关于TPANEL隐藏TCANVAS属性

Question

一下是TPanel在D6中的申明
  TPanel = class(TCustomPanel)
  public
    property DockManager;
  published
    property Align;
    property Alignment;
    property Anchors;
    property AutoSize;
    property BevelInner;
    property BevelOuter;
    property BevelWidth;
    property BiDiMode;
    property BorderWidth;
    property BorderStyle;
    property Caption;
    property Color;
    property Constraints;
    property Ctl3D;
    property UseDockManager default True;
    property DockSite;
    property DragCursor;
    property DragKind;
    property DragMode;
    property Enabled;
    property FullRepaint;
    property Font;
    property Locked;
    property ParentBiDiMode;
    property ParentColor;
    property ParentCtl3D;
    property ParentFont;
    property ParentShowHint;
    property PopupMenu;
    property ShowHint;
    property TabOrder;
    property TabStop;
    property Visible;
    property OnCanResize;
    property OnClick;
    property OnConstrainedResize;
    property OnContextPopup;
    property OnDockDrop;
    property OnDockOver;
    property OnDblClick;
    property OnDragDrop;
    property OnDragOver;
    property OnEndDock;
    property OnEndDrag;
    property OnEnter;
    property OnExit;
    property OnGetSiteInfo;
    property OnMouseDown;
    property OnMouseMove;
    property OnMouseUp;
    property OnResize;
    property OnStartDock;
    property OnStartDrag;
    property OnUnDock;
  end;
你瞧，Canvas 属性被屏蔽了，而其他的被继承了。这是published干的。

Answer 1

type TMyPanel = class(TCustomPanel)
  published:
  propery Canvas;
  end;((TMyPanel)Panel).Canvas ...

Answer 2

在应用程序里实现被TPANEL隐藏起来的TCANVAS属性。不明白你的意思，

Answer 3

自己声明啊
type
  TMyPanel = class(TPanel)
    property Canvas;
  end;
 
  TForm1 = class...
  ...在程序中自己创建控件var Panel1:TMyPanel;
begin
  Panel1:=TMyPanel.Create(Self);
  Panel1.Parent:=Self;
  Panel1.Left:=10;
  Panel1.Top:=10;
  Panel1.Canvas....//As you like
  ...
end;

Answer 4

type
  THackPanel = class(TCustomPanel);begin
  with THackPanel(Panel1).Canvas do
  begin
    ....
  end;
end;

Answer 5

procedure TForm1.Button2Click(Sender: TObject);var c:TCanvas;begin c:=TControlCanvas.Create; TControlCanvas(c).Control:=Panel1; c.Brush.Style:=bsClear; c.Pen.Color:=clBlue; c.Rectangle(5,5,15,15); c.Free;end;

Answer 6

procedure TForm1.Button1Click(Sender: TObject);
var
  PanelCanvas: TCanvas;
begin
  PanelCanvas := TControlCanvas.Create;
  TControlCanvas(PanelCanvas).Control := Panel1;
  PanelCanvas.Brush.Style := bsClear;
  PanelCanvas.Pen.Color := clBlue;
  PanelCanvas.Rectangle(2, 2, Panel1.Width - 2, Panel1.Height - 2);
  PanelCanvas.Font.Name:='楷体_GB2312';
  PanelCanvas.Font.Size:=24;
  PanelCanvas.TextOut(Panel1.Width div 2,Panel1.Height div 2,'OK');
  PanelCanvas.Free;
end;
拿分过来

Answer 7

这样也可以。
procedure TForm1.Button1Click(Sender: TObject);
var
  PanelCanvas: TCanvas;
begin
  PanelCanvas := TControlCanvas.Create;
  PanelCanvas.Handle := GetDC(Panel1.Handle); //////
  PanelCanvas.Brush.Style := bsClear;
  PanelCanvas.Pen.Color := clBlue;
  PanelCanvas.Rectangle(2, 2, Panel1.Width - 2, Panel1.Height - 2);
  PanelCanvas.Font.Name:='楷体_GB2312';
  PanelCanvas.Font.Size:=24;
  PanelCanvas.TextOut(Panel1.Width div 2,Panel1.Height div 2,'OK');
  PanelCanvas.Free;
end;