那位高手能不能告訴我下面的問題(50分)

unit StringGridEx;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
Grids;
type TBtns = (CheckBoxes,RadioButtons);
type
TStringGridEx = class(TStringGrid)
private
{ Private declarations }
FTickCol:Integer;
FShowTick:Boolean;
FSelArray:Array of Boolean;
FSelRows:Array of TStrings;
FRowHeight:integer;
FDblClick:TNotifyEvent;
FSelectCell:TSelectCellEvent;
FBtns : TBtns;
IsDblClicked:Boolean;
FTitles:TStrings;
procedure SetTickCol(Value : integer);
procedure SetShowTick(Value : Boolean);
procedure SetRowHeight(Value:Integer);
procedure SetBtns(Value : TBtns);
procedure SetRowSelected(RowIndex:integer;Value:Boolean);
procedure DoSelectCell(Sender: TObject; ACol, ARow: Longint;
var CanSelect: Boolean);
procedure DoDblClick(Sender:TObject);
function GetCurrentRow:integer;
function GetRowSelected(RowIndex : Integer):Boolean;
function GetSelCells(ColIndex,RowIndex:integer):String;
function GetSelCnt:Integer;
procedure SetTitles(Value : TStrings);
protected
{ Protected declarations }
procedure SizeChanged(OldColCount, OldRowCount: Longint);override;
procedure DrawCell(ACol, ARow: Longint; ARect: TRect;
AState: TGridDrawState);override;
public
{ Public declarations }
constructor Create(AOwner:Tcomponent);override;
destructor Destroy;override;
property ColWidths;
property RowHeights;
procedure SelectAll;
procedure UnSelectAll;
property CurrentRow :Integer read GetCurrentRow;
property SelectCount:Integer read GetSelCnt;
property RowSelected[RowIndex:Integer]:Boolean read GetRowSelected write SetRowSelected;
property CellsOfSelection[Col,Row:Integer]:String read GetSelCells;
published
{ Published declarations }
property ShowTick:Boolean read FShowTick write SetShowTick default false;
property TickCol:integer read FTickCol write SetTickCol default -1;
property TickButton : TBtns read FBtns write SetBtns default CheckBoxes;
property Titles:TStrings read FTitles write SetTitles;
property RowHeight:Integer read FRowHeight write SetRowHeight default 18;
property OnCellDblClick:TNotifyEvent read FDblClick write FDblClick;
property OnCellSelected:TSelectCellEvent read FSelectCell write FSelectCell;
end;
procedure Register;
implementation
procedure Register;
begin
RegisterComponents('MyControls', [TStringGridEx]);
end;
constructor TStringGridEx.Create(AOwner:Tcomponent);
var i:integer;
begin
inherited;
FTitles := TStringList.Create;
FTitles.Clear;
SetLength(FSelArray,RowCount);
SetLength(FSelRows,RowCount);
for i:=0 to Rowcount-1 do
FSelRows := TStringList.Create;
IsDblClicked := False;
OnDblClick := DoDblClick;
OnSelectCell := DoSelectCell;
for i:=0 to RowCount -1 do
if FRowHeight < RowHeights then FRowHeight := RowHeights;
end;
destructor TStringGridEx.Destroy;
var i:integer;
begin
for i:=0 to RowCount-1 do
FSelRows.Free;
FTitles.Free;
inherited;
end;
procedure TStringGridEx.DrawCell(ACol, ARow: Longint; ARect: TRect;
AState: TGridDrawState);
var Checked:Boolean;
const
CheckBox : array[Boolean] of Integer = (DFCS_BUTTONCHECK,
DFCS_BUTTONCHECK or DFCS_CHECKED);
RadioButton : array[Boolean] of Integer = (DFCS_BUTTONRADIO,
DFCS_BUTTONRADIO or DFCS_CHECKED);
begin
inherited DrawCell(ACol, ARow,ARect,AState);
if FShowTick and (ACol = FTickCol) and (ARow >= FixedRows) then
begin
Checked := FSelArray[ARow];
Canvas.FillRect(ARect);
if FBtns = CheckBoxes then
DrawFrameControl(Canvas.Handle,ARect,DFC_BUTTON,
CheckBox[Checked])
