forked from unidoc/unidoc
/
xobject.go
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/
xobject.go
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/*
* This file is subject to the terms and conditions defined in
* file 'LICENSE.md', which is part of this source code package.
*/
package model
import (
"errors"
"github.com/unidoc/unidoc/common"
. "github.com/unidoc/unidoc/pdf/core"
)
// XObjectForm (Table 95 in 8.10.2).
type XObjectForm struct {
Filter StreamEncoder
FormType PdfObject
BBox PdfObject
Matrix PdfObject
Resources *PdfPageResources
Group PdfObject
Ref PdfObject
MetaData PdfObject
PieceInfo PdfObject
LastModified PdfObject
StructParent PdfObject
StructParents PdfObject
OPI PdfObject
OC PdfObject
Name PdfObject
// Stream data.
Stream []byte
// Primitive
primitive *PdfObjectStream
}
var ErrTypeCheck = errors.New("Type check error")
// Create a brand new XObject Form. Creates a new underlying PDF object stream primitive.
func NewXObjectForm() *XObjectForm {
xobj := &XObjectForm{}
stream := &PdfObjectStream{}
stream.PdfObjectDictionary = MakeDict()
xobj.primitive = stream
return xobj
}
// Build the Form XObject from a stream object.
// XXX: Should this be exposed? Consider different access points.
func NewXObjectFormFromStream(stream *PdfObjectStream) (*XObjectForm, error) {
form := &XObjectForm{}
form.primitive = stream
dict := *(stream.PdfObjectDictionary)
encoder, err := NewEncoderFromStream(stream)
if err != nil {
return nil, err
}
form.Filter = encoder
if obj := dict.Get("Subtype"); obj != nil {
name, ok := obj.(*PdfObjectName)
if !ok {
return nil, errors.New("Type error")
}
if *name != "Form" {
common.Log.Debug("Invalid form subtype")
return nil, errors.New("Invalid form subtype")
}
}
if obj := dict.Get("FormType"); obj != nil {
form.FormType = obj
}
if obj := dict.Get("BBox"); obj != nil {
form.BBox = obj
}
if obj := dict.Get("Matrix"); obj != nil {
form.Matrix = obj
}
if obj := dict.Get("Resources"); obj != nil {
obj = TraceToDirectObject(obj)
d, ok := obj.(*PdfObjectDictionary)
if !ok {
common.Log.Debug("Invalid XObject Form Resources object, pointing to non-dictionary")
return nil, errors.New("Type check error")
}
res, err := NewPdfPageResourcesFromDict(d)
if err != nil {
common.Log.Debug("Failed getting form resources")
return nil, err
}
form.Resources = res
common.Log.Trace("Form resources: %#v", form.Resources)
}
form.Group = dict.Get("Group")
form.Ref = dict.Get("Ref")
form.MetaData = dict.Get("MetaData")
form.PieceInfo = dict.Get("PieceInfo")
form.LastModified = dict.Get("LastModified")
form.StructParent = dict.Get("StructParent")
form.StructParents = dict.Get("StructParents")
form.OPI = dict.Get("OPI")
form.OC = dict.Get("OC")
form.Name = dict.Get("Name")
form.Stream = stream.Stream
return form, nil
}
func (xform *XObjectForm) GetContainingPdfObject() PdfObject {
return xform.primitive
}
func (xform *XObjectForm) GetContentStream() ([]byte, error) {
decoded, err := DecodeStream(xform.primitive)
if err != nil {
return nil, err
}
return decoded, nil
}
// Update the content stream with specified encoding. If encoding is null, will use the xform.Filter object
// or Raw encoding if not set.
func (xform *XObjectForm) SetContentStream(content []byte, encoder StreamEncoder) error {
encoded := content
if encoder == nil {
if xform.Filter != nil {
encoder = xform.Filter
} else {
encoder = NewRawEncoder()
}
}
enc, err := encoder.EncodeBytes(encoded)
if err != nil {
return err
}
encoded = enc
xform.Stream = encoded
return nil
}
// Return a stream object.
func (xform *XObjectForm) ToPdfObject() PdfObject {
stream := xform.primitive
dict := stream.PdfObjectDictionary
if xform.Filter != nil {
// Pre-populate the stream dictionary with the encoding related fields.
