Image Processing

The Image module provides APIs for image processing. You can use the APIs to create a PixelMap object with specified properties or read image pixel data (even in an area).

NOTE

The initial APIs of this module are supported since API version 6. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

import image from '@ohos.multimedia.image';

image.createPixelMap⁸⁺

createPixelMap(colors: ArrayBuffer, options: InitializationOptions): Promise<PixelMap>

Creates a PixelMap object. This API uses a promise to return the result.

System capability: SystemCapability.Multimedia.Image.Core

Parameters

Return value

Example

const color = new ArrayBuffer(96);
let bufferArr = new Uint8Array(color);
let opts = { editable: true, pixelFormat: 3, size: { height: 4, width: 6 } }
image.createPixelMap(color, opts)
    .then((pixelmap) => {
        })

image.createPixelMap⁸⁺

createPixelMap(colors: ArrayBuffer, options: InitializationOptions, callback: AsyncCallback<PixelMap>): void

Creates a PixelMap object. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Multimedia.Image.Core

Parameters

Example

const color = new ArrayBuffer(96);
let bufferArr = new Uint8Array(color);
let opts = { editable: true, pixelFormat: 3, size: { height: 4, width: 6 } }
image.createPixelMap(color, opts, (pixelmap) => {
        })

PixelMap⁷⁺

Provides APIs to read or write image pixel map data and obtain image pixel map information. Before calling any API in PixelMap, you must use createPixelMap to create a PixelMap object.

Attributes

System capability: SystemCapability.Multimedia.Image.Core

readPixelsToBuffer⁷⁺

readPixelsToBuffer(dst: ArrayBuffer): Promise<void>

Reads image pixel map data and writes the data to an ArrayBuffer. This API uses a promise to return the result.

System capability: SystemCapability.Multimedia.Image.Core

Parameters

Return value

Example

const readBuffer = new ArrayBuffer(400);
pixelmap.readPixelsToBuffer(readBuffer).then(() => {
    console.log('Succeeded in reading image pixel data.'); // Called if the condition is met.
}).catch(error => {
    console.log('Failed to read image pixel data.'); // Called if no condition is met.
})

readPixelsToBuffer⁷⁺

readPixelsToBuffer(dst: ArrayBuffer, callback: AsyncCallback<void>): void

Reads image pixel map data and writes the data to an ArrayBuffer. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Multimedia.Image.Core

Parameters

Example

const readBuffer = new ArrayBuffer(400);
pixelmap.readPixelsToBuffer(readBuffer, (err, res) => {
    if(err) {
        console.log('Failed to read image pixel data.');  // Called if no condition is met.
    } else {
        console.log('Succeeded in reading image pixel data.'); // Called if the condition is met.
    }
})

readPixels⁷⁺

readPixels(area: PositionArea): Promise<void>

Reads image pixel map data in an area. This API uses a promise to return the data read.

System capability: SystemCapability.Multimedia.Image.Core

Parameters

Return value

Example

const area = new ArrayBuffer(400);
pixelmap.readPixels(area).then(() => {
    console.log('Succeeded in reading the image data in the area.'); // Called if the condition is met.
}).catch(error => {
    console.log('Failed to read the image data in the area.'); // Called if no condition is met.
})

readPixels⁷⁺

readPixels(area: PositionArea, callback: AsyncCallback<void>): void

Reads image pixel map data in an area. This API uses an asynchronous callback to return the data read.

System capability: SystemCapability.Multimedia.Image.Core

Parameters

Example

const color = new ArrayBuffer(96);
let bufferArr = new Uint8Array(color);
let opts = { editable: true, pixelFormat: 3, size: { height: 4, width: 6 } }
image.createPixelMap(color, opts, (err, pixelmap) => {
    if(pixelmap == undefined){
        console.info('createPixelMap failed.');
    } else {
        const area = { pixels: new ArrayBuffer(8),
            offset: 0,
            stride: 8,
            region: { size: { height: 1, width: 2 }, x: 0, y: 0 }};
        pixelmap.readPixels(area, () => {
            console.info('readPixels success');
        })
    }
})

writePixels⁷⁺

writePixels(area: PositionArea): Promise<void>

Writes image pixel map data to an area. This API uses a promise to return the operation result.

