Support collapsing margins for flex container

DEVSIX-5137

Author: Eugene Bochilo

io/src/main/java/com/itextpdf/io/LogMessageConstant.java

@@ -167,6 +167,8 @@ public final class LogMessageConstant {
     public static final String ORPHANS_CONSTRAINT_VIOLATED = "Orphans constraint violated for paragraph split at page {0}. Min number of orphans: {1}; actual: {2}. \nComment: {3}";
     public static final String OUTLINE_DESTINATION_PAGE_NUMBER_IS_OUT_OF_BOUNDS = "Outline destination page number {0} is out of bounds";
     public static final String PAGE_TREE_IS_BROKEN_FAILED_TO_RETRIEVE_PAGE = "Page tree is broken. Failed to retrieve page number {0}. Null will be returned.";
+    public static final String PAGE_WAS_FLUSHED_ACTION_WILL_NOT_BE_PERFORMED =
+            "Page was flushed. {0} will not be performed.";
     public static final String PASSED_PAGE_SHALL_BE_ON_WHICH_CANVAS_WILL_BE_RENDERED = "The page passed to Canvas#enableAutoTagging(PdfPage) method shall be the one on which this canvas will be rendered. However the actual passed PdfPage instance sets not such page. This might lead to creation of malformed PDF document.";
     public static final String PATH_KEY_IS_PRESENT_VERTICES_WILL_BE_IGNORED = "Path key is present. Vertices will be ignored";
     public static final String PDF_OBJECT_FLUSHING_NOT_PERFORMED = "PdfObject flushing is not performed: PdfDocument is opened in append mode and the object is not marked as modified ( see PdfObject#setModified() ).";

layout/src/main/java/com/itextpdf/layout/renderer/AbstractRenderer.java

@@ -1900,11 +1900,11 @@ protected void applyAction(PdfDocument document) {
     }
 
     protected void applyLinkAnnotation(PdfDocument document) {
+        Logger logger = LoggerFactory.getLogger(AbstractRenderer.class);
         PdfLinkAnnotation linkAnnotation = this.<PdfLinkAnnotation>getProperty(Property.LINK_ANNOTATION);
         if (linkAnnotation != null) {
             int pageNumber = occupiedArea.getPageNumber();
             if (pageNumber < 1 || pageNumber > document.getNumberOfPages()) {
-                Logger logger = LoggerFactory.getLogger(AbstractRenderer.class);
                 String logMessageArg = "Property.LINK_ANNOTATION, which specifies a link associated with this element content area, see com.itextpdf.layout.element.Link.";
                 logger.warn(MessageFormatUtil.format(LogMessageConstant.UNABLE_TO_APPLY_PAGE_DEPENDENT_PROP_UNKNOWN_PAGE_ON_WHICH_ELEMENT_IS_DRAWN, logMessageArg));
                 return;
@@ -1918,7 +1918,14 @@ protected void applyLinkAnnotation(PdfDocument document) {
             linkAnnotation.setRectangle(new PdfArray(pdfBBox));
 
             PdfPage page = document.getPage(pageNumber);
-            page.addAnnotation(linkAnnotation);
+            // TODO DEVSIX-1655 This check is necessary because, in some cases, our renderer's hierarchy may contain
+            //  a renderer from the different page that was already flushed
+            if (page.isFlushed()) {
+                logger.error(MessageFormatUtil.format(
+                        LogMessageConstant.PAGE_WAS_FLUSHED_ACTION_WILL_NOT_BE_PERFORMED, "link annotation applying"));
+            } else {
+                page.addAnnotation(linkAnnotation);
+            }
         }
     }
 

layout/src/main/java/com/itextpdf/layout/renderer/BlockFormattingContextUtil.java

