Web Front-end
HTML Tutorial
How to implement adaptive layout of Y-axis position in web annotation?
How to implement adaptive layout of Y-axis position in web annotation?
Apr 04, 2025 pm 11:30 PM
Detailed explanation of the Y-axis position adaptive algorithm for web page annotation
This article discusses how to build a web annotation function similar to Word documents, focusing on solving the problem of overlapping comments and realizing an adaptive layout of the Y-axis position of the annotation. Ideally, annotations should be closely arranged to avoid overlapping, while maintaining reasonable spacing between annotations.
The core challenge is to design an algorithm that automatically calculates its Y-axis position when adding new annotations. An effective solution is to use absolute positioning and combine data structures and algorithms to manage annotation locations.
Data structure:
We use an array to store the information for each annotation, each element containing top (initial top position) and height (height) properties. For example:
[
{ top: 100, height: 200 },
{ top: 800, height: 200 },
{ top: 820, height: 200 },
{ top: 1020, height: 200 },
]
Adaptive algorithm:
We use an algorithm similar to waterfall flow layout, use the reduce method to iterate the array, and calculate the final Y-axis position of each annotation ( currentTop ). The core of the algorithm is to compare the initial top value of the current annotation with the bottom position of the previous annotation, and select a larger value as the final currentTop of the current annotation, thereby avoiding overlap.
const arr = [
{ top: 100, height: 200 },
{ top: 800, height: 200 },
{ top: 820, height: 200 },
{ top: 1020, height: 200 },
{ top: 1430, height: 180 },
];
arr.reduce((s, n, i) => {
n.currentTop = Math.max(n.top, (s.currentTop || s.top) s.height);
return n;
});
console.log(arr);
Math.max(n.top, (s.currentTop || s.top) s.height) This line of code is the core of the algorithm. s.currentTop || s.top handles the case of the first annotation.
application:
The currentTop value calculated by this algorithm can be applied to the CSS style of the annotation element, such as top: ${currentTop}px; , thereby realizing the adaptive layout of the annotation, effectively solving the annotation overlap problem, and achieving an effect similar to the annotation spacing of Word documents. This algorithm ensures that the annotations are arranged closely, while avoiding mutual obstruction, achieving a smooth web annotation experience.
The above is the detailed content of How to implement adaptive layout of Y-axis position in web annotation?. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
What is 'render-blocking CSS'?
Jun 24, 2025 am 12:42 AM
CSS blocks page rendering because browsers view inline and external CSS as key resources by default, especially with imported stylesheets, header large amounts of inline CSS, and unoptimized media query styles. 1. Extract critical CSS and embed it into HTML; 2. Delay loading non-critical CSS through JavaScript; 3. Use media attributes to optimize loading such as print styles; 4. Compress and merge CSS to reduce requests. It is recommended to use tools to extract key CSS, combine rel="preload" asynchronous loading, and use media delayed loading reasonably to avoid excessive splitting and complex script control.
How can CSS be used to implement dark mode theming on a website?
Jun 19, 2025 am 12:51 AM
ToimplementdarkmodeinCSSeffectively,useCSSvariablesforthemecolors,detectsystempreferenceswithprefers-color-scheme,addamanualtogglebutton,andhandleimagesandbackgroundsthoughtfully.1.DefineCSSvariablesforlightanddarkthemestomanagecolorsefficiently.2.Us
Can you explain the difference between em, rem, px, and viewport units (vh, vw)?
Jun 19, 2025 am 12:51 AM
The topic differencebetweenem, Rem, PX, andViewportunits (VH, VW) LiesintheirreFerencepoint: PXISFixedandbasedonpixelvalues, emissrelative EtothefontsizeFheelementoritsparent, Remisrelelatotherootfontsize, AndVH/VwarebaseDontheviewporttimensions.1.PXoffersprecis
External vs. Internal CSS: What's the Best Approach?
Jun 20, 2025 am 12:45 AM
ThebestapproachforCSSdependsontheproject'sspecificneeds.Forlargerprojects,externalCSSisbetterduetomaintainabilityandreusability;forsmallerprojectsorsingle-pageapplications,internalCSSmightbemoresuitable.It'scrucialtobalanceprojectsize,performanceneed
Does my CSS must be on lower case?
Jun 19, 2025 am 12:29 AM
No,CSSdoesnothavetobeinlowercase.However,usinglowercaseisrecommendedfor:1)Consistencyandreadability,2)Avoidingerrorsinrelatedtechnologies,3)Potentialperformancebenefits,and4)Improvedcollaborationwithinteams.
What are the key differences between inline, block, inline-block, and flex display values?
Jun 20, 2025 am 01:01 AM
Choosing the correct display value in CSS is crucial because it controls the behavior of elements in the layout. 1.inline: Make elements flow like text, without occupying a single line, and cannot directly set width and height, suitable for elements in text, such as; 2.block: Make elements exclusively occupy one line and occupy all width, can set width and height and inner and outer margins, suitable for structured elements, such as; 3.inline-block: has both block characteristics and inline layout, can set size but still display in the same line, suitable for horizontal layouts that require consistent spacing; 4.flex: Modern layout mode, suitable for containers, easy to achieve alignment and distribution through justify-content, align-items and other attributes, yes
How can you animate an SVG with CSS?
Jun 30, 2025 am 02:06 AM
AnimatingSVGwithCSSispossibleusingkeyframesforbasicanimationsandtransitionsforinteractiveeffects.1.Use@keyframestodefineanimationstagesforpropertieslikescale,opacity,andcolor.2.ApplytheanimationtoSVGelementssuchas,,orviaCSSclasses.3.Forhoverorstate-b
What is Autoprefixer and how does it work?
Jul 02, 2025 am 01:15 AM
Autoprefixer is a tool that automatically adds vendor prefixes to CSS attributes based on the target browser scope. 1. It solves the problem of manually maintaining prefixes with errors; 2. Work through the PostCSS plug-in form, parse CSS, analyze attributes that need to be prefixed, and generate code according to configuration; 3. The usage steps include installing plug-ins, setting browserslist, and enabling them in the build process; 4. Notes include not manually adding prefixes, keeping configuration updates, prefixes not all attributes, and it is recommended to use them with the preprocessor.
