Minor image profiling tweaks.

Fixed minor and major issues with the naming and comments.
Added licenses information to files.

contentstream/processor.go

@@ -124,7 +124,7 @@ func (proc *ContentStreamProcessor) getColorspace(name string, resources *model.
 		return model.NewPdfColorspaceSpecialPattern(), nil
 	}
 
-	// ReadSample check the colorspace dictionary.
+	// Next check the colorspace dictionary.
 	cs, has := resources.GetColorspaceByName(core.PdfObjectName(name))
 	if has {
 		return cs, nil

core/encoding.go

@@ -188,7 +188,7 @@ func newFlateEncoderFromStream(streamObj *PdfObjectStream, decodeParams *PdfObje
 		return encoder, nil
 	}
 
-	encoder.img = encDict.extractImage()
+	encoder.img = dictExtractImage(encDict)
 
 	// If decodeParams not provided, see if we can get from the stream.
 	if decodeParams == nil {
@@ -2087,7 +2087,7 @@ func newMultiEncoderFromStream(streamObj *PdfObjectStream) (*MultiEncoder, error
 			dParams = dict
 		}
 
-		common.Log.Trace("ReadSample name: %s, dp: %v, dParams: %v", *name, dp, dParams)
+		common.Log.Trace("Next name: %s, dp: %v, dParams: %v", *name, dp, dParams)
 		if *name == StreamEncodingFilterNameFlate {
 			// TODO: need to separate out the DecodeParms..
 			encoder, err := newFlateEncoderFromStream(streamObj, dParams)

core/parser.go

@@ -1540,7 +1540,7 @@ func (parser *PdfParser) ParseIndirectObject() (PdfObject, error) {
 					nextObjectOffset := parser.xrefNextObjectOffset(streamStartOffset)
 					if streamStartOffset+int64(streamLength) > nextObjectOffset && nextObjectOffset > streamStartOffset {
 						common.Log.Debug("Expected ending at %d", streamStartOffset+int64(streamLength))
-						common.Log.Debug("ReadSample object starting at %d", nextObjectOffset)
+						common.Log.Debug("Next object starting at %d", nextObjectOffset)
 						// endstream + "\n" endobj + "\n" (17)
 						newLength := nextObjectOffset - streamStartOffset - 17
 						if newLength < 0 {

core/primitives.go

@@ -1035,7 +1035,7 @@ func (streams *PdfObjectStreams) WriteString() string {
 	return b.String()
 }
 
-func (d *PdfObjectDictionary) extractImage() (img *imageutil.ImageBase) {
+func dictExtractImage(d *PdfObjectDictionary) (img *imageutil.ImageBase) {
 	var (
 		integer *PdfObjectInteger
 		ok      bool

extractor/text_para.go

@@ -177,7 +177,7 @@ func removeLastRune(text string) string {
 }
 
 // getSpace returns the space to insert between lines of depth `depth1` and `depth2`.
-// ReadSample line is the same depth so it's the same line as this one in the extracted text
+// Next line is the same depth so it's the same line as this one in the extracted text
 func getSpace(depth1, depth2 float64) string {
 	eol := !isZero(depth1 - depth2)
 	if eol {

internal/bitwise/substream.go

@@ -45,7 +45,7 @@ func NewSubstreamReader(r StreamReader, offset, length uint64) (*SubstreamReader
 		return nil, errors.New("root reader is nil")
 	}
 
-	common.Log.Trace("NewReader substream at offset: %d with length: %d", offset, length)
+	common.Log.Trace("NewSubstreamReader at offset: %d with length: %d", offset, length)
 	return &SubstreamReader{
 		wrapped: r,
 		offset:  offset,

internal/bitwise/writer_test.go

@@ -544,7 +544,48 @@ func TestWrite(t *testing.T) {
 	})
 }
 
-//
+// TestWriterWriteBits
 func TestWriterWriteBits(t *testing.T) {
+	t.Run("NonMSB", func(t *testing.T) {
+		w := NewWriter(make([]byte, 2))
 
