# @ohos.display (Display) (System API)

The **Display** module provides APIs for managing displays, such as obtaining information about the default display, obtaining information about all displays, and listening for the addition and removal of displays.

> **NOTE**
>
> - The initial APIs of this module are supported since API version 7. Newly added APIs will be marked with a superscript to indicate their earliest API version.
>
> - This topic describes only system APIs provided by the module. For details about its public APIs, see [@ohso.display (Display)](js-apis-display.md).

## Modules to Import

```ts
import { display } from '@kit.ArkUI';
```

## display.hasPrivateWindow<sup>9+</sup>

hasPrivateWindow(displayId: number): boolean

Checks whether there is a visible privacy window on a display. The privacy window can be set by calling [setWindowPrivacyMode()](js-apis-window.md#setwindowprivacymode9). The content in the privacy window cannot be captured or recorded.

**System API**: This is a system API.

**System capability**: SystemCapability.WindowManager.WindowManager.Core

**Parameters**

| Name| Type                     | Mandatory| Description      |
| ------ | ------------------------- | ---- |----------|
| id     | number                    | Yes  | ID of the display. The value must be an integer greater than or equal to 0.|

**Return value**

| Type                            | Description                                                                   |
| -------------------------------- |-----------------------------------------------------------------------|
|boolean | Whether there is a visible privacy window on the display.<br>The value **true** means that there is a visible privacy window on the display, and **false** means the opposite.<br>|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Display Error Codes](errorcode-display.md).

| ID| Error Message|
| ------- | -------------------------------------------- |
| 202     | Permission verification failed. A non-system application calls a system API.|
| 401     | Parameter error. Possible causes: 1.Mandatory parameters are left unspecified. 2.Incorrect parameter types. 3.Parameter verification failed.|
| 1400003 | This display manager service works abnormally. |

**Example**

```ts
import { display } from '@kit.ArkUI';

let displayClass: display.Display | null = null;
try {
  displayClass = display.getDefaultDisplaySync();

  let ret: boolean = true;
  try {
    ret = display.hasPrivateWindow(displayClass.id);
  } catch (exception) {
    console.error('Failed to check has privateWindow or not. Code: ' + JSON.stringify(exception));
  }
  if (ret == undefined) {
    console.log("Failed to check has privateWindow or not.");
  }
  if (ret) {
    console.log("There has privateWindow.");
  } else if (!ret) {
    console.log("There has no privateWindow.");
  }
} catch (exception) {
  console.error('Failed to obtain the default display object. Code: ' + JSON.stringify(exception));
}
```

## display.on('privateModeChange')<sup>10+</sup>

on(type: 'privateModeChange', callback: Callback&lt;boolean&gt;): void

Subscribes to privacy mode changes of this display. When there is a privacy window in the foreground of the display, the display is in privacy mode, and the content in the privacy window cannot be captured or recorded.

**System API**: This is a system API.

**System capability**: SystemCapability.WindowManager.WindowManager.Core

**Parameters**

| Name  | Type                                      | Mandatory| Description                                                   |
| -------- |------------------------------------------| ---- | ------------------------------------------------------- |
| type     | string                                   | Yes  | Event type. The value is fixed at 'privateModeChange', indicating the event of display privacy mode changes.|
| callback | Callback&lt;boolean&gt; | Yes  | Callback used to return whether the privacy mode of the display is changed. The value **true** means that the display changes to the privacy mode, and **false** means the opposite.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md).

| ID| Error Message|
| ------- | ----------------------- |
| 202     | Permission verification failed. A non-system application calls a system API.|
| 401     | Parameter error. Possible causes: 1.Mandatory parameters are left unspecified. 2.Incorrect parameter types.|

**Example**

```ts
import { Callback } from '@kit.BasicServicesKit';

let callback: Callback<boolean> = (data: boolean) => {
  console.info('Listening enabled. Data: ' + JSON.stringify(data));
};
try {
  display.on("privateModeChange", callback);
} catch (exception) {
  console.error('Failed to register callback. Code: ' + JSON.stringify(exception));
}
```

## display.off('privateModeChange')<sup>10+</sup>

off(type: 'privateModeChange', callback?: Callback&lt;boolean&gt;): void

Unsubscribes from privacy mode changes of this display. When there is a privacy window in the foreground of the display, the display is in privacy mode, and the content in the privacy window cannot be captured or recorded.

**System API**: This is a system API.

**System capability**: SystemCapability.WindowManager.WindowManager.Core

**Parameters**

| Name  | Type                                      | Mandatory| Description                                                   |
| -------- |------------------------------------------| ---- | ------------------------------------------------------- |
| type     | string                                   | Yes  | Event type. The value is fixed at 'privateModeChange', indicating the event of display privacy mode changes.|
| callback | Callback&lt;boolean&gt; | No  | Callback used to return whether the privacy mode of the display is changed. The value **true** means that the display changes to the privacy mode, and **false** means the opposite.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md).

| ID| Error Message|
| ------- | ----------------------- |
| 202     | Permission verification failed. A non-system application calls a system API.|
| 401     | Parameter error. Possible causes: 1.Mandatory parameters are left unspecified. 2.Incorrect parameter types.|

**Example**

```ts
try {
  display.off("privateModeChange");
} catch (exception) {
  console.error('Failed to unregister callback. Code: ' + JSON.stringify(exception));
}
```

## display.setFoldDisplayMode<sup>10+</sup>
setFoldDisplayMode(mode: FoldDisplayMode): void

Sets the display mode of the foldable device.

