关于 panel继承 Canvas 后重绘闪烁问题

Question

我在 Panel 继承了 Canvas ，用一个线程不停地绘图，当鼠标在窗口或其它控件上面随便移动一下 这个 panel 就会闪烁，鼠标在窗口外就没问题，请问为什么？谢谢。主窗口 与 panel
DoubleBuffered:=True;也没效果

Answer 1

什么叫继承了canvas?是某控件继承自panel然后重写canvas属性，还是你的panel继承自canvaa?你这样说让人迷惑。。

Answer 2

  TWealshPnl = class(TPanel)
  private
    FOnMouseEnter: TNotifyEvent;
    FOnMouseLeave: TNotifyEvent;
    FPaint:TNotifyEvent;
    procedure CMMouseEnter(var Message: TMessage); message CM_MOUSEENTER;
    procedure CMMouseLeave(var Message: TMessage); message CM_MOUSELEAVE;
  protected
    procedure Paint;override;
  public
    TmpSpBmp:TBitmap;
    procedure CBShowSp(pData:Pointer;pSize:Integer);
    property Canvas;
    procedure ResizeBmp1(SrcBM, DstBM: TBitmap; Nwide, Nheight: integer);
  published
    property OnMouseEnter:TNotifyEvent  read FOnMouseEnter write FOnMouseEnter;
    property OnMouseLeave:TNotifyEvent  read FOnMouseLeave write FOnMouseLeave;
    property OnPaint:TNotifyEvent read FPaint write FPaint;
  end;
procedure TWealshPnl.CBShowSp(pData:Pointer;pSize:Integer);
var
  B:TBitmap;
begin
  if not Assigned(TmpSpBmp) then
    begin
      TmpSpBmp:=TBitmap.Create;
      DoubleBuffered:=True;
    end;
  TmpSpBmp.Canvas.Lock;
  Canvas.Lock;
  TmpSpBmp.Handle := HBitmap(pData^);
  B:=TBitmap.Create;
  ResizeBmp1(TmpSpBmp,B,Width-6,Height-6);
  Canvas.Draw(3,3,B);
  B.Free;
end;

Answer 3

  TWealshPnl = class(TPanel)
  private
    FOnMouseEnter: TNotifyEvent;
    FOnMouseLeave: TNotifyEvent;
    FPaint:TNotifyEvent;
    procedure CMMouseEnter(var Message: TMessage); message CM_MOUSEENTER;
    procedure CMMouseLeave(var Message: TMessage); message CM_MOUSELEAVE;
  protected
    procedure Paint;override;
  public
    TmpSpBmp:TBitmap;
    procedure CBShowSp(pData:Pointer;pSize:Integer);
    property Canvas;
    procedure ResizeBmp1(SrcBM, DstBM: TBitmap; Nwide, Nheight: integer);
  published
    property OnMouseEnter:TNotifyEvent  read FOnMouseEnter write FOnMouseEnter;
    property OnMouseLeave:TNotifyEvent  read FOnMouseLeave write FOnMouseLeave;
    property OnPaint:TNotifyEvent read FPaint write FPaint;
  end;
procedure TWealshPnl.CBShowSp(pData:Pointer;pSize:Integer);
var
  B:TBitmap;
begin
  if not Assigned(TmpSpBmp) then
    begin
      TmpSpBmp:=TBitmap.Create;
      DoubleBuffered:=True;
    end;
  TmpSpBmp.Canvas.Lock;
  Canvas.Lock;
  TmpSpBmp.Handle := HBitmap(pData^);
  B:=TBitmap.Create;
  ResizeBmp1(TmpSpBmp,B,Width-6,Height-6);
  Canvas.Draw(3,3,B);
  B.Free;
end;

Answer 4

使用双缓存，每次重绘时用缓存里的图形，而不是直接在Draw里绘制