Unable to save captured signature image during saveEvent function in React Native

I am a beginner in the world of React Native and I am facing an issue with saving a signature image. It seems like the function responsible for this task is not being called properly. I suspect there might be an issue with the onPress event handler, as when I include a console.log statement it works fine. There could be something wrong within the function itself. Any help would be greatly appreciated. Thank you.

import SignatureCapture from 'react-native-signature-capture';

this.ref = React.createRef();
this.sign = React.createRef();

saveSign = () => {
  this.refs['sign'].saveImage();
};

_onSaveEvent = (result) => {
  this.checkAndroidPermission(result);
};

checkAndroidPermission = async (result) => {
  if (Platform.OS === 'ios') {
    save(result);
  } else {
    try {
      const granted = await PermissionsAndroid.request(
        PermissionsAndroid.PERMISSIONS.WRITE_EXTERNAL_STORAGE,
      );
      if (granted === PermissionsAndroid.RESULTS.GRANTED) {

        this.save(result);
      } else {
        if (Platform.OS === 'android') {
          ToastAndroid.show('Storage Permission denied.', ToastAndroid.SHORT);
        } else {
          AlertIOS.alert('Storage Permission denied.');
        }
      }
    } catch (err) {
      console.warn('tryerr', err);
    }
  }
};

save = async (result) => {
  const paths = `${RNFetchBlob.fs.dirs.DCIMDir}/${new Date().getTime()}.png`;
  try {
    RNFetchBlob.fs
      .writeFile(paths, result.encoded, 'base64')
      .then((value) => {
        RNFetchBlob.fs
          .scanFile([{ path: paths }])
          .then(() => {
            const file = {
              uri:
                Platform.OS == 'android'
                  ? 'file://' + paths 
                  : paths,
              name: 'sign.png', 
              type: 'image/png', 
            };

            this.setState({ base64: file });
            console.log('scan file success');
            console.log('this is the file ' + JSON.stringify(this.state.base64));
          })
          .catch((err) => {
            console.log('scan file error');
          });
      })
      .catch((e) => console.log(e.message));
  } catch (error) {
    console.log('fileerror', error.message);
  }
};

Please disregard the repeated plea for assistance at the end of the text.

Answer №1

Initially, it seems like there is not enough information provided to give accurate advice without understanding your perspective. I recommend familiarizing yourself with how refs operate for a clearer understanding.

When incorporating refs, ensure you utilize the syntax this.refs.current to access the targeted object.

In addition, while creating a reference using const ref = React.createRef();, in the function saveSign there appears to be a possible typo as this.refs is being accessed. This might lead to errors related to the variable name.

If you are working with a Class-based Component, employing const ref = React.createRef(); is acceptable. However, for a Functional-based Component, utilizing const ref = React.useRef(); is preferred. Although both methods are functional, using createRef in a Functional-based Component could result in unforeseen consequences. Therefore, opting for useRef (a hook) is a more reliable choice.

Based on personal experience, there are some improvements I would suggest implementing in your code. While your current code may function correctly based on the package example, there are more efficient ways of accomplishing the task:

After reviewing the sample code associated with the package you are employing, I propose replacing the ref within the <SignatureCapture /> component with ref={ref}. Subsequently, within the saveSign() function, consider calling this.ref.current.saveImage(); instead of

this.refs["sign"].saveImage();
.

Regarding the <TouchableHighlight> component within the rendering process, it is advisable to structure your onPress callback like this:

onPress={saveSign} and adjust your saveSign() function accordingly:

saveSign = () => {
  this.ref.current.saveImage();
}

If problems persist with certain functions not executing, I recommend troubleshooting potential issues related to function binding, particularly if dealing with a Class-based component.

Answer №2

Here is the resolution. Simply delete the specified line

storeImageInExternalStorage={true}

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