Summary of issues related to image processing in WeChat mini programs

In the development process of small programs, in page layout, we often encounter some pictureprocessing problems, for example, if the picture is not fixed Height and height, but the image is set to a fixed height and width. At this time, the original image is not proportional to the fixed height and width set by the image, then the image will be deformed and unclear. At this time, you can use the following proportional scaling method to scale the image so that the image does not deform. Or dynamically obtain the height and width of the image through the bindload method of image, and dynamically set the height and width of the image so that the height and width of the image layout are equal to the height and width of the original image.

1. Image scaling tool

[AppleScript]

//Util.js  
  
class Util{  
  
    /*** 
     * 按照显示图片的宽等比例缩放得到显示图片的高 
     * @params originalWidth  原始图片的宽 
     * @params originalHeight 原始图片的高 
     * @params imageWidth     显示图片的宽，如果不传就使用屏幕的宽 
     * 返回图片的宽高对象 
    ***/  
    static imageZoomHeightUtil(originalWidth,originalHeight,imageWidth){  
        let imageSize = {};  
        if(imageWidth){  
            imageSize.imageWidth = imageWidth;  
            imageSize.imageHeight = (imageWidth * originalHeight) / originalWidth;  
        }else{//如果没有传imageWidth,使用屏幕的宽  
            wx.getSystemInfo({    
                success: function (res) {    
                    imageWidth = res.windowWidth;    
                    imageSize.imageWidth = imageWidth;  
                    imageSize.imageHeight = (imageWidth * originalHeight) / originalWidth;  
                }    
            });  
        }  
        return imageSize;  
    }  
  
    /*** 
     * 按照显示图片的高等比例缩放得到显示图片的宽 
     * @params originalWidth  原始图片的宽 
     * @params originalHeight 原始图片的高 
     * @params imageHeight    显示图片的高，如果不传就使用屏幕的高 
     * 返回图片的宽高对象 
    ***/  
    static imageZoomWidthUtil(originalWidth,originalHeight,imageHeight){  
        let imageSize = {};  
        if(imageHeight){  
            imageSize.imageWidth = (imageHeight *originalWidth) / originalHeight;  
            imageSize.imageHeight = imageHeight;  
        }else{//如果没有传imageHeight,使用屏幕的高  
            wx.getSystemInfo({    
                success: function (res) {    
                    imageHeight = res.windowHeight;  
                    imageSize.imageWidth = (imageHeight *originalWidth) / originalHeight;  
                    imageSize.imageHeight = imageHeight;  
                }    
            });  
        }  
        return imageSize;  
    }  
  
}  
  
export default Util;

2. Use the image component to load the image, dynamically obtain the height and width of the image through bindload, and dynamically set the height and width of the image

[AppleScript]

<image bindload="imageLoad" style="width:{{imageWidth}}px;;height:{{imageHeight}}px;" src="../pro.png"/>

index.js code is as follows

[AppleScript]

import Util from '../common/Util';  
  
Page({  
  data:{  
        imageWidth:0,  
        imageHeight:0  
  },  
  imageLoad: function (e) {    
        //获取图片的原始宽度和高度  
        let originalWidth = e.detail.width;  
        let originalHeight = e.detail.height;  
        //let imageSize = Util.imageZoomHeightUtil(originalWidth,originalHeight);  
  
        //let imageSize = Util.imageZoomHeightUtil(originalWidth,originalHeight,375);  
        let imageSize = Util.imageZoomWidthUtil(originalWidth,originalHeight,145);  
  
        this.setData({imageWidth:imageSize.imageWidth,imageHeight:imageSize.imageHeight});    
  }  
})

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