README-EN.md · jiaojunying/zxing

# zxing

## Introduction
zxing is a library for parsing and generating one-dimensional and two-dimensional barcodes.
>
> ![code128.png](images/code128-EN.png)
>
> ![qrCode.png](images/qrCode-EN.png)

## Barcode Formats

| 1D product   | 1D industrial | 2D          |
| :----------- | :------------ | :---------- |
| UPC-A        | Code 39       | QR Code     |
| UPC-E        | Code 93       | Data Matrix |
| EAN-8        | Code 128      | Aztec       |
| EAN-13       | Codabar       | PDF 417     |
| RSS-14       | ITF           | MaxiCode    |
| RSS-Expanded |               |             |

## Download and Installation

````
ohpm install @ohos/zxing 
````
For details, see [Installing an OpenHarmony HAR](https://gitee.com/openharmony-tpc/docs/blob/master/OpenHarmony_har_usage.md).

## How to Use

### Decoding

```js
import {MultiFormatReader, BarcodeFormat, DecodeHintType, RGBLuminanceSource, BinaryBitmap, HybridBinarizer } from "@ohos/zxing";
const hints = new Map();
const formats = [BarcodeFormat.QR_CODE];
hints.set(DecodeHintType.POSSIBLE_FORMATS, formats);
const reader = new MultiFormatReader();
reader.setHints(hints);
const luminanceSource = new RGBLuminanceSource(luminances, width, height);
const binaryBitmap = new BinaryBitmap(new HybridBinarizer(luminanceSource));
let result = reader.decode(binaryBitmap);
let text = result.getText();
```

### Encoding

```js
import {BarcodeFormat, MultiFormatWriter, BitMatrix, ZXingStringEncoding, EncodeHintType} from '@ohos/zxing';
 const encodeHintTypeMap = new Map();
 // Set the margin width for the QR code.
 encodeHintTypeMap.set(EncodeHintType.MARGIN, 0);
 const writer: MultiFormatWriter = new MultiFormatWriter();
 let matrix: BitMatrix = writer.encode(content, BarcodeFormat.QR_CODE, width, height, encodeHintTypeMap);
```

In OpenHarmony, images are displayed in **\<Image>** components, which do not support the bit matrix. Therefore, you need to convert the matrix into a pixel map so that the image can be properly displayed.

1. Convert the matrix into the pixel map buffer.

2. Create a pixel map based on the buffer.

3. Note the following constraints on barcode parsing and generation:

A Codabar barcode can contain only digits.

An EAN-8 barcode must be a 7-digit number.

An EAN-13 barcode must be a 12-digit number.

An ITF barcode can contain only digits and must be an even number. The generated code can be parsed only when the value length is greater than or equal to 6.

An UPC-A barcode must be an 11-digit number.

An UPC-E barcode must be a 7-digit number.

For details, see the demo code. The main conversion logic is encapsulated in the **imageUtils** class.

## Available APIs

#### Encoding
| Class             | API                                                      | Description                                                        |
| ----------------- | ------------------------------------------------------------ | ------------------------------------------------------------ |
| QRCodeWriter      | encode(contents: string,format:  BarcodeFormat,width: int,height:int,hints: Map<EncodeHintType, any>): BitMatrix | Generates a QR code.                                              |
| DataMatrixWriter  | encode(contents: string,format: BarcodeFormat,width:  int,height:int,hints: Map<EncodeHintType, any>): BitMatrix | Generates a data matrix barcode.                                          |
| AztecWriter       | encode(contents: string,format: BarcodeFormat,width:  int,height:int,hints: Map<EncodeHintType, any>): BitMatrix | Generates an Aztec barcode.                                               |
| PDF417Writer      | encode(contents: string,format: BarcodeFormat,width:  int,height:int,hints: Map<EncodeHintType, any>): BitMatrix | Generates a PDF417 barcode.                                              |
| Code39Writer      | encode(contents: string,format: BarcodeFormat,width:  int,height:int,hints: Map<EncodeHintType, any>): BitMatrix | Generates a Code 39 barcode.                                              |
| Code93Writer      | encode(contents: string,format: BarcodeFormat,width:  int,height:int,hints: Map<EncodeHintType, any>): BitMatrix | Generates a Code 93 barcode.                                              |
| Code128Writer     | encode(contents: string,format: BarcodeFormat,width:  int,height:int,hints: Map<EncodeHintType, any>): BitMatrix | Generates a Code 128 barcode.                                             |
| CodaBarWriter     | encode(contents: string,format: BarcodeFormat,width:  int,height:int,hints: Map<EncodeHintType, any>): BitMatrix | Generates a CodaBar barcode.                                             |
| ITFWriter         | encode(contents: string,format: BarcodeFormat,width:  int,height:int,hints: Map<EncodeHintType, any>): BitMatrix | Generates an ITF barcode.                                                 |
| UPCAWriter        | encode(contents: string,format: BarcodeFormat,width:  int,height:int,hints: Map<EncodeHintType, any>): BitMatrix | Generates a UPC-A barcode.                                                |
| UPCEWriter        | encode(contents: string,format: BarcodeFormat,width:  int,height:int,hints: Map<EncodeHintType, any>): BitMatrix | Generates a UPC-E barcode.                                                |
| EAN8Writer        | encode(contents: string,format: BarcodeFormat,width:  int,height:int,hints: Map<EncodeHintType, any>): BitMatrix | Generates an EAN-8 barcode.                                                |
| EAN13Writer       | encode(contents: string,format: BarcodeFormat,width:  int,height:int,hints: Map<EncodeHintType, any>): BitMatrix | Generates an EAN-13 barcode.                                               |
| MultiFormatWriter | encode(contents: string,format: BarcodeFormat,width:  int,height:int,hints: Map<EncodeHintType, any>): BitMatrix | Finds an appropriate Writer subclass for the barcode format requested and encodes the barcode with the supplied content. It is a factory class method.|