@@ -68,6 +68,7 @@ public static boolean isRendererCreateBfc(IRenderer renderer) {
         return (renderer instanceof RootRenderer)
                 || (renderer instanceof CellRenderer)
                 || isInlineBlock(renderer)
+                || renderer.getParent() instanceof FlexContainerRenderer
                 || FloatingHelper.isRendererFloating(renderer)
                 || isAbsolutePosition(renderer)
                 || isFixedPosition(renderer)

layout/src/main/java/com/itextpdf/layout/renderer/BlockRenderer.java

@@ -48,6 +48,7 @@ This file is part of the iText (R) project.
 import com.itextpdf.kernel.geom.AffineTransform;
 import com.itextpdf.kernel.geom.Point;
 import com.itextpdf.kernel.geom.Rectangle;
+import com.itextpdf.kernel.pdf.PdfPage;
 import com.itextpdf.kernel.pdf.canvas.PdfCanvas;
 import com.itextpdf.kernel.pdf.tagutils.TagTreePointer;
 import com.itextpdf.layout.borders.Border;
@@ -229,7 +230,7 @@ public LayoutResult layout(LayoutContext layoutContext) {
             }
 
             if (marginsCollapsingEnabled) {
-                childMarginsInfo = marginsCollapseHandler.startChildMarginsHandling(childRenderer, layoutBox);
+                childMarginsInfo = startChildMarginsHandling(childRenderer, layoutBox, marginsCollapseHandler);
             }
             Rectangle changedLayoutBox =
                     recalculateLayoutBoxBeforeChildLayout(layoutBox, childRenderer, areas.get(0).clone());
@@ -465,8 +466,8 @@ public LayoutResult layout(LayoutContext layoutContext) {
 
     @Override
     public void draw(DrawContext drawContext) {
+        Logger logger = LoggerFactory.getLogger(BlockRenderer.class);
         if (occupiedArea == null) {
-            Logger logger = LoggerFactory.getLogger(BlockRenderer.class);
             logger.error(MessageFormatUtil.format(LogMessageConstant.OCCUPIED_AREA_HAS_NOT_BEEN_INITIALIZED, "Drawing won't be performed."));
             return;
         }
@@ -513,7 +514,16 @@ public void draw(DrawContext drawContext) {
             if (pageNumber < 1 || pageNumber > drawContext.getDocument().getNumberOfPages()) {
                 clippedArea = new Rectangle(-INF / 2 , -INF / 2, INF, INF);
             } else {
-                clippedArea = drawContext.getDocument().getPage(pageNumber).getPageSize();
+                PdfPage page = drawContext.getDocument().getPage(pageNumber);
+                // TODO DEVSIX-1655 This check is necessary because, in some cases, our renderer's hierarchy may contain
+                //  a renderer from the different page that was already flushed
+                if (page.isFlushed()) {
+                    logger.error(MessageFormatUtil.format(
+                            LogMessageConstant.PAGE_WAS_FLUSHED_ACTION_WILL_NOT_BE_PERFORMED, "area clipping"));
+                    clippedArea = new Rectangle(-INF / 2 , -INF / 2, INF, INF);
+                } else {
+                    clippedArea = page.getPageSize();
+                }
             }
             Rectangle area = getBorderAreaBBox();
             if (overflowXHidden) {
@@ -587,6 +597,11 @@ protected AbstractRenderer createOverflowRenderer(int layoutResult) {
     void recalculateOccupiedAreaAfterChildLayout(Rectangle resultBBox, Float blockMaxHeight) {
         occupiedArea.setBBox(Rectangle.getCommonRectangle(occupiedArea.getBBox(), resultBBox));
     }
+    
+    MarginsCollapseInfo startChildMarginsHandling(IRenderer childRenderer,
+                                                  Rectangle layoutBox, MarginsCollapseHandler marginsCollapseHandler) {
+        return marginsCollapseHandler.startChildMarginsHandling(childRenderer, layoutBox);
+    }
 
     Rectangle recalculateLayoutBoxBeforeChildLayout(Rectangle layoutBox,
                                                     IRenderer childRenderer, Rectangle initialLayoutBox) {

layout/src/main/java/com/itextpdf/layout/renderer/FlexContainerRenderer.java

@@ -48,6 +48,8 @@ This file is part of the iText (R) project.
 import com.itextpdf.layout.element.Div;
 import com.itextpdf.layout.layout.LayoutContext;
 import com.itextpdf.layout.layout.LayoutResult;
+import com.itextpdf.layout.margincollapse.MarginsCollapseHandler;
+import com.itextpdf.layout.margincollapse.MarginsCollapseInfo;
 import com.itextpdf.layout.minmaxwidth.MinMaxWidth;
 import com.itextpdf.layout.minmaxwidth.MinMaxWidthUtils;
 import com.itextpdf.layout.property.OverflowPropertyValue;
@@ -268,6 +270,12 @@ void recalculateOccupiedAreaAfterChildLayout(Rectangle resultBBox, Float blockMa
         }
     }
 
