gradle draft

.gitignore

@@ -27,3 +27,11 @@
 **/classpath-data.json
 **/dependencies-and-licenses-overview.txt
 git.tag
+
+gradle.properties
+gradlew
+gradlew.bat
+gradle/
+
+**/.gradle
+**/build

.gitlab-ci.yml

@@ -1,4 +1,21 @@
 include:
   - project: 'gitlab/gitlab'
     ref: 'main'
-    file: 'ci-templates/maven_deps.yml'
+    file: 'ci-templates/gradle_java.yml'
+
+deploy:
+  stage: deploy
+  tags:
+    - dind
+  script:
+    - echo "Building with gradle version ${BUILDVERSION}"
+    - gradle -Pversion=${BUILDVERSION} publish
+    - gradle bootBuildImage --cleanCache --publishImage -PbuildbootDockerHostNetwork=true -Pversion=${BUILDVERSION}
+    - echo "BUILDVERSION=$BUILDVERSION" >> version.env
+  artifacts:
+    reports:
+      dotenv: version.env
+  rules:
+    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
+    - if: $CI_COMMIT_BRANCH =~ /^release/
+    - if: $CI_COMMIT_TAG

build.gradle.kts

@@ -0,0 +1,136 @@
+plugins {
+    `java-library`
+    `maven-publish`
+    `kotlin-dsl`
+    pmd
+    checkstyle
+    jacoco
+    id("io.freefair.lombok") version "8.4"
+}
+
+java.sourceCompatibility = JavaVersion.VERSION_17
+java.targetCompatibility = JavaVersion.VERSION_17
+
+repositories {
+    mavenLocal()
+    maven {
+        url = uri("https://nexus.knecon.com/repository/gindev/")
+    }
+
+    maven {
+        url = uri("https://pdftron.com/maven/release")
+    }
+
+    maven {
+        url = uri("https://repo.spring.io/milestone")
+    }
+
+    maven {
+        url = uri("http://dist.wso2.org/maven2/")
+        isAllowInsecureProtocol = true
+    }
+
+    maven {
+        url = uri("https://projectlombok.org/edge-releases")
+    }
+
+    maven {
+        url = uri("https://repo.maven.apache.org/maven2/")
+    }
+
+    maven {
+        url = uri("https://pdftron.com/maven/release")
+    }
+
+    maven {
+        url = uri("https://nexus.knecon.com/repository/red-platform-releases/")
+        credentials {
+            username = providers.gradleProperty("mavenUser").getOrNull();
+            password = providers.gradleProperty("mavenPassword").getOrNull();
+        }
+    }
+}
+
+dependencies {
+    api(libs.org.projectlombok.lombok)
+    api(libs.org.springframework.boot.spring.boot.configuration.processor)
+    api(libs.com.google.guava.guava)
+    api(libs.org.projectlombok.lombok)
+    api(libs.org.springframework.boot.spring.boot.configuration.processor)
+    implementation("com.pdftron:PDFNet:10.5.0")
+    testImplementation(libs.org.junit.jupiter.junit.jupiter)
+    testImplementation(libs.org.assertj.assertj.core)
+    testImplementation(libs.org.mockito.mockito.core)
+    testImplementation(libs.org.apache.logging.log4j.log4j.slf4j2.impl)
+    testImplementation(libs.org.junit.jupiter.junit.jupiter)
+    testImplementation(libs.org.assertj.assertj.core)
+    testImplementation(libs.org.mockito.mockito.core)
+    compileOnly(libs.org.slf4j.slf4j.api)
+    compileOnly(libs.com.pdftron.pdfnet)
+}
+
+group = "com.iqser.red.commons"
+version = "2.0-SNAPSHOT"
+description = "pdftron-logic-commons"
+java.sourceCompatibility = JavaVersion.VERSION_17
+
+val testsJar by tasks.registering(Jar::class) {
+    archiveClassifier.set("tests")
+    from(sourceSets["test"].output)
+}
+
+java {
+    withSourcesJar()
+    withJavadocJar()
+}
+
+publishing {
+    publications.create<MavenPublication>("maven") {
+        from(components["java"])
+        artifact(testsJar)
+    }
+}
+
+tasks.withType<JavaCompile>() {
+    options.encoding = "UTF-8"
+}
+
+tasks.withType<Javadoc>() {
+    options.encoding = "UTF-8"
+}
+
+pmd {
+    isConsoleOutput = true
+}
+
+tasks.pmdMain {
+    pmd.ruleSetFiles = files("${rootDir}/config/pmd/pmd.xml")
+}
+
+tasks.pmdTest {
+    pmd.ruleSetFiles = files("${rootDir}/config/pmd/test_pmd.xml")
+}
+
+tasks.named<Test>("test") {
+    useJUnitPlatform()
+    reports {
+        junitXml.outputLocation.set(layout.buildDirectory.dir("reports/junit"))
+    }
+}
+
+tasks.test {
+    finalizedBy(tasks.jacocoTestReport) // report is always generated after tests run
+}
+
+tasks.jacocoTestReport {
+    dependsOn(tasks.test) // tests are required to run before generating the report
+    reports {
+        xml.required.set(true)
+        csv.required.set(false)
+        html.outputLocation.set(layout.buildDirectory.dir("jacocoHtml"))
+    }
+}
+
+java {
+    withJavadocJar()
+}