else
DrawFrameControl(Canvas.Handle,ARect,DFC_BUTTON,
RadioButton[Checked]);
end;
end;
procedure TStringGridEx.SetTickCol(Value : Integer);
begin
FTickCol := Value;
end;
procedure TStringGridEx.SetShowTick(Value : Boolean);
begin
FShowTick := Value;
end;
function TStringGridEx.GetRowSelected(RowIndex : Integer):Boolean;
begin
Result := FSelArray[RowIndex];
end;
procedure TStringGridEx.SetRowSelected(RowIndex:integer;Value:Boolean);
var i:integer;
begin
Row := RowIndex;
if Value then begin
FSelRows[RowIndex].Clear;
for i:=0 to ColCount-1 do
FSelRows[RowIndex].Add(Cells[i,RowIndex]);
end;
FSelArray[RowIndex] := Value;
end;
function TStringGridEx.GetCurrentRow : Integer;
begin
Result := Row;
end;
procedure TStringGridEx.DoDblClick(Sender : TObject);
begin
if FShowTick and (Col = FTickCol) then
FSelArray[Row] := not FSelArray[Row];
If FSelArray[Row] then
SetRowSelected(Row,FSelArray[Row]);
if Assigned(FDblClick) then FDblClick(Sender);
IsDblClicked := True;
end;
procedure TStringGridEx.DoSelectCell(Sender: TObject; ACol, ARow: Longint;
var CanSelect: Boolean);
var i:integer;
begin
if IsDblClicked then
begin
if FShowTick and (ACol = FTickCol) then
FSelArray[ARow] := not FSelArray[ARow];
end;
If FSelArray[ARow] then begin
FSelRows[ARow].Clear;
for i:=0 to ColCount-1 do
FSelRows[ARow].Add(Cells[i,ARow]);
end;
if Assigned(FSelectCell) then FSelectCell(Sender,ACol,ARow,CanSelect);
end;
procedure TStringGridEx.SetRowHeight(Value : Integer);
var i:integer;
begin
for i:=0 to RowCount -1 do
RowHeights := Value;
FRowHeight := Value;
Invalidate;
end;
procedure TStringGridEx.SetBtns(Value : TBtns);
begin
FBtns := value;
Invalidate;
end;
procedure TStringGridEx.SizeChanged(OldColCount, OldRowCount: Longint);
var i:integer;
begin
inherited SizeChanged(OldColCount,oldRowCount);
SetLength(FSelArray,RowCount);
if RowCount<>OldrowCount then
for i:=0 to OldRowCount-1 do
FSelRows.Free;
SetLength(FSelRows,RowCount);
for i:=0 to Rowcount-1 do
FSelRows := TStringList.Create;
IsDblClicked := False;
end;
procedure TStringGridEx.SelectAll;
var i:integer;
begin
for i:=1 to RowCount-1 do
begin
SetRowSelected(i,True);
end;
IsDblClicked := False;
Row := 0;
invalidate;
end;
procedure TStringGridEx.UnSelectAll;
var i:integer;
begin
for i:=1 to RowCount-1 do
begin
SetRowSelected(i,False);
FSelRows.Clear;
end;
Row :=0;
IsDblClicked := False;
invalidate;
end;
procedure TStringGridEx.SetTitles(Value : TStrings);
begin
if FTitles<>Value then FTitles.Assign(Value);
Rows[0].Assign(Ftitles);
Invalidate;
end;
function TStringGridEx.GetSelCells(ColIndex,RowIndex:integer):String;
var i,SelRow:integer;
begin
SelRow := 0;
for i:=1 to RowCount-1 do
begin
if RowSelected then inc(SelRow);
if SelRow = RowIndex then Break;
end;
Result := FSelRows.Strings[ColIndex];
end;
function TStringGridEx.GetSelCnt:Integer;
var i,R:integer;
begin
R:=0;
for i:=0 to Rowcount-1 do
if RowSelected then Inc(R);
Result := R;
end;
end.
*******************
CheckBox : array[Boolean] of Integer = (DFCS_BUTTONCHECK,
DFCS_BUTTONCHECK or DFCS_CHECKED);
RadioButton : array[Boolean] of Integer = (DFCS_BUTTONRADIO,
DFCS_BUTTONRADIO or DFCS_CHECKED);
上面几條代碼怎麼理解的

RadioButton 是一个有2个元素的数组 因为Boolean只有0 和 1 并对其值进行了初始化
那么RadioButton[0] 就是 DFCS_BUTTONRADIO,
RadioButton[1] 就是 DFCS_BUTTONRADIO or DFCS_CHECKED

CheckBox同理

只是delphi耍的小把戏，开始还觉得好玩，后来觉得只是一个语言成分而已。
也可以参照delphi对TMessage的定义，也同样用了这个手法。

多人接受答案了。