经过一些原型设计后，我能够制作一个可拖动的山墙弹性表。我创建了一个扩展弹性表的类。这里是代码
public class DragFlexTable extends FlexTable implements
MouseDownHandler,MouseUpHandler,MouseMoveHandler,
MouseOutHandler
{
private int row,column,draggedrow,draggedcolumn;
private Element td;
private Widget w;
private boolean emptycellclicked;
DragFlexTable()
{
sinkEvents(Event.ONMOUSEOVER | Event.ONMOUSEOUT | Event.ONMOUSEDOWN | Event.ONMOUSEMOVE);
this.addMouseDownHandler(this);
this.addMouseMoveHandler(this);
this.addMouseUpHandler(this);
this.addMouseOutHandler(this);
}
@Override
public void onBrowserEvent(Event event)
{
super.onBrowserEvent(event);
td = getEventTargetCell(event);
if (td == null)
{
return;
}
Element tr = DOM.getParent((com.google.gwt.user.client.Element) td);
Element body = DOM.getParent((com.google.gwt.user.client.Element) tr);
row = DOM.getChildIndex((com.google.gwt.user.client.Element) body, (com.google.gwt.user.client.Element) tr);//(body, tr);
column = DOM.getChildIndex((com.google.gwt.user.client.Element) tr, (com.google.gwt.user.client.Element) td);
}
boolean mousedown;
@Override
public void onMouseDown(MouseDownEvent event)
{
if (event.getNativeButton() == NativeEvent.BUTTON_LEFT)
{
//to ensure empty cell is not clciked
if (!td.hasChildNodes())
{
emptycellclicked = true;
}
event.preventDefault();
start(event);
mousedown = true;
}
}
@Override
public void onMouseMove(MouseMoveEvent event)
{
if (mousedown)
{
drag(event);
}
}
@Override
public void onMouseUp(MouseUpEvent event)
{
if (event.getNativeButton() == NativeEvent.BUTTON_LEFT)
{
if (!emptycellclicked)
{
end(event);
}
emptycellclicked = false;
mousedown = false;
}
}
@Override
public void onMouseOut(MouseOutEvent event)
{
this.getCellFormatter().getElement(row, column).getStyle().clearBorderStyle();
this.getCellFormatter().getElement(row, column).getStyle().clearBorderColor();
this.getCellFormatter().getElement(row, column).getStyle().clearBorderWidth();
w.getElement().getStyle().setOpacity(1);
mousedown = false;
}
private void start(MouseDownEvent event)
{
w = this.getWidget(row, column);
w.getElement().getStyle().setOpacity(0.5);
}
private void drag(MouseMoveEvent event)
{
if (draggedrow != row || draggedcolumn != column)
{
this.getCellFormatter().getElement(draggedrow, draggedcolumn).getStyle().clearBorderStyle();
this.getCellFormatter().getElement(draggedrow, draggedcolumn).getStyle().clearBorderColor();
this.getCellFormatter().getElement(draggedrow, draggedcolumn).getStyle().clearBorderWidth();
this.draggedrow = row;
this.draggedcolumn = column;
this.getCellFormatter().getElement(row, column).getStyle().setBorderStyle(BorderStyle.DASHED);
this.getCellFormatter().getElement(row, column).getStyle().setBorderColor("black");
this.getCellFormatter().getElement(row, column).getStyle().setBorderWidth(2, Unit.PX);
}
}
private void end(MouseUpEvent event)
{
insertDraggedWidget(row, column);
}
private void insertDraggedWidget(int r,int c)
{
this.getCellFormatter().getElement(r, c).getStyle().clearBorderStyle();
this.getCellFormatter().getElement(r, c).getStyle().clearBorderColor();
this.getCellFormatter().getElement(r, c).getStyle().clearBorderWidth();
w.getElement().getStyle().setOpacity(1);
if (this.getWidget(r, c) != null)
{
//pushing down the widgets already in the column
// int widgetheight = (this.getWidget(r, c).getOffsetHeight() / 2) + this.getWidget(r, c).getAbsoluteTop();
// int rw;
//placing the widget above the dropped widget
for (int i = this.getRowCount() - 1; i >= r; i--)
{
if (this.isCellPresent(i, c))
{
this.setWidget(i + 1, c, this.getWidget(i, c));
}
}
}
this.setWidget(r, c, w);
//removes unneccesary blank rows
cleanupRows();
//pushing up the column in the stack
// for (int i = oldrow;i<this.getRowCount()-1 ;i++)
// {
//
// this.setWidget(i ,oldcolumn, this.getWidget(i+1, oldcolumn));
//
// }
}
private void cleanupRows()
{
ArrayList<Integer> rowsfilled = new ArrayList<Integer>();
for (int i = 0; i <= this.getRowCount() - 1; i++)
{
for (int j = 0; j <= this.getCellCount(i) - 1; j++)
{
if (this.getWidget(i, j) != null)
{
rowsfilled.add(i);
break;
}
}
}
//replace the empty rows
for (int i = 0; i < rowsfilled.size(); i++)
{
int currentFilledRow = rowsfilled.get(i);
if (i != currentFilledRow)
{
for (int j = 0; j < this.getCellCount(currentFilledRow); j++)
{
this.setWidget(i, j, this.getWidget(currentFilledRow, j));
}
}
}
for (int i = rowsfilled.size(); i < this.getRowCount(); i++)
{
this.removeRow(i);
}
}
public HandlerRegistration addMouseUpHandler(MouseUpHandler handler)
{
return addDomHandler(handler, MouseUpEvent.getType());
}
public HandlerRegistration addMouseDownHandler(MouseDownHandler handler)
{
return addDomHandler(handler, MouseDownEvent.getType());
}
public HandlerRegistration addMouseMoveHandler(MouseMoveHandler handler)
{
return addDomHandler(handler, MouseMoveEvent.getType());
}
public HandlerRegistration addMouseOutHandler(MouseOutHandler handler)
{
return addDomHandler(handler, MouseOutEvent.getType());
}
}
上述自定义小部件的模块加载为
public void onModuleLoad()
{
Label a = new Label("asad");
Label b = new Label("ad");
Label c = new Label("qwad");
Label w = new Label("zxd");
a.setPixelSize(200, 200);
a.getElement().getStyle().setBorderStyle(BorderStyle.SOLID);
a.getElement().getStyle().setBorderWidth(1, Unit.PX);
b.setPixelSize(200, 200);
c.setPixelSize(200, 200);
w.setPixelSize(200, 200);
a.getElement().getStyle().setBackgroundColor("red");
b.getElement().getStyle().setBackgroundColor("yellowgreen");
c.getElement().getStyle().setBackgroundColor("lightblue");
w.getElement().getStyle().setBackgroundColor("grey");
DragFlexTable d = new DragFlexTable();
d.setWidget(0, 0, a);
d.setWidget(0, 1, b);
d.setWidget(1, 0, c);
d.setWidget(1, 1, w);
d.setCellPadding(20);
RootPanel.get().add(d);
}