• ## How HUAWEI CLOUD CDN Improves the Cache Hit Rate

Time：2022-9-21

Background Information The low CDN cache hit rate will lead to high pressure on the origin site and low access efficiency to static resources. You can select the corresponding optimization strategy to improve the CDN cache hit rate based on the specific reasons that cause the low CDN cache hit rate. CDN cache hit rate […]

• ## 2011 Stanford iOS App Development Lesson 4 — Views

Time：2022-9-7

Views View draws a rectangular space and handles events in it. Views have a hierarchy. A View can only have one parent View, but can have multiple child Views. The order of the child Views is related. The higher the position in the array or the larger the number, the more it will be displayed […]

• ## npm ERR! network timeout…

Time：2022-9-3

The article is not easy, please pay attention to the public numberCaterpillar's little crayons, a lot of support, thank you. question Once I modified a few simple lines of code, then merged the branch into develop, and then automatically triggered gitlab's ci.But after looking at the log for a while, I found that an error […]

• ## iOS Transform coordinate change

Time：2022-8-11

When using CGContext, since Quartz 2D is inconsistent with UIKit coordinates, it is necessary to change the context again to achieve the desired effect. 1. Introduction of different coordinate origins In Quartz 2D, the coordinate origin is at the lower left corner of the canvas, while in UIKit, it is consistent with the screen coordinates, […]

Time：2022-7-29

order This article mainly records whether the leetcode robot can return to the origin subject On the two-dimensional plane, there is a robot starting from the origin (0, 0). Give its moving order, and judge whether the robot ends at (0, 0) after completing the movement. The move order is represented by a string. The […]

• ## [course notes] convex optimization of University of science and technology of China (II)

Time：2022-7-9

Affine set definition Equivalent definition:Solution set of linear equations$$C=\{x \mid A x=b\}$$Is an affine set, and the corresponding subspace is$$A$$Zeroing space of understand The line of any two points in the affine set is also in the affine set Affine combination of multiple points in affine set$$\theta_{1} x_{1}+\cdots+\theta_{k} x_{k},\theta_{1}+\cdots+\theta_{k}=1$$Also in the radiation set Proof idea: […]

Time：2022-6-25

First, before we talk about uiscrollview, let’s first understand how coordinate systems work in UIKit. Coordinate system Because everyviewDefines its own coordinate system, which looks like this: the X axis points to the right and the Y axis points down (as shown in the following figure). Logical coordinate system png However, it should be noted […]

• ## Drawing dynamic clock with canvas

Time：2022-6-20

Draw a dynamic clock as shown in the following figure <body><canvas width=”600px” height=”600px” style=”background-color: #ccc; display:block; margin: 0 auto”></canvas></body> <script> window.onload = function(){ //Get canvas object var canvas = document.querySelector(“canvas”); //Get context var context = canvas.getContext(“2d”); //Encapsulates a function used for clock dynamics function clock(){ //Draw disc context. beginPath();// start context.arc(300,300,200,0,2*Math.PI); context. fillStyle = “pink”;// […]

• ## Study java programming ideas

Time：2022-4-24

The so-called study is “like a duel, like a chisel, like a thought” in the University. I have been working on the book “Java programming ideas” for three years. It is the best written Java programming book in the world and one of the most helpful books to me. Every time I open it, I […]

• ## Where did Python’s metaclass design originate?

Time：2022-3-31

A veteran Python core developer once suggested that we（Click to read）, we should widely learn the excellent features of other programming languages, so as to improve Python’s ability in related fields. In terms of metaprogramming, his advice is to learn hy and ruby. However, he also mentioned that he did not know which language to […]

• ## Fishing – digression – trivia essay

Time：2022-3-10

Today, I was invited to fill in the report on the publicity of my alma mater. It was a pity that there was no online reason for the epidemic, and I felt there was nothing to write about. Unexpectedly, when I wrote in the column of feeling, I was amorous and recalled a bit of […]

• ## Alternative cutaway drawing scheme: SVG editor + CSS

Time：2022-3-7

Background: all charts of the internship company should be usedechartsAfter painting for a period of time, I wanted to draw faster, so I had this article. This scheme isechartsAs a supplement rather than a substitute, it is best to use basic charts such as line chart, bar chart or simpler relationship chartecharts, forechartsIt is cumbersome […]