GWT : Celltable Multiselection , MouseDown event?

Question

I've got a CellTable, which has 4 columns:

| Column 1 | Column 2 | Column 3 | Column 4 |

Goal:

User can select multiple columns while holding mouse button down and hovering over the columns.

e.g User clicks on column 1 and holds the mouse button down, moves over column 2 and 3 resulting in column 2 and 3 being selected.

I tried:

final MultiSelectionModel<data> selectionModel = new MultiSelectionModel<BestellungData>();
    cellTable.setSelectionModel(selectionModel);

    cellTable.addCellPreviewHandler(new Handler<data>()
            {

                @Override
                public void onCellPreview(
                        CellPreviewEvent<data> event) {
                    // TODO Auto-generated method stub
                    if ("click".equals(event.getNativeEvent().getType())) {

                        selectionModel.setSelected(event.getValue(), true);

                    }
                }


    });

However it doesn't work.

Answer 1

Try this one

private boolean isFocus, isFocusMouseDown;
private int lastStyledRow = -1;
private Set<Integer> columns = new HashSet<Integer>();

...

table.addCellPreviewHandler(new Handler<Contact>() {

    @Override
    public void onCellPreview(CellPreviewEvent<Contact> event) {
        if ("focus".equals(event.getNativeEvent().getType())) {
            isFocus = true;
            if (lastStyledRow != -1) {
                NodeList<TableCellElement> cells = table.getRowElement(lastStyledRow)
                        .getCells();
                for (int col : columns) {
                    cells.getItem(col).removeClassName("selectedCell");
                }
                columns.clear();
            }
        }
        if ("blur".equals(event.getNativeEvent().getType())) {
            isFocus = false;
            isFocusMouseDown = false;
            lastStyledRow = event.getIndex();

            NodeList<TableCellElement> cells = table.getRowElement(event.getIndex())
                    .getCells();
            for (int col : columns) {
                cells.getItem(col).addClassName("selectedCell");
            }
        }

        if ("mousedown".equals(event.getNativeEvent().getType()) && isFocus) {
            isFocusMouseDown = true;
        }

        if ("mouseover".equals(event.getNativeEvent().getType()) && isFocusMouseDown) {
            columns.add(event.getColumn());
        }
    }

});

Here is the dummy CSS for selected cell

.selectedCell{
    border: 2px solid #F3F7FB;
    background-color: #F00;
    font-weight: bold;
}

In the above code, we are listening for few events and based on their sequence we can identify the selected columns.

Sequence of events:

• Starting point is focus event on any column
• Then mousedown event to start dragging on anther columns
• If focus and mousedown both are true then collect all the columns on mouseover event
• Finally on blur event, change the style of all the selected cells.
• Reset the style of last selected cells on next focus event

snapshots