**System API**: This is a system API.

**System capability**: SystemCapability.Window.SessionManager

**Parameters**

| Name  | Type                                      | Mandatory| Description                                                   |
| -------- |------------------------------------------| ---- | ------------------------------------------------------- |
| mode     | [FoldDisplayMode](js-apis-display.md#folddisplaymode10)    | Yes  | Display mode.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Display Error Codes](errorcode-display.md).

| ID| Error Message|
| ------- | ----------------------- |
| 202     | Permission verification failed. A non-system application calls a system API.|
| 401     | Parameter error. Possible causes: 1.Mandatory parameters are left unspecified. 2.Incorrect parameter types.|
| 1400003 | This display manager service works abnormally. |

**Example**

```ts
import { display } from '@kit.ArkUI';

try {
  let mode: display.FoldDisplayMode = display.FoldDisplayMode.FOLD_DISPLAY_MODE_FULL;
  display.setFoldDisplayMode(mode);
} catch (exception) {
  console.error('Failed to change the fold display mode. Code: ' + JSON.stringify(exception));
}
```

## display.setFoldStatusLocked<sup>11+</sup>
setFoldStatusLocked(locked: boolean): void

Sets whether to lock the current fold status of the foldable device.

**System API**: This is a system API.

**System capability**: SystemCapability.Window.SessionManager

**Parameters**

| Name  | Type                                      | Mandatory| Description                                                   |
| -------- |------------------------------------------| ---- | ------------------------------------------------------- |
| locked     | boolean    | Yes  | Whether to lock the current fold status of the foldable device. The value **true** means to lock the current fold status, and **false** means the opposite.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Display Error Codes](errorcode-display.md).

| ID| Error Message|
| ------- | ----------------------- |
| 202     | Permission verification failed. A non-system application calls a system API.|
| 401     | Parameter error. Possible causes: 1.Mandatory parameters are left unspecified. 2.Incorrect parameter types.|
| 1400003 | This display manager service works abnormally. |

**Example**

```ts
import { display } from '@kit.ArkUI';

try {
  let locked: boolean = false;
  display.setFoldStatusLocked(locked);
} catch (exception) {
  console.error('Failed to change the fold status locked mode. Code: ' + JSON.stringify(exception));
}
```

## Display
Implements a **Display** instance, with properties and APIs defined.

Before calling any API in **Display**, you must use [getAllDisplays()](js-apis-display.md#displaygetalldisplays9) or [getDefaultDisplaySync()](js-apis-display.md#displaygetdefaultdisplaysync9) to obtain a **Display** instance.

### hasImmersiveWindow<sup>11+</sup>
hasImmersiveWindow(callback: AsyncCallback&lt;boolean&gt;): void

Checks whether this screen contains an immersive window. This API uses an asynchronous callback to return the result.

**System API**: This is a system API.

**System capability**: SystemCapability.Window.SessionManager

**Parameters**

| Name     | Type                       | Mandatory| Description                                                        |
| ----------- | --------------------------- | ---- | ------------------------------------------------------------ |
| callback    | AsyncCallback&lt;boolean&gt;   | Yes  | Callback used to return the result. The value **true** means that the screen contains immersive windows, and **false** means the opposite.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Display Error Codes](errorcode-display.md).

| ID| Error Message|
| ------- | ----------------------- |
| 202     | Permission verification failed. A non-system application calls a system API.|
| 801 | Capability not supported on this device. |
| 1400001 | Invalid display or screen. |
| 1400003 | This display manager service works abnormally. |

**Example**

```ts
import { BusinessError } from '@kit.BasicServicesKit';
import { display } from '@kit.ArkUI';

let displayClass: display.Display | null = null;
displayClass = display.getDefaultDisplaySync();
displayClass.hasImmersiveWindow((err: BusinessError, data) => {
    const errCode: number = err.code;
    if (errCode) {
      console.error('Failed to check whether there is immersive window. Code: ' + JSON.stringify(err));
      return;
    }
    console.info('Succeeded in checking whether there is immersive window. data: ' + JSON.stringify(data));
});
```
### hasImmersiveWindow<sup>11+</sup>
hasImmersiveWindow(): Promise&lt;boolean&gt;

Checks whether this screen contains an immersive window. This API uses a promise to return the result.

**System API**: This is a system API.

**System capability**: SystemCapability.Window.SessionManager

**Return value**

| Type               | Description                     |
| ------------------- | ------------------------- |
| Promise&lt;boolean&gt; | Promise used to return the result. The value **true** means that the screen contains immersive windows, and **false** means the opposite.|

**Error codes**

For details about the error codes, see [Universal Error Codes](../errorcode-universal.md) and [Display Error Codes](errorcode-display.md).

| ID| Error Message|
| ------- | ----------------------- |
| 202     | Permission verification failed. A non-system application calls a system API.|
| 801 | Capability not supported on this device. |
| 1400001 | Invalid display or screen. |
| 1400003 | This display manager service works abnormally. |

**Example**

```ts
import { BusinessError } from '@kit.BasicServicesKit';
import { display } from '@kit.ArkUI';

let displayClass: display.Display | null = null;
displayClass = display.getDefaultDisplaySync();
let promise = displayClass.hasImmersiveWindow();
promise.then((data) => {
  console.info('Succeeded in checking whether there is immersive window. data: ' + JSON.stringify(data));
}).catch((err: BusinessError) => {
  console.error('Failed to check whether there is immersive window. Code: ' + JSON.stringify(err));
})
```