Add tests for absolutely positioned elements added to Canvas

DEVSIX-4835

(cherry picked from commit 54b0b000fdffec55012fed10dc775ca1e362601f)

Autoported commit.
Original commit hash: [0784a4e78]

Author: Kate Ivanova

itext.tests/itext.layout.tests/itext/layout/CanvasTest.cs

@@ -145,5 +145,69 @@ public virtual void CanvasWithPageEnableTaggingTest02() {
             pdf.Close();
             NUnit.Framework.Assert.IsNull(new CompareTool().CompareByContent(@out, cmp, destinationFolder));
         }
+
+        [NUnit.Framework.Test]
+        public virtual void ElementWithAbsolutePositioningInCanvasTest() {
+            String testName = "elementWithAbsolutePositioningInCanvas";
+            String @out = destinationFolder + testName + ".pdf";
+            String cmp = sourceFolder + "cmp_" + testName + ".pdf";
+            using (PdfDocument pdf = new PdfDocument(new PdfWriter(@out))) {
+                pdf.AddNewPage();
+                iText.Layout.Canvas canvas = new iText.Layout.Canvas(new PdfCanvas(pdf.GetFirstPage()), new Rectangle(120, 
+                    650, 60, 80));
+                Div notFittingDiv = new Div().SetWidth(100).Add(new Paragraph("Paragraph in Div with Not set position"));
+                canvas.Add(notFittingDiv);
+                Div divWithPosition = new Div().SetFixedPosition(120, 300, 80);
+                divWithPosition.Add(new Paragraph("Paragraph in Div with set position"));
+                canvas.Add(divWithPosition);
+                canvas.Close();
+            }
+            NUnit.Framework.Assert.IsNull(new CompareTool().CompareByContent(@out, cmp, destinationFolder));
+        }
+
+        [NUnit.Framework.Test]
+        //TODO: DEVSIX-4820 (discuss the displaying of element with absolute position)
+        [LogMessage(iText.IO.LogMessageConstant.CANVAS_ALREADY_FULL_ELEMENT_WILL_BE_SKIPPED)]
+        public virtual void ParentElemWithAbsolPositionKidNotSuitCanvasTest() {
+            String testName = "parentElemWithAbsolPositionKidNotSuitCanvas";
+            String @out = destinationFolder + testName + ".pdf";
+            String cmp = sourceFolder + "cmp_" + testName + ".pdf";
+            using (PdfDocument pdf = new PdfDocument(new PdfWriter(@out))) {
+                pdf.AddNewPage();
+                iText.Layout.Canvas canvas = new iText.Layout.Canvas(new PdfCanvas(pdf.GetFirstPage()), new Rectangle(120, 
+                    650, 55, 80));
+                Div notFittingDiv = new Div().SetWidth(100).Add(new Paragraph("Paragraph in Div with Not set position"));
+                canvas.Add(notFittingDiv);
+                Div divWithPosition = new Div().SetFixedPosition(120, 300, 80);
+                divWithPosition.Add(new Paragraph("Paragraph in Div with set position"));
+                canvas.Add(divWithPosition);
+                canvas.Close();
+            }
+            NUnit.Framework.Assert.IsNull(new CompareTool().CompareByContent(@out, cmp, destinationFolder));
+        }
+
+        [NUnit.Framework.Test]
+        public virtual void NestedElementWithAbsolutePositioningInCanvasTest() {
+            NUnit.Framework.Assert.That(() =>  {
+                //TODO: DEVSIX-4820 (NullPointerException on processing absolutely positioned elements in small canvas area)
+                String testName = "nestedElementWithAbsolutePositioningInCanvas";
+                String @out = destinationFolder + testName + ".pdf";
+                String cmp = sourceFolder + "cmp_" + testName + ".pdf";
+                using (PdfDocument pdf = new PdfDocument(new PdfWriter(@out))) {
+                    pdf.AddNewPage();
+                    iText.Layout.Canvas canvas = new iText.Layout.Canvas(new PdfCanvas(pdf.GetFirstPage()), new Rectangle(120, 
+                        650, 55, 80));
+                    Div notFittingDiv = new Div().SetWidth(100).Add(new Paragraph("Paragraph in Div with Not set position"));
+                    Div divWithPosition = new Div().SetFixedPosition(50, 20, 80);
+                    divWithPosition.Add(new Paragraph("Paragraph in Div with set position"));
+                    notFittingDiv.Add(divWithPosition);
+                    canvas.Add(notFittingDiv);
+                    canvas.Close();
+                }
+                NUnit.Framework.Assert.IsNull(new CompareTool().CompareByContent(@out, cmp, destinationFolder));
+            }
+            , NUnit.Framework.Throws.InstanceOf<NullReferenceException>())
+;
+        }
     }
 }

itext.tests/itext.layout.tests/resources/itext/layout/CanvasTest/cmp_elementWithAbsolutePositioningInCanvas.pdf

@@ -80,6 +80,8 @@ public sealed class LogMessageConstant {
 
         public const String CANNOT_RESOLVE_ROLE_TOO_MUCH_TRANSITIVE_MAPPINGS = "Cannot resolve \"{0}\" role mapping to standard role, because of the too much transitive mappings.";
 
+        public const String CANVAS_ALREADY_FULL_ELEMENT_WILL_BE_SKIPPED = "Canvas is already full. Element will be skipped.";
+
         public const String CHARACTER_DIRECTION_HAS_NOT_BEEN_DETECTED = "The direction for this character has not been detected: code point {0}. The Other Neutrals algorithm will be used.";
 
         public const String CLIP_ELEMENT = "Element content was clipped because some height properties are set.";

itext.tests/itext.layout.tests/resources/itext/layout/CanvasTest/cmp_parentElemWithAbsolPositionKidNotSuitCanvas.pdf

@@ -88,7 +88,7 @@ public CanvasRenderer(Canvas canvas, bool immediateFlush) {
 
         public override void AddChild(IRenderer renderer) {
             if (true.Equals(GetPropertyAsBoolean(Property.FULL))) {
-                LogManager.GetLogger(typeof(iText.Layout.Renderer.CanvasRenderer)).Warn("Canvas is already full. Element will be skipped."
+                LogManager.GetLogger(typeof(iText.Layout.Renderer.CanvasRenderer)).Warn(iText.IO.LogMessageConstant.CANVAS_ALREADY_FULL_ELEMENT_WILL_BE_SKIPPED
                     );
             }
             else {

itext/itext.io/itext/io/LogMessageConstant.cs

@@ -1 +1 @@
-86693c07db09b5d3691d2cc47d65878a5006b6f5
+0784a4e78069c3c2d5201e89284f30e6fb6257d1