@icanvas/apis/libs/canvas.js

这是icanvas的Api功能包

/**
 * 获得一个canvas对象
 *
 * @param {String} key 特殊模版标识
 *
 * 打包模式为wxgame时
 * key取share则获得主域内开放canvas
 * key取shared则获得开发域内开放canvas
 * 打包模式为web时
 * key取main则该canvas将上屏
 */
let GetCanvas = function(key) {
	if (ENV.core == 'wxgame') {
		if (key == 'main') return GetCanvas.main;
		if (key == 'share') {
			let context = wx.getOpenDataContext();
			context.canvas.getContext = () => context;
			return context.canvas;
		}
		if (key == 'shared' && typeof wx.getSharedCanvas == 'function') return wx.getSharedCanvas();
		return wx.createCanvas();
	} else {
		if (key == 'main') {
			let main = GetCanvas.main;
			document.body.appendChild(main);
			return main;
		}
		let canvas = document.createElement('canvas');
		return canvas;
	}
};
GetCanvas.main = GetCanvas();
export default GetCanvas;