+		// having empty buffered MSB.
+		n, err := w.WriteBits(0xb, 4)
+		require.NoError(t, err)
+		assert.Zero(t, n)
+
+		assert.Equal(t, byte(0xb), w.data[0])
+
+		n, err = w.WriteBits(0xdf, 8)
+		require.NoError(t, err)
+		assert.Equal(t, 1, n)
+
+		assert.Equal(t, byte(0xd), w.data[1])
+		assert.Equal(t, byte(0xfb), w.data[0])
+	})
+
+	t.Run("MSB", func(t *testing.T) {
+		w := NewWriterMSB(make([]byte, 2))
+
+		n, err := w.WriteBits(0xf, 4)
+		require.NoError(t, err)
+
+		assert.Zero(t, n)
+
+		// the output now should be
+		// 11110000
+		//     ^
+		assert.Equal(t, byte(0xf0), w.data[0], "%08b", w.data[0])
+
+		// write 10111 = 0x17, 5
+		n, err = w.WriteBits(0x17, 5)
+		require.NoError(t, err)
+
+		// current output should be
+		// 11111011 10000000
+		//           ^
+		assert.Equal(t, byte(0xfb), w.data[0])
+		assert.Equal(t, byte(0x80), w.data[1])
+		assert.Equal(t, uint8(1), w.bitIndex)
+	})
 }

internal/imageutil/cmyk.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package imageutil
 
 import (

internal/imageutil/cmyk_test.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package imageutil
 
 import (

internal/imageutil/colors.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package imageutil
 
 import (
@@ -6,7 +11,7 @@ import (
 	"image/color"
 )
 
-// ColorConverter is an enum that defines image color colorConverter.
+// ColorConverter is an interface that allows to convert images between different color spaces.
 type ColorConverter interface {
 	// Convert converts images to given color colorConverter.
 	Convert(src image.Image) (Image, error)
@@ -34,7 +39,7 @@ var (
 	CMYKConverter       = ConverterFunc(cmykConverter)
 )
 
-// Models
+// Additional models for images.
 var (
 	Gray2Model   = color.ModelFunc(gray2Model)
 	Gray4Model   = color.ModelFunc(gray4Model)

internal/imageutil/convert_test.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package imageutil
 
 import (

internal/imageutil/doc.go

@@ -0,0 +1,12 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
+// Package imageutil provides utility functions, structures and interfaces that allows to operate on images.
+// The function NewImage creates a new Image implementation based on provided input parameters.
+// The functions ColorXXXAt allows to get the the colors from provided data and parameters without the need of creating
+// image abstraction.
+// Image converters allows to convert between different color spaces. As Image interface implements also image.Image
+// it was possible to use standard golang image.Image as an input for the converters.
+package imageutil

internal/imageutil/grayscale.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package imageutil
 
 import (
@@ -11,7 +16,7 @@ func init() {
 	makePixelSumAtByte()
 }
 
-// Gray is an interface used for creating histograms for given image.
+// Gray is an interface that allows to get and set color.Gray for grayscale images.
 type Gray interface {
 	GrayAt(x, y int) color.Gray
 	SetGray(x, y int, g color.Gray)
@@ -111,7 +116,7 @@ func (m *Monochrome) Copy() Image {
 // Compile time check if Monochrome implements image.Image interface.
 var _ image.Image = &Monochrome{}
 
-// At implements image.Image interface
+// At implements image.Image interface.
 func (m *Monochrome) At(x, y int) color.Color {
 	c, _ := m.ColorAt(x, y)
 	return c
@@ -173,7 +178,7 @@ func (m *Monochrome) Validate() error {
 // Compile time check if Monochrome implements Gray interface.
 var _ Gray = &Monochrome{}
 
-// Histogram implements Gray interface.
+// Histogram implements Histogramer interface.
 func (m *Monochrome) Histogram() (histogram [256]int) {
 	for _, bt := range m.Data {
 		histogram[0xff] += int(tab8[m.Data[bt]])
@@ -229,12 +234,7 @@ func ColorAtGray1BPC(x, y, bytesPerLine int, data []byte, decode []float64) (col
 	return color.Gray{Y: c * 255}, nil
 }
 
-// Compile time check if Gray2 implements Image interface.
-var (
-	_ Gray = &Gray2{}
-)
-
-// Gray2 is an image
+// Gray2 is a 2-bit base grayscale image. It implements image.Image, draw.Image, Image and Gray interfaces.
 type Gray2 struct {
 	ImageBase
 }
@@ -285,7 +285,8 @@ func (i *Gray2) Validate() error {
 // Gray2 image.Image methods.
 //
 
-// Compile time check if Gray2 implements Gray interface.
+// Compile time check if Gray2 implements image.Image interface.
+var _ image.Image = &Gray2{}
 
 // At implements image.Image interface.
 func (i *Gray2) At(x, y int) color.Color {
@@ -319,6 +320,9 @@ func gray2ModelGray(g color.Gray) color.Gray {
 // Gray2 - Gray interface.
 //
 
