cxgrid技巧集

==========================================================================

在主从TableView中根据主TableView得到对应的从TableView
var
ADetailDC: TcxGridDataController;
AView: TcxCustomGridTableView;
begin
with cxGrid1DBTableView1.DataController do
ADetailDC := TcxGridDataController(GetDetailDataController(FocusedRecordIndex, 0));
AView := ADetailDC.GridView;
end;

==============================================================================

定位在第一行并显示内置编辑器

cxDBVerticalGrid1.FocusedRow := cxDBVerticalGrid1.Rows[0];
cxDBVerticalGrid1.ShowEdit;

==============================================================================

隐藏 "<No data to display>" 字符串

该文本存储在scxGridNoDataInfoText资源字符串,可以将该资源字符串的内容设为空
来隐藏该文本。

uses cxClasses, cxGridStrs;
...
cxSetResourceString(@scxGridNoDataInfoText, '');

//如果"<No data to display>" 字符串已经显示，需要调用：
<View>.LayoutChanged;

============================================================

删除应用过滤后的行

var
I: Integer;
begin
with <GridView> do
for I := 0 to ViewData.RecordCount - 1 do
begin
ViewData.Records[0].Focused := True;
DataController.DataSet.Delete;
end;

=============================================================

根据单元的值设置样式

procedure <aForm>.<aColumn>StylesGetContentStyle(
Sender: TcxCustomGridTableView; ARecord: TcxCustomGridRecord;
AItem: TcxCustomGridTableItem; out AStyle: TcxStyle);
begin
if ARecord.Values[AItem.Index] = aSomeValue then
AStyle := <aSomeStyle>;
end;

procedure <aForm>.<aView>StylesGetContentStyle(
Sender: TcxCustomGridTableView; ARecord: TcxCustomGridRecord;
AItem: TcxCustomGridTableItem; out AStyle: TcxStyle);
var
AColumn: TcxCustomGridTableItem;
begin
AColumn := (Sender as TcxGridDBTableView).GetColumnByFieldName('Email');
if VarToStr(ARecord.Values[AColumn.Index]) = '' then
AStyle := cxStyleNullEmail;
end;

==============================================================================

TcxCustomGridTableView.FindItemByName, TcxGridDBTableView.GetColumnByFieldName or
TcxGridDBDataController.GetItemByFieldName

with cxGrid1DBBandedTableView1.DataController do
AValue := Values[FocusedRecordIndex, GetItemByFieldName('SomeFieldName').Index];

===================================================================

动态生成BandedView

var
AView: TcxCustomGridView;
begin
AView := <cxGrid>.CreateView(TcxGridDBBandedTableView);
TcxGridDBBandedTableView(AView).DataController.DataSource := <DataSource>;
TcxGridDBBandedTableView(AView).Bands.Add;
with TcxGridDBBandedTableView(AView).Bands.Add do
begin
Visible := False;
FixedKind := fkLeft;
end;
TcxGridDBBandedTableView(AView).DataController.CreateAllItems;
<cxGridLevel>.GridView := AView;  

======================================================================

当底层数据集为空时显示一条空记录

procedure <Form>.<cxGrid>Enter(Sender: TObject);
var
View: TcxGridDBTableView;
begin
View := TcxGridDBTableView((Sender as TcxGrid).FocusedView);
if View.DataController.DataSet.IsEmpty then
begin
View.DataController.DataSet.Append;
View.Controller.EditingController.ShowEdit;
end;
end;

=======================================================================

在当前View插入记录

使用FocusedView属性得到当前焦点View，用View.DataController得到对应的Data Controller，
之后使用Data Controller的方法来操作数据：
- Append
- Insert
- Post
- Cancel
- DeleteFocused
- DeleteSelection

示例：
var
ARecIndex: Integer;
…
View.DataController.Append;
ARecIndex := View.DataController.FocusedRecordIndex;
View.DataController.Values[ARecIndex, SomeItemIndex] := SomeValue;
View.DataController.Post;

