Fix forms moved while flattening on a rotated page

Default appearances for fields with no AP dictionary
were generated incorrectly, causing them to appear moved when flattening.
Additionally, fields only took page rotation
into account and not their own.
Fix by properly calculating transformation matrix during
default appearance generation.

SUP-1555, DEVSIX-832

Author: Samuel Huylebroeck

forms/src/main/java/com/itextpdf/forms/fields/PdfFormField.java

@@ -58,6 +58,8 @@ This file is part of the iText (R) project.
 import com.itextpdf.kernel.color.DeviceRgb;
 import com.itextpdf.kernel.font.PdfFont;
 import com.itextpdf.kernel.font.PdfFontFactory;
+import com.itextpdf.kernel.geom.AffineTransform;
+import com.itextpdf.kernel.geom.Matrix;
 import com.itextpdf.kernel.geom.Rectangle;
 import com.itextpdf.kernel.pdf.*;
 import com.itextpdf.kernel.pdf.action.PdfAction;
@@ -1654,8 +1656,10 @@ public PdfFormField setRotation(int degRotation) {
         PdfDictionary mk = getWidgets().get(0).getAppearanceCharacteristics();
         if (mk == null) {
             mk = new PdfDictionary();
+            this.put(PdfName.MK,mk);
         }
         mk.put(PdfName.R, new PdfNumber(degRotation));
+
         this.rotation = degRotation;
         regenerateField();
         return this;
@@ -1761,17 +1765,74 @@ public boolean regenerateField() {
                     fontSize = (float)DEFAULT_FONT_SIZE;
                 }
 
-                int rotation = 0;
+                //Apply Page rotation, clockwise
+                int pageRotation = 0;
                 if (page != null) {
-                    rotation = page.getRotation();
+                    pageRotation = page.getRotation();
                 }
                 PdfArray matrix = null;
-                if (rotation != 0 && rotation % 90 == 0) {
-                    double angle = Math.PI * rotation / 180;
-                    matrix = new PdfArray(new double[]{Math.cos(angle), Math.sin(angle), -Math.sin(angle), Math.cos(angle), 0, 0});
+                if (pageRotation % 90 == 0) {
+                    //Cast angle to [0, 360]
+                    double angle = pageRotation%360;
+                    //Get angle in radians
+                    angle = Math.PI * angle / 180;
+                    //Calculate origin offset
+                    double translationWidth = 0;
+                    double translationHeight = 0;
+                    if(angle >= Math.PI/2 && angle <= Math.PI){
+                        translationWidth = bBox.toRectangle().getWidth();
+                    }
+                    if(angle >= Math.PI){
+                        translationHeight = bBox.toRectangle().getHeight();
+                    }
+                    //Store rotation and translation in the matrix
+                    matrix = new PdfArray(new double[]{Math.cos(angle), Math.sin(angle), -Math.sin(angle), Math.cos(angle),translationWidth, translationHeight});
                     Rectangle rect = bBox.toRectangle();
-                    rect.setWidth(bBox.toRectangle().getHeight());
-                    rect.setHeight(bBox.toRectangle().getWidth());
+                    //If the angle is 90 or 270, height and width of the bounding box need to be switched
+                    if(angle == Math.PI/2 || angle == 3*Math.PI/2){
+                        rect.setWidth(bBox.toRectangle().getHeight());
+                        rect.setHeight(bBox.toRectangle().getWidth());
+                    }
+                    //Copy Bounding box
+                    bBox = new PdfArray(rect);
+                }
+                //Apply field rotation
+                float rotation = 0;
+                if(this.getPdfObject().getAsDictionary(PdfName.MK)!= null
+                        && this.getPdfObject().getAsDictionary(PdfName.MK).get(PdfName.R) != null){
+                    rotation = this.getPdfObject().getAsDictionary(PdfName.MK).getAsFloat(PdfName.R);
+                }
+                //rotation = this.rotation;
+                //Field rotation is specified as counterclockwise
+                //rotation *=-1;
+                if (rotation % 90 == 0) {
+                    //Cast angle to [0, 360]
+                    double angle = rotation%360;
+                    //Get angle in radians
+                    angle = Math.PI * angle / 180;
+                    //Calculate origin offset
+                    double translationWidth = 0;
+                    double translationHeight = 0;
+                    if(angle >= Math.PI/2 && angle <= Math.PI){
+                        translationWidth = bBox.toRectangle().getWidth();
+                    }
+                    if(angle >= Math.PI){
+                        translationHeight = bBox.toRectangle().getHeight();
+                    }
+                    //Concatenate rotation and translation into the matrix
+                    Matrix currentMatrix = new Matrix(matrix.getAsNumber(0).floatValue(),matrix.getAsNumber(1).floatValue(),matrix.getAsNumber(2).floatValue(),matrix.getAsNumber(3).floatValue(),matrix.getAsNumber(4).floatValue(),matrix.getAsNumber(5).floatValue());
+                    Matrix toConcatenate = new Matrix((float)Math.cos(angle), (float)Math.sin(angle),(float) (-Math.sin(angle)), (float)(Math.cos(angle)),(float)translationWidth, (float)translationHeight);
+                    currentMatrix = currentMatrix.multiply(toConcatenate);
+
+                    matrix = new PdfArray(new float[]{currentMatrix.get(0), currentMatrix.get(1), currentMatrix.get(3), currentMatrix.get(4),currentMatrix.get(6), currentMatrix.get(7)});
+
+                    Rectangle rect = bBox.toRectangle();
+                    //If the angle is 90 or 270, height and width of the bounding box need to be switched
+                    if(angle == Math.PI/2 || angle == 3*Math.PI/2){
+                        rect.setWidth(bBox.toRectangle().getHeight());
+                        rect.setHeight(bBox.toRectangle().getWidth());
+                    }
+                    //Copy Bounding box
                     bBox = new PdfArray(rect);
                 }
 

forms/src/test/java/com/itextpdf/forms/FormFieldFlatteningTest.java

@@ -1,5 +1,6 @@
 package com.itextpdf.forms;
 
