田辺  亮介

田辺 亮介

1660890306

如何使用 React-easy-crop 處理圖像

圖像處理涉及使用各種方法和技術更改圖像以實現所需的結果。這使您可以專注於圖像方面而忽略其他方面。結果,圖像的縱橫比、形式或大小都會減小。圖像處理在前端應用程序中起著重要作用。

react-easy-crop包是一個免費的開源 JavaScript 庫。它支持作為 URL 或base64字符串的圖像格式(JPEG、PNG 和 GIF)以及 HTML5 支持的視頻格式。它是在前端應用程序中處理圖像/視頻的有效工具。

在本文中,我們的重點是使用 react-easy-crop 處理圖像。我們將創建一個簡單的文件上傳應用程序。裁剪區域的結果將使用 react-easy-crop 支持的以下功能顯示:

  • 拖動功能
  • 縱橫比
  • 裁剪
  • 縮放
  • 作物形狀
  • 旋轉交互

創建我們的 React 應用程序

首先,使用以下命令啟動 React 應用程序。

npx create-react-app easy-crop
 cd easy-crop
 npm i react-easy-crop
 npm i @material-ui/core
 npm start

在開始之前,我們將修改app.css為應用程序添加一些樣式。將下面的代碼塊複製並粘貼到app.css.

.App {
  background-color: #c4c4c4;
  font-family: 'Helvetica Neue', sans-serif;
}

.App-header {
  padding-top: 20px;
  height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start;
  color: #fff;
}

label {
  font-weight: bold;
  padding-left: 10px;
}

button {
  z-index: 2;
  cursor: pointer;
  width: 100%;
  background-color: #000;
  color: #fff;
  padding: 10px 0;
}

.cropped-image {
  height: 600px;
  width: auto;
}

.cropped-image-container {
  margin-top: 20px;
  display: flex;
  flex-direction: column;
}

._coverImage-holder  {
  padding: 25px 40px;
  background-color:black;
  border-radius: 5px;
  cursor: pointer;
  margin-bottom: 20px;
}


.container {
  display: flex;
  flex-direction: column;
  position: relative;
}

.crop-container {
  height: 600px;
  width: 600px;
}

.controls {
  display: flex;
  flex-direction: column;
  width: 600px;
  position: absolute;
  bottom: -15px;
}

設置 react-easy-crop

我們將創建一個名為的組件EasyCrop.js並將下面的代碼塊粘貼到其中。

import React, { useState } from "react";
import Cropper from 'react-easy-crop';

const EasyCrop = () => {
 const [crop, setCrop] = useState({ x: 0, y: 0 });

  return (
    <Cropper
      image="https://cdn.pixabay.com/photo/2016/07/07/16/46/dice-1502706__340.jpg"
      crop={crop}
      onCropChange={setCrop}
    />
  )
}

export default EasyCrop;

在深入研究 react-easy-crop 支持的功能之前,我們將App.js使用下面的代碼塊更新我們的組件。

import EasyCrop from "./EasyCrop";

function App() {
  return (
    <div className="App">
      <header className="App-header">
        <EasyCrop  />
      </header>
    </div>
  );
}

export default App;

drag功能默認啟用。展望未來,我們將實現 react-easy-crop 必須提供的其他功能。

1 拖動

縱橫比

縱橫比代表圖像的寬度和高度。可以通過將aspectprop 添加到Cropper組件來對其進行操作。

prop 的值語法是width/height,它的默認值是4/3.

我們將修改5/5我們的“Cropper”組件的值。

<Cropper
  image="https://cdn.pixabay.com/photo/2016/07/07/16/46/dice-1502706__340.jpg"
  crop={crop}
  aspect={5 / 5}
  onCropChange={setCrop}
/>

2 縱橫比

作物形狀

可以通過添加cropShape道具來改變圖像形狀。這個道具接受一串rector round。默認值為rect; 為了使圖像變圓,我們將 的值更改cropShaperound

<Cropper
  image="https://cdn.pixabay.com/photo/2016/07/07/16/46/dice-1502706__340.jpg"
  crop={crop}
  aspect={4 / 4}
  cropShape="round"
  onCropChange={setCrop}
/>

3 作物形狀

飛漲

為了激活縮放功能,react-easy-crop 提供了五個道具。這些道具包括zoom, zoomWithScroll, zoomSpeed, minZoom, 和maxZoom.