config/checkstyle/checkstyle.xml

@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
+        "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
+<module name="Checker">
+    <property
+            name="severity"
+            value="error"/>
+    <module name="TreeWalker">
+        <module name="SuppressWarningsHolder"/>
+        <module name="MissingDeprecated"/>
+        <module name="MissingOverride"/>
+        <module name="AnnotationLocation"/>
+        <module name="JavadocStyle"/>
+        <module name="NonEmptyAtclauseDescription"/>
+        <module name="IllegalImport"/>
+        <module name="RedundantImport"/>
+        <module name="RedundantModifier"/>
+        <module name="EmptyBlock"/>
+        <module name="DefaultComesLast"/>
+        <module name="EmptyStatement"/>
+        <module name="EqualsHashCode"/>
+        <module name="ExplicitInitialization"/>
+        <module name="IllegalInstantiation"/>
+        <module name="ModifiedControlVariable"/>
+        <module name="MultipleVariableDeclarations"/>
+        <module name="PackageDeclaration"/>
+        <module name="ParameterAssignment"/>
+        <module name="SimplifyBooleanExpression"/>
+        <module name="SimplifyBooleanReturn"/>
+        <module name="StringLiteralEquality"/>
+        <module name="OneStatementPerLine"/>
+        <module name="FinalClass"/>
+        <module name="ArrayTypeStyle"/>
+        <module name="UpperEll"/>
+        <module name="OuterTypeFilename"/>
+    </module>
+    <module name="FileTabCharacter"/>
+    <module name="SuppressWarningsFilter"/>
+</module>

config/pmd/pmd.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0"?>
+<ruleset name="Custom ruleset"
+         xmlns="http://pmd.sourceforge.net/ruleset/2.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 http://pmd.sourceforge.net/ruleset_2_0_0.xsd">
+
+    <description>
+        Knecon ruleset checks the code for bad stuff
+    </description>
+
+    <rule ref="category/java/errorprone.xml">
+        <exclude name="MissingSerialVersionUID"/>
+        <exclude name="AvoidLiteralsInIfCondition"/>
+        <exclude name="AvoidDuplicateLiterals"/>
+        <exclude name="NullAssignment"/>
+        <exclude name="AssignmentInOperand"/>
+        <exclude name="BeanMembersShouldSerialize"/>
+    </rule>
+
+</ruleset>

config/pmd/test_pmd.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0"?>
+<ruleset name="Custom ruleset"
+         xmlns="http://pmd.sourceforge.net/ruleset/2.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 http://pmd.sourceforge.net/ruleset_2_0_0.xsd">
+
+    <description>
+        Knecon test ruleset checks the code for bad stuff
+    </description>
+
+
+    <rule ref="category/java/errorprone.xml">
+        <exclude name="MissingSerialVersionUID"/>
+        <exclude name="AvoidLiteralsInIfCondition"/>
+        <exclude name="AvoidDuplicateLiterals"/>
+        <exclude name="NullAssignment"/>
+        <exclude name="AssignmentInOperand"/>
+        <exclude name="TestClassWithoutTestCases"/>
+        <exclude name="BeanMembersShouldSerialize"/>
+    </rule>
+
+</ruleset>

settings.gradle.kts

@@ -0,0 +1 @@
+rootProject.name = "pdftron-logic-commons"

src/main/java/com/iqser/red/pdftronlogic/commons/Converter.java

@@ -62,10 +62,11 @@ public class Converter {
     @SneakyThrows
     public static Color convertColor(ColorSpace colorSpace, ColorPt colorPt) {
 
