我们什么时候知道 Angular 中元素的实际宽度? [英] When do we know the actual width of an element in Angular?

问题描述

我正在尝试创建一个将 div 居中的指令.

I'm tring to create a directive that will center a div.

到目前为止，我有这个代码:

So far, I have this code:

app.directive("setcenter", function () {
    return {
        scope:{
            setcenter: '='
        },
        link: function (scope, element, attrs) {

            scope.$watch('setcenter', function (newValue) {
                if (newValue == true) {
                    var width = element.width();
                    element.css('position', 'absolute');
                    element.css('top', '80px');
                    element.css('left', '50%');
                    element.css('z-index', '200');
                    element.css('margin-left', '-' + width / 2 + 'px');
                }
            });
        }
    }
});

问题是元素的宽度.该指令的重点是使用该指令的 div 没有设置宽度.我希望这个指令计算出宽度并使 div 居中.

The problem is the width of the element. The whole point for this directive is that the div that uses this directive, don't have a width set. I want this directive to figure out the width and center the div.

我遇到的问题是，当指令被调用时，div的实际宽度还不知道.当我在我的情况下使用它时，div 是 800px，但是当页面加载完成时，div 是 221px.

The problem I encounter is that when the directive is invoked, the actual width of the div is not yet known. When I use this in my situation, the div is 800px, but when the page is finished loading, the div is 221px.

那么，我该怎么做才能等到知道 div 的实际宽度?

So, what can I do to wait till the actual width is known of the div?

推荐答案

首先，我只在为指令定义了控制器而不是一个链接功能.所以在链接函数中定义它可能会导致不同的行为，但我建议你先在那里尝试，如果你不能让它工作，然后切换到使用控制器.

First, I only have used this logic when I defined a controller for a directive rather than a link function. So defining it in a link function instead may cause different behavior, but I suggest you try it there first and if you can't get it to work then switch to using a controller.

据我所知，您需要进行的唯一更改是将 $scope 更改为作用域调用，将 $element 更改为元素，因为依赖项注入的对象成为标准链接函数参数.

As far as I can tell, the only change you would need to make this work would be to change $scope to scope calls and $element to element since the dependency injected objects become standard link function parameters.

  $scope.getElementDimensions = function () {
    return { 'h': $element.height(), 'w': $element.width() };
  };

  $scope.$watch($scope.getElementDimensions, function (newValue, oldValue) {
    //<<perform your logic here using newValue.w and set your variables on the scope>>
  }, true);

  $element.bind('resize', function () {
    $scope.$apply();
  });

在阅读了一个非常相似的关于观察 $window 而不是当前元素的用法后，我想到了这种用法，原始作品可以在这里找到.

The idea for this usage came to me after reading a very similar type of usage about watching the $window rather than the current element, the original work can be found here.

Angular.js:在页面加载时设置元素高度

这篇关于我们什么时候知道 Angular 中元素的实际宽度?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！