angular的例子：
<!DOCTYPE html> <html ng-app="APP"> <head> <meta charset="UTF-8"> <script src="http://cdn.bootcss.com/angular.js/1.3.0-beta.12/angular.min.js"></script> </head> <body ng-controller="MainCtrl"> <!-- 界面的这个元素会被替换成canvas元素; --> <div ang:round:progress data-round-progress-model="roundProgressData"></div> <br> <input type="number" ng-model="roundProgressData.label"/> <script> //引用angular.directives-round-progress这个模块; var APP = angular.module('APP', ['angular.directives-round-progress']). controller('MainCtrl', function($scope) { $scope.roundProgressData = { //这个是初始化的数据; label: 11, percentage: 0.11 } //通过监听scope下的这个roundProgressData属性, 对界面的canvas进行重绘; $scope.$watch('roundProgressData', function (newValue) { newValue.percentage = newValue.label / 100; }, true); }); </script> <script> /*! * AngularJS Round Progress Directive * * Copyright 2013 Stephane Begaudeau * Released under the MIT license */ angular.module('angular.directives-round-progress', []).directive('angRoundProgress', [function () { var compilationFunction = function (templateElement, templateAttributes, transclude) { if (templateElement.length === 1) { //初始化DOM模型, 包括初始化canvas等; var node = templateElement[0]; var width = node.getAttribute('data-round-progress-width') || '400'; var height = node.getAttribute('data-round-progress-height') || '400'; var canvas = document.createElement('canvas'); canvas.setAttribute('width', width); canvas.setAttribute('height', height); canvas.setAttribute('data-round-progress-model', node.getAttribute('data-round-progress-model')); //相当于demo, 替换原来的元素; node.parentNode.replaceChild(canvas, node); //各种配置; var outerCircleWidth = node.getAttribute('data-round-progress-outer-circle-width') || '20'; var innerCircleWidth = node.getAttribute('data-round-progress-inner-circle-width') || '5'; var outerCircleBackgroundColor = node.getAttribute('data-round-progress-outer-circle-background-color') || '#505769'; var outerCircleForegroundColor = node.getAttribute('data-round-progress-outer-circle-foreground-color') || '#12eeb9'; var innerCircleColor = node.getAttribute('data-round-progress-inner-circle-color') || '#505769'; var labelColor = node.getAttribute('data-round-progress-label-color') || '#12eeb9'; var outerCircleRadius = node.getAttribute('data-round-progress-outer-circle-radius') || '100'; var innerCircleRadius = node.getAttribute('data-round-progress-inner-circle-radius') || '70'; var labelFont = node.getAttribute('data-round-progress-label-font') || '50pt Calibri'; return { pre: function preLink(scope, instanceElement, instanceAttributes, controller) { var expression = canvas.getAttribute('data-round-progress-model'); //监听模型, O了 //就监听一个属性; scope.$watch(expression, function (newValue, oldValue) { // Create the content of the canvas //包括新建和重绘; var ctx = canvas.getContext('2d'); ctx.clearRect(0, 0, width, height); // The "background" circle var x = width / 2; var y = height / 2; ctx.beginPath(); ctx.arc(x, y, parseInt(outerCircleRadius), 0, Math.PI * 2, false); ctx.lineWidth = parseInt(outerCircleWidth); ctx.strokeStyle = outerCircleBackgroundColor; ctx.stroke(); // The inner circle ctx.beginPath(); ctx.arc(x, y, parseInt(innerCircleRadius), 0, Math.PI * 2, false); ctx.lineWidth = parseInt(innerCircleWidth); ctx.strokeStyle = innerCircleColor; ctx.stroke(); // The inner number ctx.font = labelFont; ctx.textAlign = 'center'; ctx.textBaseline = 'middle'; ctx.fillStyle = labelColor; ctx.fillText(newValue.label, x, y); // The "foreground" circle var startAngle = - (Math.PI / 2); var endAngle = ((Math.PI * 2 ) * newValue.percentage) - (Math.PI / 2); var anticlockwise = false; ctx.beginPath(); ctx.arc(x, y, parseInt(outerCircleRadius), startAngle, endAngle, anticlockwise); ctx.lineWidth = parseInt(outerCircleWidth); ctx.strokeStyle = outerCircleForegroundColor; ctx.stroke(); }, true); }, post: function postLink(scope, instanceElement, instanceAttributes, controller) {} }; } }; var roundProgress = { //compile里面先对dom进行操作, 再对$socpe进行监听; compile: compilationFunction, replace: true }; return roundProgress; }]); </script> </body> </html>