-        ColorPt rgbColor = colorSpace.convert2RGB(colorPt);
+        try (ColorPt rgbColor = colorSpace.convert2RGB(colorPt)) {
-        Color color = new Color((float) rgbColor.get(0), (float) rgbColor.get(1), (float) rgbColor.get(2));
+            Color color = new Color((float) rgbColor.get(0), (float) rgbColor.get(1), (float) rgbColor.get(2));
-        rgbColor.destroy();
+            rgbColor.destroy();
-        return color;
+            return color;
+        }
     }
 
 

src/main/java/com/iqser/red/pdftronlogic/commons/ElementFeatures.java

@@ -103,6 +103,7 @@ public class ElementFeatures {
     @Getter
     @SuperBuilder
     @FieldDefaults(makeFinal = true, level = AccessLevel.PRIVATE)
+    @SuppressWarnings("PMD")
     public static class Text extends ElementFeatures {
 
         String text;

src/main/java/com/iqser/red/pdftronlogic/commons/ImageHashFactory.java

@@ -35,17 +35,19 @@ public class ImageHashFactory {
     @SneakyThrows
     private byte[] getBytesOfImage(com.pdftron.pdf.Image inputImage) {
         // 0 because the memory filter determines the size
-        var memFilter = new MemoryFilter(0, false);
+        try(var memFilter = new MemoryFilter(0, false)) {
-        var filterWriter = new FilterWriter(memFilter);
+            try(var filterWriter = new FilterWriter(memFilter)) {
 
-        inputImage.export(filterWriter);
+                inputImage.export(filterWriter);
-        filterWriter.flushAll();
+                filterWriter.flushAll();
-        byte[] res = memFilter.getBuffer();
+                byte[] res = memFilter.getBuffer();
 
-        memFilter.flushAll();
+                memFilter.flushAll();
-        memFilter.destroy();
+                memFilter.destroy();
-        filterWriter.destroy();
+                filterWriter.destroy();
-        return res;
+                return res;
+            }
+        }
     }
 
 

src/main/java/com/iqser/red/pdftronlogic/commons/InvisibleElementRemovalService.java

@@ -151,39 +151,40 @@ public class InvisibleElementRemovalService {
     private void execute(PDFDoc pdfDoc, boolean delta, boolean removePaths, Set<String> markedContentToIgnore) {
 
         log.info("Start removing invisible Elements");
-        ElementWriter writer = new ElementWriter();
+        try(ElementWriter writer = new ElementWriter()) {
-        ElementReader reader = new ElementReader();
+            try(ElementReader reader = new ElementReader()) {
-        Set<Long> visitedXObjIds = new TreeSet<>();
+                Set<Long> visitedXObjIds = new TreeSet<>();
 
-        for (PageIterator iterator = pdfDoc.getPageIterator(); iterator.hasNext(); ) {
+                for (PageIterator iterator = pdfDoc.getPageIterator(); iterator.hasNext(); ) {
 
-            Page page = iterator.next();
+                    Page page = iterator.next();
 
-            visitedXObjIds.add(page.getSDFObj().getObjNum());
+                    visitedXObjIds.add(page.getSDFObj().getObjNum());
 
-            InvisibleElementRemovalContext context = InvisibleElementRemovalContext.builder()
+                    InvisibleElementRemovalContext context = InvisibleElementRemovalContext.builder()
-                    .reader(reader)
+                            .reader(reader)
-                    .clippingPathStack(new ClippingPathStack(page.getMediaBox()))
+                            .clippingPathStack(new ClippingPathStack(page.getMediaBox()))
-                    .markedContentStack(new MarkedContentStack())
+                            .markedContentStack(new MarkedContentStack())
-                    .removePaths(removePaths)
+                            .removePaths(removePaths)
-                    .delta(delta)
+                            .delta(delta)
-                    .overlappedElements(new ArrayList<>())
+                            .overlappedElements(new ArrayList<>())
-                    .visibleElements(new ArrayList<>())
+                            .visibleElements(new ArrayList<>())
-                    .visitedXObjIds(visitedXObjIds)
+                            .visitedXObjIds(visitedXObjIds)
-                    .markedContentToIgnore(markedContentToIgnore)
+                            .markedContentToIgnore(markedContentToIgnore)
-                    .build();
+                            .build();
 
-            removeClippedElementsAndInvisibleTextAndRememberOverlappedElements(page, writer, context);
+                    removeClippedElementsAndInvisibleTextAndRememberOverlappedElements(page, writer, context);
 
