我坚持将 gwt 与 JCrop 或 imgareaselect javascript 库集成我有一个图像，每次客户端更改从其文件系统中选择的文件（使用上传小部件）时，该 url 都会发生变化。我希望用户在其图像中选择区域，这样我将能够获得尊重客户愿望的纵横比的图像。问题是我无法成功在加载事件上调用 imgareaselect 或 jcrop，每次我有 null，如果我尝试 jquery ("imagepreview") jquery 在执行时是未知的，如果我尝试一些 $("#imagepreview")我得到一个 $ 未定义...
请提供任何帮助...问候。
public class ThisWidget extends LayoutContainer {
public void onRender(Element parent, int index) {
super.onRender(parent, index);
setLayout(new VBoxLayout());
setWidth("100%");
final FormPanel uploadPhotoPanel = new FormPanel();
uploadPhotoPanel.setWidth("100%");
uploadPhotoPanel.setHeight("150px");
Label label = new Label("Ajouter une photo");
add(label);
uploadPhotoPanel.setAction(GWT.getModuleBaseURL()
+ "photoload/uploadpreview.ctz");
uploadPhotoPanel.setEncoding(FormPanel.ENCODING_MULTIPART);
uploadPhotoPanel.setMethod(FormPanel.METHOD_POST);
final FileUploadField file = new FileUploadField();
file.setName("FILE");
uploadPhotoPanel.add(file);
file.addHandler(new ChangeHandler() {
@Override
public void onChange(ChangeEvent event) {
uploadPhotoPanel.submit();
}
}, ChangeEvent.getType());
final Button btn = new Button("Ajouter",
new SelectionListener<ButtonEvent>() {
@Override
public void componentSelected(ButtonEvent ce) {
uploadPhotoPanel.submit();
}
});
final Image previewimage;
previewimage = new Image();
DOM.setElementAttribute(previewimage.getElement(), "id",
"previewimage");
previewimage.setSize("200px", "200px");
previewimage.addLoadHandler(new LoadHandler(){
protected native void onPreviewLoad() /*-{
document.getElementById("previewimage").imgAreaSelect({
aspectRatio : '1:1',
handles : true,
fadeSpeed : 200
});
}-*/;
@Override
public void onLoad(LoadEvent event) {
onPreviewLoad();
}});
uploadPhotoPanel
.addSubmitCompleteHandler(new SubmitCompleteHandler() {
@Override
public void onSubmitComplete(SubmitCompleteEvent event) {
previewimage.setUrl(GWT.getModuleBaseURL()
+ "photoload/downloadpreview.ctz?tsp="
+ System.currentTimeMillis());
}
});
add(uploadPhotoPanel);
add(previewimage);
add(btn);
}