dict = xform.Filter.MakeStreamDict()
stream.PdfObjectDictionary = dict
}
dict.Set("Type", MakeName("XObject"))
dict.Set("Subtype", MakeName("Form"))
dict.SetIfNotNil("FormType", xform.FormType)
dict.SetIfNotNil("BBox", xform.BBox)
dict.SetIfNotNil("Matrix", xform.Matrix)
if xform.Resources != nil {
dict.SetIfNotNil("Resources", xform.Resources.ToPdfObject())
}
dict.SetIfNotNil("Group", xform.Group)
dict.SetIfNotNil("Ref", xform.Ref)
dict.SetIfNotNil("MetaData", xform.MetaData)
dict.SetIfNotNil("PieceInfo", xform.PieceInfo)
dict.SetIfNotNil("LastModified", xform.LastModified)
dict.SetIfNotNil("StructParent", xform.StructParent)
dict.SetIfNotNil("StructParents", xform.StructParents)
dict.SetIfNotNil("OPI", xform.OPI)
dict.SetIfNotNil("OC", xform.OC)
dict.SetIfNotNil("Name", xform.Name)
dict.Set("Length", MakeInteger(int64(len(xform.Stream))))
stream.Stream = xform.Stream
return stream
}
// XObjectImage (Table 89 in 8.9.5.1).
// Implements PdfModel interface.
type XObjectImage struct {
//ColorSpace PdfObject
Width *int64
Height *int64
ColorSpace PdfColorspace
BitsPerComponent *int64
Filter StreamEncoder
Intent PdfObject
ImageMask PdfObject
Mask PdfObject
Matte PdfObject
Decode PdfObject
Interpolate PdfObject
Alternatives PdfObject
SMask PdfObject
SMaskInData PdfObject
Name PdfObject // Obsolete. Currently read if available and write if available. Not setting on new created files.
StructParent PdfObject
ID PdfObject
OPI PdfObject
Metadata PdfObject
OC PdfObject
Stream []byte
// Primitive
primitive *PdfObjectStream
}
func NewXObjectImage() *XObjectImage {
xobj := &XObjectImage{}
stream := &PdfObjectStream{}
stream.PdfObjectDictionary = MakeDict()
xobj.primitive = stream
return xobj
}
// Creates a new XObject Image from an image object with default options.
// If encoder is nil, uses raw encoding (none).
func NewXObjectImageFromImage(img *Image, cs PdfColorspace, encoder StreamEncoder) (*XObjectImage, error) {
xobj := NewXObjectImage()
return UpdateXObjectImageFromImage(xobj, img, cs, encoder)
}
// UpdateXObjectImageFromImage creates a new XObject Image from an Image object `img` and default
// masks from xobjIn.
// The default masks are overriden if img.hasAlpha
// If `encoder` is nil, uses raw encoding (none).
func UpdateXObjectImageFromImage(xobjIn *XObjectImage, img *Image, cs PdfColorspace,
encoder StreamEncoder) (*XObjectImage, error) {
xobj := NewXObjectImage()
if encoder == nil {
encoder = NewRawEncoder()
}
encoded, err := encoder.EncodeBytes(img.Data)
if err != nil {
common.Log.Debug("Error with encoding: %v", err)
return nil, err
}
xobj.Filter = encoder
xobj.Stream = encoded
// Width and height.
imWidth := img.Width
imHeight := img.Height
xobj.Width = &imWidth
xobj.Height = &imHeight
// Bits.
xobj.BitsPerComponent = &img.BitsPerComponent
// Guess colorspace if not explicitly set.
if cs == nil {
if img.ColorComponents == 1 {
xobj.ColorSpace = NewPdfColorspaceDeviceGray()
} else if img.ColorComponents == 3 {
xobj.ColorSpace = NewPdfColorspaceDeviceRGB()
} else if img.ColorComponents == 4 {
xobj.ColorSpace = NewPdfColorspaceDeviceCMYK()
} else {
return nil, errors.New("Colorspace undefined")
}
} else {
xobj.ColorSpace = cs
}
if img.hasAlpha {
// Add the alpha channel information as a stencil mask (SMask).
// Has same width and height as original and stored in same
// bits per component (1 component, hence the DeviceGray channel).
