GWT - 检索未显示的小部件的大小 [英] GWT - Retrieve size of a widget that is not displayed

问题描述

我需要设置一个关于其子尺寸的absolutePanel大小，但getOffset *方法返回0，因为（我认为）该子项还没有显示出来。

I need to set the size of an absolutePanel regarding to its child size, but the getOffset* methods return 0 because (i think) the child has not been displayed yet.

一个简单的例子：

A Quick example:

AbsolutePanel aPanel = new AbsolutePanel();
HTML text = new HTML(/*variable lenght text*/);
int xPosition = 20; // actually variable
aPanel.add(text, xPosition, 0);
aPanel.setSize(xPosition + text .getOffsetWidth() + "px", "50px"); // 20px 50px

我也可以通过使用AbsolutePanel大小设置子位置和size：

I could also solve my problem by using the AbsolutePanel size to set the child position and size:

AbsolutePanel aPanel = new AbsolutePanel();
aPanel.setSize("100%", "50px");
HTML text = new HTML(/*variable lenght text*/);
int xPosition = aPanel.getOffsetWidth() / 3; // Once again, getOffsetWidth() returns 0;
 aPanel.add(text, xPosition, 0);

在这两种情况下，我都必须找到一种方法：

In both case, i have to find a way to either:

• 检索尚未显示的小部件的大小


• 当小部件显示时通知
  

• retrieve the size of a widget that has not been displayed
• be notified when a widget is displayed

推荐答案

我认为你应该尝试用CSS样式来解决这个问题。如果我是你，我会尝试使用addStyle或addStyleNames设置父级和/或绝对面板的样式。可能类似...

I think you should try to solve this with css styles. If I were you, I would try to set a style for parent and/or absolute panel, using addStyle or addStyleNames. Maybe something like...

AbsolutePanel aPanel = new AbsolutePanel();
aPanel.setSize("100%", "50px");
HTML text = new HTML(/*variable lenght text*/);
text.addStyleName("my-custom-style");

在css中，您将创建一个css样式，然后适当调整您的小部件的大小。

in css you would create a css style which would then size your widget appropriately.

另一种方法是......

The other approach would be....

您可以创建一个函数来精确地创建HTML小部件您需要的尺寸。

You could create a function that creates a HTML widget exactly the size you need.

以下是您的一些代码，以便您开始使用：

Here's some code for you, to get you started:

public native void customizeHTMLElement(Element elem, String widthInPx) /*-{ 
  elem.style.width = widthInPx;   //this is basically pure js. 
}-*/ 

Then somewhere within your widget make a call to the above function like

public void foo() {
  ...
  customizeHTMLElement(someElement, "20");
  ...
}

关于JSNI的一些信息 - http://code.google.com/webtoolkit/doc/latest/DevGuideCodingBasicsJSNI.html

Some info about JSNI - http://code.google.com/webtoolkit/doc/latest/DevGuideCodingBasicsJSNI.html

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