-            context.visitedXObjIds().clear();
+                    context.visitedXObjIds().clear();
-            context.markedContentStack().clear();
+                    context.markedContentStack().clear();
 
-            removeOverlappedElements(page, writer, context);
+                    removeOverlappedElements(page, writer, context);
 
+                }
+                writer.destroy();
+                reader.destroy();
+            }
         }
-        writer.destroy();
-        reader.destroy();
-
         log.info("Finished removing invisible Elements");
     }
 
@@ -239,68 +240,70 @@ public class InvisibleElementRemovalService {
 
     private void processImages(Element imageElement, ElementWriter writer, InvisibleElementRemovalContext context) throws PDFNetException {
 
-        Rect rect = imageElement.getBBox();
+        try(Rect rect = imageElement.getBBox()) {
 
-        if (rect == null) {
+            if (rect == null) {
-            return;
+                return;
-        }
+            }
 
-        boolean inClippingPath = context.clippingPathStack().almostIntersects(rect.getX1(), rect.getY1(), rect.getWidth(), rect.getHeight());
+            boolean inClippingPath = context.clippingPathStack().almostIntersects(rect.getX1(), rect.getY1(), rect.getWidth(), rect.getHeight());
 
-        if (!context.delta() && inClippingPath) {
+            if (!context.delta() && inClippingPath) {
-            context.visibleElements().add(ElementFeatureFactory.extractFeatures(imageElement));
+                context.visibleElements().add(ElementFeatureFactory.extractFeatures(imageElement));
-        }
+            }
 
-        if (context.delta() ^ inClippingPath) {
+            if (context.delta() ^ inClippingPath) {
-            writer.writeElement(imageElement);
+                writer.writeElement(imageElement);
+            }
         }
     }
 
 
     private void processText(Element textElement, ElementWriter writer, InvisibleElementRemovalContext context) throws PDFNetException {
 
-        Rect textBBox = textElement.getBBox();
+        try(Rect textBBox = textElement.getBBox()) {
 
-        if (textBBox == null) {
+            if (textBBox == null) {
-            writer.writeElement(textElement);
-            return;
-        }
-
-        GState gState = textElement.getGState();
-
-        boolean inClippingPath = context.clippingPathStack().almostIntersects(textBBox.getX1(), textBBox.getY1(), textBBox.getWidth(), textBBox.getHeight());
-
-        boolean isTextVisible = isTextRenderedVisibly(gState, textBBox, context);
-
-        if (inClippingPath && isTextVisible) {
-            context.visibleElements().add(ElementFeatureFactory.extractFeatures(textElement));
-        }
-        if (!context.delta()) {
-            if (inClippingPath && isTextVisible) {
                 writer.writeElement(textElement);
-            } else if (textElement.hasTextMatrix()) {
+                return;
+            }
+
+            GState gState = textElement.getGState();
+
+            boolean inClippingPath = context.clippingPathStack().almostIntersects(textBBox.getX1(), textBBox.getY1(), textBBox.getWidth(), textBBox.getHeight());
+
+            boolean isTextVisible = isTextRenderedVisibly(gState, textBBox, context);
+
+            if (inClippingPath && isTextVisible) {
+                context.visibleElements().add(ElementFeatureFactory.extractFeatures(textElement));
+            }
+            if (!context.delta()) {
+                if (inClippingPath && isTextVisible) {
+                    writer.writeElement(textElement);
+                } else if (textElement.hasTextMatrix()) {
                 /*
                 PDFTron Element with type "text" refers to a Tj command. If a Tm command is just above it in the pdf file, PDFTron will join the two commands and treat them as one Element.
                 hasTextMatrix() checks for this case specifically. Also, Tm changes the position for a whole BT/ET segment, possibly containing multiple Tj commands.
                 Therefore, the position of a following Tj is affected by not writing the first Element.
                 This is why, we write only the Tm command:
                 */
-                writer.writeGStateChanges(textElement);
+                    writer.writeGStateChanges(textElement);
-            }
+                }
-        } else {
+            } else {
-            if (!inClippingPath) {
+                if (!inClippingPath) {
-                gState.setFillColorSpace(ColorSpace.createDeviceRGB());
+                    gState.setFillColorSpace(ColorSpace.createDeviceRGB());
-                // red for elements removed by clipping path
+                    // red for elements removed by clipping path
-                gState.setFillColor(new ColorPt(1, 0, 0));
+                    gState.setFillColor(new ColorPt(1, 0, 0));
-                writer.writeElement(textElement);
+                    writer.writeElement(textElement);
-            }
+                }
-            if (!isTextVisible) {
+                if (!isTextVisible) {
-                gState.setFillColorSpace(ColorSpace.createDeviceRGB());
+                    gState.setFillColorSpace(ColorSpace.createDeviceRGB());
-                // blue for elements removed due to transparency or not rendered or same color as background
+                    // blue for elements removed due to transparency or not rendered or same color as background
-                gState.setFillColor(new ColorPt(0, 0, 1));
+                    gState.setFillColor(new ColorPt(0, 0, 1));
-                gState.setTextRenderMode(GState.e_fill_text);
+                    gState.setTextRenderMode(GState.e_fill_text);
-                gState.setFillOpacity(1);
+                    gState.setFillOpacity(1);
-                writer.writeElement(textElement);
+                    writer.writeElement(textElement);
+                }
             }
         }
     }
@@ -315,20 +318,21 @@ public class InvisibleElementRemovalService {
             context.visitedXObjIds().add(formObj.getObjNum());
             // writer needs to be newly initialized when entering a new content stream
             // see ElementEditTest in PDFTron (https://www.pdftron.com/documentation/samples/android/java/ElementEditTest)
-            ElementWriter formWriter = new ElementWriter();
+            try(ElementWriter formWriter = new ElementWriter()) {
-            context.clippingPathStack().enterNewGState();
+                context.clippingPathStack().enterNewGState();
-            context.clippingPathStack().intersectClippingPath(new GeneralPath(Converter.toRectangle2D(formElement.getBBox())));
+                context.clippingPathStack().intersectClippingPath(new GeneralPath(Converter.toRectangle2D(formElement.getBBox())));
-            context.reader().formBegin();
+                context.reader().formBegin();
-            formWriter.begin(formObj);
+                formWriter.begin(formObj);
 
