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wxml代码 <view class='container'> <canvas style='width:300px;height:200px;' canvas-id='canvas'></canvas> </view> js代码 Page({ data: { // 开始角度 startAngle: -(1 / 2 * Math.PI), // 结束角度 endAngle: 3 / 2 * Math.PI, // 偏移角度 xAngle: Math.PI / 180 }, onLoad: function() { var that = this; var cxt_arc = wx.createContext(); var endAngle = that.data.endAngle; var xAngle = that.data.xAngle; var templeAngle = that.data.startAngle; var rander = function() { if (templeAngle >= endAngle) { return; } else if (templeAngle + xAngle > endAngle) { templeAngle = endAngle; } else { templeAngle += xAngle } cxt_arc.beginPath(); cxt_arc.setStrokeStyle('red') cxt_arc.arc(100, 50, 50, that.data.startAngle, templeAngle); cxt_arc.stroke(); cxt_arc.closePath(); wx.drawCanvas({ canvasId: 'canvas', actions: cxt_arc.getActions() }) requestAnimationFrame(rander); } rander() }, }) 对requestAnimationFrame的解释 window.requestAnimFrame = (function(){
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
function( callback ){
window.setTimeout(callback, 1000 / 60);
};
})();
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