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。
