!1814 Done! 1677:修改display接口资料，增加screenshot接口资料

Merge pull request !1814 from wusongqing/TR1677

en/application-dev/reference/apis/js-apis-screenshot.md

+# Screenshot
+
+> ![icon-note.gif](public_sys-resources/icon-note.gif) **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.
+
+## Modules to Import
+
+```
+import screenshot from '@ohos.screenshot';
+```
+
+## ScreenshotOptions
+
+Describes screenshot options.
+
+| Name| Type| Mandatory| Description|
+| ---------- | ------------- | ---- | ------------------------------------------------------------ |
+| screenRect | [Rect](#Rect) | No| Region of the screen to capture. If this parameter is null, the full screen will be captured. <br/>**System capabilities**: SystemCapability.WindowManager.WindowManager.Core|
+| imageSize  | [Size](#Size) | No| Size of the screen region to capture. If this parameter is null, the full screen will be captured. <br/>**System capabilities**: SystemCapability.WindowManager.WindowManager.Core|
+| rotation   | number        | No| Rotation angle of the screenshot. The value can be **0**, **90**, **180**, or **270**. The default value is **0**. <br/>**System capabilities**: SystemCapability.WindowManager.WindowManager.Core|
+
+
+## Rect
+
+Describes the region of the screen to capture.
+
+| Name| Type| Mandatory| Description|
+| ------ | ------ | ---- | ------------------------------------------------------------ |
+| left   | number | Yes| Left boundary of the screen region to capture. <br/>**System capabilities**: SystemCapability.WindowManager.WindowManager.Core|
+| top    | number | Yes| Top boundary of the screen region to capture. <br/>**System capabilities**: SystemCapability.WindowManager.WindowManager.Core|
+| width  | number | Yes| Width of the screen region to capture. <br/>**System capabilities**: SystemCapability.WindowManager.WindowManager.Core|
+| height | number | Yes| Height of the screen region to capture. <br/>**System capabilities**: SystemCapability.WindowManager.WindowManager.Core|
+
+
+## Size
+
+Describes the size of the screen region to capture.
+
+| Name| Type| Mandatory| Description|
+| ------ | ------ | ---- | ------------------------------------------------------------ |
+| width  | number | Yes| Width of the screen region to capture. <br/>**System capabilities**: SystemCapability.WindowManager.WindowManager.Core|
+| height | number | Yes| Height of the screen region to capture. <br/>**System capabilities**: SystemCapability.WindowManager.WindowManager.Core|
+
+## screenshot.save
+
+save(options?: ScreenshotOptions, callback: AsyncCallback&lt;image.PixelMap&gt;): void
+
+Takes a screenshot and saves it as a **PixelMap** object. This method uses a callback to return the result.
+
+**System capabilities**: SystemCapability.WindowManager.WindowManager.Core
+
+**Required permissions**: ohos.permission.CAPTURE_SCREEN
+
+- Parameters
+
+  | Name| Type| Mandatory| Description|
+  | -------- | --------------------------------------- | ---- | ------------------------------------------------------------ |
+  | options  | [ScreenshotOptions](#ScreenshotOptions) | No| Screenshot options, which consist of **screenRect**, **imageSize**, and **rotation**. You need to set these parameters.|
+  | callback | AsyncCallback&lt;image.PixelMap&gt;     | Yes| Callback used to return a **PixelMap** object.|
+
+- Example
+
+  ```
+  var ScreenshotOptions = {
+  	"screenRect": {
+  		"left": 200,
+  		"top": 100,
+  		"width": 200,
+  		"height": 200},
+  	"imageSize": {
+  		"width": 300,
+  		"height": 300},
+  	"rotation": 0
+  };
+  screenshot.save(ScreenshotOptions, (err, data) => {
+  	if (err) {
+  		console.error('Failed to save the screenshot. Error: ' + JSON.stringify(err));
+  		return;
+  	}
+  	console.info('Screenshot saved. Data: ' + JSON.stringify(data));
+  });
+  ```
+
+## screenshot.save
+
+save(options?: ScreenshotOptions): Promise&lt;image.PixelMap&gt;
+
+Takes a screenshot and saves it as a **PixelMap** object. This method uses a promise to return the result.
+
+**System capabilities**: SystemCapability.WindowManager.WindowManager.Core
+
+**Required permissions**: ohos.permission.CAPTURE_SCREEN
+
+- Parameters
+
+  | Name| Type| Mandatory| Description|
+  | ------- | --------------------------------------- | ---- | ------------------------------------------------------------ |
+  | options | [ScreenshotOptions](#ScreenshotOptions) | No| Screenshot options, which consist of **screenRect**, **imageSize**, and **rotation**. You need to set these parameters.|
+
+- Return value
+
+  | Type| Description|
+  | ----------------------------- | ----------------------------------------------- |
+  | Promise&lt;image.PixelMap&gt; | Promise used to return an **image.PixelMap** object.|
+
+- Example
+
+  ```
+  var ScreenshotOptions = {
+  	"screenRect": {
+  		"left": 200,
+  		"top": 100,
+  		"width": 200,
+  		"height": 200},
+  	"imageSize": {
+  		"width": 300,
+  		"height": 300},
+  	"rotation": 0
+  };
+  let promise = screenshot.save(ScreenshotOptions);
+  promise.then(() => {
+      console.log('screenshot save success');
+  }).catch((err) => {
+      console.log('screenshot save fail: ' + JSON.stringify(err));
+  });
+  ```