import React, { useState } from "react";
import Slider from "@material-ui/core/Slider";
import Cropper from "react-easy-crop";

const EasyCrop = () => {
  const [crop, setCrop] = useState({ x: 0, y: 0 });
  const [zoom, setZoom] = useState(1);

  return (
    <div>
      <div className="crop-container">
        <Cropper
          image="https://cdn.pixabay.com/photo/2016/07/07/16/46/dice-1502706__340.jpg"
          crop={crop}
          zoom={zoom}
          zoomSpeed={4}
          maxZoom={3}
          zoomWithScroll={true}
          showGrid={true}
          aspect={4 / 3}
          onCropChange={setCrop}
          onZoomChange={setZoom}
        />
      </div>
      <div className="controls">
        <label>
          Zoom
          <Slider
            value={zoom}
            min={1}
            max={3}
            step={0.1}
            aria-labelledby="zoom"
            onChange={(e, zoom) => setZoom(zoom)}
            className="range"
          />
        </label>
      </div>
    </div>
  );
};

export default EasyCrop;

4 縮放

迴轉

可以使用兩個道具添加旋轉功能:rotationonRotationChange.

import React, { useState } from "react";
import Slider from "@material-ui/core/Slider";
import Cropper from "react-easy-crop";

  const EasyCrop = () => {
  const [crop, setCrop] = useState({ x: 0, y: 0 });
  const [zoom, setZoom] = useState(1);
  const [rotation, setRotation] = useState(0);

  return (
     <div>
        <div className="crop-container">
          <Cropper
            image='https://cdn.pixabay.com/photo/2016/07/07/16/46/dice-1502706__340.jpg'
            crop={crop}
            rotation={rotation}
            zoom={zoom}
            zoomSpeed={4}
            maxZoom={3}
            zoomWithScroll={true}
            showGrid={true}
            aspect={4 / 3}
            onCropChange={setCrop}
            onZoomChange={setZoom}
            onRotationChange={setRotation}
          />
        </div>
        <div className="controls">
          <label>
            Rotate
            <Slider
              value={rotation}
              min={0}
              max={360}
              step={1}
              aria-labelledby="rotate"
              onChange={(e, rotation) => setRotation(rotation)}
              className="range"
            />
          </label>
        </div>
      </div>
  );
};

export default EasyCrop;
5 旋轉

顯示裁剪圖像

接下來,使用 react-easy-crop 提供的支持功能,我們將在應用程序中實現文件上傳功能以使其動態化。為此,我們將首先創建一個名為Crop.js並粘貼下面的代碼塊的組件。

export const createImage = (url) =>
  new Promise((resolve, reject) => {
    const image = new Image();
    image.addEventListener("load", () => resolve(image));
    image.addEventListener("error", (error) => reject(error));
    image.setAttribute("crossOrigin", "anonymous"); 
    image.src = url;
  });

export function getRadianAngle(degreeValue) {
  return (degreeValue * Math.PI) / 180;
}

export function rotateSize(width, height, rotation) {
  const rotRad = getRadianAngle(rotation);

  return {
    width:
      Math.abs(Math.cos(rotRad) * width) + Math.abs(Math.sin(rotRad) * height),
    height:
      Math.abs(Math.sin(rotRad) * width) + Math.abs(Math.cos(rotRad) * height),
  };
}

export default async function getCroppedImg(
  imageSrc,
  pixelCrop,
  rotation = 0,
  flip = { horizontal: false, vertical: false }
) {
  const image = await createImage(imageSrc);
  const canvas = document.createElement("canvas");
  const ctx = canvas.getContext("2d");

  if (!ctx) {
    return null;
  }

  const rotRad = getRadianAngle(rotation);

  const { width: bBoxWidth, height: bBoxHeight } = rotateSize(
    image.width,
    image.height,
    rotation
  );

  // set canvas size to match the bounding box
  canvas.width = bBoxWidth;
  canvas.height = bBoxHeight;

  ctx.translate(bBoxWidth / 2, bBoxHeight / 2);
  ctx.rotate(rotRad);
  ctx.scale(flip.horizontal ? -1 : 1, flip.vertical ? -1 : 1);
  ctx.translate(-image.width / 2, -image.height / 2);

  ctx.drawImage(image, 0, 0);

  const data = ctx.getImageData(
    pixelCrop.x,
    pixelCrop.y,
    pixelCrop.width,
    pixelCrop.height
  );


  canvas.width = pixelCrop.width;
  canvas.height = pixelCrop.height;

  ctx.putImageData(data, 0, 0);

  return new Promise((resolve, reject) => {
    canvas.toBlob((file) => {
      resolve(URL.createObjectURL(file));
    }, "image/jpeg");
  });
}

