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Introduction

Use the render function to create a document flow in the canvas and quickly implement the layout.

If there is a problem in use, check the code in the example, click to view DEMO

Try it in CodePen

Analysis of easyCanvas implementation principle

• vue component vue-easy-canvas
• Support document flow, refer to web, no need to set x, y, width and height
• Compatible with small programs and web, no third-party dependencies
• Support componentization, global components and local components
• Support events
• High performance, scroll-view supports dirty rectangles and only draws the visible part
• Support operation element, similar to operation dom to modify document flow

Supporting elements

• [x] view basic element, similar to div
• [x] text text supports automatic line wrapping and over omitted functions, currently text is implemented as inline-block
• [x] ʻimageimagesrcmodesupports aspectFit and aspectFill, other css features are the same as web supportload` event to monitor image loading and drawing completion
• [x] scroll-view scroll container, you need to set direction in the style to support x, y, xy, and set the specific size. Set renderOnDemand to draw only the visible part

Styles

Use numbers where the attribute uses pixels

• [x] display block | inline-block | flex, text is inline by default
• [x] width auto 100% Number This box model uses border-box and cannot be modified
• [x] height
• [x] flex flex does not support auto, use width directly for fixed width
• [x] minWidth maxWidth minHeight maxHeight If the specific width is set, the height will not take effect
• [x] margin marginLeft,marginRight,marginTop,marginBottom margin supports array abbreviations such as [10,20] [10,20,10,20]
• [x] paddingLeft,paddingRight,paddingTop,paddingBottom Same as above
• [x] backgroundColor
• [x] borderRadius
• [x] borderWidth borderTopWidth ... Set the thin border directly to 0.5
• [x] borderColor
• [x] lineHeight font related only valid in text
• [x] color
• [x] fontSize
• [x] textAlign left right center
• [x] textIndent Number
• [x] verticalAlign top middle bottom
• [x] justifyContent flex-start center flex-end flex layout align horizontally
• [x] ʻalignItems` flex-start center flex-end flex layout align it vertically
• [x] maxLine maximum number of lines, exceeding the automatic ellipsis, only supports use in text
• [x] whiteSpace normal nowrap controls line breaks, not fonts
• [x] ʻoverflow` hidden If rounded corners are added, hidden will be added automatically
• [] flexDirection
• [x] borderStyle dash Array See ctx.setLineDash() for details
• [x] shadowBlur set the shadow will automatically add overflow:hidden;
• [x] shadowColor
• [x] shadowOffsetX
• [x] shadowOffsetY
• [x] position static ʻabsolute`
• [x] ʻopacityNumber`

Installation

npm install easy-canvas-layout --save

Usage

Basic

    import easyCanvas from'easy-canvas-layout'

    // create a layer bind with ctx
    const layer = easyCanvas.createLayer(ctx, {
      dpr: 2,
      width: 300,
      height: 600,
    })

    // create a node tree
    // c(tag,options,children)
    const node = easyCanvas.createElement((c) => {
      return c('view', {
        styles: {backgroundColor:'#000' }, // style
        attrs:(), // attributes such as src
        on:{} // events such as click load
      },
      [
        c('text',{color:'#fff'},'Hello World')
      ])
    })

    // mount
    node.mount(layer)

Register Component

    ...

    function button(c,text){
      return c(
        'view',
        {
          styles: {
            backgroundColor:'#ff6c79',
            borderRadius: 10,
            borderColor:'#fff',
            display:'inline-block',
            margin: 2,
            padding:[0,10]
          },
        },
        [
          c(
            'text',
            {
              styles: {
                lineHeight: 20,
                color:'#fff',
                textAlign:'center',
                fontSize: 11,
              },
            },
            text
          ),
        ]
      )
    }

    easyCanvas.component('button',(opt,children,c) => button(c,children))

    const node = easyCanvas.createElement((c) => {
      return c('view',{},[
        c('button',(),'This is a global component')
      ])
    })

    ...

TodoList

• ~~Support position~~
• ~~inline-block line break and textAlign~~
• ~~Realize attribute inheritance through the stack~~
• ~~Support flex-direction~~
• ~~box-shadow to be optimized~~
• ~~Compatible with small program measuretext~~
• ~~Compatible with applet image~~
• ~~Packing problem solved~~
• ~~scroll-view nesting~~~~translate value inheritance~~
• Supplement other attributes
• ~~image supports mode~~
• ~~Release npm~~
• ~~max-width~~
• ~~vue template support~~
• ~~Scroll-view click area judgment optimization~~
• ~~Remove event when removing element~~
• ~~Scrolling optimization~~
• ~~Render on demand~~
• zIndex Hurry! ! !

Known issues

• Linear-gradient must be created in the view to take effect
• If there is a problem with the element event judgment that is not in the document flow, it will be triggered together with the following elements

MIT License

Copyright (c) 2020 Gitjinfeiyang

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTW