GWT Cell Tree Right Click Selection

问题

So I have created a CellTree and what I want to do is select the cell that receives a right click so that when I open my context menu to do things, I will know what cell I am working with. Maybe I am going about it the wrong way, I can override the onBrowserEvent method and detect when someone right clicks on the tree but I can't figure out which cell is being clicked so I can manually select it. Has anyone found a solution for this problem?

回答1:

The solution consists of two steps:

1) Add a TreeViewModel to the constructor of your CellTree. With that model you can set the names of your elements in the tree. Here is a simple implementation from the API:

private static class CustomTreeModel implements TreeViewModel {

    /**
     * Get the {@link NodeInfo} that provides the children of the specified
     * value.
     */
    public <T> NodeInfo<?> getNodeInfo(T value) {
      /*
       * Create some data in a data provider. Use the parent value as a prefix
       * for the next level.
       */
      ListDataProvider<String> dataProvider = new ListDataProvider<String>();
      for (int i = 0; i < 2; i++) {
        dataProvider.getList().add(value + "." + String.valueOf(i));
      }

      // Return a node info that pairs the data with a cell.
      return new DefaultNodeInfo<String>(dataProvider, new TextCell());
    }

    /**
     * Check if the specified value represents a leaf node. Leaf nodes cannot be
     * opened.
     */
    public boolean isLeaf(Object value) {
      // The maximum length of a value is ten characters.
      return value.toString().length() > 10;
    }
  }

2) When you receive the right click Event, get the EventTarget name and compare it with the name of that item you set using the model.

回答2:

I found a solution, I hope this helps others as I have been searching for this for a long time. There might be a better way, but here is how I accomplished the functionality that I desired:

In the cells that I used inside my tree, I did an override on the onbrowserevent to catch the mouse events and set the selection model. With abstract cells you can sink events you want it to listen to and in my case I chose mouse down.

public class CustomContactCell extends AbstractCell<ContactInfo> {

    private SetSelectionModel<ContactInfo> selectionModel;

    public CustomContactCell(SetSelectionModel<ContactInfo> selectionModel) {
        super("mousedown");
        this.selectionModel = selectionModel;
    }

    @Override
    public void render(Context context, ContactInfo value, SafeHtmlBuilder sb) {
        ...
    }

    @Override
    public void onBrowserEvent(com.google.gwt.cell.client.Cell.Context context, Element parent, ContactInfo value, NativeEvent event, ValueUpdater<ContactInfo> valueUpdater) {
        if (event.getButton() == NativeEvent.BUTTON_RIGHT) {
            if (selectionModel != null) {
                selectionModel.clear();
                selectionModel.setSelected(value, true);
            }
        }
        super.onBrowserEvent(context, parent, value, event, valueUpdater);
    }
}

来源：https://stackoverflow.com/questions/18599619/gwt-cell-tree-right-click-selection

标签

gwt

tree

cell