delphi – 当我释放画布时,DC会发生什么？

在这段代码中,我希望在MyCanvas.Free中调用ReleaseDC,但是这段代码运行正常,怎么样？
TCanvas自己的DC会发生什么？

var GlobalDC: THandle;

procedure TForm1.FormCreate(Sender: TObject);
begin
   GlobalDC:= GetDC(0);
end;

function LoopMeOften(const X,Y: Integer): TColor;
var
  MyCanvas: TCanvas;
begin
  MyCanvas := TCanvas.Create;
  MyCanvas.Handle := GlobalDC;
  Result := GetPixel(MyCanvas.Handle,X,Y);
  MyCanvas.Free;
end;

解决方法

TCanvas没有自己的DC,它既不获取也不释放DC.它的后代TControlCanvas呢.

从TCanvas.Handle Property起

TCanvas does not own the HDC. Applications must create an HDC and set the Handle property. Applications must release the HDC when the canvas no longer needs it.