+// Compile time check if Gray2 implements Gray interface.
+var _ Gray = &Gray2{}
+
 // GrayAt implements Gray interface.
 func (i *Gray2) GrayAt(x, y int) color.Gray {
 	c, _ := ColorAtGray2BPC(x, y, i.BytesPerLine, i.Data, i.Decode)
@@ -337,6 +341,16 @@ func (i *Gray2) SetGray(x, y int, gray color.Gray) {
 	i.Data[index] = (i.Data[index] & (^(0xc0 >> uint(2*((x)&3))))) | (value << uint(6-2*(x&3)))
 }
 
+// Histogram implements Histogramer interface.
+func (i *Gray2) Histogram() (histogram [256]int) {
+	for x := 0; x < i.Width; x++ {
+		for y := 0; y < i.Height; y++ {
+			histogram[i.GrayAt(x, y).Y]++
+		}
+	}
+	return histogram
+}
+
 // ColorAtGray2BPC gets the color of image in grayscale color space with two bits per component specific 'width',
 // 'bytesPerLine' and 'data' at the 'x' and 'y' coordinates position.
 func ColorAtGray2BPC(x, y, bytesPerLine int, data []byte, decode []float64) (color.Gray, error) {
@@ -413,7 +427,7 @@ func (i *Gray4) Validate() error {
 // Gray4 image.Image interface methods.
 //
 
-// Compile time check if Gray4 implements Gray interface.
+// Compile time check if Gray4 implements image.Image interface.
 var _ image.Image = &Gray4{}
 
 // At implements image.Image interface.
@@ -445,7 +459,7 @@ func (i *Gray4) GrayAt(x, y int) color.Gray {
 	return c
 }
 
-// Histogram implements Gray interface.
+// Histogram implements Histogramer interface.
 func (i *Gray4) Histogram() (histogram [256]int) {
 	for x := 0; x < i.Width; x++ {
 		for y := 0; y < i.Height; y++ {
@@ -587,7 +601,7 @@ func (i *Gray8) ColorModel() color.Model {
 // Compile time check if Gray8 implements Gray interface.
 var _ Gray = &Gray8{}
 
-// Histogram creates histogram based on the given image.
+// Histogram implements Histogramer interface.
 func (i *Gray8) Histogram() (histogram [256]int) {
 	for j := 0; j < len(i.Data); j++ {
 		histogram[i.Data[j]]++
@@ -718,7 +732,7 @@ func (i *Gray16) GrayAt(x, y int) color.Gray {
 	return color.Gray{Y: uint8(c.(color.Gray16).Y >> 8)}
 }
 
-// Histogram implements Gray interface.
+// Histogram implements Histogramer interface.
 func (i *Gray16) Histogram() (histogram [256]int) {
 	for x := 0; x < i.Width; x++ {
 		for y := 0; y < i.Height; y++ {

internal/imageutil/grayscale_test.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package imageutil
 
 import (

internal/imageutil/image.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package imageutil
 
 import (
@@ -103,9 +108,7 @@ func NewImage(width, height, bitsPerComponent, colorComponents int, data, alpha
 	if img == nil {
 		return nil, ErrInvalidImage
 	}
-	// if err := img.Validate(); err != nil {
-	// 	return nil, err
-	// }
+
 	return img, nil
 }
 

internal/imageutil/interpolate.go

@@ -1,10 +1,15 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package imageutil
 
 import (
 	"math"
 )
 
-// LinearInterpolate is the simple linear interpolation from the PDF manual.
+// LinearInterpolate is the simple linear interpolation from the PDF manual - PDF 32000-1:2008 - 7.10.2.
 func LinearInterpolate(x, xmin, xmax, ymin, ymax float64) float64 {
 	if math.Abs(xmax-xmin) < 0.000001 {
 		return ymin

internal/imageutil/padding.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package imageutil
 
 import (

internal/imageutil/rgb.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package imageutil
 
 import (

internal/imageutil/rgb_test.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package imageutil
 
 import (

internal/imageutil/rgbtobw.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package imageutil
 
 import (
@@ -92,19 +97,27 @@ func AutoThresholdTriangle(histogram [256]int) uint8 {
 	return uint8(split)
 }
 
