我使用 GWT 显示带有 ClickHandler 的图像缩略图,然后在居中的 PopupPanel 中显示完整图像(可以是几 MB)。为了使其居中,必须在显示弹出窗口之前加载图像,否则图像的左上角将位于屏幕中间(图像认为它是 1px 大)。这是我用来执行此操作的代码:
private void showImagePopup() {
final PopupPanel popupImage = new PopupPanel();
popupImage.setAutoHideEnabled(true);
popupImage.setStyleName("popupImage"); /* Make image fill 90% of screen */
final Image image = new Image();
image.addLoadHandler(new LoadHandler() {
@Override
public void onLoad(LoadEvent event) {
popupImage.add(image);
popupImage.center();
}
});
image.setUrl(attachmentUrl + CFeedPostAttachment.ATTACHMENT_FILE);
Image.prefetch(attachmentUrl + CFeedPostAttachment.ATTACHMENT_FILE);
}
但是,LoadEvent
事件永远不会触发,因此图像永远不会显示。我怎样才能克服这个?我想避免使用 http://code.google.com/p/gwt-image-loader/因为如果我能完全避免的话,我不想添加额外的库。谢谢。
最佳答案
onLoad()
方法只会在图像加载到 DOM 后触发。这是一个快速解决方法:
...
final Image image = new Image(attachmentUrl + CFeedPostAttachment.ATTACHMENT_FILE);
image.addLoadHandler(new LoadHandler() {
@Override
public void onLoad(LoadEvent event) {
// since the image has been loaded, the dimensions are known
popupImage.center();
// only now show the image
popupImage.setVisible(true);
}
});
popupImage.add(image);
// hide the image until it has been fetched
popupImage.setVisible(false);
// this causes the image to be loaded into the DOM
popupImage.show();
...
希望对您有所帮助。
关于java - 在居中的 PopupPanel onLoad 中显示 GWT 图像,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/5258157/