GWT使用ImageResource创建图像 [英] GWT create Image using ImageResource
问题描述
我们可以通过多种方式创建GWT图像。
Image image = new Image((ImageResource)imageRes);
Image image = new Image((ImageResource)imageRes.getSafeUri());
Image image = new Image();
image.setUrl((ImageResource)imageRes.getSafeUri()。asString());
我的问题是:使用ImageResouce创建新图像的3种方法有什么区别。第一次加载哪一个最好或更快?
谢谢
一个 ImageResource
在技术上代表一个区域内的一个区域, sprited图像:它有一个指向精灵的URL和该图像上区域的坐标。在许多浏览器和大多数图像中,URL实际上都是 data:
URL,该区域将表示整个图像。这可以通过使用 @ImageOptions(preventInlining = true)
或全局地使用 set-property
在你的 gwt.xml
上。换句话说,你的代码不应该依赖它,并且应该总是把一个 ImageResource
作为一个被添加图像的区域。
FYI,the实际上使用spr图像的情况默认情况下是针对不支持 data:
URL的IE6 / 7,对于图像太大以适应数据:
URL(所有浏览器)。
然而,这正是你在做的最后两种情况:只使用 ImageResource
的URL,就好像它不是(可能)是一个spr图片。
My question is really simple and shot. but hope I can have a clear answer. We can create GWT Image in many ways.
Image image = new Image ( (ImageResource)imageRes);
Image image = new Image ( (ImageResource)imageRes.getSafeUri() );
Image image = new Image ();
image.setUrl((ImageResource)imageRes.getSafeUri().asString() );
My question is: what are the difference among these 3 ways to create a new image using ImageResouce. Which one is best or faster for first-time loading?
Thanks
First, you should not use the last two.
An ImageResource
technically represents a region within a "sprited" image: it has a URL to the sprite and the coordinates of the region on that image. In many browsers, and for most images, the URL will actually be a data:
URL and the region will represent the whole image. This can be controlled on a per-image basis using @ImageOptions(preventInlining=true)
or globally with a set-property
on your gwt.xml
. In other words, your code shouldn't rely on it, and should always treat an ImageResource
as a region within a sprited image.
FYI, the cases where a sprited image is actually used by default are for IE6/7 which does not support data:
URLs, and for images that are too large to fit within a data:
URL (all browsers).
This is however exactly what you're doing in the last two cases: use only the URL of the ImageResource
, as if it weren't (potentially) a sprited image.
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