如何使用EXPO React Native相机拍摄照片? [英] How to snap pictures using expo react native camera?

问题描述

我刚刚开始在Expo上使用React Native，所以我有点困惑.因此，我制作了一个相机组件，并在主屏幕中导入了该组件.一切看起来都很好.但是我不能拍照.我无法单击捕捉图标并保存图像.有没有我错过的组件? 我只在下面发布了CameraComponent类.

I have just started using React Native with Expo so I am kind of confused. So, I have made a camera component which I imported in the main screen. Everything looks good. But I can't take pictures. I cannot click the snap icon and save the image. Is there a component that I missed? I have only posted the CameraComponent class below.

Camera.js

class CameraComponent extends Component {

  state = {
    hasCameraPermission: null,
    type: Camera.Constants.Type.back
  }

  async componentWillMount() {
    const { status } = await Permissions.askAsync(Permissions.CAMERA);
    this.setState({ hasCameraPermission: status === 'granted' })
  }

  render() {
    const { hasCameraPermission } = this.state

    if (hasCameraPermission === null) {
      return <View />
    }
    else if (hasCameraPermission === false) {
      return <Text> No access to camera</Text>
    }
    else {
      return (
        <View style={{ flex: 1 }}>
          <Camera 
            style={{ flex: 1, justifyContent: 'space-between' }}
            type={this.state.type}
          >
            <Header
              searchBar
              rounded
              style={{
                position: 'absolute',
                backgroundColor: 'transparent',
                left: 0,
                top: 0,
                right: 0,
                zIndex: 100,
                alignItems: 'center'
              }}
            >
              <View style={{ flexDirection: 'row', flex: 4 }}>
                <Ionicons name="md-camera" style={{ color: 'white' }} />
                <Item style={{ backgroundColor: 'transparent' }}>
                  <Icon name="ios-search" style={{ color: 'white', fontSize: 24, fontWeight: 'bold' }}></Icon>
                </Item>
              </View>

              <View style={{ flexDirection: 'row', flex: 2, justifyContent: 'space-around' }}>
                <Icon name="ios-flash" style={{ color: 'white', fontWeight: 'bold' }} />
                <Icon
                  onPress={() => {
                    this.setState({
                      type: this.state.type === Camera.Constants.Type.back ?                                        
                                            Camera.Constants.Type.front :
                                            Camera.Constants.Type.back
                    })
                  }}
                  name="ios-reverse-camera"
                  style={{ color: 'white', fontWeight: 'bold' }}
                />
              </View>
            </Header>

            <View style={{ flexDirection: 'row', justifyContent: 'space-between', paddingHorizontal: 30, marginBottom: 15, alignItems: 'flex-end' }}>
              <Ionicons name="ios-map" style={{ color: 'white', fontSize: 36 }}></Ionicons>
              <View></View>
              <View style={{ alignItems: 'center' }}>
                <MaterialCommunityIcons name="circle-outline"   // This is the icon which should take and save image
                  style={{ color: 'white', fontSize: 100 }}
                ></MaterialCommunityIcons>
                <Icon name="ios-images" style={{ color: 'white', fontSize: 36 }} />
              </View>
            </View>
          </Camera>
        </View>
      )
    }
  }
}

export default CameraComponent;

位于中心的图标(即圆圈图标)应自动拍摄并保存图像.

The icon in the center i;e circle icon should automatically take and save image.

推荐答案

当异步takePictureAsync函数返回时，可以使用"onPictureSaved"，以便抓取照片对象:

You can use "onPictureSaved" when the asynchronous takePictureAsync function returns so that you can grab the photo object:

  takePicture = () => {
      if (this.camera) {
          this.camera.takePictureAsync({ onPictureSaved: this.onPictureSaved });
      }
   };

  onPictureSaved = photo => {
      console.log(photo);
  } 

在视图中，您将有一个带参考的Camera组件:

In the view you would have a Camera component that has a ref:

<Camera style={styles.camera} type={this.state.type} ref={(ref) => { this.camera = ref }} >

还有一个在按下时将调用takePicture函数的按钮:

As well as a button that will call the takePicture function on press:

<TouchableOpacity style={styles.captureButton} onPress={this.takePicture} />

这篇关于如何使用EXPO React Native相机拍摄照片?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！