TUniDBGrid控件之Summary例子

TUniDBGrid控件之Summary例子
（记录一下，方便以后备查）
在这个例子中，主要用到TUniDBGrid、TClientDataSet和TDataSource三个控件。
本文除去介绍使用TUniDBGrid控件之Summary外，TClientDataSet使用FieldDefs用于自定义的字段名表（即：不使用 data provider）参考：Delphi中ClientDataSet的用法小结。
例子的步骤如下：

1. 新建一个UniGUI App，在MainForm上放入这三个控件：TUniDBGrid、TClientDataSet和TDataSource。
   
2. 使用FieldDefs用于自定义的字段名表
   
   修改第一个字段的属性
   
   依次修改另外两个字段的属性
   
3. 以FieldDefs中的字段名表为结构建立数据集
   
4. 增加 Fields
   
   建立后这模样：
   
5. 设置显示属性
   
6. 设置DataSource1的的dataset为ClientDataSet1。
7. 设置UniDBGrid1的属性：DataSource为DataSource1；另外一个是：
   
8. 增加列及修改列的属性
   
   修改需要显示统计信息的列：
   
9. 定义两个事件：
   
10. Main.pas 的代码如下：

unit Main;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics,
  Controls, Forms, uniGUITypes, uniGUIAbstractClasses,
  uniGUIClasses, uniGUIRegClasses, uniGUIForm, Data.DB, Datasnap.DBClient,
  uniGUIBaseClasses, uniBasicGrid, uniDBGrid;

type
  TMainForm = class(TUniForm)
    ClientDataSet1: TClientDataSet;
    DataSource1: TDataSource;
    ClientDataSet1Item: TStringField;
    ClientDataSet1UnitPrice: TFloatField;
    ClientDataSet1Quantity: TIntegerField;
    UniDBGrid1: TUniDBGrid;
    procedure UniFormCreate(Sender: TObject);
    procedure UniDBGrid1ColumnSummary(Column: TUniDBGridColumn;
      GroupFieldValue: Variant);
    procedure UniDBGrid1ColumnSummaryResult(Column: TUniDBGridColumn;
      GroupFieldValue: Variant; Attribs: TUniCellAttribs; var Result: string);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

function MainForm: TMainForm;

implementation

{$R *.dfm}

uses
  uniGUIVars, MainModule, uniGUIApplication;

function MainForm: TMainForm;
begin
  Result := TMainForm(UniMainModule.GetFormInstance(TMainForm));
end;

procedure TMainForm.UniDBGrid1ColumnSummary(Column: TUniDBGridColumn;
  GroupFieldValue: Variant);
begin
  if SameText(Column.FieldName, 'quantity') then
  begin
    if Column.AuxValue = NULL then Column.AuxValue:=0;
    Column.AuxValue := Column.AuxValue + Column.Field.AsInteger;
  end
  else if SameText(Column.FieldName, 'unitprice') then
  begin
    if Column.AuxValue = NULL then Column.AuxValue:=0.0;
    Column.AuxValue := Column.AuxValue + (Column.Field.AsFloat * ClientDataSet1Quantity.AsInteger);
  end;
end;

procedure TMainForm.UniDBGrid1ColumnSummaryResult(Column: TUniDBGridColumn;
  GroupFieldValue: Variant; Attribs: TUniCellAttribs; var Result: string);
var
  I : Integer;
  F : Real;
begin
  if SameText(Column.FieldName, 'quantity') then
  begin
    I:=Column.AuxValue;
    Result:=Format('Total Units: %d', [I]);
    Attribs.Font.Style:=[fsBold];
    Attribs.Font.Color:=clGreen;
  end
  else if SameText(Column.FieldName, 'unitprice') then
  begin
    F:=Column.AuxValue;
    Result:='Total Cost: '+FmtSettings.CurrencyString + FormatCurr('0,0.00 ', F);
    Attribs.Font.Style:=[fsBold];
    Attribs.Font.Color:=clNavy;
  end;
  Column.AuxValue:=NULL;
end;

procedure TMainForm.UniFormCreate(Sender: TObject);
var
  I : Integer;
begin
  for I := 1 to 15 do
  begin
    with ClientDataSet1 do
    begin
      Append;
      FieldByName('Item').AsString:='AG-'+Format('%0.5d', [I]);
      FieldByName('UnitPrice').AsFloat:=Random(2000000)/100;
      if I=10 then FieldByName('UnitPrice').AsFloat:=0/100;

      FieldByName('Quantity').AsInteger:=Random(500);
    end;
  end;
end;

initialization
  RegisterAppFormClass(TMainForm);

end.

UniGUI自带范例参考：..\Framework\uniGUI\Demos\Desktop\GridSummary