-            context.reader().clearChangeList();
+                context.reader().clearChangeList();
-            formWriter.setDefaultGState(context.reader());
+                formWriter.setDefaultGState(context.reader());
 
-            processElements(formWriter, context);
+                processElements(formWriter, context);
-            formWriter.end();
+                formWriter.end();
-            formWriter.destroy();
+                formWriter.destroy();
-            context.reader().end();
+                context.reader().end();
-            context.clippingPathStack().leaveGState();
+                context.clippingPathStack().leaveGState();
+            }
         }
     }
 
@@ -481,17 +485,18 @@ public class InvisibleElementRemovalService {
             context.visitedXObjIds().add(formObj.getObjNum());
             // writer needs to be newly initialized when entering a new content stream
             // see ElementEditTest in PDFTron (https://www.pdftron.com/documentation/samples/android/java/ElementEditTest)
-            ElementWriter formWriter = new ElementWriter();
+            try(ElementWriter formWriter = new ElementWriter()) {
-            context.reader().formBegin();
+                context.reader().formBegin();
-            formWriter.begin(formObj);
+                formWriter.begin(formObj);
 
-            context.reader().clearChangeList();
+                context.reader().clearChangeList();
-            formWriter.setDefaultGState(context.reader());
+                formWriter.setDefaultGState(context.reader());
 
-            processOverlappedElements(formWriter, context);
+                processOverlappedElements(formWriter, context);
-            formWriter.end();
+                formWriter.end();
-            formWriter.destroy();
+                formWriter.destroy();
-            context.reader().end();
+                context.reader().end();
+            }
         }
     }
 
@@ -582,18 +587,20 @@ public class InvisibleElementRemovalService {
     @SneakyThrows
     private void drawBBox(ElementWriter writer, Rectangle2D r, String hexcolor) {
 
-        ColorPt colorPt = new ColorPt(Integer.valueOf(hexcolor.substring(1, 3), 16) / 255d,
+        try(ColorPt colorPt = new ColorPt(Integer.valueOf(hexcolor.substring(1, 3), 16) / 255d,
                 Integer.valueOf(hexcolor.substring(3, 5), 16) / 255d,
-                Integer.valueOf(hexcolor.substring(5, 7), 16) / 255d);
+                Integer.valueOf(hexcolor.substring(5, 7), 16) / 255d)) {
-        ElementBuilder eb = new ElementBuilder();
+            try(ElementBuilder eb = new ElementBuilder()) {
-        Element rect = eb.createRect(r.getX(), r.getY(), r.getWidth(), r.getHeight());
+                Element rect = eb.createRect(r.getX(), r.getY(), r.getWidth(), r.getHeight());
-        rect.setPathStroke(true);
+                rect.setPathStroke(true);
-        rect.getGState().setStrokeColorSpace(ColorSpace.createDeviceRGB());
+                rect.getGState().setStrokeColorSpace(ColorSpace.createDeviceRGB());
-        rect.getGState().setStrokeColor(colorPt);
+                rect.getGState().setStrokeColor(colorPt);
-        writer.writePlacedElement(rect);
+                writer.writePlacedElement(rect);
 
