delphi – 为什么我的自定义组件在更改属性时更新？

在对象资源管理器中,我可以设置某些属性.最重要的是我可以设置网格尺寸(跨/下两个单元格),还可以设置与图形有关的选项.细胞是否应该是正方形,奇/偶细胞的颜色等

我的这个组件的第一个版本的属性直接在类上,当我更改了一个属性时,设计时间图被立即更新.随着组件的增长,我想组织我的属性一点更好,并介绍了一些“选项属性”,如绘图选项,行为选项等.介绍后,设计时间图不再像以前一样更新.更改属性后,我必须单击要更新的组件.谁能告诉我为什么会发生这种情况？

这是一个被删除的代码版本.我希望能解释这个行为：

(PS：这是我的第一个组件,即使我自1997年以来一直在使用Delphi,所以如果任何人可以按照我的方式发现任何愚蠢的事情,请随时告诉我)

unit GridPaintBox;

interface

type
  TGridDrawOption = (gdoSquareCells,gdoCenterCells,gdoDrawCellEdges,gdoDrawFocus);
  TGridDrawOptions = set of TGridDrawOption;

  TGridOptions = class(TPersistent)
  private
    FCellsX : integer;
    FCellsY : integer;
    FDrawOptions : TGridDrawOptions;
  public
    constructor Create(aGridPaintBox : TGridPaintBox);
    procedure Assign(Source : TPersistent); override;
  published
    property CellsX : integer read FCellsX write FCellsX;
    property CellsY : integer read FCellsY write FCellsY;
    property DrawOptions : TGridDrawOptions read FDrawOptions write FDrawOptions;
  end;

  TGridPaintBox = class(TPaintBox)
  private
    FGridOptions : TGridOptions;
    FFocusedX,FFocusedY : integer;
    FOnFocusChanged: TNotifyEvent; 
    procedure CalculateSizeAndPosition; 
    procedure DrawCell(X,Y : integer);
    procedure DrawCells;
    procedure SetGridOptions(const Value: TGridOptions);
  protected
    procedure MouseDown(Button: TMouseButton; Shift: TShiftState; X,Y: Integer); override;
  public
    constructor Create(aOwner : TComponent); override;
    destructor Destroy; override;
    procedure Paint; override;
    procedure SetFocus(X,Y : integer);
  published
    property OnFocusChanged : TNotifyEvent read FOnFocusChanged write FOnFocusChanged;
    property Options : TGridOptions read FGridOptions write SetGridOptions;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('Samples',[TGridPaintBox]);
end;

procedure TGridPaintBox.CalculateSizeAndPosition;
begin
  <...>
end;

constructor TGridPaintBox.Create(aOwner: TComponent);
begin
  inherited;
  FGridOptions := TGridOptions.Create(self);
end;

procedure TGridPaintBox.DrawCell(X,Y: integer);
begin
  <...>
end;

procedure TGridPaintBox.DrawCells;
var
  X,Y : integer;
begin
  CalculateSizeAndPosition;

  for Y := 0 to FGridOptions.CellsY-1 do
    for X := 0 to FGridOptions.CellsX-1 do
      DrawCell(X,Y);
end;

procedure TGridPaintBox.Paint;
begin
  Canvas.Font := Font;
  Canvas.Brush.Color := Color;
  Canvas.Brush.Style := bsSolid;
  Canvas.FillRect(Rect(0,Width,Height));
  DrawCells;
  if Assigned(OnPaint) then
    OnPaint(Self); 
end;

procedure TGridPaintBox.SetGridOptions(const Value: TGridOptions);
begin
  FGridOptions.Assign(Value);
  invalidate;
end;

procedure TGridPaintBox.MouseDown(Button: TMouseButton; Shift: TShiftState; X,Y: Integer);
begin
  SetFocus(PixelToCellX(X),PixelToCellY(Y));
  inherited;
end;

procedure TGridPaintBox.SetFocus(X,Y: integer);
begin
  if (FocusedX=X) and (FocusedY=Y) then 
    exit;

  FFocusedX := X;
  FFocusedY := Y;

  if assigned(OnFocusChanged) then
    OnFocusChanged(self);

  invalidate;
end;

constructor TGridOptions.Create(aGridPaintBox : TGridPaintBox);
begin
  FCellsX := 20;
  FCellsY := 8;
  FDrawOptions := [gdoSquareCells,gdoDrawCellEdges];
end;

procedure TGridOptions.Assign(Source : TPersistent);
begin
  if Source is TGridOptions then
  begin
    FCellsX := TGridOptions(Source).CellsX;
    FCellsY := TGridOptions(Source).CellsY;
    FDrawOptions := TGridOptions(Source).DrawOptions;
  end
  else
    inherited;
end;

end.