js-apis-system-app.md

# Application Context

> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**
> - The APIs of this module are no longer maintained since API version 7. You are advised to use the new APIs.
> 
> - The initial APIs of this module are supported since API version 3. Newly added APIs will be marked with a superscript to indicate their earliest API version.


## Modules to Import


```
import app from '@system.app';
```


## app.getInfo

getInfo(): AppResponse

Obtains the declared information in the **config.json** file of an application.

> **Note: ** [`@ohos.bundle`](js-apis-Bundle.md) is recommended from API version 7.

**System capability**: SystemCapability.ArkUI.ArkUI.Lite

**Return value**

| Type| Description|
| -------- | -------- |
| [AppResponse](#appresponse) | Application response information.|

**Example**

  ```
  export default {    
    getInfo(){        
      var info = app.getInfo();        
        console.log(JSON.stringify(info));    
    } 
  }
  ```

## app.terminate

terminate(): void

Terminates the current ability.

> **Note: ** [`@ohos.ability.featureAbility`](js-apis-featureAbility.md) is recommended from API version 7.

**System capability**: SystemCapability.ArkUI.ArkUI.Lite

**Example**

  ```
  export default {    
    terminate(){        
      app.terminate();    
    }}
  ```
## app.requestFullWindow

requestFullWindow(options?: RequestFullWindowOptions): void

Requests the application to run in full window. You can call this API when the FA runs in a non-full window, for example, semi-modal FA. This API is invalid for an application already in full-window mode.

This is a system API and cannot be called by third-party applications.

> **Note: ** [`@ohos.window`](js-apis-window.md) is recommended from API version 7.

**System capability**: SystemCapability.ArkUI.ArkUI.Full

**Parameters**
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| options | [RequestFullWindowOptions](#requestfullwindowoptions) | No| Duration for transition from the non-full window to the full window, in milliseconds. By default, the value is in direct proportion to the distance between the non-full window and the full window.|

**Example**

  ```
  export default {    
    requestFullWindow(){        
      app.requestFullWindow({            
        duration: 200});    
    }
  }
  ```

## app.setImageCacheCount<sup>7+</sup>

setImageCacheCount(value: number): void

Sets the maximum number of decoded images that can be cached in the memory to speed up the loading of images from the same sources. If the input parameter is not set, the default value **0** is used, indicating that images are not cached. The built-in Least Recently Used (LRU) policy is used for caching. If the maximum number is exceeded, the images that have not been updated for the longest time will be removed. You are advised to set the parameter based on the application memory requirements. If the number of images is too large, the memory usage may be too high.

**System capability**: SystemCapability.ArkUI.ArkUI.Full

**Parameters**
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| value | number | No| Number of decoded images that are cached in the memory.|

**Example**

  ```
  // app.ets
  import app from '@system.app';
  
  export default {
      onCreate() { 
          app.setImageCacheCount(100)    // Set the maximum number of decoded images that can be cached in the memory to 100.
          console.info('Application onCreate')
      },
      onDestroy() {
          console.info('Application onDestroy')
      },
  }
  ```

## app.setImageRawDataCacheSize<sup>7+</sup>

setImageRawDataCacheSize(value: number): void

Sets the maximum size (in bytes) of the image data cached in the memory before decoding to speed up the loading of images from the same sources. If the input parameter is not set, the default value **0** is used, indicating that images are not cached. The LRU policy is used for caching. If the maximum size is exceeded, the images that have not been updated for the longest time will be removed. You are advised to set the parameter based on the application memory requirements. If the image cache is too large, the memory usage may be too high.

**System capability**: SystemCapability.ArkUI.ArkUI.Full

**Parameters**
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| value | number | No| Size of the image data cached before decoding, in bytes.|

**Example**

  ```
  // app.ets
  import app from '@system.app';
  
  export default {
      onCreate() {
          app.setImageRawDataCacheSize(100) // Set the upper limit of the memory for caching image data before decoding to 100 MB.
          console.info('Application onCreate')
      },
      onDestroy() {
          console.info('Application onDestroy')
      },
  }
  ```

## app.setImageFileCacheSize<sup>7+</sup>

setImageFileCacheSize(value: number): void

Sets the maximum size of the image file cache (in bytes) to speed up the loading of images from the same sources, especially online image sources and thumbnails. If the input parameter is not set, the default value 100 MB is used. The LRU policy is used for caching. If the maximum size is exceeded, the images that have not been updated for the longest time will be removed. You are advised to set the parameter based on the application memory requirements. If the image cache is too large, the disk usage may be too high.

**System capability**: SystemCapability.ArkUI.ArkUI.Full

**Parameters**
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| value | number | No| Size of the image file cache, in bytes.|

**Example**

  ```
  // app.ets
  import app from '@system.app';
  
  export default {  
      onCreate() {    
          app.setImageFileCacheSize(200) // Set the upper limit of the image file cache to 200 MB.  
          console.info('Application onCreate')
      },  
      onDestroy() {
          console.info('Application onDestroy')
      },
  }
  ```

## AppResponse

Defines the application response information.

**System capability**: The items in the table below require different system capabilities. For details, see the table.

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- |-------- |
| appID<sup>6+</sup> | string | Yes| Bundle name of an application. It uniquely identifies the application.<br> **System capability**: SystemCapability.ArkUI.ArkUI.Full|
| appName | string | Yes| Application name.<br> **System capability**: SystemCapability.ArkUI.ArkUI.Lite|
| versionName | string | Yes| Application version name.<br> **System capability**: SystemCapability.ArkUI.ArkUI.Lite|
| versionCode | number | Yes| Application version number.<br> **System capability**: SystemCapability.ArkUI.ArkUI.Lite|

## ScreenOnVisibleOptions

Defines the options of the visible interface on the screen.

**System capability**: SystemCapability.ArkUI.ArkUI.Full

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| visible | boolean | No| Whether to keep the application visible. The default value is **false**.|
| success | () => void | No| Callback upon success.|
| fail | (data: string, code: number) => void | No| Callback upon failure.|
| complete | () => void | No| Called when the API call is complete.|

## RequestFullWindowOptions

Defines the options of the **RequestFullWindow** API.

**System capability**: SystemCapability.ArkUI.ArkUI.Full

| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| duration | number | Yes| Number of animation options.|