我有以下 javascript 代码块,但不是很清楚:
var level = this.getLevelForResolution(this.map.getResolution());
var coef = 360 / Math.pow(2, level);
var x_num = this.topTileFromX < this.topTileToX ? Math.round((bounds.left - this.topTileFromX) / coef) : Math.round((this.topTileFromX - bounds.right) / coef);
var y_num = this.topTileFromY < this.topTileToY ? Math.round((bounds.bottom - this.topTileFromY) / coef) : Math.round((this.topTileFromY - bounds.top) / coef);
<
in是什么this.topTileFromX <
意思?