System capability: SystemCapability.Multimedia.Image.Core

Parameters

Return value

Example

const color = new ArrayBuffer(96);
let bufferArr = new Uint8Array(color);
let opts = { editable: true, pixelFormat: 3, size: { height: 4, width: 6 } }
image.createPixelMap(color, opts)
    .then( pixelmap => {
        if (pixelmap == undefined) {
            console.info('createPixelMap failed.');
        }
        const area = { pixels: new ArrayBuffer(8),
            offset: 0,
            stride: 8,
            region: { size: { height: 1, width: 2 }, x: 0, y: 0 }
        }
        let bufferArr = new Uint8Array(area.pixels);
        for (var i = 0; i < bufferArr.length; i++) {
            bufferArr[i] = i + 1;
        }

        pixelmap.writePixels(area).then(() => {
            const readArea = { pixels: new ArrayBuffer(8),
                offset: 0,
                stride: 8,
                // region.size.width + x < opts.width, region.size.height + y < opts.height
                region: { size: { height: 1, width: 2 }, x: 0, y: 0 }
            }        
        })
    }).catch(error => {
        console.log('error: ' + error);
    })

writePixels⁷⁺

writePixels(area: PositionArea, callback: AsyncCallback<void>): void

Writes image pixel map data to an area. This API uses an asynchronous callback to return the operation result.

System capability: SystemCapability.Multimedia.Image.Core

Parameters

Example

const area = new ArrayBuffer(400);
pixelmap.writePixels(area, (error) => {
    if (error!=undefined) {
		console.info('Failed to write pixelmap into the specified area.');
	} else {
	    const readArea = {
            pixels: new ArrayBuffer(20),
            offset: 0,
            stride: 8,
            region: { size: { height: 1, width: 2 }, x: 0, y: 0 },
        }
	}
})

writeBufferToPixels⁷⁺

writeBufferToPixels(src: ArrayBuffer): Promise<void>

Reads image data in an ArrayBuffer and writes the data to a PixelMap object. This API uses a promise to return the result.

System capability: SystemCapability.Multimedia.Image.Core

Parameters

Return value

Example

const color = new ArrayBuffer(96);
const pixelMap = new ArrayBuffer(400);
let bufferArr = new Uint8Array(color);
pixelMap.writeBufferToPixels(color).then(() => {
    console.log("Succeeded in writing data from a buffer to a PixelMap.");
}).catch((err) => {
    console.error("Failed to write data from a buffer to a PixelMap.");
})

writeBufferToPixels⁷⁺

writeBufferToPixels(src: ArrayBuffer, callback: AsyncCallback<void>): void

Reads image data in an ArrayBuffer and writes the data to a PixelMap object. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Multimedia.Image.Core

Parameters

Example

const color = new ArrayBuffer(96);\
const pixelMap = new ArrayBuffer(400);
let bufferArr = new Uint8Array(color);
pixelMap.writeBufferToPixels(color, function(err) {
    if (err) {
        console.error("Failed to write data from a buffer to a PixelMap.");
        return;
    } else {
		console.log("Succeeded in writing data from a buffer to a PixelMap.");
	}
});

getImageInfo⁷⁺

getImageInfo(): Promise<ImageInfo>

Obtains pixel map information of this image. This API uses a promise to return the information.

System capability: SystemCapability.Multimedia.Image.Core

Return value

Example

const pixelMap = new ArrayBuffer(400);
pixelMap.getImageInfo().then(function(info) {
    console.log("Succeeded in obtaining the image pixel map information.");
}).catch((err) => {
    console.error("Failed to obtain the image pixel map information.");
});

getImageInfo⁷⁺

getImageInfo(callback: AsyncCallback<ImageInfo>): void

Obtains pixel map information of this image. This API uses an asynchronous callback to return the information.

