XtraGrid滚轮翻页
滚轮翻页与传动的翻页更为方便，经过本人一番探讨与琢磨终于在XtraGrid的GridView中实现了鼠标滚轮翻页。
我新建了一个组件继承原本的GridControl，在组件中添加了一个ImageList,专门存放一些资源图片。用于实现动态图的效果。
添加一个自定义委托的参数与枚举，委托参数用于传递分页的信息。
public class PagingEventArgs : EventArgs
{
public int PageSize { get; set; }
public int PageIndex { get; set; }
}
public enum LoadState
{
/// <summary>
/// 就绪
/// </summary>
Ready,
/// <summary>
/// 正在读取
/// </summary>
Loading,
/// <summary>
/// 读取完成
/// </summary>
Finish
}
在组件的类里面添加以下字段
/// <summary>
/// 页面大小
/// </summary>
private int _int_page_size=20;
/// <summary>
/// 当前页索引
/// </summary>
private int _int_page_index=1;
/// <summary>
/// 总记录数
/// </summary>
private int _int_record_count;
/// <summary>
/// 读取状态
/// </summary>
private LoadState _LodaState_state;
添加以下属性
/// <summary>
/// 总记录数
/// </summary>
public int RecordCount
{
get
{
if (!IsPaging) return 0;
return _int_record_count;
}
set
{
if (!IsPaging) return ;
_int_record_count = value;
//当设置了新的记录总数，自动读取第一页的内容
if(value>0)
gridView_TopRowChanged(this, new EventArgs());
else
{
while (this.MainView.DataRowCount > 0)
GridView_main_view.DeleteRow(0);
this.RefreshDataSource();
}
}
}
/// <summary>
/// 每次读取的行数
/// </summary>
public int PageSize
{
get
{
if (!IsPaging) return 0;
return _int_page_size;
}
set
{
if (!IsPaging) return ;
_int_page_size = value;
}
}
/// <summary>
/// 总页数
/// </summary>
private int PageCount
{
get
{
if (RecordCount % PageSize == 0)
return RecordCount / PageSize;
return RecordCount / PageSize + 1;
}
}
/// <summary>
/// Grid
/// </summary>
private GridView _GridView_main_view
{
get { return (GridView)this.MainView; }
}
/// <summary>
/// 是否启用分页
/// </summary>
public bool IsPaging { get; set; }
添加以下委托与事件
/// <summary>
/// 内部使用的委托
/// </summary>
private delegate void myDelegate();
/// <summary>
/// 滚动翻页的委托
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
public delegate void ScrollingToPageEventHandler(object sender, PagingEventArgs e);
/// <summary>
/// 滚动翻页的事件
/// </summary>
public event ScrollingToPageEventHandler OnScrollingToPage;
以下则是一些对控件的设置，按照各人喜好可以有所更改。
/// <summary>
/// 设置分页栏
/// </summary>
private void InitEmbeddedNavigator()
{this.EmbeddedNavigator.CustomButtons.AddRange(new DevExpress.XtraEditors.NavigatorCustomButton[] {
new DevExpress.XtraEditors.NavigatorCustomButton(-1, -1, true, false, "", null)});
this.EmbeddedNavigator.TextStringFormat = " 当前 {1} 行数据 ";
this.UseEmbeddedNavigator = true;
}
/// <summary>
/// 设置gridView
/// </summary>
private void InitGridView()
{
_GridView_main_view.TopRowChanged += new EventHandler(gridView_TopRowChanged);
}
为控件的事件注册以下方法
private void gridControl_Load(object sender, EventArgs e)
{
if (IsPaging)
{
_LodaState_state = LoadState.Ready;
InitEmbeddedNavigator();
InitGridView();
}
}
private void gridView_TopRowChanged(object sender, EventArgs e)
{
lock (this)
{
if ( _int_page_index > PageCount || _LodaState_state != LoadState.Ready) return;
}
//检查是否到达底部
if (_GridView_main_view.IsRowVisible(_GridView_main_view.RowCount - 1) == RowVisibleState.Visible||
_int_page_index==1)
{
lock (this)//设置成开始读取状态
{
_LodaState_state = LoadState.Loading;
}
Thread thread_load_data = new Thread(new ThreadStart(LoadData));
Thread thread_change_text = new Thread(new ThreadStart(ChangeLoadingImage));
thread_change_text.Start();
thread_load_data.Start();
}
}
TopRowChanged事件在grid的首行改变了就会触发，类似于滚动条的Scroll事件。这里开了两个线程，第一个线程用于读取数据，第二个线程用于实现动态图。两个线程调用的方法都在下面
/// <summary>
/// 读取数据
/// </summary>
private void LoadData()
{
int top_row_index = 0;
int focus_index = 0;
lock (this)
{
top_row_index = _GridView_main_view.TopRowIndex;
focus_index = _GridView_main_view.FocusedRowHandle;
//执行事件
if (OnScrollingToPage == null)
throw new Exception("OnScrollingToPage can not be null");
PagingEventArgs e = new PagingEventArgs();
e.PageIndex = this._int_page_index;
e.PageSize = this._int_page_size;
OnScrollingToPage(this,e);
}
//刷新grid的数据
if (this.Parent.InvokeRequired)
{
this.Parent.Invoke(new myDelegate(delegate
{
_GridView_main_view.TopRowIndex = top_row_index;
_GridView_main_view.FocusedRowHandle = focus_index;
_GridView_main_view.RefreshData();
}));
}
lock (this)
{
_LodaState_state = LoadState.Finish;//设置成读取完成状态
}
}
/// <summary>
/// 更替图片
/// </summary>
private void ChangeLoadingImage()
{
int image_index = 0;
if (this.Parent.InvokeRequired)//显示loading的gif
{
this.Parent.Invoke(new myDelegate(delegate
{
this.EmbeddedNavigator.Buttons.CustomButtons[0].Visible = true;
}));
}
while (true)//循环更替图片实现动态图效果
{
lock (this)
{
if (_LodaState_state != LoadState.Loading)//判定数据是否完成
break;
}
Thread.Sleep(120);
if (image_index == 3)
image_index = 0;
else
image_index++;
if (this.Parent.InvokeRequired)
{
//轮流更换图片实现gif动态图
this.Parent.Invoke(new myDelegate(delegate
{
this.EmbeddedNavigator.Buttons.CustomButtons[0].ImageIndex = image_index;
}));
}
}
if (this.Parent.InvokeRequired)//隐藏loading的gif
{
this.Parent.Invoke(new myDelegate(delegate
{
this.EmbeddedNavigator.Buttons.CustomButtons[0].Visible = false;
}));
}
lock (this)
{
_LodaState_state = 0;
_int_page_index++;
}
}
不过这个代码有点问题，当GridControl绑定的数据源有相同实例的子项时，随着RefreshData方法的调用会不停触发TopRowChanged事件，确切的原因还没搞清楚，解决这个问题就是要不去除数据源上相同的实例子项，要不就不调用RefreshData方法。还有更好的办法还请高手们的指点。
