Synnefo » Pithos Web Client

package gr.grnet.pithos.web.client;

import com.google.gwt.cell.client.AbstractCell;

import com.google.gwt.cell.client.Cell.Context;

import com.google.gwt.dom.client.Element;

import com.google.gwt.dom.client.NativeEvent;

import com.google.gwt.dom.client.Style.Cursor;

import com.google.gwt.event.shared.HandlerRegistration;

import com.google.gwt.safehtml.shared.SafeHtmlBuilder;

import com.google.gwt.safehtml.shared.SafeHtmlUtils;

import com.google.gwt.user.cellview.client.AbstractCellTable;

import com.google.gwt.user.cellview.client.Column;

import com.google.gwt.user.client.Event;

import com.google.gwt.user.client.Event.NativePreviewEvent;

import com.google.gwt.user.client.Event.NativePreviewHandler;

public class ResizableHeader<T> extends SortableHeader { 

        private Column<T, ?> column = null;

        private AbstractCellTable<T> cellTable;

        private String title = "";

        static private final int width = 10;

        public ResizableHeader(String title, AbstractCellTable<T> cellTable, Column<T, ?> column) {

                super(title);

                this.title  = title;

                this.cellTable = cellTable;

                this.column = column;

        }

        @Override 

        public String getValue() 

        { 

                return title;

        }

        @Override

        public void onBrowserEvent(Context context, Element target, NativeEvent event) {

            String eventType = event.getType();

                int clientX = event.getClientX();

                int absoluteLeft = target.getAbsoluteLeft();

                int offsetWidth = target.getOffsetWidth();

                if (clientX > absoluteLeft + offsetWidth - width) {

                        setCursor(target, Cursor.COL_RESIZE);

                } else {

                        setCursor(target, Cursor.DEFAULT);

                }

            if(eventType.equals("mousedown")) {

                        if (clientX > absoluteLeft + offsetWidth - width) {

                    new ColumnResizeHelper<T>(cellTable, column, target);

                        }

                event.preventDefault();

                event.stopPropagation();

            } else {

                    return;

            }

        }

        private void setCursor(Element element, Cursor cursor) {

                element.getStyle().setCursor(cursor);

        }

class ColumnResizeHelper<T> implements NativePreviewHandler {

          private HandlerRegistration handler;

          private AbstractCellTable<T> table;

          private Column<T, ?> col;

          private Element el;

          public ColumnResizeHelper(AbstractCellTable<T> table, Column<T, ?> col, Element el) {

            this.el = el;

            this.table = table;

            this.col = col;

            handler = Event.addNativePreviewHandler(this);

          }

          @Override

          public void onPreviewNativeEvent(NativePreviewEvent event) {

            NativeEvent nativeEvent = event.getNativeEvent();

            nativeEvent.preventDefault();

            nativeEvent.stopPropagation();

            if (nativeEvent.getType().equals("mousemove")) {

              int absoluteLeft = el.getAbsoluteLeft();

              int clientX = nativeEvent.getClientX();

              int newWidth = clientX - absoluteLeft;

              newWidth = newWidth < 10 ? 10 : newWidth;

              table.setColumnWidth(col, newWidth + "px");

            } else if (nativeEvent.getType().equals("mouseup")) {

              handler.removeHandler();

            }

          }

        }

        static class HeaderCell extends AbstractCell<String> {

                public HeaderCell() {

                        super("click", "mousedown", "mousemove");

                }

                @Override

                public void render(com.google.gwt.cell.client.Cell.Context context, String value, SafeHtmlBuilder sb) {

                        sb.append(

                                        new SafeHtmlBuilder()

                                .append(SafeHtmlUtils.fromString(value))

                                .toSafeHtml());

                }

        }

};