-        colorPt.destroy();
+                colorPt.destroy();
-        eb.destroy();
+                eb.destroy();
+            }
+        }
     }
 
 

src/main/java/com/iqser/red/pdftronlogic/commons/MarkedContentStack.java

@@ -7,33 +7,33 @@ import java.util.Set;
 
 public class MarkedContentStack {
 
-    Deque<MarkedContent> markedContentStack = new LinkedList<>();
+    Deque<MarkedContent> markedContentQueue = new LinkedList<>();
 
 
     public void enterMarkedContent(String name) {
 
-        markedContentStack.push(new MarkedContent(name));
+        markedContentQueue.push(new MarkedContent(name));
     }
 
 
     public void leaveMarkedContent() {
 
-        markedContentStack.pop();
+        markedContentQueue.pop();
     }
 
 
     public String currentMarkedContent() {
 
-        if (markedContentStack.isEmpty()) {
+        if (markedContentQueue.isEmpty()) {
             return "";
         }
-        return markedContentStack.peek().name();
+        return markedContentQueue.peek().name();
     }
 
 
     public boolean currentMarkedContentContains(String name) {
 
-        Iterator<MarkedContent> markedContentIterator = markedContentStack.descendingIterator();
+        Iterator<MarkedContent> markedContentIterator = markedContentQueue.descendingIterator();
         while (markedContentIterator.hasNext()) {
             var markedContent = markedContentIterator.next();
             if (markedContent.name().equals(name)) {
@@ -46,10 +46,10 @@ public class MarkedContentStack {
 
     public boolean currentMarkedContentContainsAny(Set<String> names) {
 
-        if (markedContentStack.isEmpty()) {
+        if (markedContentQueue.isEmpty()) {
             return false;
         }
-        Iterator<MarkedContent> markedContentIterator = markedContentStack.descendingIterator();
+        Iterator<MarkedContent> markedContentIterator = markedContentQueue.descendingIterator();
         while (markedContentIterator.hasNext()) {
             var markedContent = markedContentIterator.next();
             if (names.contains(markedContent.name())) {
@@ -62,7 +62,7 @@ public class MarkedContentStack {
 
     public void clear() {
 
-        markedContentStack.clear();
+        markedContentQueue.clear();
     }
 
 

src/main/java/com/iqser/red/pdftronlogic/commons/OCGWatermarkRemovalService.java

@@ -43,18 +43,20 @@ public class OCGWatermarkRemovalService {
     @SneakyThrows
     private void removeOCGWatermarks(PDFDoc pdfDoc) {
 
-        ElementReader reader = new ElementReader();
+        try(ElementReader reader = new ElementReader()) {
-        ElementWriter writer = new ElementWriter();
+            try(ElementWriter writer = new ElementWriter()) {
-        Set<Long> visitedXObjIds = new TreeSet<>();
+                Set<Long> visitedXObjIds = new TreeSet<>();
 
-        for (PageIterator iterator = pdfDoc.getPageIterator(); iterator.hasNext(); ) {
+                for (PageIterator iterator = pdfDoc.getPageIterator(); iterator.hasNext(); ) {
 
-            Page page = iterator.next();
+                    Page page = iterator.next();
-            writeAllElementsExceptWatermarks(page, reader, writer, visitedXObjIds);
+                    writeAllElementsExceptWatermarks(page, reader, writer, visitedXObjIds);
+                }
+
+                reader.destroy();
+                writer.destroy();
+            }
         }
-
-        reader.destroy();
-        writer.destroy();
     }
 
