arkts-graphics-display.md

# Displaying Images


More often than not, you may need to display images in your application, for example, logos in buttons, online images, and local images. To do so, you need to use the **\<Image>** component, which supports a wide range of image formats, including PNG, JPG, BMP, SVG, and GIF. For details, see [Image](../reference/arkui-ts/ts-basic-components-image.md).


You can call the API in the following format to create an image:



```ts
Image(src: string | Resource | media.PixelMap)
```


Obtains a local or online image from the image data source specified by **src**. For details about how to load the data source, see [Loading Image Resources](#loading-image-resources).


## Loading Image Resources

The **\<Image>** component supports two types of images: archived and pixel map.


### Archived Type Data Source

Data sources of the archived type can be classified into local resources, online resources, **Resource** objects, media library data share resources, and Base64 resources.

- Local resources
  Create a folder and place a local image in any position in the **ets** folder.

  In the **\<Image>** component, import the local image path to display the image. The root directory is the **ets** folder.

  ```ts
  Image('images/view.jpg')
  .width(200)
  ```

- Online resources
  To use online images, first apply for the **ohos.permission.INTERNET** permission. For details, see [Applying for Permissions](../security/accesstoken-guidelines.md). Under this scenario, the **src** parameter of the **\<Image>** component is the URL of the online image.

  ```ts
  Image('https://www.example.com/example.JPG') // Replace the URL with the actual URL.
  ```

- **Resource** objects
  **Resource** objects can be used to import images across bundles and modules. All images in the **resources** folder can be read and converted to the **Resource** objects through **$r**.

  **Figure 1** resources folder 

  ![image-resource](figures/image-resource.jpg)

  API:

  ```
  Image($r('app.media.icon'))
  ```

  You can also place the images in the **rawfile** folder.

  **Figure 2** rawfile folder

 ![image-rawfile](figures/image-rawfile.jpg)

  API:

  ```
  Image($rawfile('snap'))
  ```

- Media library data share resources
  To display images from the media library, use a path string that starts with **datashare://**.

  1. Call the API to obtain the image URL in the media library.
      ​    
      ```ts
      import picker from '@ohos.file.picker';

      @Entry
      @Component
      struct Index {
        @State imgDatas: string[] = [];
        // Obtain the image URL set.
        getAllImg() {
          let photoPicker = new picker.PhotoViewPicker();
          let result = new Array<string>();
          try {
            let PhotoSelectOptions = new picker.PhotoSelectOptions();
            PhotoSelectOptions.MIMEType = picker.PhotoViewMIMETypes.IMAGE_TYPE;
            PhotoSelectOptions.maxSelectNumber = 5;
            let photoPicker = new picker.PhotoViewPicker();
            photoPicker.select(PhotoSelectOptions).then((PhotoSelectResult) => {
              this.imgDatas = PhotoSelectResult.photoUris;
              console.info('PhotoViewPicker.select successfully, PhotoSelectResult uri: ' + JSON.stringify(PhotoSelectResult));
            }).catch((err) => {
              console.error(`PhotoViewPicker.select failed with. Code: ${err.code}, message: ${err.message}`);
            });
          } catch (err) {
            console.error(`PhotoViewPicker failed with. Code: ${err.code}, message: ${err.message}`);    }
        }

        // Call the preceding function in aboutToAppear to obtain the URLs of all images in the gallery and store the URLs in imgDatas.
        async aboutToAppear() {
          this.getAllImg();
        }
        // Use the URL of imgDatas to load the image.
        build() {
          Column() {
            Grid() {
              ForEach(this.imgDatas, item => {
                GridItem() {
                  Image(item)
                    .width(200)
                }
              }, item => JSON.stringify(item))
            }
          }.width('100%').height('100%')
        }
      }
      ```
  2. Check the format of the URL obtained from the media library:
      ​    
      ```ts
      Image('file://media/5')
      .width(200)
      ```

- base64

  As shown above, the URL format is data:image/[png|jpeg|bmp|webp];base64,[base64 data], in which **[base64 data]** indicates Base64 string data.

  Base64 strings are widely used on web pages for storing pixel data of images.


### Pixel Map

A pixel map is a pixel image obtained after image decoding. For details, see [Image Development](../media/image-overview.md). In the following example, the data returned by the loaded online image is decoded into a pixel map, which is then displayed on the **\<Image>** component.

1. Create a **PixelMap** state variable.

   ```ts
   @State image: PixelMap = undefined;
   ```

2. Reference multimedia.
   Request an online image and implement transcoding to generate a pixel map.

   1. Reference the network access permission and media library permission.
       ​    
       ```ts
       import http from '@ohos.net.http';
       import ResponseCode from '@ohos.net.http';
       import image from '@ohos.multimedia.image';
       ```
   2. Enter the online image address.
       ​    
       ```ts
       http.createHttp().request("https://www.example.com/xxx.png",
         (error, data) => {
           if (error){
             console.error(`http reqeust failed with. Code: ${error.code}, message: ${error.message}`);
           } else {
           }
         }
       )
       ```
   3. Transcode the data returned by the online image address to a pixel map.
       ​    
       ```ts
       let code = data.responseCode;
       if(ResponseCode.ResponseCode.OK === code) {
         let imageSource = image.createImageSource(data.result);
         let options = {
           alphaType: 0,                     // Alpha type.
           editable: false,                  // Whether the image is editable.
           pixelFormat: 3,                   // Pixel format.
           scaleMode: 1,                     // Scale mode.
           size: {height: 100, width: 100}
          }  // Image size.
           imageSource.createPixelMap(options).then((pixelMap) => {
           this.image = pixelMap
       })
       ```
   4. Display the image.
       ​    
       ```ts
       Button ("Get Online Image")
         .onClick(() => {
           this.httpRequest()
         })
       Image(this.image).height(100).width(100)
       ```


## Display the vector image.

The **\<Image>** component can display vector images in SVG format. The supported SVG labels are **svg**, **rect**, **circle**, **ellipse**, **path**, **line**, **polyline**, **polygon**, and **animate**.

