luojianingfix: add beta notes in markdown

Using ImageSource for Image Decoding

Note:

Currently in the beta phase.

Image decoding refers to the process of converting supported archive image formats into a unified PixelMap for image display or image processing in applications or systems. Currently supported archive image formats include JPEG, PNG, GIF, WebP, BMP, SVG, ICO, DNG, and HEIF (support may vary across different hardware devices).

Development Steps

For detailed API documentation on image decoding, refer to: Image Decoding API Reference.

Import the Image module globally.
```
import kit.ImageKit.*
```

Obtain the image.

Method 1: Get the file descriptor through the sandbox path. Refer to the file.fs API documentation for details. This method requires importing the kit.CoreFileKit and kit.AbilityKit modules first.
```
import kit.CoreFileKit.*
import kit.AbilityKit.*
```
Then call FileFs.open() to obtain the file descriptor.
```
let cacheDir = "/data/storage/el2/base/haps/entry/cache"
let filePath = cacheDir + '/test.jpg'
let file = FileIo.open(filePath, mode: OpenMode.READ_WRITE)
let fd = file.fd 
```

Method 2: Get the resource file's Array<UInt8> through the resource manager. Refer to the ResourceManager API documentation for details.

// Import the resourceManager.
import kit.LocalizationKit.*
import ohos.hilog.Hilog

var abilityContext = Global.abilityContext
// Get the resourceManager.
let resourceManager = abilityContext.resourceManager

Different models may have different ways to obtain the resource manager. After obtaining it, call getRawFileContent() to get the resource file's Array<UInt8>.

try {
  let buffer = resourceManager.getRawFileContent("test.jpg")
} catch (e: BusinessException) {
  Hilog.error(0, "Failed to get RawFileContent", e.message)
}

Method 4: Get the resource file's RawFileDescriptor through the resource manager. Refer to the ResourceManager API documentation for details.

// Import the resourceManager.
import kit.LocalizationKit.*

var abilityContext = Global.abilityContext
// Get the resourceManager.
let resourceManager = abilityContext.resourceManager

Different models may have different ways to obtain the resource manager. After obtaining it, call getRawFd() to get the resource file's RawFileDescriptor.

try {
  let rawFileDescriptor = resourceManager.getRawFd("test.jpg")
} catch (e: BusinessException) {
  Hilog.error(0, "Failed to get RawFileContent", e.message)
}

Create an ImageSource instance.
- Method 1: Create ImageSource through the sandbox path. The sandbox path can be obtained via Method 1 in Step 2.
```
// filePath is the obtained sandbox path.
let imageSource = createImageSource(filePath)
```
- Method 2: Create ImageSource through the file descriptor fd. The file descriptor can be obtained via Method 2 in Step 2.
```
// fd is the obtained file descriptor.
let imageSource = createImageSource(fd)
```
- Method 3: Create ImageSource through the buffer array. The buffer array can be obtained via Method 3 in Step 2.
```
let imageSource = createImageSource(buffer)
```
- Method 4: Create ImageSource through the resource file's RawFileDescriptor. The RawFileDescriptor can be obtained via Method 4 in Step 2.
```
let imageSource = createImageSource(rawFileDescriptor);
```

Set the decoding parameters (DecodingOptions) and decode to obtain the pixelMap image object.

Decode with the desired format:

import kit.ImageKit.*
import kit.AbilityKit.*
import ohos.resource_manager.AppResource

var abilityContext = Global.abilityContext
// Get the resourceManager.
let resourceManager = abilityContext.resourceManager

let img = resourceManager.getMediaContent(@r(app.media.layered_image))
let imageSource = createImageSource(img)
let decodingOptions = DecodingOptions(editable: true, desiredPixelFormat: PixelMapFormat.Rgba8888)

// Create pixelMap.
let pixelMap = imageSource.createPixelMap(options: decodingOptions)

HDR Image Decoding

import kit.ImageKit.*
import kit.AbilityKit.*
import ohos.resource_manager.AppResource

var abilityContext = Global.abilityContext
// Get the resourceManager.
let resourceManager = abilityContext.resourceManager

let img = resourceManager.getMediaContent(@r(app.media.layered_image))
let imageSource = createImageSource(img)
// Set to AUTO to decode based on the image resource format. If the resource is HDR, it will decode to an HDR pixelmap.
let decodingOptions = DecodingOptions(desiredDynamicRange: DecodingDynamicRange.Auto)

// Create pixelMap.
let pixelMap = imageSource.createPixelMap(options: decodingOptions)
// Check if the pixelmap contains HDR content.
let info = pixelMap.getImageInfo()

After decoding is complete and the pixelMap object is obtained, you can proceed with subsequent image processing.

Release pixelMap and imageSource.

Ensure that the pixelMap and imageSource methods have completed execution. When these variables are no longer needed, manually call the following methods to release them as required.
```
pixelMap.release();
imageSource.release();
```

Development Example - Decoding an Image from Resource Files

Obtain the resourceManager.

// Import the resourceManager.
import kit.LocalizationKit.*
import kit.AbilityKit.*

// globalcontext needs to be assigned in func onCreate in main_ability.cj: globalcontext = this.context
var abilityContext = Global.abilityContext
// Get the resourceManager.
let resourceManager = abilityContext.resourceManager

Create ImageSource.

Method 1: Create through Array<UInt8> of test.jpg in the rawfile folder.

let buffer = resourceManager.getRawFileContent("test.jpg")
let imageSource = createImageSource(buffer)

Method 2: Create through RawFileDescriptor of test.jpg in the rawfile folder.

let rawFileDescriptor = resourceManager.getRawFd("test.jpg")
let imageSource = createImageSource(rawFileDescriptor)

Create pixelMap.

let pixelMap = imageSource.createPixelMap()

Release pixelMap and imageSource.

Ensure that the pixelMap and imageSource methods have completed execution. When these variables are no longer needed, manually call the following methods to release them as required.
```
pixelMap.release();
imageSource.release();
```