From 967cba820d70ddbe7fb23fad616377fafa67bf06 Mon Sep 17 00:00:00 2001
From: RaphaelArnold <raphael.arnold@knecon.com>
Date: Wed, 19 Jul 2023 12:56:39 +0200
Subject: [PATCH] RED-7075: WIP

---
 .../pdftronlogic/commons/ElementFeatures.java | 61 +++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/src/main/java/com/iqser/red/pdftronlogic/commons/ElementFeatures.java b/src/main/java/com/iqser/red/pdftronlogic/commons/ElementFeatures.java
index 51be5ab..12e5733 100644
--- a/src/main/java/com/iqser/red/pdftronlogic/commons/ElementFeatures.java
+++ b/src/main/java/com/iqser/red/pdftronlogic/commons/ElementFeatures.java
@@ -58,6 +58,12 @@ public class ElementFeatures {
                     .componentNum(element.getComponentNum())
                     .bitsPerComponent(element.getBitsPerComponent())
                     .build();
+            case Element.e_form -> Form.builder()
+                    .elementType(element.getType())
+                    .boundingBox(Converter.toRectangle2D(element.getBBox()))
+                    .xObjectType(element.getXObject().getType())
+                    .dictOrArrayOrStreamLength(element.getXObject().getType() == 7 ? element.getXObject().getDecodedStream().size() : 0)
+                    .build();
             // This technically should never happen, it's a safetynet
             default -> throw new RuntimeException("Feature Extraction is not supported for PDFTron.Element with type: " + element.getType());
         };
@@ -71,6 +77,12 @@ public class ElementFeatures {
                 rectsAlmostMatch(element.getBBox());
     }
 
+    public boolean almostMatches(ElementFeatures elementFeatures){
+        return elementFeatures.getElementType() == elementType &&
+                elementFeatures.getBoundingBox() != null &&
+                rectsAlmostMatch(elementFeatures.getBoundingBox());
+    }
+
 
     protected boolean almostEqual(double a, double b) {
 
@@ -88,6 +100,16 @@ public class ElementFeatures {
                 almostEqual(bBox.getHeight(), boundingBox.getHeight());
     }
 
+    @SneakyThrows
+    private boolean rectsAlmostMatch(Rectangle2D bBox) {
+        // To address the inconsistencies in the calculation of the bounding box we check equality with a tolerance
+
+        return almostEqual(bBox.getX(), boundingBox.getX()) && //
+                almostEqual(bBox.getY(), boundingBox.getY()) && //
+                almostEqual(bBox.getWidth(), boundingBox.getWidth()) && //
+                almostEqual(bBox.getHeight(), boundingBox.getHeight());
+    }
+
 
     @EqualsAndHashCode(callSuper = true)
     @Getter
@@ -183,6 +205,45 @@ public class ElementFeatures {
 
     }
 
+    @EqualsAndHashCode(callSuper = true)
+    @Getter
+    @SuperBuilder
+    @FieldDefaults(makeFinal = true, level = AccessLevel.PRIVATE)
+    private static class Form extends ElementFeatures {
+
+        int xObjectType;
+        long dictOrArrayOrStreamLength;
+
+
+        @Override
+        public boolean almostMatches(Element element) throws PDFNetException {
+            return element.getType() == getElementType() && //
+                    element.getBBox() != null && //
+                    (super.rectsAlmostMatch(element.getBBox()) || almostRotateMatches(element.getBBox().getRectangle())) &&
+                    xObjectType == element.getXObject().getType() &&
+                    dictOrArrayOrStreamLength == element.getXObject().getDecodedStream().size();
+        }
+
+        public boolean almostMatches(ElementFeatures elementFeatures){
+            if(elementFeatures.getClass() != this.getClass()){
+                return false;
+            }
+            return elementFeatures.getElementType() == getElementType() &&
+                    elementFeatures.getBoundingBox() != null &&
+                    (super.rectsAlmostMatch(elementFeatures.getBoundingBox()) || almostRotateMatches(elementFeatures.getBoundingBox().getBounds2D())) &&
+                    xObjectType == ((Form)elementFeatures).getXObjectType() &&
+                    dictOrArrayOrStreamLength == ((Form)elementFeatures).getDictOrArrayOrStreamLength();
+
+        }
+
+
+        private boolean almostRotateMatches(Rectangle2D bBox) {
+            return almostEqual(bBox.getWidth(), getBoundingBox().getHeight()) && //
+                    almostEqual(bBox.getHeight(), getBoundingBox().getWidth());
+        }
+
+    }
+