另外一种方法是使用View.DataController.DataSource.DataSet得到底层数据集后，再用数据集的
方法来操作数据。

========================================================================

激活内置编辑控件

1) <aView>.Controller.EditingController.ShowEdit(<aColumn>);
2) <aView>.Controller.EditingController.StartEditShowingTimer(<aColumn>);
3) <aView>.Controller.EditingItem := <aColumn>;
4) <aColumn>.Editing := True;

隐藏内置编辑控件
<aView>.Controller.EditingController.HideEdit(True);

===========================================================================

移除一个分组列

<aColumn>.GroupIndex := -1;
<aColumn>.Visible := True;

===========================================================================

保存修改到数据库

procedure <aForm>.FormClose(Sender: TObject; var Action: TCloseAction);
begin
if (<aGrid>.FocusedView <> nil) and (<aGrid>.FocusedView.DataController.EditState <> []) then
<aGrid>.FocusedView.DataController.Post;
end;

============================================================================

设置内置右键菜单

内置右键菜单包括二个菜单:cxGridStdHeaderMenu, TcxGridStdFooterMenu

uses cxGridStdPopupMenu;

procedure TForm1.cxGridPopupMenu1Popup(ASenderMenu: TComponent;
AHitTest: TcxCustomGridHitTest; X, Y: Integer; var AllowPopup: Boolean);
begin
if ASenderMenu is TcxGridStdHeaderMenu then
TcxGridStdHeaderMenu(ASenderMenu).OnPopup := StdHeaderMenuPopup;
end;

procedure TForm1.StdHeaderMenuPopup(Sender: TObject);
var
I: Integer;
begin
with TcxGridStdHeaderMenu(Sender).Items do
for I := 0 to Count - 1 do
if Items[I].Caption = 'Group By Box' then
begin
Items[I].Enabled := False;
System.Break;
end
end;

===========================================================================

得到选中记录的值

1) View.DataController.DataModeController.GridMode = False时

RecIdx := View.Controller.SelectedRecords[i].RecordIndex;
ColIdx := View.DataController.GetItemByFieldName(AFieldName).Index;
OutputVal := View.DataController.Values[RecIdx, ColIdx];

//RecID := View.DataController.GetRecordId(RecIdx);
//OutputVal := ADataSet.Lookup(View.DataController.KeyFieldNames, RecID, AFieldName);

2) View.DataController.DataModeController.GridMode = True时
Bkm := View.DataController.GetSelectedBookmark(ASelectedRecordIndex);
if ADataSet.BookmarkValid(TBookmark(Bkm)) then
begin
ADataSet.Bookmark := TBookmark(Bkm);
OutputVal := ADataSet.FieldByName(AFieldName).Value;
end;

View.BeginUpdate;
View.DataController.BeginLocate;
try
// make changes here…
finally
View.DataController.EndLocate;
View.EndUpdate;
end;

=============================================================

在GridMode禁用内置的右键Footer菜单

uses cxGridStdPopupMenu;

procedure cxGridPopupMenuOnPopup(...)
begin
if (ASenderMenu is TcxGridStdFooterMenu) and
<GridView>.DataController.DataModeController.GridMode then
AllowPopup := False;
end;

==============================================================

主从表任何时候只能展开一个组

procedure TForm1.ADetailDataControllerCollapsing(
ADataController: TcxCustomDataController; ARecordIndex: Integer;
var AAllow: Boolean);
var
I: Integer;
C: Integer;
begin
AAllow := False;
C := 0;
for I := 0 to ADataController.RecordCount - 1 do
begin
if ADataController.GetDetailExpanding(I) then
Inc(C);
if C > 1 then
AAllow := True;
end;
end;

procedure TForm1.ADetailDataControllerExpanding(
ADataController: TcxCustomDataController; ARecordIndex: Integer;
var AAllow: Boolean);
begin
ADataController.CollapseDetails;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
cxGrid1DBTableView1.DataController.OnDetailExpanding := ADetailDataControllerExpanding;
cxGrid1DBTableView1.DataController.OnDetailCollapsing := ADetailDataControllerCollapsing;
end;

