Add flex container element and flex related properties

DEVSIX-4996

Author: ar3em

layout/src/main/java/com/itextpdf/layout/element/FlexContainer.java

@@ -0,0 +1,58 @@
+/*
+    This file is part of the iText (R) project.
+    Copyright (c) 1998-2021 iText Group NV
+    Authors: Bruno Lowagie, Paulo Soares, et al.
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License version 3
+    as published by the Free Software Foundation with the addition of the
+    following permission added to Section 15 as permitted in Section 7(a):
+    FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
+    ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
+    OF THIRD PARTY RIGHTS
+
+    This program is distributed in the hope that it will be useful, but
+    WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+    or FITNESS FOR A PARTICULAR PURPOSE.
+    See the GNU Affero General Public License for more details.
+    You should have received a copy of the GNU Affero General Public License
+    along with this program; if not, see http://www.gnu.org/licenses or write to
+    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+    Boston, MA, 02110-1301 USA, or download the license from the following URL:
+    http://itextpdf.com/terms-of-use/
+
+    The interactive user interfaces in modified source and object code versions
+    of this program must display Appropriate Legal Notices, as required under
+    Section 5 of the GNU Affero General Public License.
+
+    In accordance with Section 7(b) of the GNU Affero General Public License,
+    a covered work must retain the producer line in every PDF that is created
+    or manipulated using iText.
+
+    You can be released from the requirements of the license by purchasing
+    a commercial license. Buying such a license is mandatory as soon as you
+    develop commercial activities involving the iText software without
+    disclosing the source code of your own applications.
+    These activities include: offering paid services to customers as an ASP,
+    serving PDFs on the fly in a web application, shipping iText with a closed
+    source product.
+
+    For more information, please contact iText Software Corp. at this
+    address: [email protected]
+ */
+package com.itextpdf.layout.element;
+
+import com.itextpdf.layout.renderer.FlexContainerRenderer;
+import com.itextpdf.layout.renderer.IRenderer;
+
+public class FlexContainer extends Div {
+
+    public FlexContainer() {
+        super();
+    }
+
+    @Override
+    protected IRenderer makeNewRenderer() {
+        return new FlexContainerRenderer(this);
+    }
+}

layout/src/main/java/com/itextpdf/layout/property/Property.java

@@ -54,6 +54,7 @@ public final class Property {
 
     public static final int ACTION = 1;
     public static final int ALIGN_CONTENT = 130;
+    public static final int ALIGN_ITEMS = 134;
     public static final int ALIGN_SELF = 129;
     public static final int APPEARANCE_STREAM_LAYOUT = 82;
     public static final int AREA_BREAK_TYPE = 2;
@@ -135,6 +136,7 @@ public final class Property {
     public static final int IGNORE_FOOTER = 96;
     public static final int IGNORE_HEADER = 97;
     public static final int ITALIC_SIMULATION = 31;
+    public static final int JUSTIFY_CONTENT = 135;
     public static final int KEEP_TOGETHER = 32;
     public static final int KEEP_WITH_NEXT = 81;
     public static final int LEADING = 33;

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

@@ -59,8 +59,6 @@ This file is part of the iText (R) project.
 import java.util.Set;
 
 public class FlexContainerRenderer extends DivRenderer {
-    private static float FLEX_GROW_DEFAULT_VALUE = 0;
-    private static float FLEX_SHRINK_DEFAULT_VALUE = 1;
 
     private List<List<FlexItemInfo>> lines;
 
@@ -86,21 +84,10 @@ public IRenderer getNextRenderer() {
     @Override
     public LayoutResult layout(LayoutContext layoutContext) {
         Rectangle layoutContextRectangle = layoutContext.getArea().getBBox();
-        final List<FlexUtil.FlexItemCalculationInfo> flexItemInfos = new ArrayList<>();
-        // TODO DEVSIX-4996 Change properties FLEX_GROW/FLEX_SHRINK/FLEX_BASIS on the combined one added in this ticket
         for (final IRenderer childRenderer : this.getChildRenderers()) {
             if (childRenderer instanceof AbstractRenderer) {
                 final AbstractRenderer abstractChildRenderer = (AbstractRenderer) childRenderer;
                 abstractChildRenderer.setParent(this);
-                final UnitValue flexBasis = abstractChildRenderer.<UnitValue>getProperty(Property.WIDTH) == null ?
-                        UnitValue.createPointValue(abstractChildRenderer.getMinMaxWidth().getMinWidth()) :
-                        abstractChildRenderer.<UnitValue>getProperty(Property.WIDTH);
-                flexItemInfos.add(new FlexUtil.FlexItemCalculationInfo(
-                        (AbstractRenderer) childRenderer,
-                        childRenderer.<UnitValue>getProperty(Property.FLEX_BASIS, flexBasis),
-                        (float) childRenderer.<Float>getProperty(Property.FLEX_GROW, FLEX_GROW_DEFAULT_VALUE),
-                        (float) childRenderer.<Float>getProperty(Property.FLEX_SHRINK, FLEX_SHRINK_DEFAULT_VALUE),
-                        layoutContextRectangle.getWidth()));
             }
         }
         Float containerWidth = retrieveWidth(layoutContextRectangle.getWidth());
@@ -112,7 +99,7 @@ public LayoutResult layout(LayoutContext layoutContext) {
             containerHeight = layoutContextRectangle.getHeight();
         }
         lines = FlexUtil.calculateChildrenRectangles(
-                new Rectangle((float) containerWidth, (float) containerHeight), this, flexItemInfos);
+                new Rectangle((float) containerWidth, (float) containerHeight), this);
         final List<UnitValue> previousWidths = new ArrayList<>();
         for (final List<FlexItemInfo> line : lines) {
             for (final FlexItemInfo itemInfo : line) {
@@ -281,6 +268,7 @@ private void findMinMaxWidthIfCorrespondingPropertiesAreNotSet(MinMaxWidth minMa
         // TODO DEVSIX-5086 When flex-wrap will be fully supported we'll find min/max width with respect to the lines
         for (final IRenderer childRenderer : childRenderers) {
             MinMaxWidth childMinMaxWidth;
+            childRenderer.setParent(this);
             if (childRenderer instanceof AbstractRenderer) {
                 childMinMaxWidth = ((AbstractRenderer) childRenderer).getMinMaxWidth();
             } else {