後續階段涉及修改EasyCrop.js組件,使圖像道具動態化。

import { useCallback, useState } from "react";
import Slider from "@material-ui/core/Slider";
import Cropper from "react-easy-crop";
import getCroppedImg from "./Crop";

const EasyCrop = ({ image }) => {
  const [crop, setCrop] = useState({ x: 0, y: 0 });
  const [zoom, setZoom] = useState(1);
  const [rotation, setRotation] = useState(0);
  const [croppedAreaPixels, setCroppedAreaPixels] = useState(null);
  const [croppedImage, setCroppedImage] = useState(null);

  const onCropComplete = useCallback((croppedArea, croppedAreaPixels) => {
    setCroppedAreaPixels(croppedAreaPixels);
  }, []);

  const showCroppedImage = useCallback(async () => {
    try {
      const croppedImage = await getCroppedImg(
        image,
        croppedAreaPixels,
        rotation
      );
      console.log("donee", { croppedImage });
      setCroppedImage(croppedImage);
    } catch (e) {
      console.error(e);
    }
  }, [croppedAreaPixels, rotation, image]);

  const onClose = useCallback(() => {
    setCroppedImage(null);
  }, []);

  return (
    <div>
      <button
        style={{
          display: image === null || croppedImage !== null ? "none" : "block",
        }}
        onClick={showCroppedImage}
      >
        Crop
      </button>
      <div
        className="container"
        style={{
          display: image === null || croppedImage !== null ? "none" : "block",
        }}
      >
        <div className="crop-container">
          <Cropper
            image={image}
            crop={crop}
            rotation={rotation}
            zoom={zoom}
            zoomSpeed={4}
            maxZoom={3}
            zoomWithScroll={true}
            showGrid={true}
            aspect={4 / 3}
            onCropChange={setCrop}
            onCropComplete={onCropComplete}
            onZoomChange={setZoom}
            onRotationChange={setRotation}
          />
        </div>
        <div className="controls">
          <label>
            Rotate
            <Slider
              value={rotation}
              min={0}
              max={360}
              step={1}
              aria-labelledby="rotate"
              onChange={(e, rotation) => setRotation(rotation)}
              className="range"
            />
          </label>
          <label>
            Zoom
            <Slider
              value={zoom}
              min={1}
              max={3}
              step={0.1}
              aria-labelledby="zoom"
              onChange={(e, zoom) => setZoom(zoom)}
              className="range"
            />
          </label>
        </div>
      </div>
      <div className="cropped-image-container">
        {croppedImage && (
          <img className="cropped-image" src={croppedImage} alt="cropped" />
        )}
        {croppedImage && <button onClick={onClose}>close</button>}
      </div>
    </div>
  );
};

export default EasyCrop;

此外,我們對組件進行了最終更改App.js,包括文件上傳功能。

import React, { useState } from "react";
import EasyCrop from "./EasyCrop";

function App() {
  const [image, setImage] = useState(null);

  const handleImageUpload = async (e) => {
    setImage(URL.createObjectURL(e.target.files[0]));
  };

  return (
    <div className="App">
      <header className="App-header">
        <label className="_coverImage-holder">
          Upload Image
          <input
            type="file"
            name="cover"
            onChange={handleImageUpload}
            accept="img/*"
            style={{ display: "none" }}
          />
        </label>
        <EasyCrop image={image}  />
      </header>
    </div>
  );
}

export default App;

6 最終輸出

結論

React-easy-crop 在處理 React 應用程序中的圖像方面非常有效。它提供了在更改 Web 圖像時實現所需結果的靈活性。以下是源代碼實時應用程序的鏈接。

鏈接:https ://blog.openreplay.com/image-manipulation-with-react-easy-crop

#react #reactjs #javascript

What is GEEK

Buddha Community

如何使用 React-easy-crop 處理圖像
Autumn  Blick

Autumn Blick

1598839687

How native is React Native? | React Native vs Native App Development

If you are undertaking a mobile app development for your start-up or enterprise, you are likely wondering whether to use React Native. As a popular development framework, React Native helps you to develop near-native mobile apps. However, you are probably also wondering how close you can get to a native app by using React Native. How native is React Native?

In the article, we discuss the similarities between native mobile development and development using React Native. We also touch upon where they differ and how to bridge the gaps. Read on.

A brief introduction to React Native

Let’s briefly set the context first. We will briefly touch upon what React Native is and how it differs from earlier hybrid frameworks.

React Native is a popular JavaScript framework that Facebook has created. You can use this open-source framework to code natively rendering Android and iOS mobile apps. You can use it to develop web apps too.