 
@@ -124,17 +126,18 @@ public class OCGWatermarkRemovalService {
             visitedXObjIds.add(element.getXObject().getObjNum());
             // writer needs to be newly initialized when entering a new content stream
             // see ElementEditTest in PDFTron (https://www.pdftron.com/documentation/samples/android/java/ElementEditTest)
-            ElementWriter formWriter = new ElementWriter();
+            try(ElementWriter formWriter = new ElementWriter()) {
-            reader.formBegin();
+                reader.formBegin();
-            formWriter.begin(element.getXObject());
+                formWriter.begin(element.getXObject());
 
-            reader.clearChangeList();
+                reader.clearChangeList();
-            formWriter.setDefaultGState(reader);
+                formWriter.setDefaultGState(reader);
 
-            processElements(page, reader, formWriter, visitedXObjIds);
+                processElements(page, reader, formWriter, visitedXObjIds);
-            formWriter.end();
+                formWriter.end();
-            formWriter.destroy();
+                formWriter.destroy();
-            reader.end();
+                reader.end();
+            }
         }
 
     }

src/main/java/com/iqser/red/pdftronlogic/commons/PdfTextExtraction.java

@@ -16,20 +16,21 @@ import lombok.experimental.UtilityClass;
 @UtilityClass
 public class PdfTextExtraction {
 
-    private static String execute(PDFDoc pdfDoc) throws IOException, PDFNetException{
+    private static String execute(PDFDoc pdfDoc) throws PDFNetException{
-        TextExtractor extractor = new TextExtractor();
+        try(TextExtractor extractor = new TextExtractor()) {
-        List<String> texts = new ArrayList<>();
+            List<String> texts = new ArrayList<>();
 
-        PageIterator iterator = pdfDoc.getPageIterator();
+            PageIterator iterator = pdfDoc.getPageIterator();
-        while (iterator.hasNext()) {
+            while (iterator.hasNext()) {
-            Page page = iterator.next();
+                Page page = iterator.next();
-            extractor.begin(page);
+                extractor.begin(page);
-            texts.add(extractor.getAsText());
+                texts.add(extractor.getAsText());
+            }
+
+            extractor.destroy();
+            pdfDoc.close();
+            return String.join("\n", texts);
         }
-
-        extractor.destroy();
-        pdfDoc.close();
-        return String.join("\n", texts);
     }
 
     public static String extractAllTextFromDocument(InputStream fileStream) throws IOException, PDFNetException {

src/main/java/com/iqser/red/pdftronlogic/commons/WatermarkRemovalService.java

@@ -93,27 +93,28 @@ public class WatermarkRemovalService {
         Map<Long, List<ElementFeatures>> formObjectsAndImagesForPages = new HashMap<>();
         Set<Long> visitedXObjIds = new TreeSet<>();
 
-        ElementReader reader = new ElementReader();
+        try(ElementReader reader = new ElementReader()) {
 
-        for (PageIterator iterator = pdfDoc.getPageIterator(); iterator.hasNext(); ) {
+            for (PageIterator iterator = pdfDoc.getPageIterator(); iterator.hasNext(); ) {
 
-            Page page = iterator.next();
+                Page page = iterator.next();
 
-            double minAreaCoveringFromPage = AREA_THRESHOLD * page.getPageHeight() * page.getPageWidth();
+                double minAreaCoveringFromPage = AREA_THRESHOLD * page.getPageHeight() * page.getPageWidth();
 
-            LinkedList<ElementFeatures> elementFeaturesLinkedList = new LinkedList<>();
+                LinkedList<ElementFeatures> elementFeaturesLinkedList = new LinkedList<>();
 
-            reader.begin(page);
+                reader.begin(page);
-            for (Element element = reader.next(); element != null; element = reader.next()) {
+                for (Element element = reader.next(); element != null; element = reader.next()) {
-                processElement(element, visitedXObjIds, elementFeaturesLinkedList, formObjectsOccuringMoreThanOnceOnAPage, minAreaCoveringFromPage, page);
+                    processElement(element, visitedXObjIds, elementFeaturesLinkedList, formObjectsOccuringMoreThanOnceOnAPage, minAreaCoveringFromPage, page);
+                }
+
+                formObjectsAndImagesForPages.put(page.getSDFObj().getObjNum(), elementFeaturesLinkedList);
             }
 
-            formObjectsAndImagesForPages.put(page.getSDFObj().getObjNum(), elementFeaturesLinkedList);
+            reader.destroy();
+
+            return formObjectsAndImagesForPages;
         }
-
-        reader.destroy();
-
-        return formObjectsAndImagesForPages;
     }
 