=================================================================

动态创建层次(Level)和视图(View)

var
Grid: TcxGrid;
Level: TcxGridLevel;
View: TcxGridDBTableView;
begin
// Creates a Grid instance
Grid := TcxGrid.Create(SomeOwner);
Grid.Parent := SomeParent;
// Creates a Level
Level := Grid.Levels.Add;
Level.Name := 'SomeLevelName';
// Creates a View
View := Grid.CreateView(TcxGridDBTableView) as TcxGridDBTableView;
View.Name := 'SomeViewName';
// … and binds it to the Level
Level.GridView := View;
// Hooks up the View to the data
View.DataController.DataSource := SomeDataSource;
// … and creates all columns
View.DataController.CreateAllItems;
end;

======================================================================

获得Group Footer合计行对应的记录

procedure TForm1.cxGrid1DBTableView1CustomDrawFooterCell(
Sender: TcxGridTableView; ACanvas: TcxCanvas;
AViewInfo: TcxGridColumnHeaderViewInfo; var ADone: Boolean);
var
ALevel, ADataGroupIndex: Integer;
AGridRecord, AGroupRecord: TcxCustomGridRecord;
begin
if AViewInfo is TcxGridRowFooterCellViewInfo and // Row footer
(TcxGridDBColumn(AViewInfo.Column).DataBinding.FieldName = 'Area') then // Area column
begin
AGridRecord := TcxGridRowFooterCellViewInfo(AViewInfo).GridRecord;
ALevel := TcxGridRowFooterCellViewInfo(AViewInfo).Container.GroupLevel;
ADataGroupIndex := Sender.DataController.Groups.DataGroupIndexByRowIndex[AGridRecord.Index];
if ADataGroupIndex <> -1 then
begin
AGroupRecord := AGridRecord;
while AGroupRecord.Level <> ALevel do
AGroupRecord := AGroupRecord.ParentRecord;
AViewInfo.Text := AGroupRecord.DisplayTexts[0];
end;
end;
end;

===========================================================================

访问过滤之后的记录

var
I: Integer;
begin
Memo1.Lines.Clear;
with cxGrid1DBTableView1.DataController do
for I := 0 to FilteredRecordCount - 1 do
Memo1.Lines.Add(DisplayTexts[FilteredRecordIndex[I], 0]);
end;

============================================================================

获得单元的Font

cxGrid1DBTableView1.ViewInfo.RecordsViewInfo.Items[1].GetCellViewInfoByItem(
cxGrid1DBTableView1Company).EditViewInfo.Font;

============================================================================

根据Level名称找到Level对象

function GetLevelByName(AGrid: TcxGrid; ALevelName: string): TcxGridLevel;

function LoopThroughLevels(ALevel: TcxGridLevel; ALevelName: string): TcxGridLevel;
var
I: Integer;
begin
Result := nil;
for I := 0 to ALevel.Count - 1 do
begin
if ALevel[I].Name = ALevelName then
begin
Result := ALevel[I];
Exit;
end;
if ALevel[I].Count > 0 then
begin
Result := LoopThroughLevels(ALevel[I], ALevelName);
if Result <> nil then
Exit;
end;
end;
end;

var
I: Integer;
begin
Result := nil;
for I := 0 to AGrid.Levels.Count - 1 do
begin
if AGrid.Levels[I].Name = ALevelName then
begin
Result := AGrid.Levels[I];
Exit;
end;
if AGrid.Levels[I].Count > 0 then
begin
Result := LoopThroughLevels(AGrid.Levels[I], ALevelName);
if Result <> nil then
Exit;
end;
end;
end;

============================================================================

指定Filter Builder打开/保存过滤文件的默认路径

uses
..., cxFilterControlDialog;

procedure TForm.GridView1FilterControlDialogShow(
Sender: TObject);
begin
TfmFilterControlDialog(Sender).OpenDialog.InitialDir := 'D:/'
end;

============================================================================

保存/恢复带汇总行的布局

<TableView>.StoreToIniFile('c:/Grid.ini', True, [gsoUseSummary]);
<GridView>.RestoreFromIniFile(<inifilename>,True,False {or True, optional},[gsoUseSummary]);

