How to implement image compression function in uniapp

How to implement image compression function in uniapp

1. Introduction
In modern society, pictures have become an indispensable part of people's daily lives. However, with the popularization of mobile phone camera functions and the improvement of photo pixels, the file size of pictures is also growing. This will not only occupy the phone's memory, but also cause the image to take a long time to load during network transmission. Therefore, image compression has become one of the important tasks for developers.

2. Image compression in uniapp
Uniapp is a cross-platform development framework based on Vue.js, which can be used to develop WeChat applets, H5, APP and other applications. It provides a rich API and components to meet the needs of developers, including image compression functions.

In uniapp, you can use the uni.compressImage method to compress images. This method can receive three parameters: sourcePath, targetPath and quality.

1. sourcePath: Indicates the path of the original image, which can be a local path or a network path.
2. targetPath: Indicates the compressed image saving path. If this parameter is not set, it will be saved in a temporary folder by default.
3. quality: Indicates compression quality, the value range is 0-100, and the default value is 80. Higher numbers mean better quality, but will also increase file size.

The following is a sample code that demonstrates how to use the image compression function in uniapp:

// 在vue文件中使用图片压缩功能
<template>
  <view>
    <button @click="compressImage">压缩图片</button>
  </view>
</template>

<script>
export default {
  methods: {
    // 图片压缩方法
    compressImage() {
      uni.chooseImage({
        count: 1,
        success: (res) => {
          const tempFilePath = res.tempFilePaths[0]
          uni.compressImage({
            src: tempFilePath,
            quality: 80,
            success: (res) => {
              console.log('压缩成功', res.tempFilePath)
            },
            fail: (error) => {
              console.log('压缩失败', error)
            }
          })
        }
      })
    }
  }
}
</script>

In the above code, first select an image through the uni.chooseImage method, and Get its temporary file path. Then, use the uni.compressImage method to compress the image and set the compression quality to 80. After the compression is successful, the compressed image path will be returned.

3. Notes
During the development process, you need to pay attention to the following points:

1. Before using the uni.compressImage method, you need to introduce the uni-api module. It can be introduced using import at the top of the page script, or globally in the pages.json configuration file.
2. Compression operations may consume more CPU and memory resources. If the compressed images are too large, the operation may fail or freeze. Therefore, it is recommended to set appropriate compression quality and size in actual use to avoid problems.
3. In uniapp, although you can use the uni.compressImage method to compress images, since the underlying implementation of uniapp is different from native development, the compression effect may be slightly different. If you need higher compression effects, it is recommended to use native development or third-party libraries for image compression.

4. Summary
Through the uni.compressImage method in uniapp, we can easily implement the function of compressing images. In actual development, we can set appropriate compression quality and parameters according to needs to achieve the best effect of balancing image quality and file size. At the same time, you also need to pay attention to the performance issues that may be caused by the compression process to avoid operation failures or lags.

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