react-native-grayscale

A super lightweight react native package that converts an image passed as a base64 string to a base64 string that represents the grayscale version of that image.

This library is compatible with the following platforms:

• Android: ✅ Supported
• iOS: ✅ Supported (Version 17.4)
• React Native: ✅ Supported (Version 0.71.4)

Installation

$ yarn add react-native-grayscale

or

$ npm install react-native-grayscale --save

then,

$ cd ios

$ pod install

done.

Specs

...

import getBase64Grayscale from "react-native-grayscale"

...

getBase64Grayscale(base64)

Parameters	Required	Type	Description
base64	required	string	the base64 string of the image. The prefix data:image/[format];base64, is optional.

Returns	Description
Promise	Returns a promise that will resolve with the base64 string of the grayscale version of the image or will be rejected with an error if the input base64 image is in incorrect format

Example

import React, { useEffect, useState } from "react";
import getBase64Grayscale from "react-native-grayscale";
import { Image, View } from "react-native";

const Test = props => {
  const base64Icon =
    "data:image/png;base64,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";

  const [grayscaleBase64Img, setGrayscaleBase64Img] = useState("");

  useEffect(() => {
    const toGrayscale = async () => {
      const grayscale = await getBase64Grayscale(base64Icon);
      setGrayscaleBase64Img(grayscale);
    };
    toGrayscale();
  }, []);

  return (
    <View>
      <Image
        style={{
          width: 100,
          height: 50,
          borderWidth: 1,
          borderColor: "black"
        }}
        source={{ uri: base64Icon }}
      />
      <Image
        style={{
          width: 100,
          height: 50,
          borderWidth: 1,
          borderColor: "black"
        }}
        source={{ uri: `data:image/png;base64,${grayscaleBase64Img}` }}
      />
    </View>
  );
};

❗ Note that if the base64 is without a prefix data:image/[format];base64, setting the uri property of the source prop at Image will result in the image NOT beeing displayed.