+    @Override
+    MarginsCollapseInfo startChildMarginsHandling(IRenderer childRenderer,
+                                                  Rectangle layoutBox, MarginsCollapseHandler marginsCollapseHandler) {
+        return marginsCollapseHandler.startChildMarginsHandling(null, layoutBox);
+    }
+
     @Override
     void decreaseLayoutBoxAfterChildPlacement(Rectangle layoutBox, LayoutResult result, IRenderer childRenderer) {
         // TODO DEVSIX-5086 When flex-wrap will be fully supported

layout/src/test/java/com/itextpdf/layout/element/FlexContainerTest.java

@@ -927,6 +927,40 @@ public void linesMaxHeightShouldBeRespectedTest() throws IOException, Interrupte
         Assert.assertNull(new CompareTool().compareByContent(outFileName, cmpFileName, destinationFolder, "diff"));
     }
 
+    @Test
+    public void collapsingMarginsFlexContainerTest() throws IOException, InterruptedException {
+        String outFileName = destinationFolder + "collapsingMarginsFlexContainerTest" + testNumber + ".pdf";
+        String cmpFileName = sourceFolder + "cmp_collapsingMarginsFlexContainerTest" + testNumber + ".pdf";
+        PdfDocument pdfDocument = new PdfDocument(new PdfWriter(outFileName));
+
+        Document document = new Document(pdfDocument);
+        document.setProperty(Property.COLLAPSING_MARGINS, true);
+
+        Div flexContainer = createFlexContainer();
+        flexContainer.setProperty(Property.MARGIN_TOP, UnitValue.createPointValue(50));
+        flexContainer.setProperty(Property.BORDER, new SolidBorder(2));
+        flexContainer.setProperty(Property.BACKGROUND, new Background(ColorConstants.LIGHT_GRAY));
+
+        Div child1 = createNewDiv();
+        child1.setBackgroundColor(ColorConstants.CYAN);
+        child1.setMargin(50);
+
+        Div child2 = createNewDiv();
+        child2.setBackgroundColor(ColorConstants.CYAN);
+        child2.setMargin(50);
+
+        flexContainer.add(child1).add(child2);
+
+        Div flexContainersSibling = createNewDiv();
+        flexContainersSibling.setMarginBottom(40);
+
+        document.add(flexContainersSibling).add(flexContainer);
+
+        document.close();
+
+        Assert.assertNull(new CompareTool().compareByContent(outFileName, cmpFileName, destinationFolder, "diff"));
+    }
+
     private Div getFlexContainer(OverflowPropertyValue overflowX, Style style) {
         FlexContainer flexContainer = createFlexContainer();
         flexContainer

layout/src/test/java/com/itextpdf/layout/renderer/AbstractRendererUnitTest.java

@@ -42,6 +42,7 @@ This file is part of the iText (R) project.
  */
 package com.itextpdf.layout.renderer;
 
+import com.itextpdf.io.LogMessageConstant;
 import com.itextpdf.io.image.ImageDataFactory;
 import com.itextpdf.io.source.ByteArrayOutputStream;
 import com.itextpdf.kernel.colors.ColorConstants;
@@ -56,6 +57,7 @@ This file is part of the iText (R) project.
 import com.itextpdf.kernel.pdf.PdfDocument;
 import com.itextpdf.kernel.pdf.PdfName;
 import com.itextpdf.kernel.pdf.PdfWriter;
+import com.itextpdf.kernel.pdf.annot.PdfLinkAnnotation;
 import com.itextpdf.kernel.pdf.canvas.PdfCanvas;
 import com.itextpdf.kernel.pdf.xobject.PdfFormXObject;
 import com.itextpdf.kernel.pdf.xobject.PdfImageXObject;
@@ -73,6 +75,8 @@ This file is part of the iText (R) project.
 import com.itextpdf.layout.property.Property;
 import com.itextpdf.layout.property.UnitValue;
 import com.itextpdf.test.ExtendedITextTest;
+import com.itextpdf.test.annotations.LogMessage;
+import com.itextpdf.test.annotations.LogMessages;
 import com.itextpdf.test.annotations.type.UnitTest;
 