-// GrayHistogram gets histogram for the provided Gray8 'img'.
+// Histogramer is an interface that allows to get a histogram from the image.
+type Histogramer interface {
+	Histogram() [256]int
+}
+
+// GrayHistogram gets histogram for the provided Gray image.
 func GrayHistogram(g Gray) (histogram [256]int) {
-	img, ok := g.(image.Image)
-	if !ok {
+	switch img := g.(type) {
+	case Histogramer:
+		return img.Histogram()
+	case image.Image:
+		bounds := img.Bounds()
+		for x := 0; x < bounds.Max.X; x++ {
+			for y := 0; y < bounds.Max.Y; y++ {
+				histogram[g.GrayAt(x, y).Y]++
+			}
+		}
+		return histogram
+	default:
 		return [256]int{}
 	}
-	bounds := img.Bounds()
-	for x := 0; x < bounds.Max.X; x++ {
-		for y := 0; y < bounds.Max.Y; y++ {
-			histogram[g.GrayAt(x, y).Y]++
-		}
-	}
-	return histogram
 }
 
 // ImgToBinary gets the binary (black/white) image from the given image 'i' and provided threshold 'threshold'

internal/jbig2/bitmap/bitmap.go

@@ -56,7 +56,7 @@ type Bitmap struct {
 	XResolution, YResolution int
 }
 
-// NewReader creates new bitmap with the parameters as provided in the arguments.
+// New creates new bitmap with the parameters as provided in the arguments.
 func New(width, height int) *Bitmap {
 	bm := newBitmap(width, height)
 	bm.Data = make([]byte, height*bm.RowStride)

internal/jbig2/decoder/arithmetic/arithmetic.go

@@ -51,7 +51,7 @@ type Decoder struct {
 	streamPosition int64
 }
 
-// NewReader creates new arithmetic Decoder.
+// New creates new arithmetic Decoder.
 func New(r bitwise.StreamReader) (*Decoder, error) {
 	d := &Decoder{
 		r:                    r,

internal/jbig2/decoder/mmr/mmr.go

@@ -22,7 +22,7 @@ type Decoder struct {
 	modeTable  []*code
 }
 
-// NewReader creates new jbig2 mmr decoder for the provided data stream.
+// New creates new jbig2 mmr decoder for the provided data stream.
 func New(r bitwise.StreamReader, width, height int, dataOffset, dataLength int64) (*Decoder, error) {
 	m := &Decoder{
 		width:  width,

internal/jbig2/document/document.go

@@ -23,18 +23,18 @@ import (
 var fileHeaderID = []byte{0x97, 0x4A, 0x42, 0x32, 0x0D, 0x0A, 0x1A, 0x0A}
 
 // Document is the jbig2 document model containing pages and global segments.
-// By creating new document with method NewReader or NewWithGlobals all the jbig2
+// By creating new document with method New or NewWithGlobals all the jbig2
 // encoded data segment headers are decoded. In order to decode whole
 // document, all of it's pages should be decoded using GetBitmap method.
 // PDF encoded documents should contains only one Page with the number 1.
 type Document struct {
 	// Pages contains all pages of this document.
 	Pages map[int]*Page
-	// NumberOfPagesUnknown defines if the amout of the pages is known.
+	// NumberOfPagesUnknown defines if the amount of the pages is known.
 	NumberOfPagesUnknown bool
 	// NumberOfPages - D.4.3 - Number of pages field (4 bytes). Only presented if NumberOfPagesUnknown is true.
 	NumberOfPages uint32
-	// GBUseExtTemplate defines wether extended Template is used.
+	// GBUseExtTemplate defines whether extended Template is used.
 	GBUseExtTemplate bool
 	// SubInputStream is the source data stream wrapped into a SubInputStream.
 	InputStream bitwise.StreamReader

internal/jbig2/document/segments/region_test.go

@@ -37,9 +37,9 @@ func TestEncodeRegion(t *testing.T) {
 		0x00, 0x00, 0x00, 0x1E,
 		// Second four bytes should be the height - 150 uint32
 		0x00, 0x00, 0x00, 0x96,
-		// ReadSample four bytes should be the x location of the region - 40 uint32
+		// Next four bytes should be the x location of the region - 40 uint32
 		0x00, 0x00, 0x00, 0x28,
-		// ReadSample four bytes should be the y location of the region - 35 uint32
+		// Next four bytes should be the y location of the region - 35 uint32
 		0x00, 0x00, 0x00, 0x23,
 		// The last byte should define the region flags
 		// 5 empty bits and 3 bits for the combination operator

internal/jbig2/document/segments/symbol-dictionary_test.go

@@ -12,8 +12,8 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/unidoc/unipdf/v3/common"
-	"github.com/unidoc/unipdf/v3/internal/bitwise"
 
