**文字换行** CanvasRenderingContext2D.prototype.wrapText \= function (text, x, y, maxWidth, lineHeight) { if (typeof text != 'string' || typeof x != 'number' || typeof y != 'number') { return; } var context \= this; var canvas \= context.canvas; if (typeof maxWidth \== 'undefined') { maxWidth \= (canvas && canvas.width) || 300; } if (typeof lineHeight \== 'undefined') { lineHeight \= (canvas && parseInt(window.getComputedStyle(canvas).lineHeight)) || parseInt(window.getComputedStyle(document.body).lineHeight); } // 字符分隔为数组 var arrText \= text.split(''); var line \= ''; for (var n \= 0; n < arrText.length; n++) { var testLine \= line + arrText\[n\]; var metrics \= context.measureText(testLine); var testWidth \= metrics.width; if (testWidth \> maxWidth && n \> 0) { context.fillText(line, x, y); line \= arrText\[n\]; y += lineHeight; } else { line \= testLine; } } context.fillText(line, x, y); };