System capability: SystemCapability.Multimedia.Image.Core

Parameters

Example

pixelmap.getImageInfo((imageInfo) => { 
    console.log("Succeeded in obtaining the image pixel map information.");
})

getBytesNumberPerRow⁷⁺

getBytesNumberPerRow(): number

Obtains the number of bytes per row of this image pixel map.

System capability: SystemCapability.Multimedia.Image.Core

Return value

Example

const color = new ArrayBuffer(96);
let bufferArr = new Uint8Array(color);
let opts = { editable: true, pixelFormat: 3, size: { height: 4, width: 6 } }
image.createPixelMap(color, opts, (err,pixelmap) => {
    let rowCount = pixelmap.getBytesNumberPerRow();
})

getPixelBytesNumber⁷⁺

getPixelBytesNumber(): number

Obtains the total number of bytes of this image pixel map.

System capability: SystemCapability.Multimedia.Image.Core

Return value

Example

let pixelBytesNumber = pixelmap.getPixelBytesNumber();

release⁷⁺

release():Promise<void>

Releases this PixelMap object. This API uses a promise to return the result.

System capability: SystemCapability.Multimedia.Image.Core

Return value

Example

const color = new ArrayBuffer(96);
let bufferArr = new Uint8Array(color);
let opts = { editable: true, pixelFormat: 3, size: { height: 4, width: 6 } }
image.createPixelMap(color, opts, (pixelmap) => {
    pixelmap.release().then(() => {
	    console.log('Succeeded in releasing pixelmap object.');
    }).catch(error => {
	    console.log('Failed to release pixelmap object.');
    })
})

release⁷⁺

release(callback: AsyncCallback<void>): void

Releases this PixelMap object. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Multimedia.Image.Core

Parameters

Example

const color = new ArrayBuffer(96);
let bufferArr = new Uint8Array(color);
let opts = { editable: true, pixelFormat: 3, size: { height: 4, width: 6 } }
image.createPixelMap(color, opts, (pixelmap) => {
    pixelmap.release().then(() => {
	    console.log('Succeeded in releasing pixelmap object.');
    }).catch(error => {
	    console.log('Failed to release pixelmap object.');
    })
})

image.createImageSource

createImageSource(uri: string): ImageSource

Creates an ImageSource instance based on the URI.

System capability: SystemCapability.Multimedia.Image.ImageSource

Parameters

Return value

Example

let path = this.context.getApplicationContext().fileDirs + "test.jpg";
const imageSourceApi = image.createImageSource(path);

image.createImageSource⁷⁺

createImageSource(fd: number): ImageSource

Creates an ImageSource instance based on the file descriptor.

System capability: SystemCapability.Multimedia.Image.ImageSource

Parameters

Return value

Example

const imageSourceApi = image.createImageSource(0)

ImageSource

Provides APIs to obtain image information. Before calling any API in ImageSource, you must use createImageSource to create an ImageSource instance.

Attributes

System capability: SystemCapability.Multimedia.Image.ImageSource

getImageInfo

getImageInfo(index: number, callback: AsyncCallback<ImageInfo>): void

Obtains information about an image with the specified index. This API uses an asynchronous callback to return the information.

System capability: SystemCapability.Multimedia.Image.ImageSource

Parameters

Example

imageSourceApi.getImageInfo(0,(error, imageInfo) => { 
    if(error) {
        console.log('getImageInfo failed.');
    } else {
        console.log('getImageInfo succeeded.');
    }
})

getImageInfo

getImageInfo(callback: AsyncCallback<ImageInfo>): void

Obtains information about this image. This API uses an asynchronous callback to return the information.

System capability: SystemCapability.Multimedia.Image.ImageSource

Parameters

Example

imageSourceApi.getImageInfo(imageInfo => { 
    console.log('Succeeded in obtaining the image information.');
})

getImageInfo

getImageInfo(index?: number): Promise<ImageInfo>

Obtains information about an image with the specified index. This API uses a promise to return the image information.