+import com.itextpdf.forms.fields.PdfFormField;
 import com.itextpdf.kernel.pdf.PdfDocument;
 import com.itextpdf.kernel.pdf.PdfReader;
 import com.itextpdf.kernel.pdf.PdfWriter;
@@ -42,4 +43,116 @@ public void formFlatteningTest01() throws IOException, InterruptedException {
             Assert.fail(errorMessage);
         }
     }
+
+    @Test
+    public void formFlatteningTest_DefaultAppearanceGeneration_Rot0() throws IOException, InterruptedException {
+        String srcFilePattern = "FormFlatteningDefaultAppearance_0.0_";
+        String destPattern = "FormFlatteningDefaultAppearance_0.0_";
+
+        for(float i = 0; i<360;i+=90){
+            String src = sourceFolder + srcFilePattern + i+".pdf";
+            String dest = destinationFolder + destPattern + i +"_flattened.pdf";
+            String cmp = sourceFolder + "cmp_" + srcFilePattern + i + ".pdf";
+            PdfDocument doc = new PdfDocument(new PdfReader(src), new PdfWriter(dest));
+
+            PdfAcroForm form = PdfAcroForm.getAcroForm(doc, true);
+            for(PdfFormField field: form.getFormFields().values()){
+                field.setValue("Test");
+            }
+            form.flattenFields();
+
+            doc.close();
+
+            CompareTool compareTool = new CompareTool();
+            String errorMessage = compareTool.compareByContent(dest, cmp, destinationFolder, "diff_");
+            if (errorMessage != null) {
+                Assert.fail(errorMessage);
+            }
+        }
+
+    }
+
+    @Test
+    public void formFlatteningTest_DefaultAppearanceGeneration_Rot90() throws IOException, InterruptedException {
+        String srcFilePattern = "FormFlatteningDefaultAppearance_90.0_";
+        String destPattern = "FormFlatteningDefaultAppearance_90.0_";
+
+        for(float i = 0; i<360;i+=90){
+            String src = sourceFolder + srcFilePattern + i+".pdf";
+            String dest = destinationFolder + destPattern + i +"_flattened.pdf";
+            String cmp = sourceFolder + "cmp_" + srcFilePattern + i + ".pdf";
+            PdfDocument doc = new PdfDocument(new PdfReader(src), new PdfWriter(dest));
+
+            PdfAcroForm form = PdfAcroForm.getAcroForm(doc, true);
+            for(PdfFormField field: form.getFormFields().values()){
+                field.setValue("Test");
+            }
+            form.flattenFields();
+
+            doc.close();
+
+            CompareTool compareTool = new CompareTool();
+            String errorMessage = compareTool.compareByContent(dest, cmp, destinationFolder, "diff_");
+            if (errorMessage != null) {
+                Assert.fail(errorMessage);
+            }
+        }
+
+    }
+
+    @Test
+    public void formFlatteningTest_DefaultAppearanceGeneration_Rot180() throws IOException, InterruptedException {
+        String srcFilePattern = "FormFlatteningDefaultAppearance_180.0_";
+        String destPattern = "FormFlatteningDefaultAppearance_180.0_";
+
+        for(float i = 0; i<360;i+=90){
+            String src = sourceFolder + srcFilePattern + i+".pdf";
+            String dest = destinationFolder + destPattern + i +"_flattened.pdf";
+            String cmp = sourceFolder + "cmp_" + srcFilePattern + i + ".pdf";
+            PdfDocument doc = new PdfDocument(new PdfReader(src), new PdfWriter(dest));
+
+            PdfAcroForm form = PdfAcroForm.getAcroForm(doc, true);
+            for(PdfFormField field: form.getFormFields().values()){
+                field.setValue("Test");
+            }
+            form.flattenFields();
+
+            doc.close();
+
+            CompareTool compareTool = new CompareTool();
+            String errorMessage = compareTool.compareByContent(dest, cmp, destinationFolder, "diff_");
+            if (errorMessage != null) {
+                Assert.fail(errorMessage);
+            }
+        }
+
+    }
+
+    @Test
+    public void formFlatteningTest_DefaultAppearanceGeneration_Rot270() throws IOException, InterruptedException {
+        String srcFilePattern = "FormFlatteningDefaultAppearance_270.0_";
+        String destPattern = "FormFlatteningDefaultAppearance_270.0_";
+
+        for(float i = 0; i<360;i+=90){
+            String src = sourceFolder + srcFilePattern + i+".pdf";
+            String dest = destinationFolder + destPattern + i +"_flattened.pdf";
+            String cmp = sourceFolder + "cmp_" + srcFilePattern + i + ".pdf";
+            PdfDocument doc = new PdfDocument(new PdfReader(src), new PdfWriter(dest));
+
+            PdfAcroForm form = PdfAcroForm.getAcroForm(doc, true);
+            for(PdfFormField field: form.getFormFields().values()){
+                field.setValue("Test");
+            }
+            form.flattenFields();
+
+            doc.close();
+
+            CompareTool compareTool = new CompareTool();
+            String errorMessage = compareTool.compareByContent(dest, cmp, destinationFolder, "diff_");
+            if (errorMessage != null) {
+                Assert.fail(errorMessage);
+            }
+        }
+
+    }
 }