Combo field appearance (unidoc#370)

* Fix combo field appearances not being shown * Fix V object type for choice and button fields * Refactor form fill for combo and checkbox fields * Add fill test case for text, combo and checkbox fields * Prevent panic when flattening forms using a nil appearance generator
oliverpool · Jun 10, 2020 · 99ef1b8 · 99ef1b8
1 parent 6cb58f6
commit 99ef1b8
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Showing 6 changed files with 182 additions and 23 deletions.
diff --git a/annotator/field_appearance.go b/annotator/field_appearance.go
@@ -821,18 +821,21 @@ func genFieldComboboxAppearance(form *model.PdfAcroForm, wa *model.PdfAnnotation
 		}
 	}
 
+	// See section 12.7.4.4 "Choice Fields" (pp. 444-446 PDF32000_2008).
 	dchoiceapp := core.MakeDict()
 	for _, optObj := range fch.Opt.Elements() {
+		if optArr, ok := core.GetArray(optObj); ok && optArr.Len() == 2 {
+			optObj = optArr.Get(1)
+		}
+
 		var optstr string
 		if opt, ok := core.GetString(optObj); ok {
+			optstr = opt.Decoded()
+		} else if opt, ok := core.GetName(optObj); ok {
 			optstr = opt.String()
 		} else {
-			if opt, ok := core.GetName(optObj); ok {
-				optstr = opt.String()
-			} else {
-				common.Log.Debug("ERROR: Opt not a name/string - %T", optObj)
-				return nil, errors.New("not a name/string")
-			}
+			common.Log.Debug("ERROR: Opt not a name/string - %T", optObj)
+			return nil, errors.New("not a name/string")
 		}
 
 		if len(optstr) > 0 {

diff --git a/fjson/fielddata_test.go b/fjson/fielddata_test.go
@@ -148,6 +148,7 @@ func TestJSONExtractAndFill(t *testing.T) {
 	fieldDataExp, err := LoadFromJSONFile("./testdata/advancedform.json")
 	require.NoError(t, err)
 	jsonDataExp, err := fieldDataExp.JSON()
+	require.NoError(t, err)
 
 	// Check templates for equality.
 	require.Equal(t, jsonDataExp, jsonData)
@@ -184,6 +185,7 @@ func TestJSONExtractAndFill(t *testing.T) {
 	fieldDataExp, err = LoadFromJSON(bytes.NewReader(jsonBytes))
 	require.NoError(t, err)
 	jsonDataExp, err = fieldDataExp.JSON()
+	require.NoError(t, err)
 
 	// Fill test PDF form fields and write to buffer.
 	f, err := os.Open(inputFilePath)
@@ -212,6 +214,47 @@ func TestJSONExtractAndFill(t *testing.T) {
 	fieldData, err = LoadFromPDF(bytes.NewReader(buf.Bytes()))
 	require.NoError(t, err)
 	jsonData, err = fieldData.JSON()
+	require.NoError(t, err)
+
+	// Check field data for equality.
+	require.Equal(t, jsonDataExp, jsonData)
+}
+
+func TestJSONFillAndExtract(t *testing.T) {
+	// Read JSON fill data.
+	fieldDataExp, err := LoadFromJSONFile("./testdata/mixedfields.json")
+	require.NoError(t, err)
+	jsonDataExp, err := fieldDataExp.JSON()
+	require.NoError(t, err)
+
+	// Fill test PDF form fields and write to buffer.
+	f, err := os.Open("./testdata/mixedfields.pdf")
+	require.NoError(t, err)
+	defer f.Close()
+
+	reader, err := model.NewPdfReader(f)
+	require.NoError(t, err)
+
+	err = reader.AcroForm.Fill(fieldDataExp)
+	require.NoError(t, err)
+
+	var buf bytes.Buffer
+	writer := model.NewPdfWriter()
+	for i := range reader.PageList {
+		err := writer.AddPage(reader.PageList[i])
+		require.NoError(t, err)
+	}
+
+	err = writer.SetForms(reader.AcroForm)
+	require.NoError(t, err)
+	err = writer.Write(&buf)
+	require.NoError(t, err)
+
+	// Load field data from buffer.
+	fieldData, err := LoadFromPDF(bytes.NewReader(buf.Bytes()))
+	require.NoError(t, err)
+	jsonData, err := fieldData.JSON()
+	require.NoError(t, err)
 