System capability: SystemCapability.Multimedia.Image.ImageSource

Parameters

Return value

Example

imageSourceApi.getImageInfo(0)
    .then(imageInfo => {
		console.log('Succeeded in obtaining the image information.');
	}).catch(error => {
		console.log('Failed to obtain the image information.');
	})

getImageProperty⁷⁺

getImageProperty(key:string, options?: GetImagePropertyOptions): Promise<string>

Obtains the value of a property with the specified index in this image. This API uses a promise to return the result.

System capability: SystemCapability.Multimedia.Image.ImageSource

Parameters

Return value

Example

imageSourceApi.getImageProperty("BitsPerSample")
    .then(data => {
		console.log('Succeeded in getting the value of the specified attribute key of the image.');
	})

getImageProperty⁷⁺

getImageProperty(key:string, callback: AsyncCallback<string>): void

Obtains the value of a property with the specified index in this image. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Multimedia.Image.ImageSource

Parameters

Example

imageSourceApi.getImageProperty("BitsPerSample",(error,data) => { 
    if(error) {
        console.log('Failed to get the value of the specified attribute key of the image.');
    } else {
        console.log('Succeeded in getting the value of the specified attribute key of the image.');
    }
})

getImageProperty⁷⁺

getImageProperty(key:string, options: GetImagePropertyOptions, callback: AsyncCallback<string>): void

Obtains the value of a property in this image. This API uses an asynchronous callback to return the property value in a string.

System capability: SystemCapability.Multimedia.Image.ImageSource

Parameters

Example

const property = new ArrayBuffer(400);
imageSourceApi.getImageProperty("BitsPerSample",property,(error,data) => { 
    if(error) {
        console.log('Failed to get the value of the specified attribute key of the image.');
    } else {
        console.log('Succeeded in getting the value of the specified attribute key of the image.');
    }
})

createPixelMap⁷⁺

createPixelMap(options?: DecodingOptions): Promise<PixelMap>

Creates a PixelMap object based on image decoding parameters. This API uses a promise to return the result.

System capability: SystemCapability.Multimedia.Image.ImageSource

Parameters

Return value

Example

imageSourceApi.createPixelMap().then(pixelmap => {
    console.log('Succeeded in creating pixelmap object through image decoding parameters.');
}).catch(error => {
    console.log('Failed to create pixelmap object through image decoding parameters.');
})

createPixelMap⁷⁺

createPixelMap(callback: AsyncCallback<PixelMap>): void

Creates a PixelMap object based on the default parameters. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Multimedia.Image.ImageSource

Parameters

Example

imageSourceApi.createPixelMap(pixelmap => { 
    console.log('Succeeded in creating pixelmap object.');
}).catch(error => {
    console.log('Failed to create pixelmap object.');
})

createPixelMap⁷⁺

createPixelMap(options: DecodingOptions, callback: AsyncCallback<PixelMap>): void

Creates a PixelMap object based on image decoding parameters. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Multimedia.Image.ImageSource

Parameters

Example

const decodingOptions = new ArrayBuffer(400);
imageSourceApi.createPixelMap(decodingOptions, pixelmap => { 
    console.log('Succeeded in creating pixelmap object.');
})

release

release(callback: AsyncCallback<void>): void

Releases this ImageSource instance. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Multimedia.Image.ImageSource

Parameters

Example

imageSourceApi.release(() => { 
    console.log('release succeeded.');
})

release

release(): Promise<void>

Releases this ImageSource instance. This API uses a promise to return the result.

System capability: SystemCapability.Multimedia.Image.ImageSource

Return value

Example

imageSourceApi.release().then(()=>{
    console.log('Succeeded in releasing the image source instance.');
}).catch(error => {
    console.log('Failed to release the image source instance.');
})

image.createImagePacker

createImagePacker(): ImagePacker

Creates an ImagePacker instance.

System capability: SystemCapability.Multimedia.Image.ImageReceiver

Return value

Example

const imagePackerApi = image.createImagePacker();

ImagePacker

Provide APIs to pack images. Before calling any API in ImagePacker, you must use createImagePacker to create an ImagePacker instance.

