/2.0/pdfbox/src/main/java/org/apache/pdfbox/rendering/PDFRenderer.java
==============================================================================
---
pdfbox/branches/2.0/pdfbox/src/main/java/org/apache/pdfbox/rendering/PDFRenderer.java
Thu Sep 10 18:45:03 2026 (r1938082)
+++
pdfbox/branches/2.0/pdfbox/src/main/java/org/apache/pdfbox/rendering/PDFRenderer.java
Thu Sep 10 19:33:24 2026 (r1938083)
@@ -24,18 +24,23 @@ import java.awt.GraphicsDevice;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.IOException;
+import java.util.HashSet;
+import java.util.Set;
import java.util.StringTokenizer;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
+import org.apache.pdfbox.cos.COSDictionary;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDPageTree;
import org.apache.pdfbox.pdmodel.PDResources;
import org.apache.pdfbox.pdmodel.common.PDRectangle;
+import org.apache.pdfbox.pdmodel.graphics.PDXObject;
import org.apache.pdfbox.pdmodel.graphics.blend.BlendMode;
+import org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject;
import
org.apache.pdfbox.pdmodel.graphics.optionalcontent.PDOptionalContentGroup;
import
org.apache.pdfbox.pdmodel.graphics.optionalcontent.PDOptionalContentProperties;
import org.apache.pdfbox.pdmodel.graphics.state.PDExtendedGraphicsState;
@@ -578,9 +583,25 @@ public class PDFRenderer
private boolean hasBlendMode(PDPage page)
{
- // check the current resources for blend modes
- PDResources resources = page.getResources();
- if (resources == null)
+ // check the page resources and the resources of nested form XObjects
+ return hasBlendMode(page.getResources(), new HashSet<COSDictionary>());
+ }
+
+ /**
+ * Checks whether the given resources, or the resources of any form
XObject reachable from
+ * them, contain an extended graphics state with a blend mode other than
Normal.
+ * Blend modes are often set inside form XObjects (e.g. artwork placed
into a layout), so
+ * checking only the page level resources is not enough: a blend mode like
ColorBurn or
+ * Multiply applied to an opaque white backdrop would make the content
disappear.
+ *
+ * @param resources the resources to check, may be null.
+ * @param visited the resource dictionaries that have already been
checked, to avoid endless
+ * recursion for self-referencing forms.
+ * @return true if a blend mode other than Normal was found.
+ */
+ private boolean hasBlendMode(PDResources resources, Set<COSDictionary>
visited)
+ {
+ if (resources == null || !visited.add(resources.getCOSObject()))
{
return false;
}
@@ -598,6 +619,30 @@ public class PDFRenderer
}
}
}
+ for (COSName name : resources.getXObjectNames())
+ {
+ if (resources.isImageXObject(name))
+ {
+ // avoid creating image XObjects, they can't have resources
+ continue;
+ }
+ PDXObject xObject;
+ try
+ {
+ xObject = resources.getXObject(name);
+ }
+ catch (IOException ex)
+ {
+ // broken XObject, will be reported again when the page is
drawn
+ LOG.debug("Can't check XObject " + name + " for blend modes",
ex);
+ continue;
+ }
+ if (xObject instanceof PDFormXObject
+ && hasBlendMode(((PDFormXObject) xObject).getResources(),
visited))
+ {
+ return true;
+ }
+ }
return false;
}