 	// Check field data for equality.
 	require.Equal(t, jsonDataExp, jsonData)

diff --git a/fjson/testdata/mixedfields.json b/fjson/testdata/mixedfields.json
@@ -0,0 +1,94 @@
+[
+    {
+        "name": "Given Name Text Box",
+        "value": "Jane"
+    },
+    {
+        "name": "Family Name Text Box",
+        "value": "Doe"
+    },
+    {
+        "name": "House nr Text Box",
+        "value": "100"
+    },
+    {
+        "name": "Address 2 Text Box",
+        "value": "Generic Avenue"
+    },
+    {
+        "name": "Postcode Text Box",
+        "value": "11122"
+    },
+    {
+        "name": "Country Combo Box",
+        "value": "France"
+    },
+    {
+        "name": "Height Formatted Field",
+        "value": "175"
+    },
+    {
+        "name": "City Text Box",
+        "value": "Paris"
+    },
+    {
+        "name": "Driving License Check Box",
+        "value": "Yes",
+        "options": [
+            "Yes",
+            "Off"
+        ]
+    },
+    {
+        "name": "Favourite Colour List Box",
+        "value": "Yellow"
+    },
+    {
+        "name": "Language 1 Check Box",
+        "value": "Yes",
+        "options": [
+            "Yes",
+            "Off"
+        ]
+    },
+    {
+        "name": "Language 2 Check Box",
+        "value": "Off",
+        "options": [
+            "Yes",
+            "Off"
+        ]
+    },
+    {
+        "name": "Language 3 Check Box",
+        "value": "Yes",
+        "options": [
+            "Yes",
+            "Off"
+        ]
+    },
+    {
+        "name": "Language 4 Check Box",
+        "value": "Off",
+        "options": [
+            "Yes",
+            "Off"
+        ]
+    },
+    {
+        "name": "Language 5 Check Box",
+        "value": "Yes",
+        "options": [
+            "Yes",
+            "Off"
+        ]
+    },
+    {
+        "name": "Gender List Box",
+        "value": "Woman"
+    },
+    {
+        "name": "Address 1 Text Box",
+        "value": "Generic Street"
+    }
+]
diff --git a/fjson/testdata/mixedfields.pdf b/fjson/testdata/mixedfields.pdf
diff --git a/model/flatten.go b/model/flatten.go
@@ -85,9 +85,10 @@ func (r *PdfReader) FlattenFields(allannots bool, appgen FieldAppearanceGenerato
 		var annots []*PdfAnnotation
 
 		// Wrap the content streams.
-		err := appgen.WrapContentStream(page)
-		if err != nil {
-			return err
+		if appgen != nil {
+			if err := appgen.WrapContentStream(page); err != nil {
+				return err
+			}
 		}
 
 		annotations, err := page.GetAnnotations()

diff --git a/model/form.go b/model/form.go
@@ -317,26 +317,36 @@ func fillFieldValue(f *PdfField, val core.PdfObject) error {
 		default:
 			common.Log.Debug("ERROR: Unsupported text field V type: %T (%#v)", t, t)
 		}
-	case *PdfFieldButton, *PdfFieldChoice:
-		switch t := val.(type) {
+	case *PdfFieldButton:
+		// See section 12.7.4.2.3 "Check Boxes" (pp. 440-441 PDF32000_2008).
+		switch val.(type) {
 		case *core.PdfObjectName:
-			if len(t.String()) == 0 {
-				return nil
+			if len(val.String()) > 0 {
+				f.V = val
+				setFieldAnnotAS(f, val)
 			}
-			for _, wa := range f.Annotations {
-				wa.AS = val
+		case *core.PdfObjectString:
+			if len(val.String()) > 0 {
+				f.V = core.MakeName(val.String())
+				setFieldAnnotAS(f, f.V)
 			}
+		default:
+			common.Log.Debug("ERROR: UNEXPECTED %s -> %v", f.PartialName(), val)
 			f.V = val
-		case *core.PdfObjectString:
-			if len(t.String()) == 0 {
-				return nil
+		}
+	case *PdfFieldChoice:
+		// See section 12.7.4.4 "Choice Fields" (pp. 444-446 PDF32000_2008).
+		switch val.(type) {
+		case *core.PdfObjectName:
+			if len(val.String()) > 0 {
+				f.V = core.MakeString(val.String())
+				setFieldAnnotAS(f, val)
 			}
-			common.Log.Debug("Unexpected string for button/choice field. Converting to name: '%s'", t.String())
-			name := core.MakeName(t.String())
-			for _, wa := range f.Annotations {
-				wa.AS = name
+		case *core.PdfObjectString:
+			if len(val.String()) > 0 {
+				f.V = val
+				setFieldAnnotAS(f, core.MakeName(val.String()))
 			}
-			f.V = name
 		default:
 			common.Log.Debug("ERROR: UNEXPECTED %s -> %v", f.PartialName(), val)
 			f.V = val
@@ -347,3 +357,11 @@ func fillFieldValue(f *PdfField, val core.PdfObject) error {
 
 	return nil
 }
+
+// setFieldAnnotAS sets the appearance stream of the field annotations to `val`.
+func setFieldAnnotAS(f *PdfField, val core.PdfObject) {
+	for _, wa := range f.Annotations {
+		wa.AS = val
+		wa.ToPdfObject()
+	}
+}