Design and development practice of UniApp for image processing and image uploading

UniApp (Universal Application) is a cross-platform application development framework, an integrated solution developed based on Vue.js and Dcloud. It supports writing once and running on multiple platforms, enabling rapid development of high-quality mobile applications. In this article, we will introduce how to use UniApp to implement the design and development practice of image processing and image uploading.

1. Design and development of image processing

In mobile application development, image processing is a common requirement. UniApp provides some built-in components and APIs to implement image processing. The following takes image cropping and compression as an example to show how to use UniApp to design and develop image processing.

1.1 Image cropping

UniApp provides the uni.cropImage() method to implement the image cropping function. This method needs to pass in the temporary path of the image and the position and size of the cropping box, and returns the cropped image path.

<template>
  <view>
    <image :src="imgPath"></image>
    <button @click="cropImage">裁剪图片</button>
  </view>
</template>

<script>
export default {
  data() {
    return {
      imgPath: ""
    }
  },
  methods: {
    cropImage() {
      uni.chooseImage({
        count: 1,
        success: (res) => {
          uni.cropImage({
            src: res.tempFilePaths[0],
            success: (res) => {
              this.imgPath = res.tempImagePath;
            }
          });
        }
      });
    }
  }
}
</script>

In the above code, click the button to trigger the cropImage() method. First use the uni.chooseImage() method to select an image, then call the uni.cropImage() method to crop, and finally the cropped image Assign the path to imgPath to display the cropped image.

1.2 Image Compression

Image compression is to reduce the file size of images, improve image loading speed and save user traffic. UniApp provides the uni.compressImage() method to implement image compression function. This method needs to pass in the temporary path of the image and the quality of compression, and returns the compressed image path.

<template>
  <view>
    <image :src="imgPath"></image>
    <button @click="compressImage">压缩图片</button>
  </view>
</template>

<script>
export default {
  data() {
    return {
      imgPath: ""
    }
  },
  methods: {
    compressImage() {
      uni.chooseImage({
        count: 1,
        success: (res) => {
          uni.compressImage({
            src: res.tempFilePaths[0],
            quality: 80,
            success: (res) => {
              this.imgPath = res.tempFilePath;
            }
          });
        }
      });
    }
  }
}
</script>

In the above code, click the button to trigger the compressImage() method. First, use the uni.chooseImage() method to select an image, then call the uni.compressImage() method to compress, and finally compress the compressed image. Assign the path to imgPath to display the compressed image.

2. Design and development of image uploading

Image uploading is another common requirement in mobile application development. UniApp provides the uni.chooseImage() method to select images and the uni.uploadFile() method to upload images. The following takes image upload as an example to show how to use UniApp to design and develop image upload.

<template>
  <view>
    <image :src="imgPath"></image>
    <button @click="chooseImage">选择图片</button>
    <button @click="uploadImage">上传图片</button>
  </view>
</template>

<script>
export default {
  data() {
    return {
      imgPath: ""
    }
  },
  methods: {
    chooseImage() {
      uni.chooseImage({
        count: 1,
        success: (res) => {
          this.imgPath = res.tempFilePaths[0];
        }
      });
    },
    uploadImage() {
      uni.uploadFile({
        url: "http://example.com/upload",
        filePath: this.imgPath,
        name: "image",
        formData: {
          user: "John"
        },
        success: (res) => {
          console.log(res.data);
        }
      });
    }
  }
}
</script>

In the above code, click the select image button to trigger the chooseImage() method, use the uni.chooseImage() method to select a picture, and assign the temporary path of the picture to imgPath to display the selected picture. Click the upload image button to trigger the uploadImage() method, and call the uni.uploadFile() method to upload the image. You need to pass in the temporary path of the image, uploaded URL, file name and other form data. After the upload is successful, print the returned data.

The above are the specific steps and code examples of using UniApp to implement the design and development practice of image processing and image uploading. Through the components and API provided by UniApp, the functions of image processing and image uploading can be easily realized. I hope this article will be helpful to UniApp application development.

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