smask := NewXObjectImage()
smask.Filter = encoder
encoded, err := encoder.EncodeBytes(img.alphaData)
if err != nil {
common.Log.Debug("Error with encoding: %v", err)
return nil, err
}
smask.Stream = encoded
smask.BitsPerComponent = &img.BitsPerComponent
smask.Width = &img.Width
smask.Height = &img.Height
smask.ColorSpace = NewPdfColorspaceDeviceGray()
xobj.SMask = smask.ToPdfObject()
} else {
xobj.SMask = xobjIn.SMask
xobj.ImageMask = xobjIn.ImageMask
if xobj.ColorSpace.GetNumComponents() == 1 {
smaskMatteToGray(xobj)
}
}
return xobj, nil
}
// smaskMatteToGray converts to gray the Matte value in the SMask image referenced by `xobj` (if
// there is one)
func smaskMatteToGray(xobj *XObjectImage) error {
if xobj.SMask == nil {
return nil
}
stream, ok := xobj.SMask.(*PdfObjectStream)
if !ok {
common.Log.Debug("SMask is not *PdfObjectStream")
return ErrTypeCheck
}
dict := stream.PdfObjectDictionary
matte := dict.Get("Matte")
if matte == nil {
return nil
}
gray, err := toGray(matte.(*PdfObjectArray))
if err != nil {
return err
}
grayMatte := MakeArrayFromFloats([]float64{gray})
dict.SetIfNotNil("Matte", grayMatte)
return nil
}
// toGray converts a 1, 3 or 4 dimensional color `matte` to gray
// If `matte` is not a 1, 3 or 4 dimensional color then an error is returned
func toGray(matte *PdfObjectArray) (float64, error) {
colors, err := matte.ToFloat64Array()
if err != nil {
common.Log.Debug("Bad Matte array: matte=%s err=%v", matte, err)
}
switch len(colors) {
case 1:
return colors[0], nil
case 3:
cs := PdfColorspaceDeviceRGB{}
rgbColor, err := cs.ColorFromFloats(colors)
if err != nil {
return 0.0, err
}
return rgbColor.(*PdfColorDeviceRGB).ToGray().Val(), nil
case 4:
cs := PdfColorspaceDeviceCMYK{}
cmykColor, err := cs.ColorFromFloats(colors)
if err != nil {
return 0.0, err
}
rgbColor, err := cs.ColorToRGB(cmykColor.(*PdfColorDeviceCMYK))
if err != nil {
return 0.0, err
}
return rgbColor.(*PdfColorDeviceRGB).ToGray().Val(), nil
}
err = errors.New("Bad Matte color")
common.Log.Error("toGray: matte=%s err=%v", matte, err)
return 0.0, err
}
// Build the image xobject from a stream object.
// An image dictionary is the dictionary portion of a stream object representing an image XObject.
func NewXObjectImageFromStream(stream *PdfObjectStream) (*XObjectImage, error) {
img := &XObjectImage{}
img.primitive = stream
dict := *(stream.PdfObjectDictionary)
encoder, err := NewEncoderFromStream(stream)
if err != nil {
return nil, err
}
img.Filter = encoder
if obj := TraceToDirectObject(dict.Get("Width")); obj != nil {
iObj, ok := obj.(*PdfObjectInteger)
if !ok {
return nil, errors.New("Invalid image width object")
}
iVal := int64(*iObj)
img.Width = &iVal
} else {
return nil, errors.New("Width missing")
}
if obj := TraceToDirectObject(dict.Get("Height")); obj != nil {
iObj, ok := obj.(*PdfObjectInteger)
if !ok {
return nil, errors.New("Invalid image height object")
}
iVal := int64(*iObj)
img.Height = &iVal
} else {
return nil, errors.New("Height missing")
}
if obj := TraceToDirectObject(dict.Get("ColorSpace")); obj != nil {
cs, err := NewPdfColorspaceFromPdfObject(obj)
if err != nil {
return nil, err
}
img.ColorSpace = cs
} else {
// If not specified, assume gray..
common.Log.Debug("XObject Image colorspace not specified - assuming 1 color component")
img.ColorSpace = NewPdfColorspaceDeviceGray()
}
if obj := TraceToDirectObject(dict.Get("BitsPerComponent")); obj != nil {
iObj, ok := obj.(*PdfObjectInteger)
if !ok {
return nil, errors.New("Invalid image height object")
}
iVal := int64(*iObj)
img.BitsPerComponent = &iVal
}
img.Intent = dict.Get("Intent")
img.ImageMask = dict.Get("ImageMask")
img.Mask = dict.Get("Mask")
img.Decode = dict.Get("Decode")
img.Interpolate = dict.Get("Interpolate")
img.Alternatives = dict.Get("Alternatives")
img.SMask = dict.Get("SMask")
img.SMaskInData = dict.Get("SMaskInData")
img.Matte = dict.Get("Matte")
img.Name = dict.Get("Name")
img.StructParent = dict.Get("StructParent")
img.ID = dict.Get("ID")
img.OPI = dict.Get("OPI")
img.Metadata = dict.Get("Metadata")
img.OC = dict.Get("OC")
img.Stream = stream.Stream
return img, nil
}
// Update XObject Image with new image data.
