旋转图像并保存在 React-Native

Question

我要在 react-native 中旋转图像，我想得到旋转图像的 base64。 我用了几个库

1. react-native-image-rotate：它在 Android 上运行良好，但在 iOS 上我得到 rct-image-store://1 作为 url，所以我尝试使用 rn-fetch-blob 获取 base64，但它会引发无法识别该 url 的错误。

2. react-native-image-resizer：我用过这个但是在iOS中反应不好。如果我设置-90然后旋转-180，如果我设置-180那么它旋转为-270。

请帮我解决这个问题，如何在 iOS 中旋转图像。

我需要将图像旋转为 -90、-180、-270、-360（原始）。

Answer 1

终于找到答案了。

import ImageRotate from 'react-native-image-rotate';
import ImageResizer from 'react-native-image-resizer';
import RNFetchBlob from 'rn-fetch-blob';

ImageRotate.rotateImage(
        this.state.image.uri,
        rotateDegree,
        uri => {
          if (Platform.OS === 'android') {
            console.log('rotate', uri);
            RNFetchBlob.fs.readFile(uri, 'base64').then(data => {
              const object = {};
              object.base64 = data;
              object.width = this.state.image.height;
              object.height = this.state.image.width;
              object.uri = uri;
              this.setState({image: object, spinner: false});
            });
          } else {
            console.log(uri);
            const outputPath = `${RNFetchBlob.fs.dirs.DocumentDir}`;

            ImageResizer.createResizedImage(
              uri,
              this.state.image.height,
              this.state.image.width,
              'JPEG',
              100,
              0,
              outputPath,
            ).then(response => {
              console.log(response.uri, response.size);
              let imageUri = response.uri;
              if (Platform.OS === 'ios') {
                imageUri = imageUri.split('file://')[1];
              }
              RNFetchBlob.fs.readFile(imageUri, 'base64').then(resData => {
                const object = {};
                object.base64 = resData;
                object.width = this.state.image.height;
                object.height = this.state.image.width;
                object.uri = response.uri;
                this.setState({image: object, spinner: false});
              });
            });
          }
        },
        error => {
          console.error(error);
        },
      );
    }

Answer 2

这是我目前为止工作良好的代码

  rotateImage = (angle) => {
    const { currentImage } = this.state; // origin Image, you can pass it from params,... as you wish
    ImageRotate.rotateImage( // using 'react-native-image-rotate'
      currentImage.uri,
      angle,
      (rotatedUri) => {
        if (Platform.OS === 'ios') {
          ImageStore.getBase64ForTag( // import from react-native 
            rotatedUri,
            (base64Image) => {
              const imagePath = `${RNFS.DocumentDirectoryPath}/${new Date().getTime()}.jpg`;
              RNFS.writeFile(imagePath, `${base64Image}`, 'base64') // using 'react-native-fs'
                .then(() => {
                  // now your file path is imagePath (which is a real path)
                  if (success) {
                    this.updateCurrentImage(imagePath, currentImage.height, currentImage.width);
                    ImageStore.removeImageForTag(rotatedUri);
                  }
                })
                .catch(() => {});
            },
            () => {},
          );
        } else {
          this.updateCurrentImage(rotatedUri, currentImage.height, currentImage.width);
        }
      },
      (error) => {
        console.error(error);
      },
    );
  };

我想你已经完成了rotatedUri。

• 那么你可以通过ImageStore从react-native获取base64。
• 然后用react-native-fs写入本地镜像

之后你有imagePath 是本地图像。

Answer 3

尝试使用 Expo Image Manipulator https://docs.expo.io/versions/latest/sdk/imagemanipulator/

  const rotated = await ImageManipulator.manipulateAsync(
    image.uri,
    [{ rotate: -90 }],
    { base64: true }
  );