Class Predictor

Handles PNG and TIFF predictor encoding and decoding for PDF streams. Predictors are used to improve compression efficiency by transforming image data before or after compression.

Index

Constructors

constructor

Methods

canHandleDecodeParms decode encode getDecodeParms pngDecode pngEncode tiffDecode tiffEncode

Constructors

constructor

new Predictor(): Predictor
Returns Predictor

Methods

`Static`canHandleDecodeParms

canHandleDecodeParms(decodeParms?: PdfDictionary<PdfDictionaryEntries>): boolean
Checks if the decode parameters can be handled by this predictor.
Parameters
- OptionaldecodeParms: PdfDictionary<PdfDictionaryEntries>
  Optional PDF dictionary containing decode parameters.
Returns boolean
True if the parameters can be handled, false otherwise.
Example
```
if (Predictor.canHandleDecodeParms(dictionary)) {
  // Process with predictor
}
```
- Defined in packages/pdf-lite/src/utils/predictors.ts:326

`Static`decode

decode(data: ByteArray, params?: DecodeParms): ByteArray
Decodes data that was encoded with a predictor.
Parameters
- data: ByteArray
  The encoded data to decode.
- params: DecodeParms = {}
  Optional decode parameters including Predictor, Columns, Colors, and BitsPerComponent.
Returns ByteArray
The decoded byte array.
Example
```
const decoded = Predictor.decode(encodedData, { Predictor: 12, Columns: 100 })
```
- Defined in packages/pdf-lite/src/utils/predictors.ts:24

`Static`encode

encode(
    data: ByteArray,
    params?: DecodeParms,
    PdfStreamFilterType?: number,
): ByteArray
Encodes data using a predictor algorithm.
Parameters
- data: ByteArray
  The data to encode.
- params: DecodeParms = {}
  Optional encode parameters including Predictor, Columns, Colors, and BitsPerComponent.
- PdfStreamFilterType: number = 0
  The PNG filter type to use for encoding.
Returns ByteArray
The encoded byte array.
Example
```
const encoded = Predictor.encode(rawData, { Predictor: 12, Columns: 100 }, 1)
```
- Defined in packages/pdf-lite/src/utils/predictors.ts:54

`Static`getDecodeParms

getDecodeParms(
decodeParms?: PdfDictionary<PdfDictionaryEntries>,
): DecodeParms | null
Extracts decode parameters from a PDF dictionary.
Parameters
- OptionaldecodeParms: PdfDictionary<PdfDictionaryEntries>
  Optional PDF dictionary containing decode parameters.
Returns DecodeParms | null
The decode parameters object or null if not applicable.
Example
```
const params = Predictor.getDecodeParms(dictionary)
if (params) {
  console.log(params.Predictor)
}
```
- Defined in packages/pdf-lite/src/utils/predictors.ts:284

`Static`pngDecode

pngDecode(data: ByteArray, columns: number, bpp: number): ByteArray
Decodes PNG predictor encoded data.
Parameters
- data: ByteArray
  The PNG encoded data.
- columns: number
  The number of columns in the image.
- bpp: number
  Bytes per pixel.
Returns ByteArray
The decoded byte array.

Throws
Error if an unsupported PNG filter type is encountered.
- Defined in packages/pdf-lite/src/utils/predictors.ts:140

`Static`pngEncode

pngEncode(
    data: ByteArray,
    columns: number,
    bpp: number,
    PdfStreamFilterType: number,
): ByteArray
Encodes data using PNG predictor.
Parameters
- data: ByteArray
  The data to encode.
- columns: number
  The number of columns in the image.
- bpp: number
  Bytes per pixel.
- PdfStreamFilterType: number
  The PNG filter type (0-4) to use.
Returns ByteArray
The PNG encoded byte array.

Throws
Error if an unsupported PNG filter type is specified.
- Defined in packages/pdf-lite/src/utils/predictors.ts:197

`Static`tiffDecode

tiffDecode(data: ByteArray, columns: number, bpp: number): ByteArray
Decodes TIFF predictor encoded data.
Parameters
- data: ByteArray
  The TIFF encoded data.
- columns: number
  The number of columns in the image.
- bpp: number
  Bytes per pixel.
Returns ByteArray
The decoded byte array.
- Defined in packages/pdf-lite/src/utils/predictors.ts:83

`Static`tiffEncode

tiffEncode(data: ByteArray, columns: number, bpp: number): ByteArray
Encodes data using TIFF predictor.
Parameters
- data: ByteArray
  The data to encode.
- columns: number
  The number of columns in the image.
- bpp: number
  Bytes per pixel.
Returns ByteArray
The TIFF encoded byte array.
- Defined in packages/pdf-lite/src/utils/predictors.ts:111

Class Predictor

Index

Constructors

Methods

Constructors

constructor

Returns Predictor

Methods

`Static`canHandleDecodeParms

Parameters

Returns boolean

Example

`Static`decode

Parameters

Returns ByteArray

Example

`Static`encode

Parameters

Returns ByteArray

Example

`Static`getDecodeParms

Parameters

Returns DecodeParms | null

Example

`Static`pngDecode

Parameters

Returns ByteArray

Throws

`Static`pngEncode

Parameters

Returns ByteArray

Throws

`Static`tiffDecode

Parameters

Returns ByteArray

`Static`tiffEncode

Parameters

Returns ByteArray

Settings

On This Page

Class Predictor

Index

Constructors

Methods

Constructors

constructor

Returns Predictor

Methods

StaticcanHandleDecodeParms

Parameters

Returns boolean

Example

Staticdecode

Parameters

Returns ByteArray

Example

Staticencode

Parameters

Returns ByteArray

Example

StaticgetDecodeParms

Parameters

Returns DecodeParms | null

Example

StaticpngDecode

Parameters

Returns ByteArray

Throws

StaticpngEncode

Parameters

Returns ByteArray

Throws

StatictiffDecode

Parameters

Returns ByteArray

StatictiffEncode

Parameters

Returns ByteArray

Settings

On This Page

`Static`canHandleDecodeParms

`Static`decode

`Static`encode

`Static`getDecodeParms

`Static`pngDecode

`Static`pngEncode

`Static`tiffDecode

`Static`tiffEncode