============================================================================

取消过滤时移到第一行

uses
cxCustomData;

procedure TYour_Form.AViewDataControllerFilterChanged(Sender: TObject);
var
Filter: TcxDataFilterCriteria;
begin
with Sender as TcxDataFilterCriteria do
if IsEmpty then
DataController.FocusedRowIndex := 0;
end;

=============================================================================

排序后移到第一行

可以设置DataController.Options.FocusTopRowAfterSorting := True，也可以使用如下的代码：

uses
cxCustomData;

procedure TYour_Form.Your_ViewDataControllerSortingChanged(Sender: TObject);
begin
TcxCustomDataController(Sender).FocusedRowIndex := 0;
end;

==============================================================================

判断当前行是否第一行或最后一行

可以使用DataController的IsBOF, IsEOF方法，或者：
<AView>.Controller.Controller.FocusedRow.IsFirst
<AView>.Controller.Controller.FocusedRow.IsLast

==============================================================================

根据指定值查找记录

DataController提供了好几个方法来得到指定值对应的RecordIndex
对于Bound View可以使用FindRecordIndexByKeyValue方法

===============================================================================

编辑和显示Blob字段

该字段的Properties设置为BlobEdit，并将BlobPaintStyle 属性设为 bpsText

===============================================================================

得到可见行数

<View>.ViewInfo.VisibleRecordCount

===============================================================================

保存后的行设置为当前行

const
CM_SETFOCUSEDRECORD = WM_USER + 1002;

type
TForm1 = class(TForm)
cxGrid1DBTableView1: TcxGridDBTableView;
cxGrid1Level1: TcxGridLevel;
cxGrid1: TcxGrid;
dxMemData1: TdxMemData;
dxMemData1Field1: TStringField;
dxMemData1Field2: TIntegerField;
DataSource1: TDataSource;
cxGrid1DBTableView1RecId: TcxGridDBColumn;
cxGrid1DBTableView1Field1: TcxGridDBColumn;
cxGrid1DBTableView1Field2: TcxGridDBColumn;
Timer1: TTimer;
CheckBox1: TCheckBox;
procedure Timer1Timer(Sender: TObject);
procedure dxMemData1AfterPost(DataSet: TDataSet);
procedure CheckBox1Click(Sender: TObject);
private
procedure CMSetFocusedRecord(var Msg: TMessage); message CM_SETFOCUSEDRECORD;
public
{ Public declarations }
end;

var
Form1: TForm1;
FocusedIdx: Integer;

implementation

{$R *.dfm}

procedure TForm1.Timer1Timer(Sender: TObject);
begin
dxMemData1.AppendRecord(['', IntToStr(Random(1000)), Random(1000)]);
end;

procedure TForm1.dxMemData1AfterPost(DataSet: TDataSet);
begin
PostMessage(Handle, CM_SETFOCUSEDRECORD, Integer(cxGrid1DBTableView1), MakeLParam(cxGrid1DBTableView1.Controller.FocusedRowIndex, cxGrid1DBTableView1.Controller.TopRowIndex));
end;

procedure TForm1.CMSetFocusedRecord(var Msg: TMessage);
begin
TcxGridDBTableView(msg.WParam).Controller.FocusedRowIndex := Msg.LParamLo;
TcxGridDBTableView(msg.WParam).Controller.TopRowIndex := Msg.LParamHi;
end;

procedure TForm1.CheckBox1Click(Sender: TObject);
begin
Timer1.Enabled := TCheckBox(Sender).Checked;
end;

end.

=================================================================================

删除记录并获得焦点

procedure TForm1.BtnDeleteClick(Sender: TObject);
var
FocusedRow, TopRow: Integer;
View: TcxGridTableView;
DataController: TcxGridDataController;
begin
View := cxGrid1.FocusedView as TcxGridTableView;
DataController := View.DataController;

// Remember the top row (the vertical scrollbar position)
TopRow := View.Controller.TopRowIndex;
// Remember the focused row(!) index
FocusedRow := DataController.FocusedRowIndex;

DataController.DeleteFocused;

// After deletion the same row must be focused,
// although it will correspond to a different data record
DataController.FocusedRowIndex := FocusedRow;
// Restore the top row
View.Controller.TopRowIndex := TopRow;
end;