@ohos.arkui.componentSnapshot (Component Snapshot)

The componentSnapshot module provides APIs for obtaining component snapshots, including snapshots of components that have been loaded and snapshots of components that have not been loaded yet. Note that a component snapshot does not contain content drawn outside the area of the owning component or the parent component.

NOTE

The initial APIs of this module are supported since API version 10. Newly added APIs will be marked with a superscript to indicate their earliest API version.

In scenarios where <XComponent> is used to, for example, display video or camera streams, obtain images through surface, instead of through an API in this module.

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Modules to Import

import componentSnapshot from "@ohos.arkui.componentSnapshot";

componentSnapshot.get

get(id: string, callback: AsyncCallback<image.PixelMap>): void

Obtains the snapshot of a component that has been loaded. This API uses an asynchronous callback to return the result.

NOTE

The snapshot captures content rendered in the last frame. If this API is called when the component triggers an update, the re-rendered content will not be included in the obtained snapshot.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Error codes

Example

import componentSnapshot from '@ohos.arkui.componentSnapshot'
import image from '@ohos.multimedia.image'

@Entry
@Component
struct SnapshotExample {
  @State pixmap: image.PixelMap|undefined = undefined

  build() {
    Column() {
      Image(this.pixmap)
        .width(300).height(300)
      // ...Component
      // ...Component
      // ...Component
      Button("click to generate UI snapshot")
        .onClick(() => {
          componentSnapshot.get("root", (error: Error, pixmap: image.PixelMap) => {
                if(error){
                  console.log("error: " + JSON.stringify(error))
                  return;
                }
                this.pixmap = pixmap
                // save pixmap to file
                // ....
             })
        })
    }
    .width('80%')
    .margin({ left: 10, top: 5, bottom: 5 })
    .height(200)
    .border({ color: '#880606', width: 2 })
    .id("root")
  }
}

componentSnapshot.get

get(id: string): Promise<image.PixelMap>

Obtains the snapshot of a component that has been loaded. This API uses a promise to return the result.

NOTE

The snapshot captures content rendered in the last frame. If this API is called when the component triggers an update, the re-rendered content will not be included in the obtained snapshot.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Return value

Error codes

Example

import componentSnapshot from '@ohos.arkui.componentSnapshot'
import image from '@ohos.multimedia.image'

@Entry
@Component
struct SnapshotExample {
  @State pixmap: image.PixelMap|undefined = undefined

  build() {
    Column() {
      Image(this.pixmap)
        .width(300).height(300)
      // ...Component
      // ...Component
      // ...Component
      Button("click to generate UI snapshot")
        .onClick(() => {
          componentSnapshot.get("root")
            .then((pixmap: image.PixelMap) => {
              this.pixmap = pixmap
              // save pixmap to file
              // ....
            }).catch((err:Error) => {
            console.log("error: " + err)
          })
        })
      Image(this.pixmap)
        .margin(10)
        .height(100)
        .width(100)
    }
    .width('80%')
    .margin({ left: 10, top: 5, bottom: 5 })
    .height(200)
    .border({ color: '#880606', width: 2 })
    .id("root")
  }
}

componentSnapshot.createFromBuilder

createFromBuilder(builder: CustomBuilder, callback: AsyncCallback<image.PixelMap>): void

Renders a custom component in the application background and outputs its snapshot. This API uses an asynchronous callback to return the result. The coordinates and size of the offscreen component's drawing area can be obtained through the callback.

NOTE

To account for the time spent in awaiting component building and rendering, the callback of offscreen snapshots has a delay of less than 500 ms.

