Detailed description and source code sharing of the Canvas enhancement component instance of WeChat Applet

This article mainly introduces the details of the Canvas enhancement component instance of the applet and relevant information about source code sharing. WeZRender is a Canvas enhancement component of the applet, for more information about the Canvas enhancement components and source code sharing, WeZRender is a Canvas enhancement component, for more information, see

WeZRender is a Canvas enhancement component based on the HTML5 Canvas class library ZRender.

Use

WXML:

 
 
  canvas>
 

JS:

 var wezrender = require('../../lib/wezrender');  zr = wezrender.zrender.init("line-canvas-1", 375, 600);

Features

Data-driven

With WeZRender, you only need to define the graphic data.

 var circle = new wezrender.graphic.shape.Circle(       shape: {      cx: 50,      cy: 50,      r: 50    },    style: {      fill: 'red',      lineWidth: 10    }  });

Rich graphic options

Multiple built-in graphic elements (Circular, elliptical, ring, slice, rectangle, polygon, straight line, curve, heart-shaped, water drop, Rose Line, Trochoid, text, pictures, etc ), the unified and rich graphic attributes fully meet Personalized Requirements.

 var droplet = new wezrender.graphic.shape.Droplet({    shape: {      cx: 200,      cy: 300,      width: 50,      height: 50    },    style: {        fill: '#ff9999'    }  });

Powerful animation support

It provides promise animation interfaces and common easing functions to easily meet various animation requirements.

var image = new wezrender.graphic.Image({    style: {      x: 0,      y: 0,      image: '../../images/koala.jpg',      width: 32,      height: 24,      text: 'koala'    }  });  zr.add(image);  image.animateStyle(true)    .when(2000, {      x: 350,      y: 450,      width: 360,      height: 270,    })    .start();

Easy to expand

The divide-and-conquer graphic definition policy allows you to expand graphic elements.

var Pin = wezrender.graphic.Path.extend({    type: 'pin',    shape: {      // x, y on the cusp      x: 0,      y: 0,      width: 0,      height: 0    },    buildPath: function (path, shape) {      var x = shape.x;      var y = shape.y;      var w = shape.width / 5 * 3;      // Height must be larger than width      var h = Math.max(w, shape.height);      var r = w / 2;      // Dist on y with tangent point and circle center      var dy = r * r / (h - r);      var cy = y - h + r + dy;      var angle = Math.asin(dy / r);      // Dist on x with tangent point and circle center      var dx = Math.cos(angle) * r;      var tanX = Math.sin(angle);      var tanY = Math.cos(angle);      path.arc(        x, cy, r,        Math.PI - angle,        Math.PI * 2 + angle      );      var cpLen = r * 0.6;      var cpLen2 = r * 0.7;      path.bezierCurveTo(        x + dx - tanX * cpLen, cy + dy + tanY * cpLen,        x, y - cpLen2,        x, y      );      path.bezierCurveTo(        x, y - cpLen2,        x - dx + tanX * cpLen, cy + dy + tanY * cpLen,        x - dx, cy + dy      );      path.closePath();    }  });

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