Changes to make the lazy reader work on the PaperCut corpus (#194)

contentstream/encoding.go

@@ -88,7 +88,7 @@ func newFlateEncoderFromInlineImage(inlineImage *ContentStreamInlineImage, decod
 	if decodeParams == nil {
 		obj := inlineImage.DecodeParms
 		if obj != nil {
-			dp, isDict := obj.(*core.PdfObjectDictionary)
+			dp, isDict := core.GetDict(obj)
 			if !isDict {
 				common.Log.Debug("Error: DecodeParms not a dictionary (%T)", obj)
 				return nil, fmt.Errorf("invalid DecodeParms")
@@ -163,7 +163,7 @@ func newLZWEncoderFromInlineImage(inlineImage *ContentStreamInlineImage, decodeP
 	// If decodeParams not provided, see if we can get from the inline image directly.
 	if decodeParams == nil {
 		if inlineImage.DecodeParms != nil {
-			dp, isDict := inlineImage.DecodeParms.(*core.PdfObjectDictionary)
+			dp, isDict := core.GetDict(inlineImage.DecodeParms)
 			if !isDict {
 				common.Log.Debug("Error: DecodeParms not a dictionary (%T)", inlineImage.DecodeParms)
 				return nil, fmt.Errorf("invalid DecodeParms")

contentstream/inline-image.go

@@ -316,7 +316,7 @@ func (csp *ContentStreamParser) ParseInlineImage() (*ContentStreamInlineImage, e
 
 		if !isOperand {
 			// Not an operand.. Read key value properties..
-			param, ok := obj.(*core.PdfObjectName)
+			param, ok := core.GetName(obj)
 			if !ok {
 				common.Log.Debug("Invalid inline image property (expecting name) - %T", obj)
 				return nil, fmt.Errorf("invalid inline image property (expecting name) - %T", obj)

contentstream/processor.go

@@ -7,6 +7,7 @@ package contentstream
 
 import (
 	"errors"
+	"fmt"
 
 	"github.com/unidoc/unipdf/v3/common"
 	"github.com/unidoc/unipdf/v3/core"
@@ -141,7 +142,7 @@ func (proc *ContentStreamProcessor) getColorspace(name string, resources *model.
 
 	// Otherwise unsupported.
 	common.Log.Debug("Unknown colorspace requested: %s", name)
-	return nil, errors.New("unsupported colorspace")
+	return nil, fmt.Errorf("unsupported colorspace: %s", name)
 }
 
 // Get initial color for a given colorspace.

core/encoding.go

@@ -443,7 +443,7 @@ func (enc *FlateEncoder) EncodeBytes(data []byte) ([]byte, error) {
 		rowLength := int(enc.Columns)
 		rows := len(data) / rowLength
 		if len(data)%rowLength != 0 {
-			common.Log.Error("Invalid column length")
+			common.Log.Error("Invalid row length")
 			return nil, errors.New("invalid row length")
 		}
 
@@ -590,7 +590,7 @@ func newLZWEncoderFromStream(streamObj *PdfObjectStream, decodeParams *PdfObject
 
 	// If decodeParams not provided, see if we can get from the stream.
 	if decodeParams == nil {
-		obj := encDict.Get("DecodeParms")
+		obj := TraceToDirectObject(encDict.Get("DecodeParms"))
 		if obj != nil {
 			if dp, isDict := obj.(*PdfObjectDictionary); isDict {
 				decodeParams = dp
@@ -1751,7 +1751,7 @@ func newCCITTFaxEncoderFromStream(streamObj *PdfObjectStream, decodeParams *PdfO
 
 	// If decodeParams not provided, see if we can get from the stream.
 	if decodeParams == nil {
-		obj := encDict.Get("DecodeParms")
+		obj := TraceToDirectObject(encDict.Get("DecodeParms"))
 		if obj != nil {
 			switch t := obj.(type) {
 			case *PdfObjectDictionary:
@@ -2061,7 +2061,7 @@ func newJBIG2EncoderFromStream(streamObj *PdfObjectStream, decodeParams *PdfObje
 
 	if decodeParams != nil {
 		if globals := decodeParams.Get("JBIG2Globals"); globals != nil {
-			globalsStream, ok := globals.(*PdfObjectStream)
+			globalsStream, ok := GetStream(globals)
 			if !ok {
 				err := errors.New("the Globals stream should be an Object Stream")
 				common.Log.Debug("ERROR: %s", err.Error())

core/symbols.go

@@ -22,52 +22,26 @@ func IsFloatDigit(c byte) bool {
 
 // IsDecimalDigit checks if the character is a part of a decimal number string.
 func IsDecimalDigit(c byte) bool {
-	if c >= '0' && c <= '9' {
-		return true
-	}
-
-	return false
+	return '0' <= c && c <= '9'
 }
 
 // IsOctalDigit checks if a character can be part of an octal digit string.
 func IsOctalDigit(c byte) bool {
-	if c >= '0' && c <= '7' {
-		return true
-	}
-
-	return false
+	return '0' <= c && c <= '7'
 }
 
 // IsPrintable checks if a character is printable.
 // Regular characters that are outside the range EXCLAMATION MARK(21h)
 // (!) to TILDE (7Eh) (~) should be written using the hexadecimal notation.
-func IsPrintable(char byte) bool {
-	if char < 0x21 || char > 0x7E {
-		return false
-	}
-	return true
+func IsPrintable(c byte) bool {
+	return 0x21 <= c && c <= 0x7E
 }
 
 // IsDelimiter checks if a character represents a delimiter.
-func IsDelimiter(char byte) bool {
-	if char == '(' || char == ')' {
-		return true
-	}
-	if char == '<' || char == '>' {
-		return true
-	}
-	if char == '[' || char == ']' {
-		return true
-	}
-	if char == '{' || char == '}' {
-		return true
-	}
-	if char == '/' {
-		return true
-	}
-	if char == '%' {
-		return true
-	}
-
-	return false
+func IsDelimiter(c byte) bool {
+	return c == '(' || c == ')' ||
+		c == '<' || c == '>' ||
+		c == '[' || c == ']' ||
+		c == '{' || c == '}' ||
+		c == '/' || c == '%'
 }

model/page.go

@@ -905,7 +905,7 @@ func newPdfPageResourcesColorspacesFromPdfObject(obj core.PdfObject) (*PdfPageRe
 		obj = indObj.PdfObject
 	}
 
-	dict, ok := obj.(*core.PdfObjectDictionary)
+	dict, ok := core.GetDict(obj)
 	if !ok {
 		return nil, errors.New("CS attribute type error")
 	}

model/pattern.go

@@ -162,7 +162,7 @@ func newPdfPatternFromPdfObject(container core.PdfObject) (*PdfPattern, error) {
 	pattern := &PdfPattern{}
 
 	var dict *core.PdfObjectDictionary
-	if indObj, is := container.(*core.PdfIndirectObject); is {
+	if indObj, is := core.GetIndirect(container); is {
 		pattern.container = indObj
 		d, ok := indObj.PdfObject.(*core.PdfObjectDictionary)
 		if !ok {
@@ -170,11 +170,11 @@ func newPdfPatternFromPdfObject(container core.PdfObject) (*PdfPattern, error) {
 			return nil, core.ErrTypeError
 		}
 		dict = d
-	} else if streamObj, is := container.(*core.PdfObjectStream); is {
+	} else if streamObj, is := core.GetStream(container); is {
 		pattern.container = streamObj
 		dict = streamObj.PdfObjectDictionary
 	} else {
-		common.Log.Debug("Pattern not an indirect object or stream")
+		common.Log.Debug("Pattern not an indirect object or stream. %T", container)
 		return nil, core.ErrTypeError
 	}
 

model/resources.go

@@ -335,11 +335,7 @@ func (r *PdfPageResources) SetColorspaceByName(keyName core.PdfObjectName, cs Pd
 // HasXObjectByName checks if an XObject with a specified keyName is defined.
 func (r *PdfPageResources) HasXObjectByName(keyName core.PdfObjectName) bool {
 	obj, _ := r.GetXObjectByName(keyName)
-	if obj != nil {
-		return true
-	}
-
-	return false
+	return obj != nil
 }
 
 // GenerateXObjectName generates an unused XObject name that can be used for
@@ -362,10 +358,10 @@ type XObjectType int
 // XObject types.
 const (
 	XObjectTypeUndefined XObjectType = iota
-	XObjectTypeImage     XObjectType = iota
-	XObjectTypeForm      XObjectType = iota
-	XObjectTypePS        XObjectType = iota
-	XObjectTypeUnknown   XObjectType = iota
+	XObjectTypeImage
+	XObjectTypeForm
+	XObjectTypePS
+	XObjectTypeUnknown
 )
 
 // GetXObjectByName returns the XObject with the specified keyName and the object type.

model/shading.go

@@ -141,7 +141,7 @@ func newPdfShadingFromPdfObject(obj core.PdfObject) (*PdfShading, error) {
 	shading := &PdfShading{}
 
 	var dict *core.PdfObjectDictionary
-	if indObj, isInd := obj.(*core.PdfIndirectObject); isInd {
+	if indObj, isInd := core.GetIndirect(obj); isInd {
 		shading.container = indObj
 
 		d, ok := indObj.PdfObject.(*core.PdfObjectDictionary)
@@ -151,10 +151,10 @@ func newPdfShadingFromPdfObject(obj core.PdfObject) (*PdfShading, error) {
 		}
 
 		dict = d
-	} else if streamObj, isStream := obj.(*core.PdfObjectStream); isStream {
+	} else if streamObj, isStream := core.GetStream(obj); isStream {
 		shading.container = streamObj
 		dict = streamObj.PdfObjectDictionary
-	} else if d, isDict := obj.(*core.PdfObjectDictionary); isDict {
+	} else if d, isDict := core.GetDict(obj); isDict {
 		shading.container = d
 		dict = d
 	} else {