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

@@ -58,8 +58,13 @@ This file is part of the iText (R) project.
 import java.util.List;
 
 final class FlexUtil {
+
     private static final float EPSILON = 0.00001f;
 
+    private static final Float FLEX_GROW_INITIAL_VALUE = 0F;
+
+    private static final Float FLEX_SHRINK_INITIAL_VALUE = 1F;
+
     private FlexUtil() {
         // Do nothing
     }
@@ -73,11 +78,12 @@ private FlexUtil() {
      *
      * @param flexContainerBBox        bounding box in which flex container should be rendered
      * @param flexContainerRenderer    flex container's renderer
-     * @param flexItemCalculationInfos list of flex item descriptions
      * @return list of lines
      */
     public static List<List<FlexItemInfo>> calculateChildrenRectangles(Rectangle flexContainerBBox,
-            FlexContainerRenderer flexContainerRenderer, List<FlexItemCalculationInfo> flexItemCalculationInfos) {
+            FlexContainerRenderer flexContainerRenderer) {
+        final List<FlexItemCalculationInfo> flexItemCalculationInfos = createFlexItemCalculationInfos(
+                flexContainerRenderer, flexContainerBBox);
         Rectangle layoutBox = flexContainerBBox.clone();
         flexContainerRenderer.applyMarginsBordersPaddings(layoutBox, false);
 
@@ -503,6 +509,38 @@ static boolean isZero(final float value) {
         return Math.abs(value) < EPSILON;
     }
 
+    private static List<FlexItemCalculationInfo> createFlexItemCalculationInfos(
+            FlexContainerRenderer flexContainerRenderer, Rectangle flexContainerBBox) {
+        final List<IRenderer> childRenderers = flexContainerRenderer.getChildRenderers();
+        final List<FlexItemCalculationInfo> flexItems = new ArrayList<>();
+        for (final IRenderer renderer : childRenderers) {
+            if (renderer instanceof AbstractRenderer) {
+                Float flexGrow = renderer.<Float>getProperty(Property.FLEX_GROW);
+                if (flexGrow == null) {
+                    flexGrow = FLEX_GROW_INITIAL_VALUE;
+                }
+                Float flexShrink = renderer.<Float>getProperty(Property.FLEX_SHRINK);
+                if (flexShrink == null) {
+                    flexShrink = FLEX_SHRINK_INITIAL_VALUE;
+                }
+
+                UnitValue flexBasis = renderer.<UnitValue>getProperty(Property.FLEX_BASIS);
+                if (flexBasis == null) {
+                    // TODO DEVSIX-5091 improve determining of the flex base size when flex-basis: content
+                    flexBasis = UnitValue.createPointValue(
+                            ((AbstractRenderer) renderer).getMinMaxWidth().getMaxWidth());
+                }
+
+                final FlexItemCalculationInfo flexItemInfo = new FlexItemCalculationInfo(
+                        (AbstractRenderer) renderer, flexBasis, (float) flexGrow, (float) flexShrink,
+                        flexContainerBBox.getWidth());
+
+                flexItems.add(flexItemInfo);
+            }
+        }
+        return flexItems;
+    }
+
     static class FlexItemCalculationInfo {
         AbstractRenderer renderer;
         UnitValue flexBasis;
@@ -524,8 +562,8 @@ static class FlexItemCalculationInfo {
         float hypotheticalMainSize;
         float hypotheticalCrossSize;
 
-        public FlexItemCalculationInfo(AbstractRenderer renderer, UnitValue flexBasis, float flexGrow, float flexShrink,
-                float areaWidth) {
+        public FlexItemCalculationInfo(AbstractRenderer renderer, UnitValue flexBasis,
+                float flexGrow, float flexShrink, float areaWidth) {
             this.renderer = renderer;
             if (null == flexBasis) {
                 throw new IllegalArgumentException(LayoutExceptionMessageConstant.FLEX_BASIS_CANNOT_BE_NULL);