Facebook has developed React Native based on React, its JavaScript library. The first release of React Native came in March 2015. At the time of writing this article, the latest stable release of React Native is 0.62.0, and it was released in March 2020.

Although relatively new, React Native has acquired a high degree of popularity. The “Stack Overflow Developer Survey 2019” report identifies it as the 8th most loved framework. Facebook, Walmart, and Bloomberg are some of the top companies that use React Native.

The popularity of React Native comes from its advantages. Some of its advantages are as follows:

  • Performance: It delivers optimal performance.
  • Cross-platform development: You can develop both Android and iOS apps with it. The reuse of code expedites development and reduces costs.
  • UI design: React Native enables you to design simple and responsive UI for your mobile app.
  • 3rd party plugins: This framework supports 3rd party plugins.
  • Developer community: A vibrant community of developers support React Native.

Why React Native is fundamentally different from earlier hybrid frameworks

Are you wondering whether React Native is just another of those hybrid frameworks like Ionic or Cordova? It’s not! React Native is fundamentally different from these earlier hybrid frameworks.

React Native is very close to native. Consider the following aspects as described on the React Native website:

  • Access to many native platforms features: The primitives of React Native render to native platform UI. This means that your React Native app will use many native platform APIs as native apps would do.
  • Near-native user experience: React Native provides several native components, and these are platform agnostic.
  • The ease of accessing native APIs: React Native uses a declarative UI paradigm. This enables React Native to interact easily with native platform APIs since React Native wraps existing native code.

Due to these factors, React Native offers many more advantages compared to those earlier hybrid frameworks. We now review them.

#android app #frontend #ios app #mobile app development #benefits of react native #is react native good for mobile app development #native vs #pros and cons of react native #react mobile development #react native development #react native experience #react native framework #react native ios vs android #react native pros and cons #react native vs android #react native vs native #react native vs native performance #react vs native #why react native #why use react native

Mathew Rini

1615544450

How to Select and Hire the Best React JS and React Native Developers?

Since March 2020 reached 556 million monthly downloads have increased, It shows that React JS has been steadily growing. React.js also provides a desirable amount of pliancy and efficiency for developing innovative solutions with interactive user interfaces. It’s no surprise that an increasing number of businesses are adopting this technology. How do you select and recruit React.js developers who will propel your project forward? How much does a React developer make? We’ll bring you here all the details you need.

What is React.js?

Facebook built and maintains React.js, an open-source JavaScript library for designing development tools. React.js is used to create single-page applications (SPAs) that can be used in conjunction with React Native to develop native cross-platform apps.

React vs React Native

  • React Native is a platform that uses a collection of mobile-specific components provided by the React kit, while React.js is a JavaScript-based library.
  • React.js and React Native have similar syntax and workflows, but their implementation is quite different.
  • React Native is designed to create native mobile apps that are distinct from those created in Objective-C or Java. React, on the other hand, can be used to develop web apps, hybrid and mobile & desktop applications.
  • React Native, in essence, takes the same conceptual UI cornerstones as standard iOS and Android apps and assembles them using React.js syntax to create a rich mobile experience.

What is the Average React Developer Salary?

In the United States, the average React developer salary is $94,205 a year, or $30-$48 per hour, This is one of the highest among JavaScript developers. The starting salary for junior React.js developers is $60,510 per year, rising to $112,480 for senior roles.

* React.js Developer Salary by Country

  • United States- $120,000
  • Canada - $110,000
  • United Kingdom - $71,820
  • The Netherlands $49,095
  • Spain - $35,423.00
  • France - $44,284
  • Ukraine - $28,990
  • India - $9,843
  • Sweden - $55,173
  • Singapore - $43,801

In context of software developer wage rates, the United States continues to lead. In high-tech cities like San Francisco and New York, average React developer salaries will hit $98K and $114per year, overall.

However, the need for React.js and React Native developer is outpacing local labour markets. As a result, many businesses have difficulty locating and recruiting them locally.

It’s no surprise that for US and European companies looking for professional and budget engineers, offshore regions like India are becoming especially interesting. This area has a large number of app development companies, a good rate with quality, and a good pool of React.js front-end developers.

As per Linkedin, the country’s IT industry employs over a million React specialists. Furthermore, for the same or less money than hiring a React.js programmer locally, you may recruit someone with much expertise and a broader technical stack.

How to Hire React.js Developers?

  • Conduct thorough candidate research, including portfolios and areas of expertise.
  • Before you sit down with your interviewing panel, do some homework.
  • Examine the final outcome and hire the ideal candidate.

Why is React.js Popular?

React is a very strong framework. React.js makes use of a powerful synchronization method known as Virtual DOM, which compares the current page architecture to the expected page architecture and updates the appropriate components as long as the user input.

