WeChat applet implements image cropping function

WeChat Mini Program implements image cropping function

With the rapid development of WeChat Mini Programs, more and more developers are beginning to explore the potential of Mini Programs. Among them, image processing function is one of the common requirements in small programs. This article will introduce how to implement the image cropping function in the WeChat applet and provide specific code examples to help developers quickly implement this function.

1. Preparation
   Before we start writing code, we need to do some preparations. First, you need to have a WeChat applet development environment. If you don't have it yet, you can download and install the WeChat developer tools first.

Next, we need to introduce an image cropping plug-in into the mini program project to facilitate us to implement the image cropping function. It is recommended to use the wx-cropper plug-in, which is a powerful and easy-to-use image cropping plug-in.

2. Introducing plug-ins
   Open your mini program project in WeChat developer tools, then find the project.config.json file in the project root directory, and add the following code to it In the "plugins" field of the file:

   {
     "plugins": {
    "wx-cropper": {
      "version": "1.0.0",
      "provider": "wx9d4f990abcde1234"
    }
     }
   }

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Then, in the json file of the page that uses the image cropping function, introduce the components provided by the plug-in:

{
  "usingComponents": {
    "wx-cropper": "plugin://wx-cropper/wx-cropper"
  }
}

3. Implementing the image cropping function
   In the wxml file of the page, add a button for selecting images, and add a wx-cropper component for displaying and cropping images:

   <view>
     <button bindtap="chooseImage">选择图片</button>
     <wx-cropper src="{{croppedImageUrl}}" bind:change="onCropperChange"></wx-cropper>
   </view>

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In the js file of the page, define the following event handling function:

Page({
  data: {
    originalImageUrl: '',  // 原始图片的 URL
    croppedImageUrl: ''    // 裁剪后图片的 URL
  },

  // 选择图片事件处理函数
  chooseImage: function() {
    var self = this;
    wx.chooseImage({
      success: function(res) {
        self.setData({
          originalImageUrl: res.tempFilePaths[0]
        });
      }
    });
  },

  // 图片裁剪完成事件处理函数
  onCropperChange: function(e) {
    this.setData({
      croppedImageUrl: e.detail.url
    });
  }
})

At this point, we have completed the implementation of the image cropping function. Run the applet, click the Select Picture button, and select a picture in the pop-up picture selection window to crop the picture in the wx-cropper component. After the final cropping is completed, the cropped image will be displayed below the wx-cropper component.

It should be noted that in order to conveniently display the cropped image, we defined two variables, originalImageUrl and croppedImageUrl, in data to save the URLs of the original image and the cropped image. You can save this data to the server or other places according to your needs.

Summary
Through the above steps, we successfully implemented the image cropping function in the WeChat applet and provided specific code examples. I hope this article is helpful to you. If you encounter problems during the implementation, you can refer to the documentation of the wx-cropper plug-in or seek help in the developer community. I wish you go further and further on the road of WeChat mini program development!

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