Attributes

System capability: SystemCapability.Multimedia.Image.ImagePacker

packing

packing(source: ImageSource, option: PackingOption, callback: AsyncCallback<ArrayBuffer>): void

Packs an image. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Multimedia.Image.ImagePacker

Parameters

Example

let packOpts = { format:"image/jpeg", quality:98 };
const imageSourceApi = new ArrayBuffer(400);
imagePackerApi.packing(imageSourceApi, packOpts, data => {})

packing

packing(source: ImageSource, option: PackingOption): Promise<ArrayBuffer>

Packs an image. This API uses a promise to return the result.

System capability: SystemCapability.Multimedia.Image.ImagePacker

Parameters

Return value

Example

let packOpts = { format:"image/jpeg", quality:98 }
const imageSourceApi = new ArrayBuffer(400);
imagePackerApi.packing(imageSourceApi, packOpts)
    .then( data => {
        console.log('packing succeeded.');
	}).catch(error => {
	    console.log('packing failed.');
	})

packing⁸⁺

packing(source: PixelMap, option: PackingOption, callback: AsyncCallback<ArrayBuffer>): void

Packs an image. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Multimedia.Image.ImagePacker

Parameters

Example

let packOpts = { format:"image/jpeg", quality:98 }
const pixelMapApi = new ArrayBuffer(400);
imagePackerApi.packing(pixelMapApi, packOpts, data => { 
    console.log('Succeeded in packing the image.');
}).catch(error => {
	console.log('Failed to pack the image.');
})

packing⁸⁺

packing(source: PixelMap, option: PackingOption): Promise<ArrayBuffer>

Packs an image. This API uses a promise to return the result.

System capability: SystemCapability.Multimedia.Image.ImagePacker

Parameters

Return value

Example

let packOpts = { format:"image/jpeg", quality:98 }
const pixelMapApi = new ArrayBuffer(400);
imagePackerApi.packing(pixelMapApi, packOpts)
    .then( data => {
	    console.log('Succeeded in packing the image.');
	}).catch(error => {
	    console.log('Failed to pack the image.');
	})

release

release(callback: AsyncCallback<void>): void

Releases this ImagePacker instance. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Multimedia.Image.ImagePacker

Parameters

Example

imagePackerApi.release(()=>{ 
    console.log('Succeeded in releasing image packaging.');
})

release

release(): Promise<void>

Releases this ImagePacker instance. This API uses a promise to return the result.

System capability: SystemCapability.Multimedia.Image.ImagePacker

Return value

Example

imagePackerApi.release().then(()=>{
    console.log('Succeeded in releasing image packaging.');
}).catch((error)=>{ 
    console.log('Failed to release image packaging.'); 
}) 

PositionArea⁷⁺

Describes area information in an image.

System capability: SystemCapability.Multimedia.Image.Core

ImageInfo

Describes image information.

System capability: SystemCapability.Multimedia.Image.Core

Size

Describes the size of an image.

System capability: SystemCapability.Multimedia.Image.Core

PixelMapFormat⁷⁺

Enumerates the pixel formats of images.

System capability: SystemCapability.Multimedia.Image.Core

InitializationOptions⁸⁺

Defines pixel map initialization options.

System capability: SystemCapability.Multimedia.Image.Core

DecodingOptions⁷⁺

Defines image decoding options.

System capability: SystemCapability.Multimedia.Image.ImageSource

Region⁷⁺

Describes region information.

System capability: SystemCapability.Multimedia.Image.Core

PackingOption

Defines the option for image packing.

System capability: SystemCapability.Multimedia.Image.ImagePacker

GetImagePropertyOptions⁷⁺

Describes image properties.

System capability: SystemCapability.Multimedia.Image.ImageSource

PropertyKey⁷⁺

Describes the exchangeable image file format (EXIF) information of an image.

System capability: SystemCapability.Multimedia.Image.Core

ResponseCode

Enumerates the response codes returned upon build errors.