React is scalable. it utilises a single language, For server-client side, and mobile platform.

React is steady.React.js is completely adaptable, which means it seldom, if ever, updates the user interface. This enables legacy projects to be updated to the most new edition of React.js without having to change the codebase or make a few small changes.

React is adaptable. It can be conveniently paired with various state administrators (e.g., Redux, Flux, Alt or Reflux) and can be used to implement a number of architectural patterns.

Is there a market for React.js programmers?
The need for React.js developers is rising at an unparalleled rate. React.js is currently used by over one million websites around the world. React is used by Fortune 400+ businesses and popular companies such as Facebook, Twitter, Glassdoor and Cloudflare.

Final thoughts:

As you’ve seen, locating and Hire React js Developer and Hire React Native developer is a difficult challenge. You will have less challenges selecting the correct fit for your projects if you identify growing offshore locations (e.g. India) and take into consideration the details above.

If you want to make this process easier, You can visit our website for more, or else to write a email, we’ll help you to finding top rated React.js and React Native developers easier and with strives to create this operation

#hire-react-js-developer #hire-react-native-developer #react #react-native #react-js #hire-react-js-programmer

Franz  Becker

Franz Becker

1651604400

React Starter Kit: Build Web Apps with React, Relay and GraphQL.

React Starter Kit — "isomorphic" web app boilerplate   

React Starter Kit is an opinionated boilerplate for web development built on top of Node.js, Express, GraphQL and React, containing modern web development tools such as Webpack, Babel and Browsersync. Helping you to stay productive following the best practices. A solid starting point for both professionals and newcomers to the industry.

See getting started guide, demo, docs, roadmap  |  Join #react-starter-kit chat room on Gitter  |  Visit our sponsors:

 

Hiring

Getting Started

Customization

The master branch of React Starter Kit doesn't include a Flux implementation or any other advanced integrations. Nevertheless, we have some integrations available to you in feature branches that you can use either as a reference or merge into your project:

You can see status of most reasonable merge combination as PRs labeled as TRACKING

If you think that any of these features should be on master, or vice versa, some features should removed from the master branch, please let us know. We love your feedback!

Comparison

 

React Starter Kit

React Static Boilerplate

ASP.NET Core Starter Kit

App typeIsomorphic (universal)Single-page applicationSingle-page application
Frontend
LanguageJavaScript (ES2015+, JSX)JavaScript (ES2015+, JSX)JavaScript (ES2015+, JSX)
LibrariesReact, History, Universal RouterReact, History, ReduxReact, History, Redux
RoutesImperative (functional)DeclarativeDeclarative, cross-stack
Backend
LanguageJavaScript (ES2015+, JSX)n/aC#, F#
LibrariesNode.js, Express, Sequelize,
GraphQL
n/aASP.NET Core, EF Core,
ASP.NET Identity
SSRYesn/an/a
Data APIGraphQLn/aWeb API

Backers

♥ React Starter Kit? Help us keep it alive by donating funds to cover project expenses via OpenCollective or Bountysource!

lehneres Tarkan Anlar Morten Olsen Adam David Ernst Zane Hitchcox  

How to Contribute

Anyone and everyone is welcome to contribute to this project. The best way to start is by checking our open issues, submit a new issue or feature request, participate in discussions, upvote or downvote the issues you like or dislike, send pull requests.

Learn More

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  • Babel Starter Kit — Boilerplate for authoring JavaScript/React.js libraries

Support

License

Copyright © 2014-present Kriasoft, LLC. This source code is licensed under the MIT license found in the LICENSE.txt file. The documentation to the project is licensed under the CC BY-SA 4.0 license.


Author: kriasoft
Source Code: https://github.com/kriasoft/react-starter-kit
License: MIT License

#graphql #react 

Juned Ghanchi

1621573085

React Native App Developers India, React Native App Development Company

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To achieve growth for your business, hire react native app developers in India. You can count on us for all the technical services and support.

#react native app development company india #react native app developers india #hire react native developers india #react native app development company #react native app developers #hire react native developers

What are hooks in React JS? - INFO AT ONE

In this article, you will learn what are hooks in React JS? and when to use react hooks? React JS is developed by Facebook in the year 2013. There are many students and the new developers who have confusion between react and hooks in react. Well, it is not different, react is a programming language and hooks is a function which is used in react programming language.
Read More:- https://infoatone.com/what-are-hooks-in-react-js/

#react #hooks in react #react hooks example #react js projects for beginners #what are hooks in react js? #when to use react hooks