You can use the **fillColor** attribute to change the fill color of an SVG image.


```ts
Image($r('app.media.cloud')).width(50)
.fillColor(Color.Blue) 
```

  **Figure 3** Original image 

![screenshot_20230223_141141](figures/screenshot_20230223_141141.png)

  **Figure 4** SVG image after the fill color is set 

![screenshot_20230223_141404](figures/screenshot_20230223_141404.png)


## Adding Attributes

Setting attributes for the **\<Image>** component can spruce up the image with custom effects. The following are examples of common attributes. For details about all attributes, see [Image](../reference/arkui-ts/ts-basic-components-image.md).


### Setting the Image Scale Mode

The **objectFit** attribute is used to scale an image to fit it into a container whose height and width are determined.


```ts
@Entry
@Component
struct MyComponent {
  scroller: Scroller = new Scroller()

  build() {
    Scroll(this.scroller) {
      Row() {
        Image($r('app.media.img_2')).width(200).height(150)
          .border({ width: 1 })
          .objectFit(ImageFit.Contain).margin(15) // The image is scaled with its aspect ratio retained to fit within the display boundaries.
          .overlay('Contain', { align: Alignment.Bottom, offset: { x: 0, y: 20 } })
        Image($r('app.media.ic_img_2')).width(200).height(150)
          .border({ width: 1 })
          .objectFit(ImageFit.Cover).margin(15)
          // The image is scaled with its aspect ratio retained for both sides to be greater than or equal to the display boundaries.
          .overlay('Cover', { align: Alignment.Bottom, offset: { x: 0, y: 20 } })
        Image($r('app.media.img_2')).width(200).height(150)
          .border({ width: 1 })
            // The image is scaled automatically to fit the display area.
          .objectFit(ImageFit.Auto).margin(15)
          .overlay('Auto', { align: Alignment.Bottom, offset: { x: 0, y: 20 } })
      }
      Row() {
        Image($r('app.media.img_2')).width(200).height(150)
          .border({ width: 1 })
          .objectFit(ImageFit.Fill).margin(15)
          // The image is scaled to fill the display area, and its aspect ratio is not retained.
          .overlay('Fill', { align: Alignment.Bottom, offset: { x: 0, y: 20 } })
        Image($r('app.media.img_2')).width(200).height(150)
          .border({ width: 1 })
          // The image content is displayed with its aspect ratio retained. The size is smaller than or equal to the original size.
          .objectFit(ImageFit.ScaleDown).margin(15)
          .overlay('ScaleDown', { align: Alignment.Bottom, offset: { x: 0, y: 20 } })
        Image($r('app.media.img_2')).width(200).height(150)
          .border({ width: 1 })
          // The original size is retained.
          .objectFit(ImageFit.None).margin(15)
          .overlay('None', { align: Alignment.Bottom, offset: { x: 0, y: 20 } })
      }
    }
  }
}
```

![en-us_image_0000001511421240](figures/en-us_image_0000001511421240.png)


### Synchronously Loading Images

Generally, the image loading process is performed asynchronously to avoid blocking the main thread and to streamline UI interaction. In certain cases, however, the image may flicker when refreshed. If this occurs, you can use the **syncLoad** attribute to load the image synchronously to avoid flickering. You are not advised to use this attribute when the image loading takes a long time. Otherwise, the page may fail to respond.


```ts
Image($r('app.media.icon'))
  .syncLoad(true)
```


## Adding Events

By binding the **onComplete** event to the **\<Image>** component, you can obtain necessary information about the image after the image is successfully loaded. You can also bind the **onError** event to obtain error information when the image fails to be loaded.


```ts
@Entry
@Component
struct MyComponent {
  @State widthValue: number = 0
  @State heightValue: number = 0
  @State componentWidth: number = 0
  @State componentHeight: number = 0

  build() {
    Column() {
      Row() {
        Image($r('app.media.ic_img_2'))
          .width(200)
          .height(150)
          .margin(15)
          .onComplete((msg: {
            width: number,
            height: number,
            componentWidth: number,
            componentHeight: number
          }) => {
            this.widthValue = msg.width
            this.heightValue = msg.height
            this.componentWidth = msg.componentWidth
            this.componentHeight = msg.componentHeight
          })
            // If the image fails to be obtained, print the result.
          .onError(() => {
            console.info('load image fail')
          })
          .overlay('\nwidth: ' + String(this.widthValue) + ', height: ' + String(this.heightValue) + '\ncomponentWidth: ' + String(this.componentWidth) + '\ncomponentHeight: ' + String(this.componentHeight), {
            align: Alignment.Bottom,
            offset: { x: 0, y: 60 }
          })
      }
    }
  }
}
```


![en-us_image_0000001511740460](figures/en-us_image_0000001511740460.png)