 import java.util.Arrays;
@@ -621,4 +625,22 @@ public PdfCanvas addXObjectFittedIntoRectangle(PdfXObject xObject, Rectangle rec
         renderer.setProperty(Property.BACKGROUND_IMAGE, backgroundImage);
         renderer.drawBackground(drawContext);
     }
+
+    @Test
+    @LogMessages(messages = @LogMessage(messageTemplate = LogMessageConstant.PAGE_WAS_FLUSHED_ACTION_WILL_NOT_BE_PERFORMED))
+    public void applyLinkAnnotationFlushedPageTest() {
+        AbstractRenderer abstractRenderer = new DivRenderer(new Div());
+        abstractRenderer.occupiedArea = new LayoutArea(1, new Rectangle(100, 100));
+
+        abstractRenderer.setProperty(Property.LINK_ANNOTATION, new PdfLinkAnnotation(new Rectangle(0, 0, 0, 0)));
+
+        PdfDocument pdfDocument = new PdfDocument(new PdfWriter(new ByteArrayOutputStream()));
+        pdfDocument.addNewPage();
+        pdfDocument.getPage(1).flush();
+
+        abstractRenderer.applyLinkAnnotation(pdfDocument);
+
+        // This test checks that there is log message and there is no NPE so assertions are not required
+        Assert.assertTrue(true);
+    }
 }

layout/src/test/java/com/itextpdf/layout/renderer/BlockRendererUnitTest.java

@@ -0,0 +1,43 @@
+package com.itextpdf.layout.renderer;
+
+import com.itextpdf.io.LogMessageConstant;
+import com.itextpdf.io.source.ByteArrayOutputStream;
+import com.itextpdf.kernel.geom.Rectangle;
+import com.itextpdf.kernel.pdf.PdfDocument;
+import com.itextpdf.kernel.pdf.PdfWriter;
+import com.itextpdf.kernel.pdf.canvas.PdfCanvas;
+import com.itextpdf.layout.element.Div;
+import com.itextpdf.layout.layout.LayoutArea;
+import com.itextpdf.layout.property.OverflowPropertyValue;
+import com.itextpdf.layout.property.Property;
+import com.itextpdf.test.ExtendedITextTest;
+import com.itextpdf.test.annotations.LogMessage;
+import com.itextpdf.test.annotations.LogMessages;
+import com.itextpdf.test.annotations.type.UnitTest;
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+
+@Category(UnitTest.class)
+public class BlockRendererUnitTest extends ExtendedITextTest {
+
+    @Test
+    @LogMessages(messages = @LogMessage(messageTemplate = LogMessageConstant.PAGE_WAS_FLUSHED_ACTION_WILL_NOT_BE_PERFORMED))
+    public void clippedAreaFlushedPageTest() {
+        BlockRenderer blockRenderer = new DivRenderer(new Div());
+        blockRenderer.setProperty(Property.OVERFLOW_X, OverflowPropertyValue.HIDDEN);
+        blockRenderer.occupiedArea = new LayoutArea(1, new Rectangle(100, 100));
+
+        PdfDocument pdfDocument = new PdfDocument(new PdfWriter(new ByteArrayOutputStream()));
+        pdfDocument.addNewPage();
+        PdfCanvas pdfCanvas = new PdfCanvas(pdfDocument.addNewPage());
+        DrawContext context = new DrawContext(pdfDocument, pdfCanvas);
+
+        pdfDocument.getPage(1).flush();
+
+        blockRenderer.draw(context);
+
+        // This test checks that there is log message and there is no NPE so assertions are not required
+        Assert.assertTrue(true);
+    }
+}