#### Decoding
| Class             | API                                                      | Description                                                        |
| ----------------- | ------------------------------------------------------------ | ------------------------------------------------------------ |
| QRCodeReader      | decode(image: BinaryBitmap, hints?:  Map<DecodeHintType, any> \| null): Result; | Parses a QR code.                                              |
| DataMatrixReader  | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses a data matrix barcode.                                          |
| AztecReader       | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses an Aztec barcode.                                               |
| PDF417Reader      | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses a PDF417 barcode.                                              |
| MaxiCodeReader    | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses a MaxiCode barcode.                                            |
| Code39Reader      | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses a Code 39 barcode.                                              |
| Code93Reader      | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses a Code 93 barcode.                                              |
| CodaBarReader     | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses a CodaBar barcode.                                             |
| Code128Reader     | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses a Code 128 barcode.                                             |
| ITFReader         | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses an ITF barcode.                                                 |
| UPCAReader        | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses a UPC-A barcode.                                                |
| UPCEReader        | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses a UPC-E barcode.                                                |
| EAN8Reader        | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses an EAN-8 barcode.                                                |
| EAN13Reader       | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses an EAN-13 barcode.                                               |
| RSS14Reader       | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses an RSS 14 barcode.                                               |
| RSSExpandedReader | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Parses an RSSExpanded barcode.                                         |
| MultiFormatReader | decode(image: BinaryBitmap, hints?: Map<DecodeHintType, any> \|  null): Result; | Finds an appropriate Reader subclass for the barcode format requested and decodes the barcode with the supplied content. It is a factory class method.|

#### Camera Component
| Component  |      |      |
| ---------- | ---- | ---- |
| CameraView |      |      |

#### CameraService
| Class                 | API                                        | Description            |
| --------------------- | ---------------------------------------------- | ---------------- |
| init(context:Context) | CameraService.getInstance().init(getContext()) | Opens a camera and initializes it.|
| destroy               | CameraService.getInstance().destroy()          | Closes a camera.        |
| release               | CameraService.getInstance().release()          | Releases a camera.            |

#### GlobalContext
| Class     | API                                           | Description  |
| --------- | ------------------------------------------------- | ------ |
| setObject | GlobalContext.getContext().setObject("key",value) | Sets the value.|
| getObject | GlobalContext.getContext().getObject("key")       | Obtains the value.|

## Constraints

zxing has been verified in the following versions:
DevEco Studio: 5.0 (5.0.3.122), SDK: API12 (5.0.0.17)

DevEco Studio: 4.1 Canary(4.1.3.322), SDK: API11 (4.1.0.36)

DevEco Studio: 4.1 Canary(4.1.3.220), SDK: API11 (4.1.2.1)

DevEco Studio: 4.0 Beta2(4.0.3.500), SDK: API10 (4.0.10.7)

DevEco Studio: 4.0 Canary2(4.0.3.317), SDK: API10 (4.0.9.5)

DevEco Studio: 3.1 Beta2(3.1.0.400), SDK: API9 Release(3.2.11.9)

## How to Contribute
If you find any problem when using pdfViewer, submit an [issue](https://gitee.com/openharmony-tpc/zxing/issues) or a [PR](https://gitee.com/openharmony-tpc/zxing/pulls) to us.

## License
This project is licensed under [Apache License 2.0](https://gitee.com/openharmony-tpc/zxing/blob/master/LICENSE).

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