+	"github.com/unidoc/unipdf/v3/internal/bitwise"
 	"github.com/unidoc/unipdf/v3/internal/jbig2/bitmap"
 )
 

internal/jbig2/document/segments/text-region.go

@@ -12,8 +12,8 @@ import (
 	"strings"
 
 	"github.com/unidoc/unipdf/v3/common"
-	"github.com/unidoc/unipdf/v3/internal/bitwise"
 
+	"github.com/unidoc/unipdf/v3/internal/bitwise"
 	"github.com/unidoc/unipdf/v3/internal/jbig2/basic"
 	"github.com/unidoc/unipdf/v3/internal/jbig2/bitmap"
 	"github.com/unidoc/unipdf/v3/internal/jbig2/decoder/arithmetic"

internal/jbig2/encoder/classer/temp_state.go

@@ -35,7 +35,7 @@ func initSimilarTemplatesFinder(c *Classer, bms *bitmap.Bitmap) *similarTemplate
 	}
 }
 
-// ReadSample finds next template state.
+// Next finds next template state.
 func (f *similarTemplatesFinder) Next() int {
 	var (
 		desireDH, desireDW, size, templ int

internal/sampling/reader.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package sampling
 
 import (

internal/sampling/reader_test.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package sampling
 
 import (

internal/sampling/writer.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package sampling
 
 import (

internal/sampling/writer_test.go

@@ -1,3 +1,8 @@
+/*
+ * This file is subject to the terms and conditions defined in
+ * file 'LICENSE.md', which is part of this source code package.
+ */
+
 package sampling
 
 import (

internal/textencoding/glyphs_glyphlist.go

@@ -56,7 +56,7 @@ func GlyphToRune(glyph GlyphName) (rune, bool) {
 		return r, true
 	}
 
-	// ReadSample try all the glyph naming conventions.
+	// Next try all the glyph naming conventions.
 	if groups := reUniEncoding.FindStringSubmatch(string(glyph)); groups != nil {
 		n, err := strconv.ParseInt(groups[1], 16, 32)
 		if err == nil {

internal/textencoding/testdata/glyphlist/parse_all_glyphs.go

@@ -59,7 +59,7 @@ func buildAll() error {
 		}
 	}
 
-	// ReadSample do these mapping files
+	// Next do these mapping files
 	filenames := []string{
 		"glyphlist.txt",
 		"texglyphlist.txt",

model/action.go

@@ -76,7 +76,7 @@ func (a *PdfAction) ToPdfObject() core.PdfObject {
 
 	d.Set("Type", core.MakeName("Action"))
 	d.SetIfNotNil("S", a.S)
-	d.SetIfNotNil("ReadSample", a.Next)
+	d.SetIfNotNil("Next", a.Next)
 
 	return container
 }
@@ -679,7 +679,7 @@ func (r *PdfReader) newPdfActionFromIndirectObject(container *core.PdfIndirectOb
 		}
 	}
 
-	if obj := d.Get("ReadSample"); obj != nil {
+	if obj := d.Get("Next"); obj != nil {
 		action.Next = obj
 	}
 

model/appender.go

@@ -636,7 +636,7 @@ func (a *PdfAppender) Write(w io.Writer) error {
 					}
 				}
 				parent, hasParent = parentDict.Get("Parent").(*core.PdfIndirectObject)
-				common.Log.Trace("ReadSample parent: %T", parentDict.Get("Parent"))
+				common.Log.Trace("Next parent: %T", parentDict.Get("Parent"))
 			}
 			pDict.Set("Parent", writer.pages)
 		}

model/colorspace.go

@@ -2376,10 +2376,9 @@ func (cs *PdfColorspaceSpecialIndexed) ImageToRGB(img Image) (Image, error) {
 	w := sampling.NewWriter(dest)
 
 	var (
-		sample  uint32
-		index   int
-		err     error
-		cValues []byte
+		sample uint32
+		index  int
+		err    error
 	)
 	// Convert the indexed data to base color map data.
 	// for i := 0; i < len(samples); i++ {
@@ -2405,10 +2404,9 @@ func (cs *PdfColorspaceSpecialIndexed) ImageToRGB(img Image) (Image, error) {
 			}
 		}
 