If a component is on a time-consuming task, for example, an <Image> or <Web> component that is loading online images, its loading may be still in progress when this API is called. In this case, the output snapshot does not represent the component in the way it looks when the loading is successfully completed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Error codes

Example

import componentSnapshot from '@ohos.arkui.componentSnapshot'
import image from '@ohos.multimedia.image'
import componentUtils from '@ohos.arkui.componentUtils'

@Entry
@Component
struct OffscreenSnapshotExample {
  @State pixmap: image.PixelMap | undefined = undefined

  @Builder
  RandomBuilder() {
    Flex({ direction: FlexDirection.Column, justifyContent: FlexAlign.Center, alignItems: ItemAlign.Center }) {
      Text('Test menu item 1')
        .fontSize(20)
        .width(100)
        .height(50)
        .textAlign(TextAlign.Center)
      Divider().height(10)
      Text('Test menu item 2')
        .fontSize(20)
        .width(100)
        .height(50)
        .textAlign(TextAlign.Center)
    }
    .width(100)
    .id("builder")
  }

  build() {
    Column() {
      Button("click to generate offscreen UI snapshot")
        .onClick(() => {
          componentSnapshot.createFromBuilder(()=>{this.RandomBuilder()},
            (error: Error, pixmap: image.PixelMap) => {
              if(error){
                  console.log("error: " + JSON.stringify(error))
                  return;
              }
              this.pixmap = pixmap
              // save pixmap to file
              // ....
              // get component size and location
              let info = componentUtils.getRectangleById("builder")
              console.log(info.size.width + ' ' + info.size.height + ' ' + info.localOffset.x + ' ' + info.localOffset.y + ' ' + info.windowOffset.x + ' ' + info.windowOffset.y)
            })
        })
      Image(this.pixmap)
        .margin(10)
        .height(100)
        .width(100)
    }.width('80%').margin({ left: 10, top: 5, bottom: 5 }).height(200)
    .border({ color: '#880606', width: 2 })
  }
}

componentSnapshot.createFromBuilder

createFromBuilder(builder: CustomBuilder): Promise<image.PixelMap>

Renders a custom component in the application background and outputs its snapshot. This API uses a promise to return the result. The coordinates and size of the offscreen component's drawing area can be obtained through the callback.

NOTE

To account for the time spent in awaiting component building and rendering, the callback of offscreen snapshots has a delay of less than 500 ms.

If a component is on a time-consuming task, for example, an <Image> or <Web> component that is loading online images, its loading may be still in progress when this API is called. In this case, the output snapshot does not represent the component in the way it looks when the loading is successfully completed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Return value

Error codes

Example

import componentSnapshot from '@ohos.arkui.componentSnapshot'
import image from '@ohos.multimedia.image'
import componentUtils from '@ohos.arkui.componentUtils'

@Entry
@Component
struct OffscreenSnapshotExample {
  @State pixmap: image.PixelMap | undefined = undefined

  @Builder
  RandomBuilder() {
    Flex({ direction: FlexDirection.Column, justifyContent: FlexAlign.Center, alignItems: ItemAlign.Center }) {
      Text('Test menu item 1')
        .fontSize(20)
        .width(100)
        .height(50)
        .textAlign(TextAlign.Center)
      Divider().height(10)
      Text('Test menu item 2')
        .fontSize(20)
        .width(100)
        .height(50)
        .textAlign(TextAlign.Center)
    }
    .width(100)
    .id("builder")
  }

  build() {
    Column() {
      Button("click to generate offscreen UI snapshot")
        .onClick(() => {
          componentSnapshot.createFromBuilder(()=>{this.RandomBuilder()})
            .then((pixmap: image.PixelMap) => {
              this.pixmap = pixmap
              // save pixmap to file
              // ....
              // get component size and location
              let info = componentUtils.getRectangleById("builder")
              console.log(info.size.width + ' ' + info.size.height + ' ' + info.localOffset.x + ' ' + info.localOffset.y + ' ' + info.windowOffset.x + ' ' + info.windowOffset.y)
            }).catch((err:Error) => {
            console.log("error: " + err)
          })
        })
    }.width('80%').margin({ left: 10, top: 5, bottom: 5 }).height(200)
    .border({ color: '#880606', width: 2 })
  }
}