• Foundation of Android custom controls (1) — geometry drawing


    Although I have a few years of development experience, but the custom control together, little research, shame… When used is Baidu search, copy and paste. Working hours are tight. I always want to finish it as soon as possible( It’s all excuses. If you want to learn, there will always be time As an Android […]

  • Weekly canvas animation — circular motion


    Next to “weekly canvas animation” — wave motion Circular motion can be divided into two basic formsCircular motionandElliptical motion。Before explaining circular motion, the essential mathematical formula is about to come. So, ladies and gentlemen, please protect your knees. It doesn’t matter if you don’t understand, just understand the principle. Of course, can understand is the […]

  • CSS3 draw basic graphics, such as circle, ellipse, triangle, etc


    CSS3 circle#css3-circle{ width: 150px; height: 150px; border-radius: 50%; background-color: #232323;}CSS3 oval#css3-elipse{ width: 200px; height: 100px; border-radius: 50%; background-color: #232323;}CSS3 triangle#css3-triangle{ width: 0; height: 0; border-left: 100px solid transparent; border-right: 100px solid transparent; border-bottom: 150px solid #232323;}CSS3 parallelogram#css3-parallelogram{ width: 200px; height: 100px; background: #232323; -webkit-transform: skew(-45deg); -moz-transform: skew(-45deg); -o-transform: skew(-45deg); transform: skew(-45deg);}CSS3 trapezoid#css3-trapezoid{ width: 100px; height: 0; border-bottom: 100px solid #232323; border-left: 50px solid transparent; border-right: 50px solid transparent;}CSS3 hexagonal star#css3-six-star{ width: 0; height: 0; position: relative; border-bottom: 100px solid #232323; border-left: 50px solid transparent; border-right: 50px […]

  • [notes] secrets of CSS


    Chapter 1 Introduction DRY (don’t repeat yourself) Code is easy to maintain and a small amount of code can not have both border-width: 10px 10px 10px 0; /** better **/ border-width:10px; border-left-width: 0; currentColor /**Make the horizontal split line automatically match the color of the text**/ hr { height: 1px; background: currentColor; } inherit Inherit […]

  • 01_ Private key, public key and address


    The private key, public key and address are a string of (almost) impossible to collide.It can be illustrated by four equations = random() (0 < k < n; n = 1.158 * 10^77) =K * g (G is a constant of elliptic curve cryptography) = Hash.ripemd160(Hash.sha256(K)) = base58(0 + a + checksum) The process from […]

  • Canvas draws a cone


    I can’t find it online, so I can only draw and study; <html> <head> < title > my first HTML page < / Title > </head> <body> <canvas id=’cvs’ width=’1000′ height=”800″> </canvas> <script> const cvs =document.getElementById(‘cvs’); //Calculate the width of the canvas const width = cvs.offsetWidth; //Calculate the height of the canvas const height = […]

  • WPF inkcanvas draws rectangles and ellipses


    I mentioned the basic operation of inkcanvas before. Here is an example to illustrate the specific application: drawing rectangle and ellipse. Design sketch Xaml code <Window x:Class=”WPF_InkCanvas.ROI_InkCanvas” xmlns=”http://schemas.microsoft.com/winfx/2006/xaml/presentation” xmlns:x=”http://schemas.microsoft.com/winfx/2006/xaml” xmlns:d=”http://schemas.microsoft.com/expression/blend/2008″ xmlns:mc=”http://schemas.openxmlformats.org/markup-compatibility/2006″ xmlns:local=”clr-namespace:WPF_InkCanvas” mc:Ignorable=”d” Title=”ROI_InkCanvas” Height=”450″ Width=”800″> <Grid> <Grid.RowDefinitions> <RowDefinition/> <RowDefinition Height=”auto”/> </Grid.RowDefinitions> <Image Name=”imgMeasure” HorizontalAlignment=”Center” Stretch=”Uniform”/> <InkCanvas Name=”inkCanvasMeasure” EditingMode=”None” Background=”Transparent” Strokes=”{Binding InkStrokes, Mode=TwoWay}” HorizontalAlignment=”Center” Width=”{Binding […]

  • Teigha.net entity attribute comment


    Polyline3d: The type of 3D polyline is stored by the polytype attribute, It is an integer value defined by the poly3dtype enumeration. Polytype property is an approximate method of drawing 3D polyline Polyline3d polyline = new Polyline3d(Poly3dType.SimplePoly, p3dc, false); Closed or not: polyline.Closed = false;   The polytype property can be used to set and […]

  • Analysis of ECC


    This article was first published in the prophet community. The original link: https://xz.aliyun.com/t/6295 Mathematical foundation Parallel lines in Riemannian geometry There are five postulates in Euclid’s original geometry: If there are two different points, we can make and only make a straight line. The finite line can be extended arbitrarily. A circle can be made […]

  • CSS3 example code for elliptic trajectory rotation


    The following effects need to be achieved recently Starting with css3D rotary writing, only the following effects can be achieved There is no way to turn all the circles to the front. I don’t know if my operation is wrong or if the 3D rotation can’t be realized. The knowledgeable man also asks for advice. […]