-		cValues = cs.colorLookup[index*N : (index+1)*N]
-		common.Log.Trace("C Vals: % d", cValues)
-		for i := range cValues {
-			if err = w.WriteSample(uint32(cValues[i])); err != nil {
+		// cValues = cs.colorLookup[index*N : (index+1)*N]
+		for i := index * N; i < (index+1)*N; i++ {
+			if err = w.WriteSample(uint32(cs.colorLookup[i])); err != nil {
 				return img, err
 			}
 		}

model/functions.go

@@ -281,10 +281,10 @@ func (f *PdfFunctionType0) Evaluate(x []float64) ([]float64, error) {
 	// Fall back to default Encode/Decode params if not set.
 	encode := f.Encode
 	if encode == nil {
-		encode = []float64{}
+		encode = make([]float64, len(f.Size)*2)
 		for i := 0; i < len(f.Size); i++ {
-			encode = append(encode, 0)
-			encode = append(encode, float64(f.Size[i]-1))
+			encode[i*2] = 0
+			encode[i*2+1] = float64(f.Size[i] - 1)
 		}
 	}
 	decode := f.Decode
@@ -292,7 +292,7 @@ func (f *PdfFunctionType0) Evaluate(x []float64) ([]float64, error) {
 		decode = f.Range
 	}
 
-	var indices []int
+	indices := make([]int, len(x))
 	// Start with nearest neighbour interpolation.
 	for i := 0; i < len(x); i++ {
 		xi := x[i]
@@ -315,7 +315,7 @@ func (f *PdfFunctionType0) Evaluate(x []float64) ([]float64, error) {
 		} else if index > f.Size[i] {
 			index = f.Size[i] - 1
 		}
-		indices = append(indices, index)
+		indices[i] = index
 	}
 
 	// Calculate the index
@@ -338,7 +338,7 @@ func (f *PdfFunctionType0) Evaluate(x []float64) ([]float64, error) {
 			continue
 		}
 
-		rj := f.data[rjIdx]		
+		rj := f.data[rjIdx]
 		rjp := imageutil.LinearInterpolate(float64(rj), 0, math.Pow(2, float64(f.BitsPerSample)), decode[2*j], decode[2*j+1])
 		yj := math.Min(math.Max(rjp, f.Range[2*j]), f.Range[2*j+1])
 		outputs = append(outputs, yj)

model/outlines.go

@@ -279,7 +279,7 @@ func (oi *PdfOutlineItem) ToPdfObject() core.PdfObject {
 		dict.Set("Count", core.MakeInteger(*oi.Count))
 	}
 	if oi.Next != nil {
-		dict.Set("ReadSample", oi.Next.ToPdfObject())
+		dict.Set("Next", oi.Next.ToPdfObject())
 	}
 	if oi.First != nil {
 		dict.Set("First", oi.First.ToPdfObject())

model/reader.go

@@ -353,12 +353,12 @@ func (r *PdfReader) buildOutlineTree(obj core.PdfObject, parent *PdfOutlineTreeN
 		}
 
 		// Build outline tree for the next item.
-		nextObj := core.ResolveReference(dict.Get("ReadSample"))
+		nextObj := core.ResolveReference(dict.Get("Next"))
 		if _, processed := visited[nextObj]; nextObj != nil && nextObj != container && !processed {
 			if !core.IsNullObject(nextObj) {
 				next, last, err := r.buildOutlineTree(nextObj, parent, &outlineItem.PdfOutlineTreeNode, visited)
 				if err != nil {
-					common.Log.Debug("DEBUG: could not build outline tree for ReadSample node: %v. Skipping node.", err)
+					common.Log.Debug("DEBUG: could not build outline tree for Next node: %v. Skipping node.", err)
 				} else {
 					outlineItem.Next = next
 					return &outlineItem.PdfOutlineTreeNode, last, nil

model/writer.go

@@ -642,7 +642,7 @@ func (w *PdfWriter) AddPage(page *PdfPage) error {
 			}
 		}
 		parent, hasParent = core.GetIndirect(parentDict.Get("Parent"))
-		common.Log.Trace("ReadSample parent: %T", parentDict.Get("Parent"))
+		common.Log.Trace("Next parent: %T", parentDict.Get("Parent"))
 	}
 
 	common.Log.Trace("Traversal done")

render/internal/context/imagerender/context.go

@@ -212,7 +212,7 @@ func (dc *Context) SetRGB255(r, g, b int) {
 	dc.SetRGBA255(r, g, b, 255)
 }
 
-// SetNRGBA sets the current color. r, g, b, a values should be between 0 and 1,
+// SetRGBA sets the current color. r, g, b, a values should be between 0 and 1,
 // inclusive.
 func (dc *Context) SetRGBA(r, g, b, a float64) {
 	dc.color = color.NRGBA{