144 lines
3.4 KiB
ObjectPascal
144 lines
3.4 KiB
ObjectPascal
unit L_DBDateTime;
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interface
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uses
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Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms,db,dbtables,dbctrls,Dialogs,
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ComCtrls;
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type
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TDBDateTime = class(TDateTimePicker)
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private
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FDataLink:TFieldDataLink;
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//TFieldDataLink是TDataLink的派生类，
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// 处理单个字段与DataSource的交互
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procedure DataChange(sender:Tobject);
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//当DataSet的记录改变（如浏览记录）
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// 时触发OnDataChange
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// 事件，DataChange将作为该事件的事件处理句柄
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procedure UpdateData(sender:Tobject);
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//更新DataSet前触发OnUpdateData事件，
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// UpdateData将作为该事件的事件处理句柄
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function GetDataSource:TDataSource;
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procedure SetdataSource(value:TDataSource);
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Function GetDataField:String;
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procedure SetdataField(Value:String);
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procedure CMexit(var Message:TCMExit);
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message CM_EXIT;//当控件失去焦点时触发CM_EXIT消息
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protected
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procedure Change;override;//控件中日期、
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// 时间改变时触发OnChange事件
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procedure Notification(AComponent:TComponent;
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Operation:Toperation);override;
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//当某一控件从FORM上移走时DELPHI的
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// IDE调用该方法通知其它控件
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public
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constructor Create(AOwner:Tcomponent);override;
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destructor Destroy;override;
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published
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property DataSource:TDataSource read GetDataSource
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write SetDataSource;//为控件增加DataSource属性，
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// 使它能与DataSource构件连接
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property DataField:String read GetDataField
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write SetDataField;
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end;//为控件增加DataField属性，
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// 使它指向代表某一字段的TField对象
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procedure Register;//注册构件
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implementation
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procedure TDBDateTime.CMExit;
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begin
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try
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FDataLink.UpdateRecord;
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//控件失去焦点时更新DataSet，
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// 这将触发OnUpdateData事件
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except
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Setfocus;
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raise;
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end;
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DoExit;
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end;
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constructor TDBDateTime.Create(Aowner:Tcomponent);
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begin
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inherited Create(Aowner);
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//创建DataLink对象，挂接OnDataChange、
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//OnUpdateData事件处理句柄
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FDataLink:=TFieldDataLInk.Create;
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FDataLink.OnDataChange:=DataChange;
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FDataLink.OnUpdateData:=Updatedata;
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end;
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Destructor TDBDateTime.Destroy;
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begin
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FDataLink.OnDataChange:=nil;
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FDataLink.OnUpdateData:=nil;
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FDataLink.Free;
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inherited Destroy;
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end;
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function TDBDateTime.GetdataSource:TdataSource;
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begin
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result:=FDataLink.DataSource;
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end;
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Procedure TDBDateTime.SetDataSource
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(Value:TDataSource);
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begin
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FDataLink.DataSource:=Value;
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end;
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function TDBDateTime.GetDatafield:String;
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begin
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result:=FDataLink.FieldName;
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end;
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procedure TDBDateTime.SetDataField(value:String);
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begin
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FdataLink.FieldName:=value;
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end;
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procedure TDBDateTime.DataChange(Sender:Tobject);
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begin
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DateTime:=now;
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//若控件连了活动的DataSet则数据集变动时
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//控件显示当前记录的相应字段值
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if FDataLink.Field<>nil then
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if FDataLink.Field.Text<>'' then
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DateTime:=FDatalink.Field.AsDateTime;
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end;
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Procedure TDBDateTime.UpdateData(sender:Tobject);
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begin
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FDatalink.Field.AsDateTime:=DateTime;
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//用控件中的日期、时间更新相应字段
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end;
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procedure TDBDateTime.Change;
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begin
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//当用户改变了控件中的内容时将DataSet置为编辑状态
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FDataLink.Modified;
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if not FDataLink.Editing then
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FdataLink.Edit;
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inherited Change;
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end;
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procedure TDBDateTime.Notification
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(AComponent:TComponent;Operation:TOperation);
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begin
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inherited Notification(Acomponent,Operation);
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//当与控件相连的TdataSource
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// 被删除时将控件的DataSource属性置为空
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if (Operation=opRemove) and (FDataLink<>nil)
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and (AComponent=Datasource) then
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DataSource:=nil;
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end;
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procedure Register;
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begin
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RegisterComponents('Data Controls',[TDBDateTime]);
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end;
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end.
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