drawText: function (ctx, str, leftWidth, initHeight, titleHeight, canvasWidth) {
var lineWidth = 0;
var lastSubStrIndex = 0; //每次开始截取的字符串的索引
for (let i = 0; i < str.length; i++) {
lineWidth += ctx.measureText(str[i]).width;
if (lineWidth > canvasWidth) {
ctx.fillText(str.substring(lastSubStrIndex, i), leftWidth, initHeight); //绘制截取部分
initHeight += 20; //16为字体的高度
lineWidth = 0;
lastSubStrIndex = i;
titleHeight += 20;
}
if (i == str.length - 1) { //绘制剩余部分
ctx.fillText(str.substring(lastSubStrIndex, i + 1), leftWidth, initHeight);
}
}
// 标题border-bottom 线距顶部距离
titleHeight = titleHeight + 10;
return titleHeight
},
调用方法
that.drawText(ctx, "花时间长多久爱手机单基调是基础",150,220,2,218)
