> - The APIs of this module are no longer maintained since API version 7. You are advised to use the new APIs specified in the API descriptions.
>
> - 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.
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.
| 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.
| 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.
| 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(104,857,600) // 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.
| value | number | No| Size of the image file cache, in bytes.|
**Example**
```
// app.ets
import app from '@system.app';
export default {
onCreate() {
app.setImageFileCacheSize(209,715,200) // 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|
> 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 mediaquery from '@system.mediaquery';
```
## mediaquery.matchMedia
matchMedia(condition: string): MediaQueryList
Creates a **MediaQueryList** object based on the query condition.
Adds a listener for this **MediaQueryList** object. The listener must be added before **onShow** is called, that is, it must be added in the **onInit** or **onReady** API.
> - 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.
> - The APIs of this module are no longer maintained since API version 8. You are advised to use ['@ohos.router'](js-apis-router.md) instead.
| uri | string | Yes| URI of the destination page, in either of the following formats:<br>1. Absolute path, which is provided by the **pages** list in the **config.json** file. Example:<br>- pages/index/index<br> -pages/detail/detail<br>2. Specific path. If the URI is a slash (/), the home page is displayed.|
| params | Object | No| Data that needs to be passed to the destination page during redirection. After the destination page is displayed, it can use the passed data, for example, **this.data1** (**data1** is a key in **params**). If there is the same key (for example, **data1**) on the destination page, the passed **data1** value will replace the original value on the destination page.|
## BackRouterOptions
Defines the parameters for routing back.
**System capability**: The items in the table below require different system capabilities. For details, see the table.
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| uri | string | No| URI of the page to return to. If the specified page does not exist in the page stack, the application does not respond. If this parameter is not set, the application returns to the previous page.<br>**System capability**: SystemCapability.ArkUI.ArkUI.Full|
| params | Object | No| Data that needs to be passed to the destination page during redirection.<br>**System capability**: SystemCapability.ArkUI.ArkUI.Lite|
