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Support /DecodeParms any /Columns, not only <=4 #68

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Support /DecodeParms any /Columns, not only <=4 #68

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62 changes: 41 additions & 21 deletions reader.go
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Original file line number Diff line number Diff line change
Expand Up @@ -851,19 +851,19 @@ func (this *PdfReader) readXref() error {
// Check for /DecodeParms
paethDecode := false
if _, ok := v.Dictionary["/DecodeParms"]; ok {
columns := 0
predictor := 0

if _, ok2 := v.Dictionary["/DecodeParms"].Dictionary["/Columns"]; ok2 {
columns = v.Dictionary["/DecodeParms"].Dictionary["/Columns"].Int
}
if _, ok2 := v.Dictionary["/DecodeParms"].Dictionary["/Predictor"]; ok2 {
predictor = v.Dictionary["/DecodeParms"].Dictionary["/Predictor"].Int
}

if columns > 4 || predictor > 12 {
return errors.New("Unsupported /DecodeParms - only tested with /Columns <= 4 and /Predictor <= 12")
}
// columns := 0
// predictor := 0

// if _, ok2 := v.Dictionary["/DecodeParms"].Dictionary["/Columns"]; ok2 {
// columns = v.Dictionary["/DecodeParms"].Dictionary["/Columns"].Int
// }
// if _, ok2 := v.Dictionary["/DecodeParms"].Dictionary["/Predictor"]; ok2 {
// predictor = v.Dictionary["/DecodeParms"].Dictionary["/Predictor"].Int
// }

// if columns > 4 || predictor > 12 {
// return errors.New("Unsupported /DecodeParms - only tested with /Columns <= 4 and /Predictor <= 12")
// }
paethDecode = true
}

Expand Down Expand Up @@ -999,6 +999,7 @@ func (this *PdfReader) readXref() error {
lastFieldSize := v.Dictionary["/W"].Array[2].Int

fieldSize := firstFieldSize + middleFieldSize + lastFieldSize
column := fieldSize
if paethDecode {
fieldSize++
}
Expand All @@ -1020,36 +1021,55 @@ func (this *PdfReader) readXref() error {
copy(prevRow, result)
}

objectData := make([]byte, fieldSize)
objectData := make([]byte, column)
if paethDecode {
copy(objectData, result[1:fieldSize])
} else {
copy(objectData, result[0:fieldSize])
}

if objectData[0] == 1 {
switch objectData[0] {
case 1:
// Regular objects
b := make([]byte, 4)
copy(b[4-middleFieldSize:], objectData[1:1+middleFieldSize])
b2 := make([]byte, 4)
copy(b[4-middleFieldSize:], objectData[firstFieldSize:firstFieldSize+middleFieldSize])
copy(b2[4-lastFieldSize:], objectData[column-lastFieldSize:])

objPos = int(binary.BigEndian.Uint32(b))
objGen = int(objectData[firstFieldSize+middleFieldSize])

objGen = int(binary.BigEndian.Uint32(b2))
// Append map[int]int
this.xref[i] = make(map[int]int, 1)

// Set object id, generation, and position
this.xref[i][objGen] = objPos
} else if objectData[0] == 2 {
case 2:
// Compressed objects
b := make([]byte, 4)
copy(b[4-middleFieldSize:], objectData[1:1+middleFieldSize])
b2 := make([]byte, 4)
copy(b[4-middleFieldSize:], objectData[firstFieldSize:firstFieldSize+middleFieldSize])
copy(b2[4-lastFieldSize:], objectData[column-lastFieldSize:])

objId := int(binary.BigEndian.Uint32(b))
objIdx := int(objectData[firstFieldSize+middleFieldSize])
objIdx := int(binary.BigEndian.Uint32(b2))

// object id (i) is located in StmObj (objId) at index (objIdx)
this.xrefStream[i] = [2]int{objId, objIdx}
case 0:
//
b := make([]byte, 4)
b2 := make([]byte, 4)
copy(b[4-middleFieldSize:], objectData[firstFieldSize:firstFieldSize+middleFieldSize])
copy(b2[4-lastFieldSize:], objectData[column-lastFieldSize:])

objPos = int(binary.BigEndian.Uint32(b))
objGen = int(binary.BigEndian.Uint32(b2))

// Append map[int]int
this.xref[i] = make(map[int]int, 1)

// Set object id, generation, and position
this.xref[i][objGen] = objPos
}

i++
Expand Down