com.google.gwt.sample.showcase.client.content.cell.Cells.java Source code

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Here is the source code for com.google.gwt.sample.showcase.client.content.cell.Cells.java

Source

package com.google.gwt.sample.showcase.client.content.cell;

import java.util.HashSet;
import java.util.Set;

import com.google.gwt.cell.client.Cell;
import com.google.gwt.cell.client.ValueUpdater;
import com.google.gwt.dom.client.BrowserEvents;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.user.client.ui.HasScrolling;

public class Cells {

    private Cells() {
    }

    public static <F, T> Cell<F> adapt(Cell<T> cell, Function<F, T> transform) {
        return new CellAdapter<F, T>(cell, transform, null);
    }

    public static <F, T> Cell<F> adaptWithConstantValue(Cell<T> cell, final T value) {
        return new CellAdapter<F, T>(cell, new Function<F, T>() {
            @Override
            public T apply(F input) {
                return value;
            }
        }, null);
    }

    public static <T> Cell<T> makeClickable(Cell<T> cell, final Receiver<T> clickReceiver) {
        Set<String> events = new HashSet<>();
        events.add(BrowserEvents.CLICK);
        events.add(BrowserEvents.KEYDOWN);
        return new CellAdapter<T, T>(cell, null, events) {
            @Override
            public void onBrowserEvent(Context context, Element parent, T value, NativeEvent event,
                    ValueUpdater<T> valueUpdater) {
                super.onBrowserEvent(context, parent, value, event, valueUpdater);
                if (event.getType().equals(BrowserEvents.CLICK) || (event.getType().equals(BrowserEvents.KEYDOWN)
                        && event.getKeyCode() == KeyCodes.KEY_ENTER)) {
                    clickReceiver.accept(value);
                }
            }
        };
    }

    /**
     * Wrap the given cell so that if
     * {@link Cell#resetFocus(com.google.gwt.cell.client.Cell.Context, Element, Object)} is
     * called on it, the wrapped cell will focus itself, but will also make sure that the
     * browser window doesn't automatically scroll the cell into view. This is handy for
     * cells that should respond to keyboard commands even when out of view.
     *
     * <p>Note that refocusing on top-level cells will happen automatically when a cell widget
     * is redrawn. One surprising cause of a redraws is that HasDataPresenter optimizes extensions
     * to a short list by just redoing the whole list. See
     * {@link com.google.gwt.user.cellview.client.HasDataPresenter#REDRAW_THRESHOLD} for what
     * can trigger redraws.
     */
    public static <T> Cell<T> makeFocusableWithoutScrolling(Cell<T> cellToWrap, final HasScrolling scrollable) {
        return new CellAdapter<T, T>(cellToWrap, null, null) {
            @Override
            public boolean resetFocus(Context context, Element parent, T value) {
                int x = scrollable.getHorizontalScrollPosition();
                int y = scrollable.getVerticalScrollPosition();
                parent.focus();
                scrollable.setHorizontalScrollPosition(x);
                scrollable.setVerticalScrollPosition(y);
                return true;
            }
        };
    }
}