func (ximg *XObjectImage) SetImage(img *Image, cs PdfColorspace) error {
encoded, err := ximg.Filter.EncodeBytes(img.Data)
if err != nil {
return err
}
ximg.Stream = encoded
// Width, height and bits.
ximg.Width = &img.Width
ximg.Height = &img.Height
ximg.BitsPerComponent = &img.BitsPerComponent
// Guess colorspace if not explicitly set.
if cs == nil {
if img.ColorComponents == 1 {
ximg.ColorSpace = NewPdfColorspaceDeviceGray()
} else if img.ColorComponents == 3 {
ximg.ColorSpace = NewPdfColorspaceDeviceRGB()
} else if img.ColorComponents == 4 {
ximg.ColorSpace = NewPdfColorspaceDeviceCMYK()
} else {
return errors.New("Colorspace undefined")
}
} else {
ximg.ColorSpace = cs
}
return nil
}
// Set compression filter. Decodes with current filter sets and encodes the data with the new filter.
func (ximg *XObjectImage) SetFilter(encoder StreamEncoder) error {
encoded := ximg.Stream
decoded, err := ximg.Filter.DecodeBytes(encoded)
if err != nil {
return err
}
ximg.Filter = encoder
encoded, err = encoder.EncodeBytes(decoded)
if err != nil {
return err
}
ximg.Stream = encoded
return nil
}
// This will convert to an Image which can be transformed or saved out.
// The image data is decoded and the Image returned.
func (ximg *XObjectImage) ToImage() (*Image, error) {
image := &Image{}
if ximg.Height == nil {
return nil, errors.New("Height attribute missing")
}
image.Height = *ximg.Height
if ximg.Width == nil {
return nil, errors.New("Width attribute missing")
}
image.Width = *ximg.Width
if ximg.BitsPerComponent == nil {
return nil, errors.New("Bits per component missing")
}
image.BitsPerComponent = *ximg.BitsPerComponent
image.ColorComponents = ximg.ColorSpace.GetNumComponents()
decoded, err := DecodeStream(ximg.primitive)
if err != nil {
return nil, err
}
image.Data = decoded
if ximg.Decode != nil {
darr, ok := ximg.Decode.(*PdfObjectArray)
if !ok {
common.Log.Debug("Invalid Decode object")
return nil, errors.New("Invalid type")
}
decode, err := darr.ToFloat64Array()
if err != nil {
return nil, err
}
image.decode = decode
}
return image, nil
}
func (ximg *XObjectImage) GetContainingPdfObject() PdfObject {
return ximg.primitive
}
// Return a stream object.
func (ximg *XObjectImage) ToPdfObject() PdfObject {
stream := ximg.primitive
dict := stream.PdfObjectDictionary
if ximg.Filter != nil {
//dict.Set("Filter", ximg.Filter)
// Pre-populate the stream dictionary with the
// encoding related fields.
dict = ximg.Filter.MakeStreamDict()
stream.PdfObjectDictionary = dict
}
dict.Set("Type", MakeName("XObject"))
dict.Set("Subtype", MakeName("Image"))
dict.Set("Width", MakeInteger(*(ximg.Width)))
dict.Set("Height", MakeInteger(*(ximg.Height)))
if ximg.BitsPerComponent != nil {
dict.Set("BitsPerComponent", MakeInteger(*(ximg.BitsPerComponent)))
}
if ximg.ColorSpace != nil {
dict.SetIfNotNil("ColorSpace", ximg.ColorSpace.ToPdfObject())
}
dict.SetIfNotNil("Intent", ximg.Intent)
dict.SetIfNotNil("ImageMask", ximg.ImageMask)
dict.SetIfNotNil("Mask", ximg.Mask)
dict.SetIfNotNil("Decode", ximg.Decode)
dict.SetIfNotNil("Interpolate", ximg.Interpolate)
dict.SetIfNotNil("Alternatives", ximg.Alternatives)
dict.SetIfNotNil("SMask", ximg.SMask)
dict.SetIfNotNil("SMaskInData", ximg.SMaskInData)
dict.SetIfNotNil("Matte", ximg.Matte)
dict.SetIfNotNil("Name", ximg.Name)
dict.SetIfNotNil("StructParent", ximg.StructParent)
dict.SetIfNotNil("ID", ximg.ID)
dict.SetIfNotNil("OPI", ximg.OPI)
dict.SetIfNotNil("Metadata", ximg.Metadata)
dict.SetIfNotNil("OC", ximg.OC)
dict.Set("Length", MakeInteger(int64(len(ximg.Stream))))
stream.Stream = ximg.Stream
return stream
}