 
@@ -220,13 +221,14 @@ public class WatermarkRemovalService {
         }
 
         if (visitedXObjIds.add(element.getXObject().getObjNum())) {
-            ElementReader xObjectReader = new ElementReader();
+            try(ElementReader xObjectReader = new ElementReader()) {
-            xObjectReader.begin(element.getXObject());
+                xObjectReader.begin(element.getXObject());
-            for (Element element1 = xObjectReader.next(); element1 != null; element1 = xObjectReader.next()) {
+                for (Element element1 = xObjectReader.next(); element1 != null; element1 = xObjectReader.next()) {
-                processElement(element1, visitedXObjIds, elementFeaturesLinkedList, formObjectsOccuringMoreThanOnceOnAPage, minAreaCoveringPage, page);
+                    processElement(element1, visitedXObjIds, elementFeaturesLinkedList, formObjectsOccuringMoreThanOnceOnAPage, minAreaCoveringPage, page);
+                }
+                elementFeaturesLinkedList.add(ElementFeatureFactory.extractFeatures(element));
+                xObjectReader.destroy();
             }
-            elementFeaturesLinkedList.add(ElementFeatureFactory.extractFeatures(element));
-            xObjectReader.destroy();
         } else {
             elementFeaturesLinkedList.add(ElementFeatureFactory.extractFeatures(element));
         }
@@ -256,21 +258,22 @@ public class WatermarkRemovalService {
     @SneakyThrows
     private void removeAllWatermarks(PDFDoc pdfDoc, List<ElementFeatures> watermarksElementFeaturesList) {
 
-        ElementReader reader = new ElementReader();
+        try(ElementReader reader = new ElementReader()) {
-        ElementWriter writer = new ElementWriter();
+            try (ElementWriter writer = new ElementWriter()) {
-        Set<Long> visitedXObjIds = new TreeSet<>();
+                Set<Long> visitedXObjIds = new TreeSet<>();
 
-        for (PageIterator iterator = pdfDoc.getPageIterator(); iterator.hasNext(); ) {
+                for (PageIterator iterator = pdfDoc.getPageIterator(); iterator.hasNext(); ) {
 
-            Page page = iterator.next();
+                    Page page = iterator.next();
 
-            writeAllElementsExceptWatermarks(page, reader, writer, watermarksElementFeaturesList, visitedXObjIds);
+                    writeAllElementsExceptWatermarks(page, reader, writer, watermarksElementFeaturesList, visitedXObjIds);
 
+                }
+
+                reader.destroy();
+                writer.destroy();
+            }
         }
-
-        reader.destroy();
-        writer.destroy();
-
     }
 
 
@@ -390,17 +393,18 @@ public class WatermarkRemovalService {
             visitedXObjIds.add(element.getXObject().getObjNum());
             // writer needs to be newly initialized when entering a new content stream
             // see ElementEditTest in PDFTron (https://www.pdftron.com/documentation/samples/android/java/ElementEditTest)
-            ElementWriter formWriter = new ElementWriter();
+            try(ElementWriter formWriter = new ElementWriter()) {
-            reader.formBegin();
+                reader.formBegin();
-            formWriter.begin(element.getXObject());
+                formWriter.begin(element.getXObject());
 
-            reader.clearChangeList();
+                reader.clearChangeList();
-            formWriter.setDefaultGState(reader);
+                formWriter.setDefaultGState(reader);
 
-            processElements(page, reader, formWriter, watermarksElementFeaturesList, visitedXObjIds);
+                processElements(page, reader, formWriter, watermarksElementFeaturesList, visitedXObjIds);
-            formWriter.end();
+                formWriter.end();
-            formWriter.destroy();
+                formWriter.destroy();
-            reader.end();
+                reader.end();
+            }
         }
 
     }

src/test/java/com/iqser/red/pdftronlogic/commons/InvisibleElementRemovalServiceTest.java

@@ -13,6 +13,7 @@ import com.pdftron.pdf.PDFNet;
 
 import lombok.SneakyThrows;
 
+@SuppressWarnings("PMD")
 class InvisibleElementRemovalServiceTest {
 
     InvisibleElementRemovalService invisibleElementRemovalService;

src/test/java/com/iqser/red/pdftronlogic/commons/WatermarkRemovalServiceTest.java

@@ -13,6 +13,7 @@ import com.pdftron.pdf.PDFNet;
 import lombok.SneakyThrows;
 
 @Disabled
+@SuppressWarnings("PMD")
 class WatermarkRemovalServiceTest {
 
     @SneakyThrows